b0b8ac17fb
44 GCC PR's listed below (some have already been applied to NetBSD GCC) and at least one NetBSD PR: PR bootstrap/28400 PR c++/27369 PR c/25795 PR c/25993 PR c/29092 PR c/29736 PR c/30360 PR debug/26964 PR libstdc++/11953 PR middle-end/21032 PR middle-end/26306 PR middle-end/27826 PR middle-end/28116 PR middle-end/29241 PR middle-end/29250 PR middle-end/29584 PR middle-end/29695 PR middle-end/29753 PR middle-end/30286 PR rtl-optimization/25514 PR rtl-optimization/27736 PR rtl-optimization/27761 PR rtl-optimization/28970 PR rtl-optimization/29631 PR rtl-optimization/29797 PR target/18553 PR target/24036 PR target/29114 PR target/29319 PR target/29377 PR target/29449 PR target/30039 PR target/30173 PR target/30185 PR target/30230 PR tree-opt/28545 PR tree-opt/29788 PR tree-opt/29964 PR tree-optimization/27891 PR tree-optimization/28888 PR tree-optimization/29581 PR tree-optimization/29610 PR tree-optimization/29637 PR tree-optimization/30212
3409 lines
107 KiB
C
3409 lines
107 KiB
C
/* SSA Dominator optimizations for trees
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Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
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Contributed by Diego Novillo <dnovillo@redhat.com>
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GCC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to
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the Free Software Foundation, 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA. */
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "tree.h"
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#include "flags.h"
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#include "rtl.h"
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#include "tm_p.h"
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#include "ggc.h"
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#include "basic-block.h"
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#include "cfgloop.h"
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#include "output.h"
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#include "expr.h"
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#include "function.h"
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#include "diagnostic.h"
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#include "timevar.h"
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#include "tree-dump.h"
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#include "tree-flow.h"
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#include "domwalk.h"
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#include "real.h"
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#include "tree-pass.h"
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#include "tree-ssa-propagate.h"
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#include "langhooks.h"
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#include "params.h"
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/* This file implements optimizations on the dominator tree. */
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/* Structure for recording edge equivalences as well as any pending
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edge redirections during the dominator optimizer.
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Computing and storing the edge equivalences instead of creating
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them on-demand can save significant amounts of time, particularly
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for pathological cases involving switch statements.
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These structures live for a single iteration of the dominator
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optimizer in the edge's AUX field. At the end of an iteration we
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free each of these structures and update the AUX field to point
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to any requested redirection target (the code for updating the
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CFG and SSA graph for edge redirection expects redirection edge
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targets to be in the AUX field for each edge. */
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struct edge_info
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{
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/* If this edge creates a simple equivalence, the LHS and RHS of
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the equivalence will be stored here. */
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tree lhs;
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tree rhs;
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/* Traversing an edge may also indicate one or more particular conditions
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are true or false. The number of recorded conditions can vary, but
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can be determined by the condition's code. So we have an array
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and its maximum index rather than use a varray. */
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tree *cond_equivalences;
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unsigned int max_cond_equivalences;
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/* If we can thread this edge this field records the new target. */
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edge redirection_target;
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};
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/* Hash table with expressions made available during the renaming process.
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When an assignment of the form X_i = EXPR is found, the statement is
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stored in this table. If the same expression EXPR is later found on the
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RHS of another statement, it is replaced with X_i (thus performing
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global redundancy elimination). Similarly as we pass through conditionals
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we record the conditional itself as having either a true or false value
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in this table. */
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static htab_t avail_exprs;
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/* Stack of available expressions in AVAIL_EXPRs. Each block pushes any
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expressions it enters into the hash table along with a marker entry
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(null). When we finish processing the block, we pop off entries and
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remove the expressions from the global hash table until we hit the
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marker. */
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static VEC(tree,heap) *avail_exprs_stack;
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/* Stack of statements we need to rescan during finalization for newly
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exposed variables.
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Statement rescanning must occur after the current block's available
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expressions are removed from AVAIL_EXPRS. Else we may change the
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hash code for an expression and be unable to find/remove it from
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AVAIL_EXPRS. */
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static VEC(tree,heap) *stmts_to_rescan;
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/* Structure for entries in the expression hash table.
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This requires more memory for the hash table entries, but allows us
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to avoid creating silly tree nodes and annotations for conditionals,
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eliminates 2 global hash tables and two block local varrays.
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It also allows us to reduce the number of hash table lookups we
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have to perform in lookup_avail_expr and finally it allows us to
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significantly reduce the number of calls into the hashing routine
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itself. */
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struct expr_hash_elt
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{
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/* The value (lhs) of this expression. */
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tree lhs;
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/* The expression (rhs) we want to record. */
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tree rhs;
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/* The stmt pointer if this element corresponds to a statement. */
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tree stmt;
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/* The hash value for RHS/ann. */
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hashval_t hash;
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};
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/* Stack of dest,src pairs that need to be restored during finalization.
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A NULL entry is used to mark the end of pairs which need to be
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restored during finalization of this block. */
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static VEC(tree,heap) *const_and_copies_stack;
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/* Bitmap of SSA_NAMEs known to have a nonzero value, even if we do not
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know their exact value. */
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static bitmap nonzero_vars;
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/* Bitmap of blocks that are scheduled to be threaded through. This
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is used to communicate with thread_through_blocks. */
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static bitmap threaded_blocks;
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/* Stack of SSA_NAMEs which need their NONZERO_VARS property cleared
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when the current block is finalized.
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A NULL entry is used to mark the end of names needing their
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entry in NONZERO_VARS cleared during finalization of this block. */
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static VEC(tree,heap) *nonzero_vars_stack;
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/* Track whether or not we have changed the control flow graph. */
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static bool cfg_altered;
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/* Bitmap of blocks that have had EH statements cleaned. We should
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remove their dead edges eventually. */
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static bitmap need_eh_cleanup;
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/* Statistics for dominator optimizations. */
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struct opt_stats_d
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{
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long num_stmts;
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long num_exprs_considered;
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long num_re;
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long num_const_prop;
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long num_copy_prop;
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long num_iterations;
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};
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static struct opt_stats_d opt_stats;
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/* Value range propagation record. Each time we encounter a conditional
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of the form SSA_NAME COND CONST we create a new vrp_element to record
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how the condition affects the possible values SSA_NAME may have.
