/* Optimize jump instructions, for GNU compiler. Copyright (C) 1987, 88, 89, 91-97, 1998 Free Software Foundation, Inc. This file is part of GNU CC. GNU CC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU CC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU CC; see the file COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /* This is the jump-optimization pass of the compiler. It is run two or three times: once before cse, sometimes once after cse, and once after reload (before final). jump_optimize deletes unreachable code and labels that are not used. It also deletes jumps that jump to the following insn, and simplifies jumps around unconditional jumps and jumps to unconditional jumps. Each CODE_LABEL has a count of the times it is used stored in the LABEL_NUSES internal field, and each JUMP_INSN has one label that it refers to stored in the JUMP_LABEL internal field. With this we can detect labels that become unused because of the deletion of all the jumps that formerly used them. The JUMP_LABEL info is sometimes looked at by later passes. Optionally, cross-jumping can be done. Currently it is done only the last time (when after reload and before final). In fact, the code for cross-jumping now assumes that register allocation has been done, since it uses `rtx_renumbered_equal_p'. Jump optimization is done after cse when cse's constant-propagation causes jumps to become unconditional or to be deleted. Unreachable loops are not detected here, because the labels have references and the insns appear reachable from the labels. find_basic_blocks in flow.c finds and deletes such loops. The subroutines delete_insn, redirect_jump, and invert_jump are used from other passes as well. */ #include "config.h" #include "system.h" #include "rtl.h" #include "flags.h" #include "hard-reg-set.h" #include "regs.h" #include "insn-config.h" #include "insn-flags.h" #include "insn-attr.h" #include "recog.h" #include "expr.h" #include "real.h" #include "except.h" #include "toplev.h" /* ??? Eventually must record somehow the labels used by jumps from nested functions. */ /* Pre-record the next or previous real insn for each label? No, this pass is very fast anyway. */ /* Condense consecutive labels? This would make life analysis faster, maybe. */ /* Optimize jump y; x: ... y: jumpif... x? Don't know if it is worth bothering with. */ /* Optimize two cases of conditional jump to conditional jump? This can never delete any instruction or make anything dead, or even change what is live at any point. So perhaps let combiner do it. */ /* Vector indexed by uid. For each CODE_LABEL, index by its uid to get first unconditional jump that jumps to the label. For each JUMP_INSN, index by its uid to get the next unconditional jump that jumps to the same label. Element 0 is the start of a chain of all return insns. (It is safe to use element 0 because insn uid 0 is not used. */ static rtx *jump_chain; /* List of labels referred to from initializers. These can never be deleted. */ rtx forced_labels; /* Maximum index in jump_chain. */ static int max_jump_chain; /* Set nonzero by jump_optimize if control can fall through to the end of the function. */ int can_reach_end; /* Indicates whether death notes are significant in cross jump analysis. Normally they are not significant, because of A and B jump to C, and R dies in A, it must die in B. But this might not be true after stack register conversion, and we must compare death notes in that case. */ static int cross_jump_death_matters = 0; static int duplicate_loop_exit_test PROTO((rtx)); static void find_cross_jump PROTO((rtx, rtx, int, rtx *, rtx *)); static void do_cross_jump PROTO((rtx, rtx, rtx)); static int jump_back_p PROTO((rtx, rtx)); static int tension_vector_labels PROTO((rtx, int)); static void mark_jump_label PROTO((rtx, rtx, int)); static void delete_computation PROTO((rtx)); static void delete_from_jump_chain PROTO((rtx)); static int delete_labelref_insn PROTO((rtx, rtx, int)); static void mark_modified_reg PROTO((rtx, rtx)); static void redirect_tablejump PROTO((rtx, rtx)); #ifndef HAVE_cc0 static rtx find_insert_position PROTO((rtx, rtx)); #endif /* Delete no-op jumps and optimize jumps to jumps and jumps around jumps. Delete unused labels and unreachable code. If CROSS_JUMP is 1, detect matching code before a jump and its destination and unify them. If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes. If NOOP_MOVES is nonzero, delete no-op move insns. If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately after regscan, and it is safe to use regno_first_uid and regno_last_uid. If `optimize' is zero, don't change any code, just determine whether control drops off the end of the function. This case occurs when we have -W and not -O. It works because `delete_insn' checks the value of `optimize' and refrains from actually deleting when that is 0. */ void jump_optimize (f, cross_jump, noop_moves, after_regscan) rtx f; int cross_jump; int noop_moves; int after_regscan; { register rtx insn, next, note; int changed; int old_max_reg; int first = 1; int max_uid = 0; rtx last_insn; cross_jump_death_matters = (cross_jump == 2); /* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL notes whose labels don't occur in the insn any more. */ for (insn = f; insn; insn = NEXT_INSN (insn)) { if (GET_CODE (insn) == CODE_LABEL) LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0); else if (GET_CODE (insn) == JUMP_INSN) JUMP_LABEL (insn) = 0; else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN) for (note = REG_NOTES (insn); note; note = next) { next = XEXP (note, 1); if (REG_NOTE_KIND (note) == REG_LABEL && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn))) remove_note (insn, note); } if (INSN_UID (insn) > max_uid) max_uid = INSN_UID (insn); } max_uid++; /* If we are performing cross jump optimizations, then initialize tables mapping UIDs to EH regions to avoid incorrect movement of insns from one EH region to another. */ if (flag_exceptions && cross_jump) init_insn_eh_region (f, max_uid); /* Delete insns following barriers, up to next label. */ for (insn = f; insn;) { if (GET_CODE (insn) == BARRIER) { insn = NEXT_INSN (insn); while (insn != 0 && GET_CODE (insn) != CODE_LABEL) { if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END) insn = NEXT_INSN (insn); else insn = delete_insn (insn); } /* INSN is now the code_label. */ } else insn = NEXT_INSN (insn); } /* Leave some extra room for labels and duplicate exit test insns we make. */ max_jump_chain = max_uid * 14 / 10; jump_chain = (rtx *) alloca (max_jump_chain * sizeof (rtx)); bzero ((char *) jump_chain, max_jump_chain * sizeof (rtx)); /* Mark the label each jump jumps to. Combine consecutive labels, and count uses of labels. For each label, make a chain (using `jump_chain') of all the *unconditional* jumps that jump to it; also make a chain of all returns. */ for (insn = f; insn; insn = NEXT_INSN (insn)) if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') { mark_jump_label (PATTERN (insn), insn, cross_jump); if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN) { if (JUMP_LABEL (insn) != 0 && simplejump_p (insn)) { jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (JUMP_LABEL (insn))]; jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn; } if (GET_CODE (PATTERN (insn)) == RETURN) { jump_chain[INSN_UID (insn)] = jump_chain[0]; jump_chain[0] = insn; } } } /* Keep track of labels used from static data; they cannot ever be deleted. */ for (insn = forced_labels; insn; insn = XEXP (insn, 1)) LABEL_NUSES (XEXP (insn, 0))++; check_exception_handler_labels (); /* Keep track of labels used for marking handlers for exception regions; they cannot usually be deleted. */ for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1)) LABEL_NUSES (XEXP (insn, 0))++; exception_optimize (); /* Delete all labels already not referenced. Also find the last insn. */ last_insn = 0; for (insn = f; insn; ) { if (GET_CODE (insn) == CODE_LABEL && LABEL_NUSES (insn) == 0) insn = delete_insn (insn); else { last_insn = insn; insn = NEXT_INSN (insn); } } if (!optimize) { /* See if there is still a NOTE_INSN_FUNCTION_END in this function. If so record that this function can drop off the end. */ insn = last_insn; { int n_labels = 1; while (insn /* One label can follow the end-note: the return label. */ && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0) /* Ordinary insns can follow it if returning a structure. */ || GET_CODE (insn) == INSN /* If machine uses explicit RETURN insns, no epilogue, then one of them follows the note. */ || (GET_CODE (insn) == JUMP_INSN && GET_CODE (PATTERN (insn)) == RETURN) /* A barrier can follow the return insn. */ || GET_CODE (insn) == BARRIER /* Other kinds of notes can follow also. */ || (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END))) insn = PREV_INSN (insn); } /* Report if control can fall through at the end of the function. */ if (insn && GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END && ! INSN_DELETED_P (insn)) can_reach_end = 1; /* Zero the "deleted" flag of all the "deleted" insns. */ for (insn = f; insn; insn = NEXT_INSN (insn)) INSN_DELETED_P (insn) = 0; /* Show that the jump chain is not valid. */ jump_chain = 0; return; } #ifdef HAVE_return if (HAVE_return) { /* If we fall through to the epilogue, see if we can insert a RETURN insn in front of it. If the machine allows it at this point (we might be after reload for a leaf routine), it will improve optimization for it to be there. */ insn = get_last_insn (); while (insn && GET_CODE (insn) == NOTE) insn = PREV_INSN (insn); if (insn && GET_CODE (insn) != BARRIER) { emit_jump_insn (gen_return ()); emit_barrier (); } } #endif if (noop_moves) for (insn = f; insn; ) { next = NEXT_INSN (insn); if (GET_CODE (insn) == INSN) { register rtx body = PATTERN (insn); /* Combine stack_adjusts with following push_insns. */ #ifdef PUSH_ROUNDING if (GET_CODE (body) == SET && SET_DEST (body) == stack_pointer_rtx && GET_CODE (SET_SRC (body)) == PLUS && XEXP (SET_SRC (body), 0) == stack_pointer_rtx && GET_CODE (XEXP (SET_SRC (body), 1)) == CONST_INT && INTVAL (XEXP (SET_SRC (body), 1)) > 0) { rtx p; rtx stack_adjust_insn = insn; int stack_adjust_amount = INTVAL (XEXP (SET_SRC (body), 1)); int total_pushed = 0; int pushes = 0; /* Find all successive push insns. */ p = insn; /* Don't convert more than three pushes; that starts adding too many displaced addresses and the whole thing starts becoming a losing proposition. */ while (pushes < 3) { rtx pbody, dest; p = next_nonnote_insn (p); if (p == 0 || GET_CODE (p) != INSN) break; pbody = PATTERN (p); if (GET_CODE (pbody) != SET) break; dest = SET_DEST (pbody); /* Allow a no-op move between the adjust and the push. */ if (GET_CODE (dest) == REG && GET_CODE (SET_SRC (pbody)) == REG && REGNO (dest) == REGNO (SET_SRC (pbody))) continue; if (! (GET_CODE (dest) == MEM && GET_CODE (XEXP (dest, 0)) == POST_INC && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx)) break; pushes++; if (total_pushed + GET_MODE_SIZE (GET_MODE (SET_DEST (pbody))) > stack_adjust_amount) break; total_pushed += GET_MODE_SIZE (GET_MODE (SET_DEST (pbody))); } /* Discard the amount pushed from the stack adjust; maybe eliminate it entirely. */ if (total_pushed >= stack_adjust_amount) { delete_computation (stack_adjust_insn); total_pushed = stack_adjust_amount; } else XEXP (SET_SRC (PATTERN (stack_adjust_insn)), 1) = GEN_INT (stack_adjust_amount - total_pushed); /* Change the appropriate push insns to ordinary stores. */ p = insn; while (total_pushed > 0) { rtx pbody, dest; p = next_nonnote_insn (p); if (GET_CODE (p) != INSN) break; pbody = PATTERN (p); if (GET_CODE (pbody) != SET) break; dest = SET_DEST (pbody); /* Allow a no-op move between the adjust and the push. */ if (GET_CODE (dest) == REG && GET_CODE (SET_SRC (pbody)) == REG && REGNO (dest) == REGNO (SET_SRC (pbody))) continue; if (! (GET_CODE (dest) == MEM && GET_CODE (XEXP (dest, 0)) == POST_INC && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx)) break; total_pushed -= GET_MODE_SIZE (GET_MODE (SET_DEST (pbody))); /* If this push doesn't fully fit in the space of the stack adjust that we deleted, make another stack adjust here for what we didn't use up. There should be peepholes to recognize the resulting sequence of insns. */ if (total_pushed < 0) { emit_insn_before (gen_add2_insn (stack_pointer_rtx, GEN_INT (- total_pushed)), p); break; } XEXP (dest, 0) = plus_constant (stack_pointer_rtx, total_pushed); } } #endif /* Detect and delete no-op move instructions resulting from not allocating a parameter in a register. */ if (GET_CODE (body) == SET && (SET_DEST (body) == SET_SRC (body) || (GET_CODE (SET_DEST (body)) == MEM && GET_CODE (SET_SRC (body)) == MEM && rtx_equal_p (SET_SRC (body), SET_DEST (body)))) && ! (GET_CODE (SET_DEST (body)) == MEM && MEM_VOLATILE_P (SET_DEST (body))) && ! (GET_CODE (SET_SRC (body)) == MEM && MEM_VOLATILE_P (SET_SRC (body)))) delete_computation (insn); /* Detect and ignore no-op move instructions resulting from smart or fortuitous register allocation. */ else if (GET_CODE (body) == SET) { int sreg = true_regnum (SET_SRC (body)); int dreg = true_regnum (SET_DEST (body)); if (sreg == dreg && sreg >= 0) delete_insn (insn); else if (sreg >= 0 && dreg >= 0) { rtx trial; rtx tem = find_equiv_reg (NULL_RTX, insn, 0, sreg, NULL_PTR, dreg, GET_MODE (SET_SRC (body))); if (tem != 0 && GET_MODE (tem) == GET_MODE (SET_DEST (body))) { /* DREG may have been the target of a REG_DEAD note in the insn which makes INSN redundant. If so, reorg would still think it is dead. So search for such a note and delete it if we find it. */ if (! find_regno_note (insn, REG_UNUSED, dreg)) for (trial = prev_nonnote_insn (insn); trial && GET_CODE (trial) != CODE_LABEL; trial = prev_nonnote_insn (trial)) if (find_regno_note (trial, REG_DEAD, dreg)) { remove_death (dreg, trial); break; } #ifdef PRESERVE_DEATH_INFO_REGNO_P /* Deleting insn could lose a death-note for SREG so don't do it if final needs accurate death-notes. */ if (PRESERVE_DEATH_INFO_REGNO_P (sreg) && (trial = find_regno_note (insn, REG_DEAD, sreg))) { /* Change this into a USE so that we won't emit code for it, but still can keep the note. */ PATTERN (insn) = gen_rtx_USE (VOIDmode, XEXP (trial, 0)); INSN_CODE (insn) = -1; /* Remove all reg notes but the REG_DEAD one. */ REG_NOTES (insn) = trial; XEXP (trial, 1) = NULL_RTX; } else #endif delete_insn (insn); } } else if (dreg >= 0 && CONSTANT_P (SET_SRC (body)) && find_equiv_reg (SET_SRC (body), insn, 0, dreg, NULL_PTR, 0, GET_MODE (SET_DEST (body)))) { /* This handles the case where we have two consecutive assignments of the same constant to pseudos that didn't get a hard reg. Each SET from the constant will be converted into a SET of the spill register and an output reload will be made following it. This produces two loads of the same constant into the same spill register. */ rtx in_insn = insn; /* Look back for a death note for the first reg. If there is one, it is no longer accurate. */ while (in_insn && GET_CODE (in_insn) != CODE_LABEL) { if ((GET_CODE (in_insn) == INSN || GET_CODE (in_insn) == JUMP_INSN) && find_regno_note (in_insn, REG_DEAD, dreg)) { remove_death (dreg, in_insn); break; } in_insn = PREV_INSN (in_insn); } /* Delete the second load of the value. */ delete_insn (insn); } } else if (GET_CODE (body) == PARALLEL) { /* If each part is a set between two identical registers or a USE or CLOBBER, delete the insn. */ int i, sreg, dreg; rtx tem; for (i = XVECLEN (body, 0) - 1; i >= 0; i--) { tem = XVECEXP (body, 0, i); if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER) continue; if (GET_CODE (tem) != SET || (sreg = true_regnum (SET_SRC (tem))) < 0 || (dreg = true_regnum (SET_DEST (tem))) < 0 || dreg != sreg) break; } if (i < 0) delete_insn (insn); } /* Also delete insns to store bit fields if they are no-ops. */ /* Not worth the hair to detect this in the big-endian case. */ else if (! BYTES_BIG_ENDIAN && GET_CODE (body) == SET && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT && XEXP (SET_DEST (body), 2) == const0_rtx && XEXP (SET_DEST (body), 0) == SET_SRC (body) && ! (GET_CODE (SET_SRC (body)) == MEM && MEM_VOLATILE_P (SET_SRC (body)))) delete_insn (insn); } insn = next; } /* If we haven't yet gotten to reload and we have just run