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Each record contains the condition tested (COND), and the range of
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values the variable may legitimately have if COND is true. Note the
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range of values may be a smaller range than COND specifies if we have
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recorded other ranges for this variable. Each record also contains the
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block in which the range was recorded for invalidation purposes.
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Note that the current known range is computed lazily. This allows us
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to avoid the overhead of computing ranges which are never queried.
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When we encounter a conditional, we look for records which constrain
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the SSA_NAME used in the condition. In some cases those records allow
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us to determine the condition's result at compile time. In other cases
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they may allow us to simplify the condition.
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We also use value ranges to do things like transform signed div/mod
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operations into unsigned div/mod or to simplify ABS_EXPRs.
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Simple experiments have shown these optimizations to not be all that
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useful on switch statements (much to my surprise). So switch statement
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optimizations are not performed.
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Note carefully we do not propagate information through each statement
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in the block. i.e., if we know variable X has a value defined of
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[0, 25] and we encounter Y = X + 1, we do not track a value range
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for Y (which would be [1, 26] if we cared). Similarly we do not
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constrain values as we encounter narrowing typecasts, etc. */
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struct vrp_element
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{
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/* The highest and lowest values the variable in COND may contain when
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COND is true. Note this may not necessarily be the same values
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tested by COND if the same variable was used in earlier conditionals.
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Note this is computed lazily and thus can be NULL indicating that
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the values have not been computed yet. */
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tree low;
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tree high;
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/* The actual conditional we recorded. This is needed since we compute
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ranges lazily. */
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tree cond;
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/* The basic block where this record was created. We use this to determine
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when to remove records. */
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basic_block bb;
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};
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/* A hash table holding value range records (VRP_ELEMENTs) for a given
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SSA_NAME. We used to use a varray indexed by SSA_NAME_VERSION, but
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that gets awful wasteful, particularly since the density objects
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with useful information is very low. */
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static htab_t vrp_data;
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typedef struct vrp_element *vrp_element_p;
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DEF_VEC_P(vrp_element_p);
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DEF_VEC_ALLOC_P(vrp_element_p,heap);
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/* An entry in the VRP_DATA hash table. We record the variable and a
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varray of VRP_ELEMENT records associated with that variable. */
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struct vrp_hash_elt
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{
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tree var;
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VEC(vrp_element_p,heap) *records;
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};
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/* Array of variables which have their values constrained by operations
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in this basic block. We use this during finalization to know
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which variables need their VRP data updated. */
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/* Stack of SSA_NAMEs which had their values constrained by operations
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in this basic block. During finalization of this block we use this
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list to determine which variables need their VRP data updated.
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A NULL entry marks the end of the SSA_NAMEs associated with this block. */
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static VEC(tree,heap) *vrp_variables_stack;
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struct eq_expr_value
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{
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tree src;
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tree dst;
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};
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/* Local functions. */
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static void optimize_stmt (struct dom_walk_data *,
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basic_block bb,
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block_stmt_iterator);
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static tree lookup_avail_expr (tree, bool);
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static hashval_t vrp_hash (const void *);
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static int vrp_eq (const void *, const void *);
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static hashval_t avail_expr_hash (const void *);
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static hashval_t real_avail_expr_hash (const void *);
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static int avail_expr_eq (const void *, const void *);
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static void htab_statistics (FILE *, htab_t);
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static void record_cond (tree, tree);
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static void record_const_or_copy (tree, tree);
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static void record_equality (tree, tree);
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static tree update_rhs_and_lookup_avail_expr (tree, tree, bool);
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static tree simplify_rhs_and_lookup_avail_expr (tree, int);
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static tree simplify_cond_and_lookup_avail_expr (tree, stmt_ann_t, int);
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static tree simplify_switch_and_lookup_avail_expr (tree, int);
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static tree find_equivalent_equality_comparison (tree);
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static void record_range (tree, basic_block);
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static bool extract_range_from_cond (tree, tree *, tree *, int *);
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static void record_equivalences_from_phis (basic_block);
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static void record_equivalences_from_incoming_edge (basic_block);
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static bool eliminate_redundant_computations (tree, stmt_ann_t);
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static void record_equivalences_from_stmt (tree, int, stmt_ann_t);
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static void thread_across_edge (struct dom_walk_data *, edge);
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static void dom_opt_finalize_block (struct dom_walk_data *, basic_block);
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static void dom_opt_initialize_block (struct dom_walk_data *, basic_block);
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static void propagate_to_outgoing_edges (struct dom_walk_data *, basic_block);
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static void remove_local_expressions_from_table (void);
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static void restore_vars_to_original_value (void);
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static edge single_incoming_edge_ignoring_loop_edges (basic_block);
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static void restore_nonzero_vars_to_original_value (void);
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static inline bool unsafe_associative_fp_binop (tree);
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/* Local version of fold that doesn't introduce cruft. */
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static tree
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local_fold (tree t)
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{
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t = fold (t);
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/* Strip away useless type conversions. Both the NON_LVALUE_EXPR that
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may have been added by fold, and "useless" type conversions that might
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now be apparent due to propagation. */
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STRIP_USELESS_TYPE_CONVERSION (t);
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return t;
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}
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/* Allocate an EDGE_INFO for edge E and attach it to E.
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Return the new EDGE_INFO structure. */
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static struct edge_info *
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allocate_edge_info (edge e)
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{
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struct edge_info *edge_info;
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edge_info = xcalloc (1, sizeof (struct edge_info));
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e->aux = edge_info;
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return edge_info;
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}
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/* Free all EDGE_INFO structures associated with edges in the CFG.
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If a particular edge can be threaded, copy the redirection
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target from the EDGE_INFO structure into the edge's AUX field
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as required by code to update the CFG and SSA graph for
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jump threading. */
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static void
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free_all_edge_infos (void)
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{
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basic_block bb;
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edge_iterator ei;
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edge e;
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FOR_EACH_BB (bb)
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{
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FOR_EACH_EDGE (e, ei, bb->preds)
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{
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struct edge_info *edge_info = e->aux;
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if (edge_info)
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{
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e->aux = edge_info->redirection_target;
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if (edge_info->cond_equivalences)
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free (edge_info->cond_equivalences);
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free (edge_info);
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}
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}
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}
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}
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/* Free an instance of vrp_hash_elt. */
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static void
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vrp_free (void *data)
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{
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struct vrp_hash_elt *elt = data;
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struct VEC(vrp_element_p,heap) **vrp_elt = &elt->records;
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VEC_free (vrp_element_p, heap, *vrp_elt);
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free (elt);
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}
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/* Jump threading, redundancy elimination and const/copy propagation.
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This pass may expose new symbols that need to be renamed into SSA. For
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every new symbol exposed, its corresponding bit will be set in
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VARS_TO_RENAME. */
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static void
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tree_ssa_dominator_optimize (void)
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{
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struct dom_walk_data walk_data;
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unsigned int i;
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struct loops loops_info;
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memset (&opt_stats, 0, sizeof (opt_stats));
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/* Create our hash tables. */
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avail_exprs = htab_create (1024, real_avail_expr_hash, avail_expr_eq, free);
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vrp_data = htab_create (ceil_log2 (num_ssa_names), vrp_hash, vrp_eq,
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vrp_free);
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avail_exprs_stack = VEC_alloc (tree, heap, 20);
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const_and_copies_stack = VEC_alloc (tree, heap, 20);
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nonzero_vars_stack = VEC_alloc (tree, heap, 20);
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vrp_variables_stack = VEC_alloc (tree, heap, 20);
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stmts_to_rescan = VEC_alloc (tree, heap, 20);
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nonzero_vars = BITMAP_ALLOC (NULL);
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threaded_blocks = BITMAP_ALLOC (NULL);
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need_eh_cleanup = BITMAP_ALLOC (NULL);
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/* Setup callbacks for the generic dominator tree walker. */
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walk_data.walk_stmts_backward = false;
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walk_data.dom_direction = CDI_DOMINATORS;
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walk_data.initialize_block_local_data = NULL;
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walk_data.before_dom_children_before_stmts = dom_opt_initialize_block;
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walk_data.before_dom_children_walk_stmts = optimize_stmt;
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walk_data.before_dom_children_after_stmts = propagate_to_outgoing_edges;
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walk_data.after_dom_children_before_stmts = NULL;
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walk_data.after_dom_children_walk_stmts = NULL;
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walk_data.after_dom_children_after_stmts = dom_opt_finalize_block;
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/* Right now we only attach a dummy COND_EXPR to the global data pointer.
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When we attach more stuff we'll need to fill this out with a real
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structure. */
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walk_data.global_data = NULL;
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walk_data.block_local_data_size = 0;
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walk_data.interesting_blocks = NULL;
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/* Now initialize the dominator walker. */
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init_walk_dominator_tree (&walk_data);
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calculate_dominance_info (CDI_DOMINATORS);
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/* We need to know which edges exit loops so that we can
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aggressively thread through loop headers to an exit
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edge. */
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flow_loops_find (&loops_info);
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mark_loop_exit_edges (&loops_info);
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flow_loops_free (&loops_info);
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/* Clean up the CFG so that any forwarder blocks created by loop
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canonicalization are removed. */
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cleanup_tree_cfg ();
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calculate_dominance_info (CDI_DOMINATORS);
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/* If we prove certain blocks are unreachable, then we want to
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repeat the dominator optimization process as PHI nodes may
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have turned into copies which allows better propagation of
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values. So we repeat until we do not identify any new unreachable
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blocks. */
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do
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{
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/* Optimize the dominator tree. */
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cfg_altered = false;
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/* We need accurate information regarding back edges in the CFG
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for jump threading. */
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mark_dfs_back_edges ();
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/* Recursively walk the dominator tree optimizing statements. */
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walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
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{
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block_stmt_iterator bsi;
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basic_block bb;
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FOR_EACH_BB (bb)
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{
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for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
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{
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update_stmt_if_modified (bsi_stmt (bsi));
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}
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}
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}
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/* If we exposed any new variables, go ahead and put them into
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SSA form now, before we handle jump threading. This simplifies
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interactions between rewriting of _DECL nodes into SSA form
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and rewriting SSA_NAME nodes into SSA form after block
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duplication and CFG manipulation. */
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update_ssa (TODO_update_ssa);
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free_all_edge_infos ();
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/* Thread jumps, creating duplicate blocks as needed. */
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cfg_altered |= thread_through_all_blocks (threaded_blocks);
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/* Removal of statements may make some EH edges dead. Purge
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such edges from the CFG as needed. */
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if (!bitmap_empty_p (need_eh_cleanup))
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{
|
|
cfg_altered |= tree_purge_all_dead_eh_edges (need_eh_cleanup);
|
|
bitmap_zero (need_eh_cleanup);
|
|
}
|
|
|
|
if (cfg_altered)
|
|
free_dominance_info (CDI_DOMINATORS);
|
|
|
|
/* Only iterate if we threaded jumps AND the CFG cleanup did
|
|
something interesting. Other cases generate far fewer
|
|
optimization opportunities and thus are not worth another
|
|
full DOM iteration. */
|
|
cfg_altered &= cleanup_tree_cfg ();
|
|
|
|
if (rediscover_loops_after_threading)
|
|
{
|
|
/* Rerun basic loop analysis to discover any newly
|
|
created loops and update the set of exit edges. */
|
|
rediscover_loops_after_threading = false;
|
|
flow_loops_find (&loops_info);
|
|
mark_loop_exit_edges (&loops_info);
|
|
flow_loops_free (&loops_info);
|
|
|
|
/* Remove any forwarder blocks inserted by loop
|
|
header canonicalization. */
|
|
cleanup_tree_cfg ();
|
|
}
|
|
|
|
calculate_dominance_info (CDI_DOMINATORS);
|
|
|
|
update_ssa (TODO_update_ssa);
|
|
|
|
/* Reinitialize the various tables. */
|
|
bitmap_clear (nonzero_vars);
|
|
bitmap_clear (threaded_blocks);
|
|
htab_empty (avail_exprs);
|
|
htab_empty (vrp_data);
|
|
|
|
/* Finally, remove everything except invariants in SSA_NAME_VALUE.