regscan, delete any insn that sets a register that isn't used elsewhere. This helps some of the optimizations below by having less insns being jumped around. */ if (! reload_completed && after_regscan) for (insn = f; insn; insn = next) { rtx set = single_set (insn); next = NEXT_INSN (insn); if (set && GET_CODE (SET_DEST (set)) == REG && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn) /* We use regno_last_note_uid so as not to delete the setting of a reg that's used in notes. A subsequent optimization might arrange to use that reg for real. */ && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn) && ! side_effects_p (SET_SRC (set)) && ! find_reg_note (insn, REG_RETVAL, 0)) delete_insn (insn); } /* Now iterate optimizing jumps until nothing changes over one pass. */ changed = 1; old_max_reg = max_reg_num (); while (changed) { changed = 0; for (insn = f; insn; insn = next) { rtx reallabelprev; rtx temp, temp1, temp2, temp3, temp4, temp5, temp6; rtx nlabel; int this_is_simplejump, this_is_condjump, reversep = 0; int this_is_condjump_in_parallel; #if 0 /* If NOT the first iteration, if this is the last jump pass (just before final), do the special peephole optimizations. Avoiding the first iteration gives ordinary jump opts a chance to work before peephole opts. */ if (reload_completed && !first && !flag_no_peephole) if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN) peephole (insn); #endif /* That could have deleted some insns after INSN, so check now what the following insn is. */ next = NEXT_INSN (insn); /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional jump. Try to optimize by duplicating the loop exit test if so. This is only safe immediately after regscan, because it uses the values of regno_first_uid and regno_last_uid. */ if (after_regscan && GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG && (temp1 = next_nonnote_insn (insn)) != 0 && simplejump_p (temp1)) { temp = PREV_INSN (insn); if (duplicate_loop_exit_test (insn)) { changed = 1; next = NEXT_INSN (temp); continue; } } if (GET_CODE (insn) != JUMP_INSN) continue; this_is_simplejump = simplejump_p (insn); this_is_condjump = condjump_p (insn); this_is_condjump_in_parallel = condjump_in_parallel_p (insn); /* Tension the labels in dispatch tables. */ if (GET_CODE (PATTERN (insn)) == ADDR_VEC) changed |= tension_vector_labels (PATTERN (insn), 0); if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC) changed |= tension_vector_labels (PATTERN (insn), 1); /* If a dispatch table always goes to the same place, get rid of it and replace the insn that uses it. */ if (GET_CODE (PATTERN (insn)) == ADDR_VEC || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC) { int i; rtx pat = PATTERN (insn); int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC; int len = XVECLEN (pat, diff_vec_p); rtx dispatch = prev_real_insn (insn); rtx set; for (i = 0; i < len; i++) if (XEXP (XVECEXP (pat, diff_vec_p, i), 0) != XEXP (XVECEXP (pat, diff_vec_p, 0), 0)) break; if (i == len && dispatch != 0 && GET_CODE (dispatch) == JUMP_INSN && JUMP_LABEL (dispatch) != 0 /* Don't mess with a casesi insn. XXX according to the comment before computed_jump_p(), all casesi insns should be a parallel of the jump and a USE of a LABEL_REF. */ && ! ((set = single_set (dispatch)) != NULL && (GET_CODE (SET_SRC (set)) == IF_THEN_ELSE)) && next_real_insn (JUMP_LABEL (dispatch)) == insn) { redirect_tablejump (dispatch, XEXP (XVECEXP (pat, diff_vec_p, 0), 0)); changed = 1; } } reallabelprev = prev_active_insn (JUMP_LABEL (insn)); /* If a jump references the end of the function, try to turn it into a RETURN insn, possibly a conditional one. */ if (JUMP_LABEL (insn) && (next_active_insn (JUMP_LABEL (insn)) == 0 || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn)))) == RETURN)) changed |= redirect_jump (insn, NULL_RTX); /* Detect jump to following insn. */ if (reallabelprev == insn && condjump_p (insn)) { next = next_real_insn (JUMP_LABEL (insn)); delete_jump (insn); changed = 1; continue; } /* If we have an unconditional jump preceded by a USE, try to put the USE before the target and jump there. This simplifies many of the optimizations below since we don't have to worry about dealing with these USE insns. We only do this if the label being branch to already has the identical USE or if code never falls through to that label. */ if (this_is_simplejump && (temp = prev_nonnote_insn (insn)) != 0 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == USE && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0 && (GET_CODE (temp1) == BARRIER || (GET_CODE (temp1) == INSN && rtx_equal_p (PATTERN (temp), PATTERN (temp1)))) /* Don't do this optimization if we have a loop containing only the USE instruction, and the loop start label has a usage count of 1. This is because we will redo this optimization everytime through the outer loop, and jump opt will never exit. */ && ! ((temp2 = prev_nonnote_insn (temp)) != 0 && temp2 == JUMP_LABEL (insn) && LABEL_NUSES (temp2) == 1)) { if (GET_CODE (temp1) == BARRIER) { emit_insn_after (PATTERN (temp), temp1); temp1 = NEXT_INSN (temp1); } delete_insn (temp); redirect_jump (insn, get_label_before (temp1)); reallabelprev = prev_real_insn (temp1); changed = 1; } /* Simplify if (...) x = a; else x = b; by converting it to x = b; if (...) x = a; if B is sufficiently simple, the test doesn't involve X, and nothing in the test modifies B or X. If we have small register classes, we also can't do this if X is a hard register. If the "x = b;" insn has any REG_NOTES, we don't do this because of the possibility that we are running after CSE and there is a REG_EQUAL note that is only valid if the branch has already been taken. If we move the insn with the REG_EQUAL note, we may fold the comparison to always be false in a later CSE pass. (We could also delete the REG_NOTES when moving the insn, but it seems simpler to not move it.) An exception is that we can move the insn if the only note is a REG_EQUAL or REG_EQUIV whose value is the same as "b". INSN is the branch over the `else' part. We set: TEMP to the jump insn preceding "x = a;" TEMP1 to X TEMP2 to the insn that sets "x = b;" TEMP3 to the insn that sets "x = a;" TEMP4 to the set of "x = b"; */ if (this_is_simplejump && (temp3 = prev_active_insn (insn)) != 0 && GET_CODE (temp3) == INSN && (temp4 = single_set (temp3)) != 0 && GET_CODE (temp1 = SET_DEST (temp4)) == REG && (! SMALL_REGISTER_CLASSES || REGNO (temp1) >= FIRST_PSEUDO_REGISTER) && (temp2 = next_active_insn (insn)) != 0 && GET_CODE (temp2) == INSN && (temp4 = single_set (temp2)) != 0 && rtx_equal_p (SET_DEST (temp4), temp1) && ! side_effects_p (SET_SRC (temp4)) && ! may_trap_p (SET_SRC (temp4)) && (REG_NOTES (temp2) == 0 || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV) && XEXP (REG_NOTES (temp2), 1) == 0 && rtx_equal_p (XEXP (REG_NOTES (temp2), 0), SET_SRC (temp4)))) && (temp = prev_active_insn (temp3)) != 0 && condjump_p (temp) && ! simplejump_p (temp) /* TEMP must skip over the "x = a;" insn */ && prev_real_insn (JUMP_LABEL (temp)) == insn && no_labels_between_p (insn, JUMP_LABEL (temp)) /* There must be no other entries to the "x = b;" insn. */ && no_labels_between_p (JUMP_LABEL (temp), temp2) /* INSN must either branch to the insn after TEMP2 or the insn after TEMP2 must branch to the same place as INSN. */ && (reallabelprev == temp2 || ((temp5 = next_active_insn (temp2)) != 0 && simplejump_p (temp5) && JUMP_LABEL (temp5) == JUMP_LABEL (insn)))) { /* The test expression, X, may be a complicated test with multiple branches. See if we can find all the uses of the label that TEMP branches to without hitting a CALL_INSN or a jump to somewhere else. */ rtx target = JUMP_LABEL (temp); int nuses = LABEL_NUSES (target); rtx p; #ifdef HAVE_cc0 rtx q; #endif /* Set P to the first jump insn that goes around "x = a;". */ for (p = temp; nuses && p; p = prev_nonnote_insn (p)) { if (GET_CODE (p) == JUMP_INSN) { if (condjump_p (p) && ! simplejump_p (p) && JUMP_LABEL (p) == target) { nuses--; if (nuses == 0) break; } else break; } else if (GET_CODE (p) == CALL_INSN) break; } #ifdef HAVE_cc0 /* We cannot insert anything between a set of cc and its use so if P uses cc0, we must back up to the previous insn. */ q = prev_nonnote_insn (p); if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i' && sets_cc0_p (PATTERN (q))) p = q; #endif if (p) p = PREV_INSN (p); /* If we found all the uses and there was no data conflict, we can move the assignment unless we can branch into the middle from somewhere. */ if (nuses == 0 && p && no_labels_between_p (p, insn) && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3)) && ! reg_set_between_p (temp1, p, temp3) && (GET_CODE (SET_SRC (temp4)) == CONST_INT || ! modified_between_p (SET_SRC (temp4), p, temp2)) /* Verify that registers used by the jump are not clobbered by the instruction being moved. */ && ! regs_set_between_p (PATTERN (temp), PREV_INSN (temp2), NEXT_INSN (temp2))) { emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2); delete_insn (temp2); /* Set NEXT to an insn that we know won't go away. */ next = next_active_insn (insn); /* Delete the jump around the set. Note that we must do this before we redirect the test jumps so that it won't delete the code immediately following the assignment we moved (which might be a jump). */ delete_insn (insn); /* We either have two consecutive labels or a jump to a jump, so adjust all the JUMP_INSNs to branch to where INSN branches to. */ for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p)) if (GET_CODE (p) == JUMP_INSN) redirect_jump (p, target); changed = 1; continue; } } /* Simplify if (...) { x = a; goto l; } x = b; by converting it to x = a; if (...) goto l; x = b; if A is sufficiently simple, the test doesn't involve X, and nothing in the test modifies A or X. If we have small register classes, we also can't do this if X is a hard register. If the "x = a;" insn has any REG_NOTES, we don't do this because of the possibility that we are running after CSE and there is a REG_EQUAL note that is only valid if the branch has already been taken. If we move the insn with the REG_EQUAL note, we may fold the comparison to always be false in a later CSE pass. (We could also delete the REG_NOTES when moving the insn, but it seems simpler to not move it.) An exception is that we can move the insn if the only note is a REG_EQUAL or REG_EQUIV whose value is the same as "a". INSN is the goto. We set: TEMP to the jump insn preceding "x = a;" TEMP1 to X TEMP2 to the insn that sets "x = b;" TEMP3 to the insn that sets "x = a;" TEMP4 to the set of "x = a"; */ if (this_is_simplejump && (temp2 = next_active_insn (insn)) != 0 && GET_CODE (temp2) == INSN && (temp4 = single_set (temp2)) != 0 && GET_CODE (temp1 = SET_DEST (temp4)) == REG && (! SMALL_REGISTER_CLASSES || REGNO (temp1) >= FIRST_PSEUDO_REGISTER) && (temp3 = prev_active_insn (insn)) != 0 && GET_CODE (temp3) == INSN && (temp4 = single_set (temp3)) != 0 && rtx_equal_p (SET_DEST (temp4), temp1) && ! side_effects_p (SET_SRC (temp4)) && ! may_trap_p (SET_SRC (temp4)) && (REG_NOTES (temp3) == 0 || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV) && XEXP (REG_NOTES (temp3), 1) == 0 && rtx_equal_p (XEXP (REG_NOTES (temp3), 0), SET_SRC (temp4)))) && (temp = prev_active_insn (temp3)) != 0 && condjump_p (temp) && ! simplejump_p (temp) /* TEMP must skip over the "x = a;" insn */ && prev_real_insn (JUMP_LABEL (temp)) == insn && no_labels_between_p (temp, insn)) { rtx prev_label = JUMP_LABEL (temp); rtx insert_after = prev_nonnote_insn (temp); #ifdef HAVE_cc0 /* We cannot insert anything between a set of cc and its use. */ if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i' && sets_cc0_p (PATTERN (insert_after))) insert_after = prev_nonnote_insn (insert_after); #endif ++LABEL_NUSES (prev_label); if (insert_after && no_labels_between_p (insert_after, temp) && ! reg_referenced_between_p (temp1, insert_after, temp3) && ! reg_referenced_between_p (temp1, temp3, NEXT_INSN (temp2)) && ! reg_set_between_p (temp1, insert_after, temp) && ! modified_between_p (SET_SRC (temp4), insert_after, temp) /* Verify that registers used by the jump are not clobbered by the instruction being moved. */ && ! regs_set_between_p (PATTERN (temp), PREV_INSN (temp3), NEXT_INSN (temp3)) && invert_jump (temp, JUMP_LABEL (insn))) { emit_insn_after_with_line_notes (PATTERN (temp3), insert_after, temp3); delete_insn (temp3); delete_insn (insn); /* Set NEXT to an insn that we know won't go away. */ next = temp2; changed = 1; } if (prev_label && --LABEL_NUSES (prev_label) == 0) delete_insn (prev_label); if (changed) continue; } #ifndef HAVE_cc0 /* If we have if (...) x = exp; and branches are expensive, EXP is a single insn, does not have any side effects, cannot trap, and is not too costly, convert this to t = exp; if (...) x = t; Don't do this when we have CC0 because it is unlikely to help and we'd need to worry about where to place the new insn and the potential for conflicts. We also can't do this when we have notes on the insn for the same reason as above. We set: TEMP to the "x = exp;" insn. TEMP1 to the single set in the "x = exp;" insn. TEMP2 to "x". */ if (! reload_completed && this_is_condjump && ! this_is_simplejump && BRANCH_COST >= 3 && (temp = next_nonnote_insn (insn)) != 0 && GET_CODE (temp) == INSN && REG_NOTES (temp) == 0 && (reallabelprev == temp || ((temp2 = next_active_insn (temp)) != 0 && simplejump_p (temp2) && JUMP_LABEL (temp2) == JUMP_LABEL (insn))) && (temp1 = single_set (temp)) != 0 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG) && (! SMALL_REGISTER_CLASSES || REGNO (temp2) >= FIRST_PSEUDO_REGISTER) && GET_CODE (SET_SRC (temp1)) != REG && GET_CODE (SET_SRC (temp1)) != SUBREG && GET_CODE (SET_SRC (temp1)) != CONST_INT && ! side_effects_p (SET_SRC (temp1)) && ! may_trap_p (SET_SRC (temp1)) && rtx_cost (SET_SRC (temp1), SET) < 10) { rtx new = gen_reg_rtx (GET_MODE (temp2)); if ((temp3 = find_insert_position (insn, temp)) && validate_change (temp, &SET_DEST (temp1), new, 0)) { next = emit_insn_after (gen_move_insn (temp2, new), insn); emit_insn_after_with_line_notes (PATTERN (temp), PREV_INSN (temp3), temp); delete_insn (temp); reallabelprev = prev_active_insn (JUMP_LABEL (insn)); if (after_regscan) { reg_scan_update (temp3, NEXT_INSN (next), old_max_reg); old_max_reg = max_reg_num (); } } } /* Similarly, if it takes two insns to compute EXP but they have the same destination. Here TEMP3 will be the second insn and TEMP4 the SET from that insn. */ if (! reload_completed && this_is_condjump && ! this_is_simplejump && BRANCH_COST >= 4 && (temp = next_nonnote_insn (insn)) != 0 && GET_CODE (temp) == INSN && REG_NOTES (temp) == 0 && (temp3 = next_nonnote_insn (temp)) != 0 && GET_CODE (temp3) == INSN && REG_NOTES (temp3) == 0 && (reallabelprev == temp3 || ((temp2 = next_active_insn (temp3)) != 0 && simplejump_p (temp2) && JUMP_LABEL (temp2) == JUMP_LABEL (insn))) && (temp1 = single_set (temp)) != 0 && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG) && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT && (! SMALL_REGISTER_CLASSES || REGNO (temp2) >= FIRST_PSEUDO_REGISTER) && ! side_effects_p (SET_SRC (temp1)) && ! may_trap_p (SET_SRC (temp1)) && rtx_cost (SET_SRC (temp1), SET) < 10 && (temp4 = single_set (temp3)) != 0 && rtx_equal_p (SET_DEST (temp4), temp2) && ! side_effects_p (SET_SRC (temp4)) && ! may_trap_p (SET_SRC (temp4)) && rtx_cost (SET_SRC (temp4), SET) < 10) { rtx new = gen_reg_rtx (GET_MODE (temp2)); if ((temp5 = find_insert_position (insn, temp)) && (temp6 = find_insert_position (insn, temp3)) && validate_change (temp, &SET_DEST (temp1), new, 0)) { /* Use the earliest of temp5 and temp6. */ if (temp5 != insn) temp6 = temp5; next = emit_insn_after (gen_move_insn (temp2, new), insn); emit_insn_after_with_line_notes (PATTERN (temp), PREV_INSN (temp6), temp); emit_insn_after_with_line_notes (replace_rtx (PATTERN (temp3), temp2, new), PREV_INSN (temp6), temp3); delete_insn (temp); delete_insn (temp3); reallabelprev = prev_active_insn (JUMP_LABEL (insn)); if (after_regscan) { reg_scan_update (temp6, NEXT_INSN (next), old_max_reg); old_max_reg = max_reg_num (); } } } /* Finally, handle the case where two insns are used to compute EXP but a temporary register is used. Here we must ensure that the temporary register is not