|
|
|
|
This must be done before we iterate as we might have a
|
|
reference to an SSA_NAME which was removed by the call to
|
|
update_ssa.
|
|
|
|
Long term we will be able to let everything in SSA_NAME_VALUE
|
|
persist. However, for now, we know this is the safe thing to do. */
|
|
for (i = 0; i < num_ssa_names; i++)
|
|
{
|
|
tree name = ssa_name (i);
|
|
tree value;
|
|
|
|
if (!name)
|
|
continue;
|
|
|
|
value = SSA_NAME_VALUE (name);
|
|
if (value && !is_gimple_min_invariant (value))
|
|
SSA_NAME_VALUE (name) = NULL;
|
|
}
|
|
|
|
opt_stats.num_iterations++;
|
|
}
|
|
while (optimize > 1 && cfg_altered);
|
|
|
|
/* Debugging dumps. */
|
|
if (dump_file && (dump_flags & TDF_STATS))
|
|
dump_dominator_optimization_stats (dump_file);
|
|
|
|
/* We emptied the hash table earlier, now delete it completely. */
|
|
htab_delete (avail_exprs);
|
|
htab_delete (vrp_data);
|
|
|
|
/* It is not necessary to clear CURRDEFS, REDIRECTION_EDGES, VRP_DATA,
|
|
CONST_AND_COPIES, and NONZERO_VARS as they all get cleared at the bottom
|
|
of the do-while loop above. */
|
|
|
|
/* And finalize the dominator walker. */
|
|
fini_walk_dominator_tree (&walk_data);
|
|
|
|
/* Free nonzero_vars. */
|
|
BITMAP_FREE (nonzero_vars);
|
|
BITMAP_FREE (threaded_blocks);
|
|
BITMAP_FREE (need_eh_cleanup);
|
|
|
|
VEC_free (tree, heap, avail_exprs_stack);
|
|
VEC_free (tree, heap, const_and_copies_stack);
|
|
VEC_free (tree, heap, nonzero_vars_stack);
|
|
VEC_free (tree, heap, vrp_variables_stack);
|
|
VEC_free (tree, heap, stmts_to_rescan);
|
|
}
|
|
|
|
static bool
|
|
gate_dominator (void)
|
|
{
|
|
return flag_tree_dom != 0;
|
|
}
|
|
|
|
struct tree_opt_pass pass_dominator =
|
|
{
|
|
"dom", /* name */
|
|
gate_dominator, /* gate */
|
|
tree_ssa_dominator_optimize, /* execute */
|
|
NULL, /* sub */
|
|
NULL, /* next */
|
|
0, /* static_pass_number */
|
|
TV_TREE_SSA_DOMINATOR_OPTS, /* tv_id */
|
|
PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
|
|
0, /* properties_provided */
|
|
0, /* properties_destroyed */
|
|
0, /* todo_flags_start */
|
|
TODO_dump_func
|
|
| TODO_update_ssa
|
|
| TODO_verify_ssa, /* todo_flags_finish */
|
|
0 /* letter */
|
|
};
|
|
|
|
|
|
/* We are exiting E->src, see if E->dest ends with a conditional
|
|
jump which has a known value when reached via E.
|
|
|
|
Special care is necessary if E is a back edge in the CFG as we
|
|
will have already recorded equivalences for E->dest into our
|
|
various tables, including the result of the conditional at
|
|
the end of E->dest. Threading opportunities are severely
|
|
limited in that case to avoid short-circuiting the loop
|
|
incorrectly.
|
|
|
|
Note it is quite common for the first block inside a loop to
|
|
end with a conditional which is either always true or always
|
|
false when reached via the loop backedge. Thus we do not want
|
|
to blindly disable threading across a loop backedge. */
|
|
|
|
static void
|
|
thread_across_edge (struct dom_walk_data *walk_data, edge e)
|
|
{
|
|
block_stmt_iterator bsi;
|
|
tree stmt = NULL;
|
|
tree phi;
|
|
int stmt_count = 0;
|
|
int max_stmt_count;
|
|
|
|
|
|
/* If E->dest does not end with a conditional, then there is
|
|
nothing to do. */
|
|
bsi = bsi_last (e->dest);
|
|
if (bsi_end_p (bsi)
|
|
|| ! bsi_stmt (bsi)
|
|
|| (TREE_CODE (bsi_stmt (bsi)) != COND_EXPR
|
|
&& TREE_CODE (bsi_stmt (bsi)) != GOTO_EXPR
|
|
&& TREE_CODE (bsi_stmt (bsi)) != SWITCH_EXPR))
|
|
return;
|
|
|
|
/* The basic idea here is to use whatever knowledge we have
|
|
from our dominator walk to simplify statements in E->dest,
|
|
with the ultimate goal being to simplify the conditional
|
|
at the end of E->dest.
|
|
|
|
Note that we must undo any changes we make to the underlying
|
|
statements as the simplifications we are making are control
|
|
flow sensitive (ie, the simplifications are valid when we
|
|
traverse E, but may not be valid on other paths to E->dest. */
|
|
|
|
/* Each PHI creates a temporary equivalence, record them. Again
|
|
these are context sensitive equivalences and will be removed
|
|
by our caller. */
|
|
for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
|
|
{
|
|
tree src = PHI_ARG_DEF_FROM_EDGE (phi, e);
|
|
tree dst = PHI_RESULT (phi);
|
|
|
|
/* Do not include virtual PHIs in our statement count as
|
|
they never generate code. */
|
|
if (is_gimple_reg (dst))
|
|
stmt_count++;
|
|
|
|
/* If the desired argument is not the same as this PHI's result
|
|
and it is set by a PHI in E->dest, then we can not thread
|
|
through E->dest. */
|
|
if (src != dst
|
|
&& TREE_CODE (src) == SSA_NAME
|
|
&& TREE_CODE (SSA_NAME_DEF_STMT (src)) == PHI_NODE
|
|
&& bb_for_stmt (SSA_NAME_DEF_STMT (src)) == e->dest)
|
|
return;
|
|
|
|
record_const_or_copy (dst, src);
|
|
}
|
|
|
|
/* Try to simplify each statement in E->dest, ultimately leading to
|
|
a simplification of the COND_EXPR at the end of E->dest.
|
|
|
|
We might consider marking just those statements which ultimately
|
|
feed the COND_EXPR. It's not clear if the overhead of bookkeeping
|
|
would be recovered by trying to simplify fewer statements.
|
|
|
|
If we are able to simplify a statement into the form
|
|
SSA_NAME = (SSA_NAME | gimple invariant), then we can record
|
|
a context sensitive equivalency which may help us simplify
|
|
later statements in E->dest.
|
|
|
|
Failure to simplify into the form above merely means that the
|
|
statement provides no equivalences to help simplify later
|
|
statements. This does not prevent threading through E->dest. */
|
|
max_stmt_count = PARAM_VALUE (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS);
|
|
for (bsi = bsi_start (e->dest); ! bsi_end_p (bsi); bsi_next (&bsi))
|
|
{
|
|
tree cached_lhs = NULL;
|
|
|
|
stmt = bsi_stmt (bsi);
|
|
|
|
/* Ignore empty statements and labels. */
|
|
if (IS_EMPTY_STMT (stmt) || TREE_CODE (stmt) == LABEL_EXPR)
|
|
continue;
|
|
|
|
/* If duplicating this block is going to cause too much code
|
|
expansion, then do not thread through this block. */
|
|
stmt_count++;
|
|
if (stmt_count > max_stmt_count)
|
|
return;
|
|
|
|
/* Safely handle threading across loop backedges. This is
|
|
over conservative, but still allows us to capture the
|
|
majority of the cases where we can thread across a loop
|
|
backedge. */
|
|
if ((e->flags & EDGE_DFS_BACK) != 0
|
|
&& TREE_CODE (stmt) != COND_EXPR
|
|
&& TREE_CODE (stmt) != SWITCH_EXPR)
|
|
return;
|
|
|
|
/* If the statement has volatile operands, then we assume we
|
|
can not thread through this block. This is overly
|
|
conservative in some ways. */
|
|
if (TREE_CODE (stmt) == ASM_EXPR && ASM_VOLATILE_P (stmt))
|
|
return;
|
|
|
|
/* If this is not a MODIFY_EXPR which sets an SSA_NAME to a new
|
|
value, then do not try to simplify this statement as it will
|
|
not simplify in any way that is helpful for jump threading. */
|
|
if (TREE_CODE (stmt) != MODIFY_EXPR
|
|
|| TREE_CODE (TREE_OPERAND (stmt, 0)) != SSA_NAME)
|
|
continue;
|
|
|
|
/* At this point we have a statement which assigns an RHS to an
|
|
SSA_VAR on the LHS. We want to try and simplify this statement
|
|
to expose more context sensitive equivalences which in turn may
|
|
allow us to simplify the condition at the end of the loop. */
|
|
if (TREE_CODE (TREE_OPERAND (stmt, 1)) == SSA_NAME)
|
|
cached_lhs = TREE_OPERAND (stmt, 1);
|
|
else
|
|
{
|
|
/* Copy the operands. */
|
|
tree *copy, pre_fold_expr;
|
|
ssa_op_iter iter;
|
|
use_operand_p use_p;
|
|
unsigned int num, i = 0;
|
|
|
|
num = NUM_SSA_OPERANDS (stmt, (SSA_OP_USE | SSA_OP_VUSE));
|
|
copy = xcalloc (num, sizeof (tree));
|
|
|
|
/* Make a copy of the uses & vuses into USES_COPY, then cprop into
|
|
the operands. */
|
|
FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
|
|
{
|
|
tree tmp = NULL;
|
|
tree use = USE_FROM_PTR (use_p);
|
|
|
|
copy[i++] = use;
|
|
if (TREE_CODE (use) == SSA_NAME)
|
|
tmp = SSA_NAME_VALUE (use);
|
|
if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
|
|
SET_USE (use_p, tmp);
|
|
}
|
|
|
|
/* Try to fold/lookup the new expression. Inserting the
|
|
expression into the hash table is unlikely to help
|
|
Sadly, we have to handle conditional assignments specially
|
|
here, because fold expects all the operands of an expression
|
|
to be folded before the expression itself is folded, but we
|
|
can't just substitute the folded condition here. */
|
|
if (TREE_CODE (TREE_OPERAND (stmt, 1)) == COND_EXPR)
|
|
{
|
|
tree cond = COND_EXPR_COND (TREE_OPERAND (stmt, 1));
|
|
cond = fold (cond);
|
|
if (cond == boolean_true_node)
|
|
pre_fold_expr = COND_EXPR_THEN (TREE_OPERAND (stmt, 1));
|
|
else if (cond == boolean_false_node)
|
|
pre_fold_expr = COND_EXPR_ELSE (TREE_OPERAND (stmt, 1));
|
|
else
|
|
pre_fold_expr = TREE_OPERAND (stmt, 1);
|
|
}
|
|
else
|
|
pre_fold_expr = TREE_OPERAND (stmt, 1);
|
|
|
|
if (pre_fold_expr)
|
|
{
|
|
cached_lhs = fold (pre_fold_expr);
|
|
if (TREE_CODE (cached_lhs) != SSA_NAME
|
|
&& !is_gimple_min_invariant (cached_lhs))
|
|
cached_lhs = lookup_avail_expr (stmt, false);
|
|
}
|
|
|
|
/* Restore the statement's original uses/defs. */
|
|
i = 0;
|
|
FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
|
|
SET_USE (use_p, copy[i++]);
|
|
|
|
free (copy);
|
|
}
|
|
|
|
/* Record the context sensitive equivalence if we were able
|
|
to simplify this statement. */
|
|
if (cached_lhs
|
|
&& (TREE_CODE (cached_lhs) == SSA_NAME
|
|
|| is_gimple_min_invariant (cached_lhs)))
|
|
record_const_or_copy (TREE_OPERAND (stmt, 0), cached_lhs);
|
|
}
|
|
|
|
/* If we stopped at a COND_EXPR or SWITCH_EXPR, see if we know which arm