used anywhere else. */ if (! reload_completed && after_regscan && this_is_condjump && ! this_is_simplejump && BRANCH_COST >= 4 && (temp = next_nonnote_insn (insn)) != 0 && GET_CODE (temp) == INSN && REG_NOTES (temp) == 0 && (temp3 = next_nonnote_insn (temp)) != 0 && GET_CODE (temp3) == INSN && REG_NOTES (temp3) == 0 && (reallabelprev == temp3 || ((temp2 = next_active_insn (temp3)) != 0 && simplejump_p (temp2) && JUMP_LABEL (temp2) == JUMP_LABEL (insn))) && (temp1 = single_set (temp)) != 0 && (temp5 = SET_DEST (temp1), (GET_CODE (temp5) == REG || (GET_CODE (temp5) == SUBREG && (temp5 = SUBREG_REG (temp5), GET_CODE (temp5) == REG)))) && REGNO (temp5) >= FIRST_PSEUDO_REGISTER && REGNO_FIRST_UID (REGNO (temp5)) == INSN_UID (temp) && REGNO_LAST_UID (REGNO (temp5)) == INSN_UID (temp3) && ! side_effects_p (SET_SRC (temp1)) && ! may_trap_p (SET_SRC (temp1)) && rtx_cost (SET_SRC (temp1), SET) < 10 && (temp4 = single_set (temp3)) != 0 && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG) && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT && (! SMALL_REGISTER_CLASSES || REGNO (temp2) >= FIRST_PSEUDO_REGISTER) && rtx_equal_p (SET_DEST (temp4), temp2) && ! side_effects_p (SET_SRC (temp4)) && ! may_trap_p (SET_SRC (temp4)) && rtx_cost (SET_SRC (temp4), SET) < 10) { rtx new = gen_reg_rtx (GET_MODE (temp2)); if ((temp5 = find_insert_position (insn, temp)) && (temp6 = find_insert_position (insn, temp3)) && validate_change (temp3, &SET_DEST (temp4), new, 0)) { /* Use the earliest of temp5 and temp6. */ if (temp5 != insn) temp6 = temp5; next = emit_insn_after (gen_move_insn (temp2, new), insn); emit_insn_after_with_line_notes (PATTERN (temp), PREV_INSN (temp6), temp); emit_insn_after_with_line_notes (PATTERN (temp3), PREV_INSN (temp6), temp3); delete_insn (temp); delete_insn (temp3); reallabelprev = prev_active_insn (JUMP_LABEL (insn)); if (after_regscan) { reg_scan_update (temp6, NEXT_INSN (next), old_max_reg); old_max_reg = max_reg_num (); } } } #endif /* HAVE_cc0 */ /* Try to use a conditional move (if the target has them), or a store-flag insn. The general case is: 1) x = a; if (...) x = b; and 2) if (...) x = b; If the jump would be faster, the machine should not have defined the movcc or scc insns!. These cases are often made by the previous optimization. The second case is treated as x = x; if (...) x = b;. INSN here is the jump around the store. We set: TEMP to the "x = b;" insn. TEMP1 to X. TEMP2 to B. TEMP3 to A (X in the second case). TEMP4 to the condition being tested. TEMP5 to the earliest insn used to find the condition. */ if (/* We can't do this after reload has completed. */ ! reload_completed && this_is_condjump && ! this_is_simplejump /* Set TEMP to the "x = b;" insn. */ && (temp = next_nonnote_insn (insn)) != 0 && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == SET && GET_CODE (temp1 = SET_DEST (PATTERN (temp))) == REG && (! SMALL_REGISTER_CLASSES || REGNO (temp1) >= FIRST_PSEUDO_REGISTER) && ! side_effects_p (temp2 = SET_SRC (PATTERN (temp))) && ! may_trap_p (temp2) /* Allow either form, but prefer the former if both apply. There is no point in using the old value of TEMP1 if it is a register, since cse will alias them. It can lose if the old value were a hard register since CSE won't replace hard registers. Avoid using TEMP3 if small register classes and it is a hard register. */ && (((temp3 = reg_set_last (temp1, insn)) != 0 && ! (SMALL_REGISTER_CLASSES && GET_CODE (temp3) == REG && REGNO (temp3) < FIRST_PSEUDO_REGISTER)) /* Make the latter case look like x = x; if (...) x = b; */ || (temp3 = temp1, 1)) /* INSN must either branch to the insn after TEMP or the insn after TEMP must branch to the same place as INSN. */ && (reallabelprev == temp || ((temp4 = next_active_insn (temp)) != 0 && simplejump_p (temp4) && JUMP_LABEL (temp4) == JUMP_LABEL (insn))) && (temp4 = get_condition (insn, &temp5)) != 0 /* We must be comparing objects whose modes imply the size. We could handle BLKmode if (1) emit_store_flag could and (2) we could find the size reliably. */ && GET_MODE (XEXP (temp4, 0)) != BLKmode /* Even if branches are cheap, the store_flag optimization can win when the operation to be performed can be expressed directly. */ #ifdef HAVE_cc0 /* If the previous insn sets CC0 and something else, we can't do this since we are going to delete that insn. */ && ! ((temp6 = prev_nonnote_insn (insn)) != 0 && GET_CODE (temp6) == INSN && (sets_cc0_p (PATTERN (temp6)) == -1 || (sets_cc0_p (PATTERN (temp6)) == 1 && FIND_REG_INC_NOTE (temp6, NULL_RTX)))) #endif ) { #ifdef HAVE_conditional_move /* First try a conditional move. */ { enum rtx_code code = GET_CODE (temp4); rtx var = temp1; rtx cond0, cond1, aval, bval; rtx target; /* Copy the compared variables into cond0 and cond1, so that any side effects performed in or after the old comparison, will not affect our compare which will come later. */ /* ??? Is it possible to just use the comparison in the jump insn? After all, we're going to delete it. We'd have to modify emit_conditional_move to take a comparison rtx instead or write a new function. */ cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0))); /* We want the target to be able to simplify comparisons with zero (and maybe other constants as well), so don't create pseudos for them. There's no need to either. */ if (GET_CODE (XEXP (temp4, 1)) == CONST_INT || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE) cond1 = XEXP (temp4, 1); else cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1))); aval = temp3; bval = temp2; start_sequence (); target = emit_conditional_move (var, code, cond0, cond1, VOIDmode, aval, bval, GET_MODE (var), (code == LTU || code == GEU || code == LEU || code == GTU)); if (target) { rtx seq1,seq2,last; /* Save the conditional move sequence but don't emit it yet. On some machines, like the alpha, it is possible that temp5 == insn, so next generate the sequence that saves the compared values and then emit both sequences ensuring seq1 occurs before seq2. */ seq2 = get_insns (); end_sequence (); /* Now that we can't fail, generate the copy insns that preserve the compared values. */ start_sequence (); emit_move_insn (cond0, XEXP (temp4, 0)); if (cond1 != XEXP (temp4, 1)) emit_move_insn (cond1, XEXP (temp4, 1)); seq1 = get_insns (); end_sequence (); emit_insns_before (seq1, temp5); /* Insert conditional move after insn, to be sure that the jump and a possible compare won't be separated */ last = emit_insns_after (seq2, insn); /* ??? We can also delete the insn that sets X to A. Flow will do it too though. */ delete_insn (temp); next = NEXT_INSN (insn); delete_jump (insn); if (after_regscan) { reg_scan_update (seq1, NEXT_INSN (last), old_max_reg); old_max_reg = max_reg_num (); } changed = 1; continue; } else end_sequence (); } #endif /* That didn't work, try a store-flag insn. We further divide the cases into: 1) x = a; if (...) x = b; and either A or B is zero, 2) if (...) x = 0; and jumps are expensive, 3) x = a; if (...) x = b; and A and B are constants where all the set bits in A are also set in B and jumps are expensive, 4) x = a; if (...) x = b; and A and B non-zero, and jumps are more expensive, and 5) if (...) x = b; if jumps are even more expensive. */ if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT && ((GET_CODE (temp3) == CONST_INT) /* Make the latter case look like x = x; if (...) x = 0; */ || (temp3 = temp1, ((BRANCH_COST >= 2 && temp2 == const0_rtx) || BRANCH_COST >= 3))) /* If B is zero, OK; if A is zero, can only do (1) if we can reverse the condition. See if (3) applies possibly by reversing the condition. Prefer reversing to (4) when branches are very expensive. */ && (((BRANCH_COST >= 2 || STORE_FLAG_VALUE == -1 || (STORE_FLAG_VALUE == 1 /* Check that the mask is a power of two, so that it can probably be generated with a shift. */ && GET_CODE (temp3) == CONST_INT && exact_log2 (INTVAL (temp3)) >= 0)) && (reversep = 0, temp2 == const0_rtx)) || ((BRANCH_COST >= 2 || STORE_FLAG_VALUE == -1 || (STORE_FLAG_VALUE == 1 && GET_CODE (temp2) == CONST_INT && exact_log2 (INTVAL (temp2)) >= 0)) && temp3 == const0_rtx && (reversep = can_reverse_comparison_p (temp4, insn))) || (BRANCH_COST >= 2 && GET_CODE (temp2) == CONST_INT && GET_CODE (temp3) == CONST_INT && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2) || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3) && (reversep = can_reverse_comparison_p (temp4, insn))))) || BRANCH_COST >= 3) ) { enum rtx_code code = GET_CODE (temp4); rtx uval, cval, var = temp1; int normalizep; rtx target; /* If necessary, reverse the condition. */ if (reversep) code = reverse_condition (code), uval = temp2, cval = temp3; else uval = temp3, cval = temp2; /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL is the constant 1, it is best to just compute the result directly. If UVAL is constant and STORE_FLAG_VALUE includes all of its bits, it is best to compute the flag value unnormalized and `and' it with UVAL. Otherwise, normalize to -1 and `and' with UVAL. */ normalizep = (cval != const0_rtx ? -1 : (uval == const1_rtx ? 1 : (GET_CODE (uval) == CONST_INT && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0) ? 0 : -1)); /* We will be putting the store-flag insn immediately in front of the comparison that was originally being done, so we know all the variables in TEMP4 will be valid. However, this might be in front of the assignment of A to VAR. If it is, it would clobber the store-flag we will be emitting. Therefore, emit into a temporary which will be copied to VAR immediately after TEMP. */ start_sequence (); target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code, XEXP (temp4, 0), XEXP (temp4, 1), VOIDmode, (code == LTU || code == LEU || code == GEU || code == GTU), normalizep); if (target) { rtx seq; rtx before = insn; seq = get_insns (); end_sequence (); /* Put the store-flag insns in front of the first insn used to compute the condition to ensure that we use the same values of them as the current comparison. However, the remainder of the insns we generate will be placed directly in front of the jump insn, in case any of the pseudos we use are modified earlier. */ emit_insns_before (seq, temp5); start_sequence (); /* Both CVAL and UVAL are non-zero. */ if (cval != const0_rtx && uval != const0_rtx) { rtx tem1, tem2; tem1 = expand_and (uval, target, NULL_RTX); if (GET_CODE (cval) == CONST_INT && GET_CODE (uval) == CONST_INT && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval)) tem2 = cval; else { tem2 = expand_unop (GET_MODE (var), one_cmpl_optab, target, NULL_RTX, 0); tem2 = expand_and (cval, tem2, (GET_CODE (tem2) == REG ? tem2 : 0)); } /* If we usually make new pseudos, do so here. This turns out to help machines that have conditional move insns. */ /* ??? Conditional moves have already been handled. This may be obsolete. */ if (flag_expensive_optimizations) target = 0; target = expand_binop (GET_MODE (var), ior_optab, tem1, tem2, target, 1, OPTAB_WIDEN); } else if (normalizep != 1) { /* We know that either CVAL or UVAL is zero. If UVAL is zero, negate TARGET and `and' with CVAL. Otherwise, `and' with UVAL. */ if (uval == const0_rtx) { target = expand_unop (GET_MODE (var), one_cmpl_optab, target, NULL_RTX, 0); uval = cval; } target = expand_and (uval, target, (GET_CODE (target) == REG && ! preserve_subexpressions_p () ? target : NULL_RTX)); } emit_move_insn (var, target); seq = get_insns (); end_sequence (); #ifdef HAVE_cc0 /* If INSN uses CC0, we must not separate it from the insn that sets cc0. */ if (reg_mentioned_p (cc0_rtx, PATTERN (before))) before = prev_nonnote_insn (before); #endif emit_insns_before (seq, before); delete_insn (temp); next = NEXT_INSN (insn); delete_jump (insn); if (after_regscan) { reg_scan_update (seq, NEXT_INSN (next), old_max_reg); old_max_reg = max_reg_num (); } changed = 1; continue; } else end_sequence (); } } /* If branches are expensive, convert if (foo) bar++; to bar += (foo != 0); and similarly for "bar--;" INSN is the conditional branch around the arithmetic. We set: TEMP is the arithmetic insn. TEMP1 is the SET doing the arithmetic. TEMP2 is the operand being incremented or decremented. TEMP3 to the condition being tested. TEMP4 to the earliest insn used to find the condition. */ if ((BRANCH_COST >= 2 #ifdef HAVE_incscc || HAVE_incscc #endif #ifdef HAVE_decscc || HAVE_decscc #endif ) && ! reload_completed && this_is_condjump && ! this_is_simplejump && (temp = next_nonnote_insn (insn)) != 0 && (temp1 = single_set (temp)) != 0 && (temp2 = SET_DEST (temp1), GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT) && GET_CODE (SET_SRC (temp1)) == PLUS && (XEXP (SET_SRC (temp1), 1) == const1_rtx || XEXP (SET_SRC (temp1), 1) == constm1_rtx) && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0)) && ! side_effects_p (temp2) && ! may_trap_p (temp2) /* INSN must either branch to the insn after TEMP or the insn after TEMP must branch to the same place as INSN. */ && (reallabelprev == temp || ((temp3 = next_active_insn (temp)) != 0 && simplejump_p (temp3) && JUMP_LABEL (temp3) == JUMP_LABEL (insn))) && (temp3 = get_condition (insn, &temp4)) != 0 /* We must be comparing objects whose modes imply the size. We could handle BLKmode if (1) emit_store_flag could and (2) we could find the size reliably. */ && GET_MODE (XEXP (temp3, 0)) != BLKmode && can_reverse_comparison_p (temp3, insn)) { rtx temp6, target = 0, seq, init_insn = 0, init = temp2; enum rtx_code code = reverse_condition (GET_CODE (temp3)); start_sequence (); /* It must be the case that TEMP2 is not modified in the range [TEMP4, INSN). The one exception we make is if the insn before INSN sets TEMP2 to something which is also unchanged in that range. In that case, we can move the initialization into our sequence. */ if ((temp5 = prev_active_insn (insn)) != 0 && no_labels_between_p (temp5, insn) && GET_CODE (temp5) == INSN && (temp6 = single_set (temp5)) != 0 && rtx_equal_p (temp2, SET_DEST (temp6)) && (CONSTANT_P (SET_SRC (temp6)) || GET_CODE (SET_SRC (temp6)) == REG || GET_CODE (SET_SRC (temp6)) == SUBREG)) { emit_insn (PATTERN (temp5)); init_insn = temp5; init = SET_SRC (temp6); } if (CONSTANT_P (init) || ! reg_set_between_p (init, PREV_INSN (temp4), insn)) target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code, XEXP (temp3, 0), XEXP (temp3, 1), VOIDmode, (code == LTU || code == LEU || code == GTU || code == GEU), 1); /* If we can do the store-flag, do the addition or subtraction. */ if (target) target = expand_binop (GET_MODE (temp2), (XEXP (SET_SRC (temp1), 1) == const1_rtx ? add_optab : sub_optab), temp2, target, temp2, 0, OPTAB_WIDEN); if (target != 0) { /* Put the result back in temp2 in case it isn't already. Then replace the jump, possible a CC0-setting insn in front of the jump, and TEMP, with the sequence we have made. */ if (target != temp2) emit_move_insn (temp2, target); seq = get_insns (); end_sequence (); emit_insns_before (seq, temp4); delete_insn (temp); if (init_insn) delete_insn (init_insn); next = NEXT_INSN (insn); #ifdef HAVE_cc0 delete_insn (prev_nonnote_insn (insn)); #endif delete_insn (insn); if (after_regscan) { reg_scan_update (seq, NEXT_INSN (next), old_max_reg); old_max_reg = max_reg_num (); } changed = 1; continue; } else end_sequence (); } /* Simplify if (...) x = 1; else {...} if (x) ... We recognize this case scanning backwards as well. TEMP is the assignment to x; TEMP1 is the label at the head of the second if. */ /* ?? This should call get_condition to find the values being compared, instead of looking for a COMPARE insn when HAVE_cc0 is not defined. This would allow it to work on the m88k. */ /* ?? This optimization is only safe before cse is run if HAVE_cc0 is not defined and the condition is tested by a separate compare insn. This is because the code below assumes that the result of the compare dies in the following branch. Not only that, but there might be other insns between the compare and branch whose results are live. Those insns need to be executed. A way to fix this is to move the insns at JUMP_LABEL (insn) to before INSN. If we are running before flow, they will be deleted if they aren't needed. But this doesn't work well after flow. This is really a special-case of jump threading, anyway. The right thing to do is to replace this and jump threading with much simpler code in cse. This code has been turned off in the non-cc0 case in the meantime. */ #ifdef HAVE_cc0 else if (this_is_simplejump /* Safe to skip USE and CLOBBER insns here since they will not be deleted. */ && (temp = prev_active_insn (insn)) && no_labels_between_p (temp, insn) && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == SET && GET_CODE (SET_DEST (PATTERN (temp))) == REG && CONSTANT_P (SET_SRC (PATTERN (temp))) && (temp1 = next_active_insn (JUMP_LABEL (insn))) /* If we find that the next value tested is `x' (TEMP1 is the insn where this happens), win. */ && GET_CODE (temp1) == INSN && GET_CODE (PATTERN (temp1)) == SET #ifdef HAVE_cc0 /* Does temp1 `tst' the value of x? */ && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp)) && SET_DEST (PATTERN (temp1)) == cc0_rtx && (temp1 = next_nonnote_insn (temp1)) #else /* Does temp1 compare the value of x against zero? */ && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx && (XEXP (SET_SRC (PATTERN (temp1)), 0) == SET_DEST (PATTERN (temp))) && GET_CODE (SET_DEST (PATTERN (temp1))) == REG && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1)) #endif && condjump_p (temp1)) { /* Get the if_then_else from the condjump. */ rtx choice = SET_SRC (PATTERN (temp1)); if (GET_CODE (choice) == IF_THEN_ELSE) { enum rtx_code code = GET_CODE (XEXP (choice, 0)); rtx val = SET_SRC (PATTERN (temp)); rtx cond = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))), val, const0_rtx); rtx ultimate; if (cond == const_true_rtx) ultimate = XEXP (choice, 1); else if (cond == const0_rtx) ultimate = XEXP (choice, 2); else ultimate = 0; if (ultimate == pc_rtx) ultimate = get_label_after (temp1); else if (ultimate && GET_CODE (ultimate) != RETURN) ultimate = XEXP (ultimate, 0); if (ultimate && JUMP_LABEL(insn) != ultimate) changed |= redirect_jump (insn, ultimate); } } #endif #if 0 /* @@ This needs a bit of work before it will be right. Any type of comparison can be accepted for the first and second compare. When rewriting the first jump, we must compute the what conditions can reach label3, and use the appropriate code. We can not simply reverse/swap the code of the first jump. In some cases, the second jump must be rewritten also. For example, < == converts to > == < != converts to == > etc. If the code is written to only accept an '==' test for the second compare, then all that needs to be done is to swap the condition of the first branch. It is questionable whether we want this optimization anyways, since if the user wrote code like this because he/she knew that the jump to label1 is taken most of the time, then rewriting this gives slower code. */ /* @@ This should call get_condition to find the values being compared, instead of looking for a COMPARE insn when HAVE_cc0 is not defined. This would allow it to work on the m88k. */ /* @@ This optimization is only safe before cse is run if HAVE_cc0 is not defined and the condition is tested by a separate compare insn. This is because the code below assumes that the result of the compare dies in the following branch. */ /* Simplify test a ~= b condjump label1; test a == b condjump label2; jump label3; label1: rewriting as test a ~~= b condjump label3 test a == b condjump label2 label1: where ~= is an inequality, e.g. >, and ~~= is the swapped inequality, e.g. <. We recognize this case scanning backwards. TEMP is the conditional jump to `label2'; TEMP1 is the test for `a == b'; TEMP2 is the conditional jump to `label1'; TEMP3 is the test for `a ~= b'. */ else if (this_is_simplejump && (temp = prev_active_insn (insn)) && no_labels_between_p (temp, insn) && condjump_p (temp) && (temp1 = prev_active_insn (temp)) && no_labels_between_p (temp1, temp) && GET_CODE (temp1) == INSN && GET_CODE (PATTERN (temp1)) == SET #ifdef HAVE_cc0 && sets_cc0_p (PATTERN (temp1)) == 1 #else && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE && GET_CODE (SET_DEST (PATTERN (temp1))) == REG && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1)) #endif && (temp2 = prev_active_insn (temp1)) && no_labels_between_p (temp2, temp1) && condjump_p (temp2) && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn)) && (temp3 = prev_active_insn (temp2)) && no_labels_between_p (temp3, temp2) && GET_CODE (PATTERN (temp3)) == SET && rtx_equal_p (SET_DEST (PATTERN (temp3)), SET_DEST (PATTERN (temp1))) && rtx_equal_p (SET_SRC (PATTERN (temp1)), SET_SRC (PATTERN (temp3))) && ! inequality_comparisons_p (PATTERN (temp)) && inequality_comparisons_p (PATTERN (temp2))) { rtx fallthrough_label = JUMP_LABEL (temp2); ++LABEL_NUSES (fallthrough_label); if (swap_jump (temp2, JUMP_LABEL (insn))) { delete_insn (insn); changed = 1; } if (--LABEL_NUSES (fallthrough_label) == 0) delete_insn (fallthrough_label); } #endif /* Simplify if (...) {... x = 1;} if (x) ... We recognize this case backwards. TEMP is the test of `x'; TEMP1 is the assignment to `x' at the end of the previous statement. */ /* @@ This should call get_condition to find the values being compared, instead of looking for a COMPARE insn when HAVE_cc0 is not defined. This would allow it to work on the m88k. */ /* @@ This optimization is only safe before cse is run if HAVE_cc0 is not defined and the condition is tested by a separate compare insn. This is because the code below assumes that the result of the compare dies in the following branch. */ /* ??? This has to be turned off. The problem is that the unconditional jump might indirectly end up branching to the label between TEMP1 and TEMP. We can't detect this, in general, since it may become a jump to there after further optimizations. If that jump is done, it will be deleted, so we will retry this optimization in the next pass, thus an infinite loop. The present code prevents this by putting the jump after the label, but this is not logically correct. */ #if 0 else if (this_is_condjump /* Safe to skip USE and CLOBBER insns here since they will not be deleted. */ && (temp = prev_active_insn (insn)) && no_labels_between_p (temp, insn) && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == SET #ifdef HAVE_cc0 && sets_cc0_p (PATTERN (temp)) == 1 && GET_CODE (SET_SRC (PATTERN (temp))) == REG #else /* Temp must be a compare insn, we can not accept a register to register move here, since it may not be simply a tst insn. */ && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG && GET_CODE (SET_DEST (PATTERN (temp))) == REG && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp) #endif /* May skip USE or CLOBBER insns here for checking for opportunity, since we take care of them later. */ && (temp1 = prev_active_insn (temp)) && GET_CODE (temp1) == INSN && GET_CODE (PATTERN (temp1)) == SET #ifdef HAVE_cc0 && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1)) #else && (XEXP (SET_SRC (PATTERN (temp)), 0) == SET_DEST (PATTERN (temp1))) #endif && CONSTANT_P (SET_SRC (PATTERN (temp1))) /* If this isn't true, cse will do the job. */ && ! no_labels_between_p (temp1, temp)) { /* Get the if_then_else from the condjump. */ rtx choice = SET_SRC (PATTERN (insn)); if (GET_CODE (choice) == IF_THEN_ELSE && (GET_CODE (XEXP (choice, 0)) == EQ || GET_CODE (XEXP (choice, 0)) == NE)) { int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE); rtx last_insn; rtx ultimate; rtx p; /* Get the place that condjump will jump to if it is reached from here. */ if ((SET_SRC (PATTERN (temp1)) != const0_rtx) == want_nonzero) ultimate = XEXP (choice, 1); else ultimate = XEXP (choice, 2); /* Get it as a CODE_LABEL. */ if (ultimate == pc_rtx) ultimate = get_label_after (insn); else /* Get the label out of the LABEL_REF. */ ultimate = XEXP (ultimate, 0); /* Insert the jump immediately before TEMP, specifically after the label that is between TEMP1 and TEMP. */ last_insn = PREV_INSN (temp); /* If we would be branching to the next insn, the jump would immediately be deleted and the re-inserted in a subsequent pass over the code. So don't do anything in that case. */ if (next_active_insn (last_insn) != next_active_insn (ultimate)) { emit_barrier_after (last_insn); p = emit_jump_insn_after (gen_jump (ultimate), last_insn); JUMP_LABEL (p) = ultimate; ++LABEL_NUSES (ultimate); if (INSN_UID (ultimate) < max_jump_chain && INSN_CODE (p) < max_jump_chain) { jump_chain[INSN_UID (p)] = jump_chain[INSN_UID (ultimate)]; jump_chain[INSN_UID (ultimate)] = p; } changed = 1; continue; } } } #endif /* Detect a conditional jump going to the same place as an immediately following unconditional jump. */ else if (this_is_condjump && (temp = next_active_insn (insn)) != 0 && simplejump_p (temp) && (next_active_insn (JUMP_LABEL (insn)) == next_active_insn (JUMP_LABEL (temp)))) { rtx tem = temp; /* ??? Optional. Disables some optimizations, but makes gcov output more accurate with -O. */ if (flag_test_coverage && !reload_completed) for (tem = insn; tem != temp; tem = NEXT_INSN (tem)) if (GET_CODE (tem) == NOTE && NOTE_LINE_NUMBER (tem) > 0) break; if (tem == temp) { delete_jump (insn); changed = 1; continue; } } #ifdef HAVE_trap /* Detect a conditional jump jumping over an unconditional trap. */ else if (HAVE_trap && this_is_condjump && ! this_is_simplejump && reallabelprev != 0 && GET_CODE (reallabelprev) == INSN && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx && prev_active_insn (reallabelprev) == insn && no_labels_between_p (insn, reallabelprev) && (temp2 = get_condition (insn, &temp4)) && can_reverse_comparison_p (temp2, insn)) { rtx new = gen_cond_trap (reverse_condition (GET_CODE (temp2)), XEXP (temp2, 0), XEXP (temp2, 1), TRAP_CODE (PATTERN (reallabelprev))); if (new) { emit_insn_before (new, temp4); delete_insn (reallabelprev); delete_jump (insn); changed = 1; continue; } } /* Detect a jump jumping to an unconditional trap. */ else if (HAVE_trap && this_is_condjump && (temp = next_active_insn (JUMP_LABEL (insn))) && GET_CODE (temp) == INSN && GET_CODE (PATTERN (temp)) == TRAP_IF && (this_is_simplejump || (temp2 = get_condition (insn, &temp4)))) { rtx tc = TRAP_CONDITION (PATTERN (temp)); if (tc == const_true_rtx || (! this_is_simplejump && rtx_equal_p (temp2, tc))) { rtx new; /* Replace an unconditional jump to a trap with a trap. */ if (this_is_simplejump) { emit_barrier_after (emit_insn_before (gen_trap (), insn)); delete_jump (insn); changed = 1; continue; } new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0), XEXP (temp2, 1), TRAP_CODE (PATTERN (temp))); if (new) { emit_insn_before (new, temp4); delete_jump (insn); changed = 1; continue; } } /* If the trap condition and jump condition are mutually exclusive, redirect the jump to the following insn. */ else if (GET_RTX_CLASS (GET_CODE (tc)) == '<' && ! this_is_simplejump && swap_condition (GET_CODE (temp2)) == GET_CODE (tc) && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0)) && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1)) && redirect_jump (insn, get_label_after (temp))) { changed = 1; continue; } } #endif /* Detect a conditional jump jumping over an unconditional jump. */ else if ((this_is_condjump || this_is_condjump_in_parallel) && ! this_is_simplejump && reallabelprev != 0 && GET_CODE (reallabelprev) == JUMP_INSN && prev_active_insn (reallabelprev) == insn && no_labels_between_p (insn, reallabelprev) && simplejump_p (reallabelprev)) { /* When we invert the unconditional jump, we will be decrementing the usage count of its old label. Make sure that we don't delete it now because that might cause the following code to be deleted. */ rtx prev_uses = prev_nonnote_insn (reallabelprev); rtx prev_label = JUMP_LABEL (insn); if (prev_label) ++LABEL_NUSES (prev_label); if (invert_jump (insn, JUMP_LABEL (reallabelprev))) { /* It is very likely that if there are USE insns before this jump, they hold REG_DEAD notes. These REG_DEAD notes are no longer valid due to this optimization, and will cause the life-analysis that following passes (notably delayed-branch scheduling) to think that these registers are dead when they are not. To prevent this trouble, we just remove the USE insns from the insn chain. */ while (prev_uses && GET_CODE (prev_uses) == INSN && GET_CODE (PATTERN (prev_uses)) == USE) { rtx useless = prev_uses; prev_uses = prev_nonnote_insn (prev_uses); delete_insn (useless); } delete_insn (reallabelprev); next = insn; changed = 1; } /* We can now safely delete the label if it is unreferenced since the delete_insn above has deleted the BARRIER. */ if (prev_label && --LABEL_NUSES (prev_label) == 0) delete_insn (prev_label); continue; } else { /* Detect a jump to a jump. */ nlabel = follow_jumps (JUMP_LABEL (insn)); if (nlabel != JUMP_LABEL (insn) && redirect_jump (insn, nlabel)) { changed = 1; next = insn; } /* Look for if (foo) bar; else break; */ /* The insns look like this: insn = condjump label1; ...range1 (some insns)... jump label2; label1: ...range2 (some insns)... jump somewhere unconditionally label2: */ { rtx label1 = next_label (insn); rtx range1end = label1 ? prev_active_insn (label1) : 0; /* Don't do this optimization on the first round, so that jump-around-a-jump gets simplified before we ask here whether a jump is unconditional. Also don't do it when we are called after reload since it will confuse reorg. */ if (! first && (reload_completed ? ! flag_delayed_branch : 1) /* Make sure INSN is something we can invert. */ && condjump_p (insn) && label1 != 0 && JUMP_LABEL (insn) == label1 && LABEL_NUSES (label1) == 1 && GET_CODE (range1end) == JUMP_INSN && simplejump_p (range1end)) { rtx label2 = next_label (label1); rtx range2end = label2 ? prev_active_insn (label2) : 0; if (range1end != range2end && JUMP_LABEL (range1end) == label2 && GET_CODE (range2end) == JUMP_INSN && GET_CODE (NEXT_INSN (range2end)) == BARRIER /* Invert the jump condition, so we still execute the same insns in each case. */ && invert_jump (insn, label1)) { rtx range1beg = next_active_insn (insn); rtx range2beg = next_active_insn (label1); rtx range1after, range2after; rtx range1before, range2before; rtx rangenext; /* Include in each range any notes before it, to be sure that we get the line number note if any, even if there are other notes here. */ while (PREV_INSN (range1beg) && GET_CODE (PREV_INSN (range1beg)) == NOTE) range1beg = PREV_INSN (range1beg); while (PREV_INSN (range2beg) && GET_CODE (PREV_INSN (range2beg)) == NOTE) range2beg = PREV_INSN (range2beg); /* Don't move NOTEs for blocks or loops; shift them outside the ranges, where they'll stay put. */ range1beg = squeeze_notes (range1beg, range1end); range2beg = squeeze_notes (range2beg, range2end); /* Get current surrounds of the 2 ranges. */ range1before = PREV_INSN (range1beg); range2before = PREV_INSN (range2beg); range1after = NEXT_INSN (range1end); range2after = NEXT_INSN (range2end); /* Splice range2 where range1 was. */ NEXT_INSN (range1before) = range2beg; PREV_INSN (range2beg) = range1before; NEXT_INSN (range2end) = range1after; PREV_INSN (range1after) = range2end; /* Splice range1 where range2 was. */ NEXT_INSN (range2before) = range1beg; PREV_INSN (range1beg) = range2before; NEXT_INSN (range1end) = range2after; PREV_INSN (range2after) = range1end; /* Check for a loop end note between the end of range2, and the next code label. If there is one, then what we have really seen is if (foo) break; end_of_loop; and moved the break sequence outside the loop. We must move the LOOP_END note to where the loop really ends now, or we will confuse loop optimization. Stop if we find a LOOP_BEG note first, since we don't want to move the LOOP_END note in that case. */ for (;range2after != label2; range2after = rangenext) { rangenext = NEXT_INSN (range2after); if (GET_CODE (range2after) == NOTE) { if (NOTE_LINE_NUMBER (range2after) == NOTE_INSN_LOOP_END) { NEXT_INSN (PREV_INSN (range2after)) = rangenext; PREV_INSN (rangenext) = PREV_INSN (range2after); PREV_INSN (range2after) = PREV_INSN (range1beg); NEXT_INSN (range2after) = range1beg; NEXT_INSN (PREV_INSN (range1beg)) = range2after; PREV_INSN (range1beg) = range2after; } else if (NOTE_LINE_NUMBER (range2after) == NOTE_INSN_LOOP_BEG) break; } } changed = 1; continue; } } } /* Now that the jump has been tensioned, try cross jumping: check for identical code before the jump and before its target label. */ /* First, cross jumping of conditional jumps: */ if (cross_jump && condjump_p (insn)) { rtx newjpos, newlpos; rtx x = prev_real_insn (JUMP_LABEL (insn)); /* A