|
|
will be taken. */
|
|
if (stmt
|
|
&& (TREE_CODE (stmt) == COND_EXPR
|
|
|| TREE_CODE (stmt) == GOTO_EXPR
|
|
|| TREE_CODE (stmt) == SWITCH_EXPR))
|
|
{
|
|
tree cond, cached_lhs;
|
|
|
|
/* Now temporarily cprop the operands and try to find the resulting
|
|
expression in the hash tables. */
|
|
if (TREE_CODE (stmt) == COND_EXPR)
|
|
cond = COND_EXPR_COND (stmt);
|
|
else if (TREE_CODE (stmt) == GOTO_EXPR)
|
|
cond = GOTO_DESTINATION (stmt);
|
|
else
|
|
cond = SWITCH_COND (stmt);
|
|
|
|
if (COMPARISON_CLASS_P (cond))
|
|
{
|
|
tree dummy_cond, op0, op1;
|
|
enum tree_code cond_code;
|
|
|
|
op0 = TREE_OPERAND (cond, 0);
|
|
op1 = TREE_OPERAND (cond, 1);
|
|
cond_code = TREE_CODE (cond);
|
|
|
|
/* Get the current value of both operands. */
|
|
if (TREE_CODE (op0) == SSA_NAME)
|
|
{
|
|
tree tmp = SSA_NAME_VALUE (op0);
|
|
if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
|
|
op0 = tmp;
|
|
}
|
|
|
|
if (TREE_CODE (op1) == SSA_NAME)
|
|
{
|
|
tree tmp = SSA_NAME_VALUE (op1);
|
|
if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
|
|
op1 = tmp;
|
|
}
|
|
|
|
/* Stuff the operator and operands into our dummy conditional
|
|
expression, creating the dummy conditional if necessary. */
|
|
dummy_cond = walk_data->global_data;
|
|
if (! dummy_cond)
|
|
{
|
|
dummy_cond = build (cond_code, boolean_type_node, op0, op1);
|
|
dummy_cond = build (COND_EXPR, void_type_node,
|
|
dummy_cond, NULL, NULL);
|
|
walk_data->global_data = dummy_cond;
|
|
}
|
|
else
|
|
{
|
|
TREE_SET_CODE (COND_EXPR_COND (dummy_cond), cond_code);
|
|
TREE_OPERAND (COND_EXPR_COND (dummy_cond), 0) = op0;
|
|
TREE_OPERAND (COND_EXPR_COND (dummy_cond), 1) = op1;
|
|
}
|
|
|
|
/* If the conditional folds to an invariant, then we are done,
|
|
otherwise look it up in the hash tables. */
|
|
cached_lhs = local_fold (COND_EXPR_COND (dummy_cond));
|
|
if (! is_gimple_min_invariant (cached_lhs))
|
|
{
|
|
cached_lhs = lookup_avail_expr (dummy_cond, false);
|
|
if (!cached_lhs || ! is_gimple_min_invariant (cached_lhs))
|
|
cached_lhs = simplify_cond_and_lookup_avail_expr (dummy_cond,
|
|
NULL,
|
|
false);
|
|
}
|
|
}
|
|
/* We can have conditionals which just test the state of a
|
|
variable rather than use a relational operator. These are
|
|
simpler to handle. */
|
|
else if (TREE_CODE (cond) == SSA_NAME)
|
|
{
|
|
cached_lhs = cond;
|
|
cached_lhs = SSA_NAME_VALUE (cached_lhs);
|
|
if (cached_lhs && ! is_gimple_min_invariant (cached_lhs))
|
|
cached_lhs = NULL;
|
|
}
|
|
else
|
|
cached_lhs = lookup_avail_expr (stmt, false);
|
|
|
|
if (cached_lhs)
|
|
{
|
|
edge taken_edge = find_taken_edge (e->dest, cached_lhs);
|
|
basic_block dest = (taken_edge ? taken_edge->dest : NULL);
|
|
|
|
if (dest == e->dest)
|
|
return;
|
|
|
|
/* If we have a known destination for the conditional, then
|
|
we can perform this optimization, which saves at least one
|
|
conditional jump each time it applies since we get to
|
|
bypass the conditional at our original destination. */
|
|
if (dest)
|
|
{
|
|
struct edge_info *edge_info;
|
|
|
|
if (e->aux)
|
|
edge_info = e->aux;
|
|
else
|
|
edge_info = allocate_edge_info (e);
|
|
edge_info->redirection_target = taken_edge;
|
|
bitmap_set_bit (threaded_blocks, e->dest->index);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/* Initialize local stacks for this optimizer and record equivalences
|
|
upon entry to BB. Equivalences can come from the edge traversed to
|
|
reach BB or they may come from PHI nodes at the start of BB. */
|
|
|
|
static void
|
|
dom_opt_initialize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
|
|
basic_block bb)
|
|
{
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
fprintf (dump_file, "\n\nOptimizing block #%d\n\n", bb->index);
|
|
|
|
/* Push a marker on the stacks of local information so that we know how
|
|
far to unwind when we finalize this block. */
|
|
VEC_safe_push (tree, heap, avail_exprs_stack, NULL_TREE);
|
|
VEC_safe_push (tree, heap, const_and_copies_stack, NULL_TREE);
|
|
VEC_safe_push (tree, heap, nonzero_vars_stack, NULL_TREE);
|
|
VEC_safe_push (tree, heap, vrp_variables_stack, NULL_TREE);
|
|
|
|
record_equivalences_from_incoming_edge (bb);
|
|
|
|
/* PHI nodes can create equivalences too. */
|
|
record_equivalences_from_phis (bb);
|
|
}
|
|
|
|
/* Given an expression EXPR (a relational expression or a statement),
|
|
initialize the hash table element pointed to by ELEMENT. */
|
|
|
|
static void
|
|
initialize_hash_element (tree expr, tree lhs, struct expr_hash_elt *element)
|
|
{
|
|
/* Hash table elements may be based on conditional expressions or statements.