conditional jump may be crossjumped only if the place it jumps to follows an opposing jump that comes back here. */ if (x != 0 && ! jump_back_p (x, insn)) /* We have no opposing jump; cannot cross jump this insn. */ x = 0; newjpos = 0; /* TARGET is nonzero if it is ok to cross jump to code before TARGET. If so, see if matches. */ if (x != 0) find_cross_jump (insn, x, 2, &newjpos, &newlpos); if (newjpos != 0) { do_cross_jump (insn, newjpos, newlpos); /* Make the old conditional jump into an unconditional one. */ SET_SRC (PATTERN (insn)) = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn)); INSN_CODE (insn) = -1; emit_barrier_after (insn); /* Add to jump_chain unless this is a new label whose UID is too large. */ if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain) { jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (JUMP_LABEL (insn))]; jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn; } changed = 1; next = insn; } } /* Cross jumping of unconditional jumps: a few differences. */ if (cross_jump && simplejump_p (insn)) { rtx newjpos, newlpos; rtx target; newjpos = 0; /* TARGET is nonzero if it is ok to cross jump to code before TARGET. If so, see if matches. */ find_cross_jump (insn, JUMP_LABEL (insn), 1, &newjpos, &newlpos); /* If cannot cross jump to code before the label, see if we can cross jump to another jump to the same label. */ /* Try each other jump to this label. */ if (INSN_UID (JUMP_LABEL (insn)) < max_uid) for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))]; target != 0 && newjpos == 0; target = jump_chain[INSN_UID (target)]) if (target != insn && JUMP_LABEL (target) == JUMP_LABEL (insn) /* Ignore TARGET if it's deleted. */ && ! INSN_DELETED_P (target)) find_cross_jump (insn, target, 2, &newjpos, &newlpos); if (newjpos != 0) { do_cross_jump (insn, newjpos, newlpos); changed = 1; next = insn; } } /* This code was dead in the previous jump.c! */ if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN) { /* Return insns all "jump to the same place" so we can cross-jump between any two of them. */ rtx newjpos, newlpos, target; newjpos = 0; /* If cannot cross jump to code before the label, see if we can cross jump to another jump to the same label. */ /* Try each other jump to this label. */ for (target = jump_chain[0]; target != 0 && newjpos == 0; target = jump_chain[INSN_UID (target)]) if (target != insn && ! INSN_DELETED_P (target) && GET_CODE (PATTERN (target)) == RETURN) find_cross_jump (insn, target, 2, &newjpos, &newlpos); if (newjpos != 0) { do_cross_jump (insn, newjpos, newlpos); changed = 1; next = insn; } } } } first = 0; } /* Delete extraneous line number notes. Note that two consecutive notes for different lines are not really extraneous. There should be some indication where that line belonged, even if it became empty. */ { rtx last_note = 0; for (insn = f; insn; insn = NEXT_INSN (insn)) if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0) { /* Delete this note if it is identical to previous note. */ if (last_note && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note) && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note)) { delete_insn (insn); continue; } last_note = insn; } } #ifdef HAVE_return if (HAVE_return) { /* If we fall through to the epilogue, see if we can insert a RETURN insn in front of it. If the machine allows it at this point (we might be after reload for a leaf routine), it will improve optimization for it to be there. We do this both here and at the start of this pass since the RETURN might have been deleted by some of our optimizations. */ insn = get_last_insn (); while (insn && GET_CODE (insn) == NOTE) insn = PREV_INSN (insn); if (insn && GET_CODE (insn) != BARRIER) { emit_jump_insn (gen_return ()); emit_barrier (); } } #endif /* See if there is still a NOTE_INSN_FUNCTION_END in this function. If so, delete it, and record that this function can drop off the end. */ insn = last_insn; { int n_labels = 1; while (insn /* One label can follow the end-note: the return label. */ && ((GET_CODE (insn) == CODE_LABEL && n_labels-- > 0) /* Ordinary insns can follow it if returning a structure. */ || GET_CODE (insn) == INSN /* If machine uses explicit RETURN insns, no epilogue, then one of them follows the note. */ || (GET_CODE (insn) == JUMP_INSN && GET_CODE (PATTERN (insn)) == RETURN) /* A barrier can follow the return insn. */ || GET_CODE (insn) == BARRIER /* Other kinds of notes can follow also. */ || (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END))) insn = PREV_INSN (insn); } /* Report if control can fall through at the end of the function. */ if (insn && GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END) { can_reach_end = 1; delete_insn (insn); } /* Show JUMP_CHAIN no longer valid. */ jump_chain = 0; } /* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional jump. Assume that this unconditional jump is to the exit test code. If the code is sufficiently simple, make a copy of it before INSN, followed by a jump to the exit of the loop. Then delete the unconditional jump after INSN. Return 1 if we made the change, else 0. This is only safe immediately after a regscan pass because it uses the values of regno_first_uid and regno_last_uid. */ static int duplicate_loop_exit_test (loop_start) rtx loop_start; { rtx insn, set, reg, p, link; rtx copy = 0; int num_insns = 0; rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start))); rtx lastexit; int max_reg = max_reg_num (); rtx *reg_map = 0; /* Scan the exit code. We do not perform this optimization if any insn: is a CALL_INSN is a CODE_LABEL has a REG_RETVAL or REG_LIBCALL note (hard to adjust) is a NOTE_INSN_LOOP_BEG because this means we have a nested loop is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes are not valid We also do not do this if we find an insn with ASM_OPERANDS. While this restriction should not be necessary, copying an insn with ASM_OPERANDS can confuse asm_noperands in some cases. Also, don't do this if the exit code is more than 20 insns. */ for (insn = exitcode; insn && ! (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END); insn = NEXT_INSN (insn)) { switch (GET_CODE (insn)) { case CODE_LABEL: case CALL_INSN: return 0; case NOTE: /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is a jump immediately after the loop start that branches outside the loop but within an outer loop, near the exit test. If we copied this exit test and created a phony NOTE_INSN_LOOP_VTOP, this could make instructions immediately before the exit test look like these could be safely moved out of the loop even if they actually may be never executed. This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */ if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT) return 0; if (optimize < 2 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)) /* If we were to duplicate this code, we would not move the BLOCK notes, and so debugging the moved code would be difficult. Thus, we only move the code with -O2 or higher. */ return 0; break; case JUMP_INSN: case INSN: if (++num_insns > 20 || find_reg_note (insn, REG_RETVAL, NULL_RTX) || find_reg_note (insn, REG_LIBCALL, NULL_RTX) || asm_noperands (PATTERN (insn)) > 0) return 0; break; default: break; } } /* Unless INSN is zero, we can do the optimization. */ if (insn == 0) return 0; lastexit = insn; /* See if any insn sets a register only used in the loop exit code and not a user variable. If so, replace it with a new register. */ for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn)) if (GET_CODE (insn) == INSN && (set = single_set (insn)) != 0 && ((reg = SET_DEST (set), GET_CODE (reg) == REG) || (GET_CODE (reg) == SUBREG && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG))) && REGNO (reg) >= FIRST_PSEUDO_REGISTER && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn)) { for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p)) if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p)) break; if (p != lastexit) { /* We can do the replacement. Allocate reg_map if this is the first replacement we found. */ if (reg_map == 0) { reg_map = (rtx *) alloca (max_reg * sizeof (rtx)); bzero ((char *) reg_map, max_reg * sizeof (rtx)); } REG_LOOP_TEST_P (reg) = 1; reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg)); } } /* Now copy each insn. */ for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn)) switch (GET_CODE (insn)) { case BARRIER: copy = emit_barrier_before (loop_start); break; case NOTE: /* Only copy line-number notes. */ if (NOTE_LINE_NUMBER (insn) >= 0) { copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start); NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn); } break; case INSN: copy = emit_insn_before (copy_rtx (PATTERN (insn)), loop_start); if (reg_map) replace_regs (PATTERN (copy), reg_map, max_reg, 1); mark_jump_label (PATTERN (copy), copy, 0); /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will make them. */ for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) if (REG_NOTE_KIND (link) != REG_LABEL) REG_NOTES (copy) = copy_rtx (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link), XEXP (link, 0), REG_NOTES (copy))); if (reg_map && REG_NOTES (copy)) replace_regs (REG_NOTES (copy), reg_map, max_reg, 1); break; case JUMP_INSN: copy = emit_jump_insn_before (copy_rtx (PATTERN (insn)), loop_start); if (reg_map) replace_regs (PATTERN (copy), reg_map, max_reg, 1); mark_jump_label (PATTERN (copy), copy, 0); if (REG_NOTES (insn)) { REG_NOTES (copy) = copy_rtx (REG_NOTES (insn)); if (reg_map) replace_regs (REG_NOTES (copy), reg_map, max_reg, 1); } /* If this is a simple jump, add it to the jump chain. */ if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy) && simplejump_p (copy)) { jump_chain[INSN_UID (copy)] = jump_chain[INSN_UID (JUMP_LABEL (copy))]; jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy; } break; default: abort (); } /* Now clean up by emitting a jump to the end label and deleting the jump at the start of the loop. */ if (! copy || GET_CODE (copy) != BARRIER) { copy = emit_jump_insn_before (gen_jump (get_label_after (insn)), loop_start); mark_jump_label (PATTERN (copy), copy, 0); if (INSN_UID (copy) < max_jump_chain && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain) { jump_chain[INSN_UID (copy)] = jump_chain[INSN_UID (JUMP_LABEL (copy))]; jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy; } emit_barrier_before (loop_start); } /* Mark the exit code as the virtual top of the converted loop. */ emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode); delete_insn (next_nonnote_insn (loop_start)); return 1; } /* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and loop-end notes between START and END out before START. Assume that END is not such a note. START may be such a note. Returns the value of the new starting insn, which may be different if the original start was such a note. */ rtx squeeze_notes (start, end) rtx start, end; { rtx insn; rtx next; for (insn = start; insn != end; insn = next) { next = NEXT_INSN (insn); if (GET_CODE (insn) == NOTE && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP)) { if (insn == start) start = next; else { rtx prev = PREV_INSN (insn); PREV_INSN (insn) = PREV_INSN (start); NEXT_INSN (insn) = start; NEXT_INSN (PREV_INSN (insn)) = insn; PREV_INSN (NEXT_INSN (insn)) = insn; NEXT_INSN (prev) = next; PREV_INSN (next) = prev; } } } return start; } /* Compare the instructions before insn E1 with those before E2 to find an opportunity for cross jumping. (This means detecting identical sequences of insns followed by jumps to the same place, or followed by a label and a jump to that label, and replacing one with a jump to the other.) Assume E1 is a jump that jumps to label E2 (that is not always true but it might as well be). Find the longest possible equivalent sequences and store the first insns of those sequences into *F1 and *F2. Store zero there if no equivalent preceding instructions are found. We give up if we find a label in stream 1. Actually we could transfer that label into stream 2. */ static void find_cross_jump (e1, e2, minimum, f1, f2) rtx e1, e2; int minimum; rtx *f1, *f2; { register rtx i1 = e1, i2 = e2; register rtx p1, p2; int lose = 0; rtx last1 = 0, last2 = 0; rtx afterlast1 = 0, afterlast2 = 0; *f1 = 0; *f2 = 0; while (1) { i1 = prev_nonnote_insn (i1); i2 = PREV_INSN (i2); while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL)) i2 = PREV_INSN (i2); if (i1 == 0) break; /* Don't allow the range of insns preceding E1 or E2 to include the other (E2 or E1). */ if (i2 == e1 || i1 == e2) break; /* If we will get to this code by jumping, those jumps will be tensioned to go directly to the new label (before I2), so this cross-jumping won't cost extra. So reduce the minimum. */ if (GET_CODE (i1) == CODE_LABEL) { --minimum; break; } if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2)) break; /* Avoid moving insns across EH regions. ??? This is only necessary if i1 or i2 can throw an exception. */ if (flag_exceptions && !in_same_eh_region (i1, i2)) break; p1 = PATTERN (i1); p2 = PATTERN (i2); /* If this is a CALL_INSN, compare register usage information. If we don't check this on stack register machines, the two CALL_INSNs might be merged leaving reg-stack.c with mismatching numbers of stack registers in the same basic block. If we don't check this on machines with delay slots, a delay slot may be filled that clobbers a parameter expected by the subroutine. ??? We take the simple route for now and assume that if they're equal, they were constructed identically. */ if (GET_CODE (i1) == CALL_INSN && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1), CALL_INSN_FUNCTION_USAGE (i2))) lose = 1; #ifdef STACK_REGS /* If cross_jump_death_matters is not 0, the insn's mode indicates whether or not the insn contains any stack-like regs. */ if (!lose && cross_jump_death_matters && GET_MODE (i1) == QImode) { /* If register stack conversion has already been done, then death notes must also be compared before it is certain that the two instruction streams match. */ rtx note; HARD_REG_SET i1_regset, i2_regset; CLEAR_HARD_REG_SET (i1_regset); CLEAR_HARD_REG_SET (i2_regset); for (note = REG_NOTES (i1); note; note = XEXP (note, 1)) if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0))) SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0))); for (note = REG_NOTES (i2); note; note = XEXP (note, 1)) if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0))) SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0))); GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done); lose = 1; done: ; } #endif /* Don't allow old-style asm or volatile extended asms to be accepted for cross jumping purposes. It is conceptually correct to allow them, since cross-jumping preserves the dynamic instruction order even though it is changing the static instruction order. However, if an asm is being used to emit an assembler pseudo-op, such as the MIPS `.set reorder' pseudo-op, then the static instruction order matters and it must be preserved. */ if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1)) || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2))) lose = 1; if (lose || GET_CODE (p1) != GET_CODE (p2) || ! rtx_renumbered_equal_p (p1, p2)) { /* The following code helps take care of G++ cleanups. */ rtx equiv1; rtx equiv2; if (!lose && GET_CODE (p1) == GET_CODE (p2) && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0 || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0) && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0 || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0) /* If the equivalences are not to a constant, they may reference pseudos that no longer exist, so we can't use them. */ && CONSTANT_P (XEXP (equiv1, 0)) && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0))) { rtx s1 = single_set (i1); rtx s2 = single_set (i2); if (s1 != 0 && s2 != 0 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2))) { validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1); validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1); if (! rtx_renumbered_equal_p (p1, p2)) cancel_changes (0); else if (apply_change_group ()) goto win; } } /* Insns fail to match; cross jumping is limited to the following insns. */ #ifdef HAVE_cc0 /* Don't allow the insn after a compare to be shared by cross-jumping unless the compare is also shared. Here, if either of these non-matching insns is a compare, exclude the following insn from possible cross-jumping. */ if (sets_cc0_p (p1) || sets_cc0_p (p2)) last1 = afterlast1, last2 = afterlast2, ++minimum; #endif /* If cross-jumping here will feed a jump-around-jump optimization, this jump won't cost extra, so reduce the minimum. */ if (GET_CODE (i1) == JUMP_INSN && JUMP_LABEL (i1) && prev_real_insn (JUMP_LABEL (i1)) == e1) --minimum; break; } win: if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER) { /* Ok, this insn is potentially includable in a cross-jump here. */ afterlast1 = last1, afterlast2 = last2; last1 = i1, last2 = i2, --minimum; } } if (minimum <= 0 && last1 != 0 && last1 != e1) *f1 = last1, *f2 = last2; } static void do_cross_jump (insn, newjpos, newlpos) rtx insn, newjpos, newlpos; { /* Find an existing label at this point or make a new one if there is none. */ register rtx label = get_label_before (newlpos); /* Make the same jump insn jump to the new point. */ if (GET_CODE (PATTERN (insn)) == RETURN) { /* Remove from jump chain of returns. */ delete_from_jump_chain (insn); /* Change the insn. */ PATTERN (insn) = gen_jump (label); INSN_CODE (insn) = -1; JUMP_LABEL (insn) = label; LABEL_NUSES (label)++; /* Add to new the jump chain. */ if (INSN_UID (label) < max_jump_chain && INSN_UID (insn) < max_jump_chain) { jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (label)]; jump_chain[INSN_UID (label)] = insn; } } else redirect_jump (insn, label); /* Delete the matching insns before the jump. Also, remove any REG_EQUAL or REG_EQUIV note in the NEWLPOS stream that isn't also present in the NEWJPOS stream. */ while (newjpos != insn) { rtx lnote; for (lnote = REG_NOTES (newlpos); lnote; lnote = XEXP (lnote, 1)) if ((REG_NOTE_KIND (lnote) == REG_EQUAL || REG_NOTE_KIND (lnote) == REG_EQUIV) && ! find_reg_note (newjpos, REG_EQUAL, XEXP (lnote, 0)) && ! find_reg_note (newjpos, REG_EQUIV, XEXP (lnote, 0))) remove_note (newlpos, lnote); delete_insn (newjpos); newjpos = next_real_insn (newjpos); newlpos = next_real_insn (newlpos); } } /* Return the label before INSN, or put a new label there. */ rtx get_label_before (insn) rtx insn; { rtx label; /* Find an existing label at this point or make a new one if there is none. */ label = prev_nonnote_insn (insn); if (label == 0 || GET_CODE (label) != CODE_LABEL) { rtx prev = PREV_INSN (insn); label = gen_label_rtx (); emit_label_after (label, prev); LABEL_NUSES (label) = 0; } return label; } /* Return the label after INSN, or put a new label there. */ rtx get_label_after (insn) rtx insn; { rtx label; /* Find an existing label at this point or make a new one if there is none. */ label = next_nonnote_insn (insn); if (label == 0 || GET_CODE (label) != CODE_LABEL) { label = gen_label_rtx (); emit_label_after (label, insn); LABEL_NUSES (label) = 0; } return label; } /* Return 1 if INSN is a jump that jumps to right after TARGET only on the condition that TARGET itself would drop through. Assumes that TARGET is a conditional jump. */ static int jump_back_p (insn, target) rtx insn, target; { rtx cinsn, ctarget; enum rtx_code codei, codet; if (simplejump_p (insn) || ! condjump_p (insn) || simplejump_p (target) || target != prev_real_insn (JUMP_LABEL (insn))) return 0; cinsn = XEXP (SET_SRC (PATTERN (insn)), 0); ctarget = XEXP (SET_SRC (PATTERN (target)), 0); codei = GET_CODE (cinsn); codet = GET_CODE (ctarget); if (XEXP (SET_SRC (PATTERN (insn)), 1) == pc_rtx) { if (! can_reverse_comparison_p (cinsn, insn)) return 0; codei = reverse_condition (codei); } if (XEXP (SET_SRC (PATTERN (target)), 2) == pc_rtx) { if (! can_reverse_comparison_p (ctarget, target)) return 0; codet = reverse_condition (codet); } return (codei == codet && rtx_renumbered_equal_p (XEXP (cinsn, 0), XEXP (ctarget, 0)) && rtx_renumbered_equal_p (XEXP (cinsn, 1), XEXP (ctarget, 1))); } /* Given a comparison, COMPARISON, inside a conditional jump insn, INSN, return non-zero if it is safe to reverse this comparison. It is if our floating-point is not IEEE, if this is an NE or EQ comparison, or if this is known to be an integer comparison. */ int can_reverse_comparison_p (comparison, insn) rtx comparison; rtx insn; { rtx arg0; /* If this is not actually a comparison, we can't reverse it. */ if (GET_RTX_CLASS (GET_CODE (comparison)) != '<') return 0; if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT /* If this is an NE comparison, it is safe to reverse it to an EQ comparison and vice versa, even for floating point. If no operands are NaNs, the reversal is valid. If some operand is a NaN, EQ is always false and NE is always true, so the reversal is also valid. */ || flag_fast_math || GET_CODE (comparison) == NE || GET_CODE (comparison) == EQ) return 1; arg0 = XEXP (comparison, 0); /* Make sure ARG0 is one of the actual objects being compared. If we can't do this, we can't be sure the comparison can be reversed. Handle cc0 and a MODE_CC register. */ if ((GET_CODE (arg0) == REG && GET_MODE_CLASS (GET_MODE (arg0)) == MODE_CC) #ifdef HAVE_cc0 || arg0 == cc0_rtx #endif ) { rtx prev = prev_nonnote_insn (insn); rtx set = single_set (prev); if (set == 0 || SET_DEST (set) != arg0) return 0; arg0 = SET_SRC (set); if (GET_CODE (arg0) == COMPARE) arg0 = XEXP (arg0, 0); } /* We can reverse this if ARG0 is a CONST_INT or if its mode is not VOIDmode and neither a MODE_CC nor MODE_FLOAT type. */ return (GET_CODE (arg0) == CONST_INT || (GET_MODE (arg0) != VOIDmode && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_CC && GET_MODE_CLASS (GET_MODE (arg0)) != MODE_FLOAT)); } /* Given an rtx-code for a comparison, return the code for the negated comparison. WATCH OUT! reverse_condition is not safe to use on a jump that might be acting on the results of an IEEE floating point comparison, because of the special treatment of non-signaling nans in comparisons. Use can_reverse_comparison_p to be sure. */ enum rtx_code reverse_condition (code) enum rtx_code code; { switch (code) { case EQ: return NE; case NE: return EQ; case GT: return LE; case GE: return LT; case LT: return GE; case LE: return GT; case GTU: return LEU; case GEU: return LTU; case LTU: return GEU; case LEU: return GTU; default: abort (); return UNKNOWN; } } /* Similar, but return the code when two operands of a comparison are swapped. This IS safe for IEEE floating-point. */ enum rtx_code swap_condition (code) enum rtx_code code; { switch (code) { case EQ: case NE: return code; case GT: return LT; case GE: return LE; case LT: return GT; case LE: return GE; case GTU: return LTU; case GEU: return LEU; case LTU: return GTU; case LEU: return GEU; default: abort (); return UNKNOWN; } } /* Given a comparison CODE, return the corresponding unsigned comparison. If CODE is an equality comparison or already an unsigned comparison, CODE is returned. */ enum rtx_code unsigned_condition (code) enum rtx_code code; { switch (code) { case EQ: case NE: case GTU: case GEU: case LTU: case LEU: return code; case GT: return GTU; case GE: return GEU; case LT: return LTU; case LE: return LEU; default: abort (); } } /* Similarly, return the signed version of a comparison. */ enum rtx_code signed_condition (code) enum rtx_code code; { switch (code) { case EQ: case NE: case GT: case GE: case LT: case LE: return code; case GTU: return GT; case GEU: return GE; case LTU: return LT; case LEU: return LE; default: abort (); } } /* Return non-zero if CODE1 is more strict than CODE2, i.e., if the truth of CODE1 implies the truth of CODE2. */ int comparison_dominates_p (code1, code2) enum rtx_code code1, code2; { if (code1 == code2) return 1; switch (code1) { case EQ: if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU) return 1; break; case LT: if (code2 == LE || code2 == NE) return 1; break; case GT: if (code2 == GE || code2 == NE) return 1; break; case LTU: if (code2 == LEU || code2 == NE) return 1; break; case GTU: if (code2 == GEU || code2 == NE) return 1; break; default: break; } return 0; } /* Return 1 if INSN is an unconditional jump and nothing else. */ int simplejump_p (insn) rtx insn; { return (GET_CODE (insn) == JUMP_INSN && GET_CODE (PATTERN (insn)) == SET && GET_CODE (SET_DEST (PATTERN (insn))) == PC && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF); } /* Return nonzero if INSN is a (possibly) conditional jump and nothing more. */ int condjump_p (insn) rtx insn; { register rtx x = PATTERN (insn); if (GET_CODE (x) != SET) return 0; if (GET_CODE (SET_DEST (x)) != PC) return 0; if (GET_CODE (SET_SRC (x)) == LABEL_REF) return 1; if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE) return 0; if (XEXP (SET_SRC (x), 2) == pc_rtx && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN)) return 1; if (XEXP (SET_SRC (x), 1) == pc_rtx && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN)) return 1; return 0; } /* Return nonzero if INSN is a (possibly) conditional jump and nothing more. */ int condjump_in_parallel_p (insn) rtx insn; { register rtx x = PATTERN (insn); if (GET_CODE (x) != PARALLEL) return 0; else x = XVECEXP (x, 0, 0); if (GET_CODE (x) != SET) return 0; if (GET_CODE (SET_DEST (x)) != PC) return 0; if (GET_CODE (SET_SRC (x)) == LABEL_REF) return 1; if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE) return 0; if (XEXP (SET_SRC (x), 2) == pc_rtx && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF || GET_CODE (XEXP (SET_SRC (x), 1)) == RETURN)) return 1; if (XEXP (SET_SRC (x), 1) == pc_rtx && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF || GET_CODE (XEXP (SET_SRC (x), 2)) == RETURN)) return 1; return 0; } /* Return 1 if X is an RTX that does nothing but set the condition codes and CLOBBER or USE registers. Return -1 if X does explicitly set the condition codes, but also does other things. */ int sets_cc0_p (x) rtx x; { #ifdef HAVE_cc0 if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx) return 1; if (GET_CODE (x) == PARALLEL) { int i; int sets_cc0 = 0; int other_things = 0; for (i = XVECLEN (x, 0) - 1; i >= 0; i--) { if (GET_CODE (XVECEXP (x, 0, i)) == SET && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx) sets_cc0 = 1; else if (GET_CODE (XVECEXP (x, 0, i)) == SET) other_things = 1; } return ! sets_cc0 ? 0 : other_things ? -1 : 1; } return 0; #else abort (); #endif } /* Follow any unconditional jump at LABEL; return the ultimate label reached by any such chain of jumps. If LABEL is not followed by a jump, return LABEL. If the chain loops or we can't find end, return LABEL, since that tells caller to avoid changing the insn. If RELOAD_COMPLETED is 0, we do not chain across a NOTE_INSN_LOOP_BEG or a USE or CLOBBER. */ rtx follow_jumps (label) rtx label; { register rtx insn; register rtx next; register rtx value = label; register int depth; for (depth = 0; (depth < 10 && (insn = next_active_insn (value)) != 0 && GET_CODE (insn) == JUMP_INSN && ((JUMP_LABEL (insn) != 0 && simplejump_p (insn)) || GET_CODE (PATTERN (insn)) == RETURN) && (next = NEXT_INSN (insn)) && GET_CODE (next) == BARRIER); depth++) { /* Don't chain through the insn that jumps into a loop from outside the loop, since that would create multiple loop entry jumps and prevent loop optimization. */ rtx tem; if (!reload_completed) for (tem = value; tem != insn; tem = NEXT_INSN (tem)) if (GET_CODE (tem) == NOTE && (NOTE_LINE_NUMBER (tem) == NOTE_INSN_LOOP_BEG /* ??? Optional. Disables some optimizations, but makes gcov output more accurate with -O. */ || (flag_test_coverage && NOTE_LINE_NUMBER (tem) > 0))) return value; /* If we have found a cycle, make the insn jump to itself. */ if (JUMP_LABEL (insn) == label) return label; tem = next_active_insn (JUMP_LABEL (insn)); if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC)) break; value = JUMP_LABEL (insn); } if (depth == 10) return label; return value; } /* Assuming that field IDX of X is a vector of label_refs, replace each of them by the ultimate label reached by it. Return nonzero if a change is made. If IGNORE_LOOPS is 0, we do not chain across a NOTE_INSN_LOOP_BEG. */ static int tension_vector_labels (x, idx) register rtx x; register int idx; { int changed = 0; register int i; for (i = XVECLEN (x, idx) - 1; i >= 0; i--) { register rtx olabel = XEXP (XVECEXP (x, idx, i), 0); register rtx nlabel = follow_jumps (olabel); if (nlabel && nlabel != olabel) { XEXP (XVECEXP (x, idx, i), 0) = nlabel; ++LABEL_NUSES (nlabel); if (--LABEL_NUSES (olabel) == 0) delete_insn (olabel); changed = 1; } } return changed; } /* Find all CODE_LABELs referred to in X, and increment their use counts. If INSN is a JUMP_INSN and there is at least one CODE_LABEL referenced in INSN, then store one of them in JUMP_LABEL (INSN). If INSN is an INSN or a CALL_INSN and there is at least one CODE_LABEL referenced in INSN, add a REG_LABEL note containing that label to INSN. Also, when there are consecutive labels, canonicalize on the last of them. Note that two labels separated by a loop-beginning note must be kept distinct if we have not yet done loop-optimization, because the gap between them is where loop-optimize will want to move invariant code to. CROSS_JUMP tells us that loop-optimization is done with. Once reload has completed (CROSS_JUMP non-zero), we need not consider two labels distinct if they are separated by only USE or CLOBBER insns. */ static void mark_jump_label (x, insn, cross_jump) register rtx x; rtx insn; int cross_jump; { register RTX_CODE code = GET_CODE (x); register int i; register char *fmt; switch (code) { case PC: case CC0: case REG: case SUBREG: case CONST_INT: case SYMBOL_REF: case CONST_DOUBLE: case CLOBBER: case CALL: return; case MEM: /* If this is a constant-pool reference, see if it is a label. */ if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0))) mark_jump_label (get_pool_constant (XEXP (x, 0)), insn, cross_jump); break; case LABEL_REF: { rtx label = XEXP (x, 0); rtx olabel = label; rtx note; rtx next; if (GET_CODE (label) != CODE_LABEL) abort (); /* Ignore references to labels of containing functions. */ if (LABEL_REF_NONLOCAL_P (x)) break; /* If there are other labels following this one, replace it with the last of the consecutive labels. */ for (next = NEXT_INSN (label); next; next = NEXT_INSN (next)) { if (GET_CODE (next) == CODE_LABEL) label = next; else if (cross_jump && GET_CODE (next) == INSN && (GET_CODE (PATTERN (next)) == USE || GET_CODE (PATTERN (next)) == CLOBBER)) continue; else if (GET_CODE (next) != NOTE) break; else if (! cross_jump && (NOTE_LINE_NUMBER (next) == NOTE_INSN_LOOP_BEG || NOTE_LINE_NUMBER (next) == NOTE_INSN_FUNCTION_END /* ??? Optional. Disables some optimizations, but makes gcov output more accurate with -O. */ || (flag_test_coverage && NOTE_LINE_NUMBER (next) > 0))) break; } XEXP (x, 0) = label; if (! insn || ! INSN_DELETED_P (insn)) ++LABEL_NUSES (label); if (insn) { if (GET_CODE (insn) == JUMP_INSN) JUMP_LABEL (insn) = label; /* If we've changed OLABEL and we had a REG_LABEL note for it, update it as well. */ else if (label != olabel && (note = find_reg_note (insn, REG_LABEL, olabel)) != 0) XEXP (note, 0) = label; /* Otherwise, add a REG_LABEL note for LABEL unless there already is one. */ else if (! find_reg_note (insn, REG_LABEL, label)) { /* This code used to ignore labels which refered to dispatch tables to avoid flow.c generating worse code. However, in the presense of global optimizations like gcse which call find_basic_blocks without calling life_analysis, not recording such labels will lead to compiler aborts because of inconsistencies in the flow graph. So we go ahead and record the label. It may also be the case that the optimization argument is no longer valid because of the more accurate cfg we build in find_basic_blocks -- it no longer pessimizes code when it finds a REG_LABEL note. */ REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, label, REG_NOTES (insn)); } } return; } /* Do walk the labels in a vector, but not the first operand of an ADDR_DIFF_VEC. Don't set the JUMP_LABEL of a vector. */ case ADDR_VEC: case ADDR_DIFF_VEC: if (! INSN_DELETED_P (insn)) { int eltnum = code == ADDR_DIFF_VEC ? 