|
|
|
|
For the former case, we have no annotation and we want to hash the
|
|
conditional expression. In the latter case we have an annotation and
|
|
we want to record the expression the statement evaluates. */
|
|
if (COMPARISON_CLASS_P (expr) || TREE_CODE (expr) == TRUTH_NOT_EXPR)
|
|
{
|
|
element->stmt = NULL;
|
|
element->rhs = expr;
|
|
}
|
|
else if (TREE_CODE (expr) == COND_EXPR)
|
|
{
|
|
element->stmt = expr;
|
|
element->rhs = COND_EXPR_COND (expr);
|
|
}
|
|
else if (TREE_CODE (expr) == SWITCH_EXPR)
|
|
{
|
|
element->stmt = expr;
|
|
element->rhs = SWITCH_COND (expr);
|
|
}
|
|
else if (TREE_CODE (expr) == RETURN_EXPR && TREE_OPERAND (expr, 0))
|
|
{
|
|
element->stmt = expr;
|
|
element->rhs = TREE_OPERAND (TREE_OPERAND (expr, 0), 1);
|
|
}
|
|
else if (TREE_CODE (expr) == GOTO_EXPR)
|
|
{
|
|
element->stmt = expr;
|
|
element->rhs = GOTO_DESTINATION (expr);
|
|
}
|
|
else
|
|
{
|
|
element->stmt = expr;
|
|
element->rhs = TREE_OPERAND (expr, 1);
|
|
}
|
|
|
|
element->lhs = lhs;
|
|
element->hash = avail_expr_hash (element);
|
|
}
|
|
|
|
/* Remove all the expressions in LOCALS from TABLE, stopping when there are
|
|
LIMIT entries left in LOCALs. */
|
|
|
|
static void
|
|
remove_local_expressions_from_table (void)
|
|
{
|
|
/* Remove all the expressions made available in this block. */
|
|
while (VEC_length (tree, avail_exprs_stack) > 0)
|
|
{
|
|
struct expr_hash_elt element;
|
|
tree expr = VEC_pop (tree, avail_exprs_stack);
|
|
|
|
if (expr == NULL_TREE)
|
|
break;
|
|
|
|
initialize_hash_element (expr, NULL, &element);
|
|
htab_remove_elt_with_hash (avail_exprs, &element, element.hash);
|
|
}
|
|
}
|
|
|
|
/* Use the SSA_NAMES in LOCALS to restore TABLE to its original
|
|
state, stopping when there are LIMIT entries left in LOCALs. */
|
|
|
|
static void
|
|
restore_nonzero_vars_to_original_value (void)
|
|
{
|
|
while (VEC_length (tree, nonzero_vars_stack) > 0)
|
|
{
|
|
tree name = VEC_pop (tree, nonzero_vars_stack);
|
|
|
|
if (name == NULL)
|
|
break;
|
|
|
|
bitmap_clear_bit (nonzero_vars, SSA_NAME_VERSION (name));
|
|
}
|
|
}
|
|
|
|
/* Use the source/dest pairs in CONST_AND_COPIES_STACK to restore
|
|
CONST_AND_COPIES to its original state, stopping when we hit a
|
|
NULL marker. */
|
|
|
|
static void
|
|
restore_vars_to_original_value (void)
|
|
{
|
|
while (VEC_length (tree, const_and_copies_stack) > 0)
|
|
{
|
|
tree prev_value, dest;
|
|
|
|
dest = VEC_pop (tree, const_and_copies_stack);
|
|
|
|
if (dest == NULL)
|
|
break;
|
|
|
|
prev_value = VEC_pop (tree, const_and_copies_stack);
|
|
SSA_NAME_VALUE (dest) = prev_value;
|
|
}
|
|
}
|
|
|
|
/* We have finished processing the dominator children of BB, perform
|
|
any finalization actions in preparation for leaving this node in
|
|
the dominator tree. */
|
|
|
|
static void
|
|
dom_opt_finalize_block (struct dom_walk_data *walk_data, basic_block bb)
|
|
{
|
|
tree last;
|
|
|
|
/* If we have an outgoing edge to a block with multiple incoming and
|
|
outgoing edges, then we may be able to thread the edge. ie, we
|
|
may be able to statically determine which of the outgoing edges
|
|
will be traversed when the incoming edge from BB is traversed. */
|
|
if (single_succ_p (bb)
|
|
&& (single_succ_edge (bb)->flags & EDGE_ABNORMAL) == 0
|
|
&& !single_pred_p (single_succ (bb))
|
|
&& !single_succ_p (single_succ (bb)))
|
|
|
|
{
|
|
thread_across_edge (walk_data, single_succ_edge (bb));
|
|
}
|
|
else if ((last = last_stmt (bb))
|
|
&& TREE_CODE (last) == COND_EXPR
|
|
&& (COMPARISON_CLASS_P (COND_EXPR_COND (last))
|
|
|| TREE_CODE (COND_EXPR_COND (last)) == SSA_NAME)
|
|
&& EDGE_COUNT (bb->succs) == 2
|
|
&& (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL) == 0
|
|
&& (EDGE_SUCC (bb, 1)->flags & EDGE_ABNORMAL) == 0)
|
|
{
|
|
edge true_edge, false_edge;
|
|
|
|
extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
|
|
|
|
/* Only try to thread the edge if it reaches a target block with
|
|
more than one predecessor and more than one successor. */
|
|
if (!single_pred_p (true_edge->dest) && !single_succ_p (true_edge->dest))
|
|
{
|
|
struct edge_info *edge_info;
|
|
unsigned int i;
|
|
|
|
/* Push a marker onto the available expression stack so that we
|
|
unwind any expressions related to the TRUE arm before processing
|
|
the false arm below. */
|
|
VEC_safe_push (tree, heap, avail_exprs_stack, NULL_TREE);
|
|
VEC_safe_push (tree, heap, const_and_copies_stack, NULL_TREE);
|
|
|
|
edge_info = true_edge->aux;
|
|
|
|