1 : 0; for (i = 0; i < XVECLEN (x, eltnum); i++) mark_jump_label (XVECEXP (x, eltnum, i), NULL_RTX, cross_jump); } return; default: break; } fmt = GET_RTX_FORMAT (code); for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) { if (fmt[i] == 'e') mark_jump_label (XEXP (x, i), insn, cross_jump); else if (fmt[i] == 'E') { register int j; for (j = 0; j < XVECLEN (x, i); j++) mark_jump_label (XVECEXP (x, i, j), insn, cross_jump); } } } /* If all INSN does is set the pc, delete it, and delete the insn that set the condition codes for it if that's what the previous thing was. */ void delete_jump (insn) rtx insn; { register rtx set = single_set (insn); if (set && GET_CODE (SET_DEST (set)) == PC) delete_computation (insn); } /* Delete INSN and recursively delete insns that compute values used only by INSN. This uses the REG_DEAD notes computed during flow analysis. If we are running before flow.c, we need do nothing since flow.c will delete dead code. We also can't know if the registers being used are dead or not at this point. Otherwise, look at all our REG_DEAD notes. If a previous insn does nothing other than set a register that dies in this insn, we can delete that insn as well. On machines with CC0, if CC0 is used in this insn, we may be able to delete the insn that set it. */ static void delete_computation (insn) rtx insn; { rtx note, next; #ifdef HAVE_cc0 if (reg_referenced_p (cc0_rtx, PATTERN (insn))) { rtx prev = prev_nonnote_insn (insn); /* We assume that at this stage CC's are always set explicitly and always immediately before the jump that will use them. So if the previous insn exists to set the CC's, delete it (unless it performs auto-increments, etc.). */ if (prev && GET_CODE (prev) == INSN && sets_cc0_p (PATTERN (prev))) { if (sets_cc0_p (PATTERN (prev)) > 0 && !FIND_REG_INC_NOTE (prev, NULL_RTX)) delete_computation (prev); else /* Otherwise, show that cc0 won't be used. */ REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED, cc0_rtx, REG_NOTES (prev)); } } #endif #ifdef INSN_SCHEDULING /* ?!? The schedulers do not keep REG_DEAD notes accurate after reload has completed. The schedulers need to be fixed. Until they are, we must not rely on the death notes here. */ if (reload_completed && flag_schedule_insns_after_reload) { delete_insn (insn); return; } #endif for (note = REG_NOTES (insn); note; note = next) { rtx our_prev; next = XEXP (note, 1); if (REG_NOTE_KIND (note) != REG_DEAD /* Verify that the REG_NOTE is legitimate. */ || GET_CODE (XEXP (note, 0)) != REG) continue; for (our_prev = prev_nonnote_insn (insn); our_prev && GET_CODE (our_prev) == INSN; our_prev = prev_nonnote_insn (our_prev)) { /* If we reach a SEQUENCE, it is too complex to try to do anything with it, so give up. */ if (GET_CODE (PATTERN (our_prev)) == SEQUENCE) break; if (GET_CODE (PATTERN (our_prev)) == USE && GET_CODE (XEXP (PATTERN (our_prev), 0)) == INSN) /* reorg creates USEs that look like this. We leave them alone because reorg needs them for its own purposes. */ break; if (reg_set_p (XEXP (note, 0), PATTERN (our_prev))) { if (FIND_REG_INC_NOTE (our_prev, NULL_RTX)) break; if (GET_CODE (PATTERN (our_prev)) == PARALLEL) { /* If we find a SET of something else, we can't delete the insn. */ int i; for (i = 0; i < XVECLEN (PATTERN (our_prev), 0); i++) { rtx part = XVECEXP (PATTERN (our_prev), 0, i); if (GET_CODE (part) == SET && SET_DEST (part) != XEXP (note, 0)) break; } if (i == XVECLEN (PATTERN (our_prev), 0)) delete_computation (our_prev); } else if (GET_CODE (PATTERN (our_prev)) == SET && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0)) delete_computation (our_prev); break; } /* If OUR_PREV references the register that dies here, it is an additional use. Hence any prior SET isn't dead. However, this insn becomes the new place for the REG_DEAD note. */ if (reg_overlap_mentioned_p (XEXP (note, 0), PATTERN (our_prev))) { XEXP (note, 1) = REG_NOTES (our_prev); REG_NOTES (our_prev) = note; break; } } } delete_insn (insn); } /* Delete insn INSN from the chain of insns and update label ref counts. May delete some following insns as a consequence; may even delete a label elsewhere and insns that follow it. Returns the first insn after INSN that was not deleted. */ rtx delete_insn (insn) register rtx insn; { register rtx next = NEXT_INSN (insn); register rtx prev = PREV_INSN (insn); register int was_code_label = (GET_CODE (insn) == CODE_LABEL); register int dont_really_delete = 0; while (next && INSN_DELETED_P (next)) next = NEXT_INSN (next); /* This insn is already deleted => return first following nondeleted. */ if (INSN_DELETED_P (insn)) return next; /* Don't delete user-declared labels. Convert them to special NOTEs instead. */ if (was_code_label && LABEL_NAME (insn) != 0 && optimize && ! dont_really_delete) { PUT_CODE (insn, NOTE); NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL; NOTE_SOURCE_FILE (insn) = 0; dont_really_delete = 1; } else /* Mark this insn as deleted. */ INSN_DELETED_P (insn) = 1; /* If this is an unconditional jump, delete it from the jump chain. */ if (simplejump_p (insn)) delete_from_jump_chain (insn); /* If instruction is followed by a barrier, delete the barrier too. */ if (next != 0 && GET_CODE (next) == BARRIER) { INSN_DELETED_P (next) = 1; next = NEXT_INSN (next); } /* Patch out INSN (and the barrier if any) */ if (optimize && ! dont_really_delete) { if (prev) { NEXT_INSN (prev) = next; if (GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SEQUENCE) NEXT_INSN (XVECEXP (PATTERN (prev), 0, XVECLEN (PATTERN (prev), 0) - 1)) = next; } if (next) { PREV_INSN (next) = prev; if (GET_CODE (next) == INSN && GET_CODE (PATTERN (next)) == SEQUENCE) PREV_INSN (XVECEXP (PATTERN (next), 0, 0)) = prev; } if (prev && NEXT_INSN (prev) == 0) set_last_insn (prev); } /* If deleting a jump, decrement the count of the label, and delete the label if it is now unused. */ if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn)) if (--LABEL_NUSES (JUMP_LABEL (insn)) == 0) { /* This can delete NEXT or PREV, either directly if NEXT is JUMP_LABEL (INSN), or indirectly through more levels of jumps. */ delete_insn (JUMP_LABEL (insn)); /* I feel a little doubtful about this loop, but I see no clean and sure alternative way to find the first insn after INSN that is not now deleted. I hope this works. */ while (next && INSN_DELETED_P (next)) next = NEXT_INSN (next); return next; } /* Likewise if we're deleting a dispatch table. */ if (GET_CODE (insn) == JUMP_INSN && (GET_CODE (PATTERN (insn)) == ADDR_VEC || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)) { rtx pat = PATTERN (insn); int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC; int len = XVECLEN (pat, diff_vec_p); for (i = 0; i < len; i++) if (--LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0) delete_insn (XEXP (XVECEXP (pat, diff_vec_p, i), 0)); while (next && INSN_DELETED_P (next)) next = NEXT_INSN (next); return next; } while (prev && (INSN_DELETED_P (prev) || GET_CODE (prev) == NOTE)) prev = PREV_INSN (prev); /* If INSN was a label and a dispatch table follows it, delete the dispatch table. The tablejump must have gone already. It isn't useful to fall through into a table. */ if (was_code_label && NEXT_INSN (insn) != 0 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC)) next = delete_insn (NEXT_INSN (insn)); /* If INSN was a label, delete insns following it if now unreachable. */ if (was_code_label && prev && GET_CODE (prev) == BARRIER) { register RTX_CODE code; while (next != 0 && (GET_RTX_CLASS (code = GET_CODE (next)) == 'i' || code == NOTE || code == BARRIER || (code == CODE_LABEL && INSN_DELETED_P (next)))) { if (code == NOTE && NOTE_LINE_NUMBER (next) != NOTE_INSN_FUNCTION_END) next = NEXT_INSN (next); /* Keep going past other deleted labels to delete what follows. */ else if (code == CODE_LABEL && INSN_DELETED_P (next)) next = NEXT_INSN (next); else /* Note: if this deletes a jump, it can cause more deletion of unreachable code, after a different label. As long as the value from this recursive call is correct, this invocation functions correctly. */ next = delete_insn (next); } } return next; } /* Advance from INSN till reaching something not deleted then return that. May return INSN itself. */ rtx next_nondeleted_insn (insn) rtx insn; { while (INSN_DELETED_P (insn)) insn = NEXT_INSN (insn); return insn; } /* Delete a range of insns from FROM to TO, inclusive. This is for the sake of peephole optimization, so assume that whatever these insns do will still be done by a new peephole insn that will replace them. */ void delete_for_peephole (from, to) register rtx from, to; { register rtx insn = from; while (1) { register rtx next = NEXT_INSN (insn); register rtx prev = PREV_INSN (insn); if (GET_CODE (insn) != NOTE) { INSN_DELETED_P (insn) = 1; /* Patch this insn out of the chain. */ /* We don't do this all at once, because we must preserve all NOTEs. */ if (prev) NEXT_INSN (prev) = next; if (next) PREV_INSN (next) = prev; } if (insn == to) break; insn = next; } /* Note that if TO is an unconditional jump we *do not* delete the BARRIER that follows, since the peephole that replaces this sequence is also an unconditional jump in that case. */ } /* Invert the condition of the jump JUMP, and make it jump to label NLABEL instead of where it jumps now. */ int invert_jump (jump, nlabel) rtx jump, nlabel; { /* We have to either invert the condition and change the label or do neither. Either operation could fail. We first try to invert the jump. If that succeeds, we try changing the label. If that fails, we invert the jump back to what it was. */ if (! invert_exp (PATTERN (jump), jump)) return 0; if (redirect_jump (jump, nlabel)) { if (flag_branch_probabilities) { rtx note = find_reg_note (jump, REG_BR_PROB, 0); /* An inverted jump means that a probability taken becomes a probability not taken. Subtract the branch probability from the probability base to convert it back to a taken probability. (We don't flip the probability on a branch that's never taken. */ if (note && XINT (XEXP (note, 0), 0) >= 0) XINT (XEXP (note, 0), 0) = REG_BR_PROB_BASE - XINT (XEXP (note, 0), 0); } return 1; } if (! invert_exp (PATTERN (jump), jump)) /* This should just be putting it back the way it was. */ abort (); return 0; } /* Invert the jump condition of rtx X contained in jump insn, INSN. Return 1 if we can do so, 0 if we cannot find a way to do so that matches a pattern. */ int invert_exp (x, insn) rtx x; rtx insn; { register RTX_CODE code; register int i; register char *fmt; code = GET_CODE (x); if (code == IF_THEN_ELSE) { register rtx comp = XEXP (x, 0); register rtx tem; /* We can do this in two ways: The preferable way, which can only be done if this is not an integer comparison, is to reverse the comparison code. Otherwise, swap the THEN-part and ELSE-part of the IF_THEN_ELSE. If we can't do either, fail. */ if (can_reverse_comparison_p (comp, insn) && validate_change (insn, &XEXP (x, 0), gen_rtx_fmt_ee (reverse_condition (GET_CODE (comp)), GET_MODE (comp), XEXP (comp, 0), XEXP (comp, 1)), 0)) return 1; tem = XEXP (x, 1); validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1); validate_change (insn, &XEXP (x, 2), tem, 1); return apply_change_group (); } fmt = GET_RTX_FORMAT (code); for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) { if (fmt[i] == 'e') if (! invert_exp (XEXP (x, i), insn)) return 0; if (fmt[i] == 'E') { register int j; for (j = 0; j < XVECLEN (x, i); j++) if (!invert_exp (XVECEXP (x, i, j), insn)) return 0; } } return 1; } /* Make jump JUMP jump to label NLABEL instead of where it jumps now. If the old jump target label is unused as a result, it and the code following it may be deleted. If NLABEL is zero, we are to turn the jump into a (possibly conditional) RETURN insn. The return value will be 1 if the change was made, 0 if it wasn't (this can only occur for NLABEL == 0). */ int redirect_jump (jump, nlabel) rtx jump, nlabel; { register rtx olabel = JUMP_LABEL (jump); if (nlabel == olabel) return 1; if (! redirect_exp (&PATTERN (jump), olabel, nlabel, jump)) return 0; /* If this is an unconditional branch, delete it from the jump_chain of OLABEL and add it to the jump_chain of NLABEL (assuming both labels have UID's in range and JUMP_CHAIN is valid). */ if (jump_chain && (simplejump_p (jump) || GET_CODE (PATTERN (jump)) == RETURN)) { int label_index = nlabel ? INSN_UID (nlabel) : 0; delete_from_jump_chain (jump); if (label_index < max_jump_chain && INSN_UID (jump) < max_jump_chain) { jump_chain[INSN_UID (jump)] = jump_chain[label_index]; jump_chain[label_index] = jump; } } JUMP_LABEL (jump) = nlabel; if (nlabel) ++LABEL_NUSES (nlabel); if (olabel && --LABEL_NUSES (olabel) == 0) delete_insn (olabel); return 1; } /* Delete the instruction JUMP from any jump chain it might be on. */ static void delete_from_jump_chain (jump) rtx jump; { int index; rtx olabel = JUMP_LABEL (jump); /* Handle unconditional jumps. */ if (jump_chain && olabel != 0 && INSN_UID (olabel) < max_jump_chain && simplejump_p (jump)) index = INSN_UID (olabel); /* Handle return insns. */ else if (jump_chain && GET_CODE (PATTERN (jump)) == RETURN) index = 0; else return; if (jump_chain[index] == jump) jump_chain[index] = jump_chain[INSN_UID (jump)]; else { rtx insn; for (insn = jump_chain[index]; insn != 0; insn = jump_chain[INSN_UID (insn)]) if (jump_chain[INSN_UID (insn)] == jump) { jump_chain[INSN_UID (insn)] = jump_chain[INSN_UID (jump)]; break; } } } /* If NLABEL is nonzero, throughout the rtx at LOC, alter (LABEL_REF OLABEL) to (LABEL_REF NLABEL). If OLABEL is zero, alter (RETURN) to (LABEL_REF NLABEL). If NLABEL is zero, alter (LABEL_REF OLABEL) to (RETURN) and check validity with validate_change. Convert (set (pc) (label_ref olabel)) to (return). Return 0 if we found a change we would like to make but it is invalid. Otherwise, return 1. */ int redirect_exp (loc, olabel, nlabel, insn) rtx *loc; rtx olabel, nlabel; rtx insn; { register rtx x = *loc; register RTX_CODE code = GET_CODE (x); register int i; register char *fmt; if (code == LABEL_REF) { if (XEXP (x, 0) == olabel) { if (nlabel) XEXP (x, 0) = nlabel; else return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0); return 1; } } else if (code == RETURN && olabel == 0) { x = gen_rtx_LABEL_REF (VOIDmode, nlabel); if (loc == &PATTERN (insn)) x = gen_rtx_SET (VOIDmode, pc_rtx, x); return validate_change (insn, loc, x, 0); } if (code == SET && nlabel == 0 && SET_DEST (x) == pc_rtx && GET_CODE (SET_SRC (x)) == LABEL_REF && XEXP (SET_SRC (x), 0) == olabel) return validate_change (insn, loc, gen_rtx_RETURN (VOIDmode), 0); fmt = GET_RTX_FORMAT (code); for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) { if (fmt[i] == 'e') if (! redirect_exp (&XEXP (x, i), olabel, nlabel, insn)) return 0; if (fmt[i] == 'E') { register int j; for (j = 0; j < XVECLEN (x, i); j++) if (! redirect_exp (&XVECEXP (x, i, j), olabel, nlabel, insn)) return 0; } } return 1; } /* Make jump JUMP jump to label NLABEL, assuming it used to be a tablejump. If the old jump target label (before the dispatch table) becomes unused, it and the dispatch table may be deleted. In that case, find the insn before the jump references that label and delete it and logical successors too. */ static void redirect_tablejump (jump, nlabel) rtx jump, nlabel; { register rtx olabel = JUMP_LABEL (jump); /* Add this jump to the jump_chain of NLABEL. */ if (jump_chain && INSN_UID (nlabel) < max_jump_chain && INSN_UID (jump) < max_jump_chain) { jump_chain[INSN_UID (jump)] = jump_chain[INSN_UID (nlabel)]; jump_chain[INSN_UID (nlabel)] = jump; } PATTERN (jump) = gen_jump (nlabel); JUMP_LABEL (jump) = nlabel; ++LABEL_NUSES (nlabel); INSN_CODE (jump) = -1; if (--LABEL_NUSES (olabel) == 0) { delete_labelref_insn (jump, olabel, 0); delete_insn (olabel); } } /* Find the insn referencing LABEL that is a logical predecessor of INSN. If we found one, delete it and then delete this insn if DELETE_THIS is non-zero. Return non-zero if INSN or a predecessor references LABEL. */ static int delete_labelref_insn (insn, label, delete_this) rtx insn, label; int delete_this; { int deleted = 0; rtx link; if (GET_CODE (insn) != NOTE && reg_mentioned_p (label, PATTERN (insn))) { if (delete_this) { delete_insn (insn); deleted = 1; } else return 1; } for (link = LOG_LINKS (insn); link; link = XEXP (link, 1)) if (delete_labelref_insn (XEXP (link, 0), label, 1)) { if (delete_this) { delete_insn (insn); deleted = 1; } else return 1; } return deleted; } /* Like rtx_equal_p except that it considers two REGs as equal if they renumber to the same value and considers two commutative operations to be the same if the order of the operands has been reversed. */ int rtx_renumbered_equal_p (x, y) rtx x, y; { register int i; register RTX_CODE code = GET_CODE (x); register char *fmt; if (x == y) return 1; if ((code == REG || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG)) && (GET_CODE (y) == REG || (GET_CODE (y) == SUBREG && GET_CODE (SUBREG_REG (y)) == REG))) { int reg_x = -1, reg_y = -1; int word_x = 0, word_y = 0; if (GET_MODE (x) != GET_MODE (y)) return 0; /* If we haven't done any renumbering, don't make any assumptions. */ if (reg_renumber == 0) return rtx_equal_p (x, y); if (code == SUBREG) { reg_x = REGNO (SUBREG_REG (x)); word_x = SUBREG_WORD (x); if (reg_renumber[reg_x] >= 0) { reg_x = reg_renumber[reg_x] + word_x; word_x = 0; } } else { reg_x = REGNO (x); if (reg_renumber[reg_x] >= 0) reg_x = reg_renumber[reg_x]; } if (GET_CODE (y) == SUBREG) { reg_y = REGNO (SUBREG_REG (y)); word_y = SUBREG_WORD (y); if (reg_renumber[reg_y] >= 0) { reg_y = reg_renumber[reg_y]; word_y = 0; } } else { reg_y = REGNO (y); if (reg_renumber[reg_y] >= 0) reg_y = reg_renumber[reg_y]; } return reg_x >= 0 && reg_x == reg_y && word_x == word_y; } /* Now we have disposed of all the cases in which different rtx codes can match. */ if (code != GET_CODE (y)) return 0; switch (code) { case PC: case CC0: case ADDR_VEC: case ADDR_DIFF_VEC: return 0; case CONST_INT: return INTVAL (x) == INTVAL (y); case LABEL_REF: /* We can't assume nonlocal labels have their following insns yet. */ if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y)) return XEXP (x, 0) == XEXP (y, 0); /* Two label-refs are equivalent if they point at labels in the same position in the instruction stream. */ return (next_real_insn (XEXP (x, 0)) == next_real_insn (XEXP (y, 0))); case SYMBOL_REF: return XSTR (x, 0) == XSTR (y, 0); case CODE_LABEL: /* If we didn't match EQ equality above, they aren't the same. */ return 0; default: break; } /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */ if (GET_MODE (x) != GET_MODE (y)) return 0; /* For commutative operations, the RTX match if the operand match in any order. Also handle the simple binary and unary cases without a loop. */ if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c') return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0)) && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1))) || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1)) && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0)))); else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2') return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0)) && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1))); else if (GET_RTX_CLASS (code) == '1') return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0)); /* Compare the elements. If any pair of corresponding elements fail to match, return 0 for the whole things. */ fmt = GET_RTX_FORMAT (code); for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) { register int j; switch (fmt[i]) { case 'w': if (XWINT (x, i) != XWINT (y, i)) return 0; break; case 'i': if (XINT (x, i) != XINT (y, i)) return 0; break; case 's': if (strcmp (XSTR (x, i), XSTR (y, i))) return 0; break; case 'e': if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i))) return 0; break; case 'u': if (XEXP (x, i) != XEXP (y, i)) return 0; /* fall through. */ case '0': break; case 'E': if (XVECLEN (x, i) != XVECLEN (y, i)) return 0; for (j = XVECLEN (x, i) - 1; j >= 0; j--) if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j))) return 0; break; default: abort (); } } return 1; } /* If X is a hard register or equivalent to one or a subregister of one, return the hard register number. If X is a pseudo register that was not assigned a hard register, return the pseudo register number. Otherwise, return -1. Any rtx is valid for X. */ int true_regnum (x) rtx x; { if (GET_CODE (x) == REG) { if (REGNO (x) >= FIRST_PSEUDO_REGISTER && reg_renumber[REGNO (x)] >= 0) return reg_renumber[REGNO (x)]; return REGNO (x); } if (GET_CODE (x) == SUBREG) { int base = true_regnum (SUBREG_REG (x)); if (base >= 0 && base < FIRST_PSEUDO_REGISTER) return SUBREG_WORD (x) + base; } return -1; } /* Optimize code of the form: for (x = a[i]; x; ...) ... for (x = a[i]; x; ...) ... foo: Loop optimize will change the above code into if (x = a[i]) for (;;) { ...; if (! (x = ...)) break; } if (x = a[i]) for (;;) { ...; if (! (x = ...)) break; } foo: In general, if the first test fails, the program can branch directly to `foo' and skip the second try which is doomed to fail. We run this after loop optimization and before flow analysis. */ /* When comparing the insn patterns, we track the fact that different pseudo-register numbers may have been used in each computation. The following array stores an equivalence -- same_regs[I] == J means that pseudo register I was used in the first set of tests in a context where J was used in the second set. We also count the number of such pending equivalences. If nonzero, the expressions really aren't the same. */ static int *same_regs; static int num_same_regs; /* Track any registers modified between the target of the first jump and the second jump. They never compare equal. */ static char *modified_regs; /* Record if memory was modified. */ static int modified_mem; /* Called via note_stores on each insn between the target of the first branch and the second branch. It marks any changed registers. */ static void mark_modified_reg (dest, x) rtx dest; rtx x ATTRIBUTE_UNUSED; { int regno, i; if (GET_CODE (dest) == SUBREG) dest = SUBREG_REG (dest); if (GET_CODE (dest) == MEM) modified_mem = 1; if (GET_CODE (dest) != REG) return; regno = REGNO (dest); if (regno >= FIRST_PSEUDO_REGISTER) modified_regs[regno] = 1; else for (i = 0; i < HARD_REGNO_NREGS (regno, GET_MODE (dest)); i++) modified_regs[regno + i] = 1; } /* F is the first insn in the chain of insns. */ void thread_jumps (f, max_reg, flag_before_loop) rtx f; int max_reg; int flag_before_loop; { /* Basic algorithm is to find a conditional branch, the label it may branch to, and the branch after that label. If the two branches test the same condition, walk back from both branch paths until the insn patterns differ, or code labels are hit. If we make it back to the target of the first branch, then we know that the first branch will either always succeed or always fail depending on the relative senses of the two branches. So adjust the first branch accordingly in this case. */ rtx label, b1, b2, t1, t2; enum rtx_code code1, code2; rtx b1op0, b1op1, b2op0, b2op1; int changed = 1; int i; int *all_reset; /* Allocate register tables and quick-reset table. */ modified_regs = (char *) alloca (max_reg * sizeof (char)); same_regs = (int *) alloca (max_reg * sizeof (int)); all_reset = (int *) alloca (max_reg * sizeof (int)); for (i = 0; i < max_reg; i++) all_reset[i] = -1; while (changed) { changed = 0; for (b1 = f; b1; b1 = NEXT_INSN (b1)) { /* Get to a candidate branch insn. */ if (GET_CODE (b1) != JUMP_INSN || ! condjump_p (b1) || simplejump_p (b1) || JUMP_LABEL (b1) == 0) continue; bzero (modified_regs, max_reg * sizeof (char)); modified_mem = 0; bcopy ((char *) all_reset, (char *) same_regs, max_reg * sizeof (int)); num_same_regs = 0; label = JUMP_LABEL (b1); /* Look for a branch after the target. Record any registers and memory modified between the target and the branch. Stop when we get to a label since we can't know what was changed there. */ for (b2 = NEXT_INSN (label); b2; b2 = NEXT_INSN (b2)) { if (GET_CODE (b2) == CODE_LABEL) break; else if (GET_CODE (b2) == JUMP_INSN) { /* If this is an unconditional jump and is the only use of its target label, we can follow it. */ if (simplejump_p (b2) && JUMP_LABEL (b2) != 0 && LABEL_NUSES (JUMP_LABEL (b2)) == 1) { b2 = JUMP_LABEL (b2); continue; } else break; } if (GET_CODE (b2) != CALL_INSN && GET_CODE (b2) != INSN) continue; if (GET_CODE (b2) == CALL_INSN) { modified_mem = 1; for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) if (call_used_regs[i] && ! fixed_regs[i] && i != STACK_POINTER_REGNUM && i != FRAME_POINTER_REGNUM && i != HARD_FRAME_POINTER_REGNUM && i != ARG_POINTER_REGNUM) modified_regs[i] = 1; } note_stores (PATTERN (b2), mark_modified_reg); } /* Check the next candidate branch insn from the label of the first. */ if (b2 == 0 || GET_CODE (b2) != JUMP_INSN || b2 == b1 || ! condjump_p (b2) || simplejump_p (b2)) continue; /* Get the comparison codes and operands, reversing the codes if appropriate. If we don't have comparison codes, we can't do anything. */ b1op0 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 0); b1op1 = XEXP (XEXP (SET_SRC (PATTERN (b1)), 0), 1); code1 = GET_CODE (XEXP (SET_SRC (PATTERN (b1)), 0)); if (XEXP (SET_SRC (PATTERN (b1)), 1) == pc_rtx) code1 = reverse_condition (code1); b2op0 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 0); b2op1 = XEXP (XEXP (SET_SRC (PATTERN (b2)), 0), 1); code2 = GET_CODE (XEXP (SET_SRC (PATTERN (b2)), 0)); if (XEXP (SET_SRC (PATTERN (b2)), 1) == pc_rtx) code2 = reverse_condition (code2); /* If they test the same things and knowing that B1 branches tells us whether or not B2 branches, check if we can thread the branch. */ if (rtx_equal_for_thread_p (b1op0, b2op0, b2) && rtx_equal_for_thread_p (b1op1, b2op1, b2) && (comparison_dominates_p (code1, code2) || (comparison_dominates_p (code1, reverse_condition (code2)) && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (b1)), 0), b1)))) { t1 = prev_nonnote_insn (b1); t2 = prev_nonnote_insn (b2); while (t1 != 0 && t2 != 0) { if (t2 == label) { /* We have reached the target of the first branch. If there are no pending register equivalents, we know that this branch will either always succeed (if the senses of the two branches are the same) or always fail (if not). */ rtx new_label; if (num_same_regs != 0) break; if (comparison_dominates_p (code1, code2)) new_label = JUMP_LABEL (b2); else new_label = get_label_after (b2); if (JUMP_LABEL (b1) != new_label) { rtx prev = PREV_INSN (new_label); if (flag_before_loop && GET_CODE (prev) == NOTE && NOTE_LINE_NUMBER (prev) == NOTE_INSN_LOOP_BEG) { /* Don't thread to the loop label. If a loop label is reused, loop optimization will be disabled for that loop. */ new_label = gen_label_rtx (); emit_label_after (new_label, PREV_INSN (prev)); } changed |= redirect_jump (b1, new_label); } break; } /* If either of these is not a normal insn (it might be a JUMP_INSN, CALL_INSN, or CODE_LABEL) we fail. (NOTEs have already been skipped above.) Similarly, fail if the insns are different. */ if (GET_CODE (t1) != INSN || GET_CODE (t2) != INSN || recog_memoized (t1) != recog_memoized (t2) || ! rtx_equal_for_thread_p (PATTERN (t1), PATTERN (t2), t2)) break; t1 = prev_nonnote_insn (t1); t2 = prev_nonnote_insn (t2); } } } } } /* This is like RTX_EQUAL_P except that it knows about our handling of possibly equivalent registers and knows to consider volatile and modified objects as not equal. YINSN is the insn containing Y. */ int rtx_equal_for_thread_p (x, y, yinsn) rtx x, y; rtx yinsn; { register int i; register int j; register enum rtx_code code; register char *fmt; code = GET_CODE (x); /* Rtx's of different codes cannot be equal. */ if (code != GET_CODE (y)) return 0; /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. (REG:SI x) and (REG:HI x) are NOT equivalent. */ if (GET_MODE (x) != GET_MODE (y)) return 0; /* For floating-point, consider everything unequal. This is a bit pessimistic, but this pass would only rarely do anything for FP anyway. */ if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT && FLOAT_MODE_P (GET_MODE (x)) && ! flag_fast_math) return 0; /* For commutative operations, the RTX match if the operand match in any order. Also handle the simple binary and unary cases without a loop. */ if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c') return ((rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn) && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn)) || (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 1), yinsn) && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 0), yinsn))); else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2') return (rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn) && rtx_equal_for_thread_p (XEXP (x, 1), XEXP (y, 1), yinsn)); else if (GET_RTX_CLASS (code) == '1') return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn); /* Handle special-cases first. */ switch (code) { case REG: if (REGNO (x) == REGNO (y) && ! modified_regs[REGNO (x)]) return 1; /* If neither is user variable or hard register, check for possible equivalence. */ if (REG_USERVAR_P (x) || REG_USERVAR_P (y) || REGNO (x) < FIRST_PSEUDO_REGISTER || REGNO (y) < FIRST_PSEUDO_REGISTER) return 0; if (same_regs[REGNO (x)] == -1) { same_regs[REGNO (x)] = REGNO (y); num_same_regs++; /* If this is the first time we are seeing a register on the `Y' side, see if it is the last use. If not, we can't thread the jump, so mark it as not equivalent. */ if (REGNO_LAST_UID (REGNO (y)) != INSN_UID (yinsn)) return 0; return 1; } else return (same_regs[REGNO (x)] == REGNO (y)); break; case MEM: /* If memory modified or either volatile, not equivalent. Else, check address. */ if (modified_mem || MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y)) return 0; return rtx_equal_for_thread_p (XEXP (x, 0), XEXP (y, 0), yinsn); case ASM_INPUT: if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y)) return 0; break; case SET: /* Cancel a pending `same_regs' if setting equivalenced registers. Then process source. */ if (GET_CODE (SET_DEST (x)) == REG && GET_CODE (SET_DEST (y)) == REG) { if (same_regs[REGNO (SET_DEST (x))] == REGNO (SET_DEST (y))) { same_regs[REGNO (SET_DEST (x))] = -1; num_same_regs--; } else if (REGNO (SET_DEST (x)) != REGNO (SET_DEST (y))) return 0; } else if (rtx_equal_for_thread_p (SET_DEST (x), SET_DEST (y), yinsn) == 0) return 0; return rtx_equal_for_thread_p (SET_SRC (x), SET_SRC (y), yinsn); case LABEL_REF: return XEXP (x, 0) == XEXP (y, 0); case SYMBOL_REF: return XSTR (x, 0) == XSTR (y, 0); default: break; } if (x == y) return 1; fmt = GET_RTX_FORMAT (code); for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) { switch (fmt[i]) { case 'w': if (XWINT (x, i) != XWINT (y, i)) return 0; break; case 'n': case 'i': if (XINT (x, i) != XINT (y, i)) return 0; break; case 'V': case 'E': /* Two vectors must have the same length. */ if (XVECLEN (x, i) != XVECLEN (y, i)) return 0; /* And the corresponding elements must match. */ for (j = 0; j < XVECLEN (x, i); j++) if (rtx_equal_for_thread_p (XVECEXP (x, i, j), XVECEXP (y, i, j), yinsn) == 0) return 0; break; case 'e': if (rtx_equal_for_thread_p (XEXP (x, i), XEXP (y, i), yinsn) == 0) return 0; break; case 'S': case 's': if (strcmp (XSTR (x, i), XSTR (y, i))) return 0; break; case 'u': /* These are just backpointers, so they don't matter. */ break; case '0': break; /* It is believed that rtx's at this level will never contain anything but integers and other rtx's, except for within LABEL_REFs and SYMBOL_REFs. */ default: abort (); } } return 1; } #ifndef HAVE_cc0 /* Return the insn that NEW can be safely inserted in front of starting at the jump insn INSN. Return 0 if it is not safe to do this jump optimization. Note that NEW must contain a single set. */ static rtx find_insert_position (insn, new) rtx insn; rtx new; { int i; rtx prev; /* If NEW does not clobber, it is safe to insert NEW before INSN. */ if (GET_CODE (PATTERN (new)) != PARALLEL) return insn; for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--) if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0), insn)) break; if (i < 0) return insn; /* There is a good chance that the previous insn PREV sets the thing being clobbered (often the CC in a hard reg). If PREV does not use what NEW sets, we can insert NEW before PREV. */ prev = prev_active_insn (insn); for (i = XVECLEN (PATTERN (new), 0) - 1; i >= 0; i--) if (GET_CODE (XVECEXP (PATTERN (new), 0, i)) == CLOBBER && reg_overlap_mentioned_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0), insn) && ! modified_in_p (XEXP (XVECEXP (PATTERN (new), 0, i), 0), prev)) return 0; return reg_mentioned_p (SET_DEST (single_set (new)), prev) ? 0 : prev; } #endif /* !HAVE_cc0 */