/* If we have info associated with this edge, record it into
|
|
our equivalency tables. */
|
|
if (edge_info)
|
|
{
|
|
tree *cond_equivalences = edge_info->cond_equivalences;
|
|
tree lhs = edge_info->lhs;
|
|
tree rhs = edge_info->rhs;
|
|
|
|
/* If we have a simple NAME = VALUE equivalency record it. */
|
|
if (lhs && TREE_CODE (lhs) == SSA_NAME)
|
|
record_const_or_copy (lhs, rhs);
|
|
|
|
/* If we have 0 = COND or 1 = COND equivalences, record them
|
|
into our expression hash tables. */
|
|
if (cond_equivalences)
|
|
for (i = 0; i < edge_info->max_cond_equivalences; i += 2)
|
|
{
|
|
tree expr = cond_equivalences[i];
|
|
tree value = cond_equivalences[i + 1];
|
|
|
|
record_cond (expr, value);
|
|
}
|
|
}
|
|
|
|
/* Now thread the edge. */
|
|
thread_across_edge (walk_data, true_edge);
|
|
|
|
/* And restore the various tables to their state before
|
|
we threaded this edge. */
|
|
remove_local_expressions_from_table ();
|
|
restore_vars_to_original_value ();
|
|
}
|
|
|
|
/* Similarly for the ELSE arm. */
|
|
if (!single_pred_p (false_edge->dest) && !single_succ_p (false_edge->dest))
|
|
{
|
|
struct edge_info *edge_info;
|
|
unsigned int i;
|
|
|
|
edge_info = false_edge->aux;
|
|
|
|
/* If we have info associated with this edge, record it into
|
|
our equivalency tables. */
|
|
if (edge_info)
|
|
{
|
|
tree *cond_equivalences = edge_info->cond_equivalences;
|
|
tree lhs = edge_info->lhs;
|
|
tree rhs = edge_info->rhs;
|
|
|
|
/* If we have a simple NAME = VALUE equivalency record it. */
|
|
if (lhs && TREE_CODE (lhs) == SSA_NAME)
|
|
record_const_or_copy (lhs, rhs);
|
|
|
|
/* If we have 0 = COND or 1 = COND equivalences, record them
|
|
into our expression hash tables. */
|
|
if (cond_equivalences)
|
|
for (i = 0; i < edge_info->max_cond_equivalences; i += 2)
|
|
{
|
|
tree expr = cond_equivalences[i];
|
|
tree value = cond_equivalences[i + 1];
|
|
|
|
record_cond (expr, value);
|
|
}
|
|
}
|
|
|
|
thread_across_edge (walk_data, false_edge);
|
|
|
|
/* No need to remove local expressions from our tables
|
|
or restore vars to their original value as that will
|
|
be done immediately below. */
|
|
}
|
|
}
|
|
|
|
remove_local_expressions_from_table ();
|
|
restore_nonzero_vars_to_original_value ();
|
|
restore_vars_to_original_value ();
|
|
|
|
/* Remove VRP records associated with this basic block. They are no
|
|
longer valid.
|
|
|
|
To be efficient, we note which variables have had their values
|
|
constrained in this block. So walk over each variable in the
|
|
VRP_VARIABLEs array. */
|
|
while (VEC_length (tree, vrp_variables_stack) > 0)
|
|
{
|
|
tree var = VEC_pop (tree, vrp_variables_stack);
|
|
struct vrp_hash_elt vrp_hash_elt, *vrp_hash_elt_p;
|
|
void **slot;
|
|
|
|
/* Each variable has a stack of value range records. We want to
|
|
invalidate those associated with our basic block. So we walk
|
|
the array backwards popping off records associated with our
|
|
block. Once we hit a record not associated with our block
|
|
we are done. */
|
|
VEC(vrp_element_p,heap) **var_vrp_records;
|
|
|
|
if (var == NULL)
|
|
break;
|
|
|
|
vrp_hash_elt.var = var;
|
|
vrp_hash_elt.records = NULL;
|
|
|
|
slot = htab_find_slot (vrp_data, &vrp_hash_elt, NO_INSERT);
|
|
|
|
vrp_hash_elt_p = (struct vrp_hash_elt *) *slot;
|
|
var_vrp_records = &vrp_hash_elt_p->records;
|
|
|
|
while (VEC_length (vrp_element_p, *var_vrp_records) > 0)
|
|
{
|
|
struct vrp_element *element
|
|
= VEC_last (vrp_element_p, *var_vrp_records);
|
|
|
|
if (element->bb != bb)
|
|
break;
|
|
|
|
VEC_pop (vrp_element_p, *var_vrp_records);
|
|
}
|
|
}
|
|
|
|
/* If we queued any statements to rescan in this block, then
|
|
go ahead and rescan them now. */
|
|
while (VEC_length (tree, stmts_to_rescan) > 0)
|
|
{
|
|
tree stmt = VEC_last (tree, stmts_to_rescan);
|
|
basic_block stmt_bb = bb_for_stmt (stmt);
|
|
|
|
if (stmt_bb != bb)
|
|
break;
|
|
|
|
VEC_pop (tree, stmts_to_rescan);
|
|
mark_new_vars_to_rename (stmt);
|
|
}
|
|
}
|
|
|
|
/* PHI nodes can create equivalences too.
|
|
|
|
Ignoring any alternatives which are the same as the result, if
|
|
all the alternatives are equal, then the PHI node creates an
|
|
equivalence.
|
|
|
|
Additionally, if all the PHI alternatives are known to have a nonzero
|
|
value, then the result of this PHI is known to have a nonzero value,
|
|
even if we do not know its exact value. */
|
|
|
|
static void
|
|
record_equivalences_from_phis (basic_block bb)
|
|
{
|
|
tree phi;
|
|
|
|
for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
|
|
{
|
|
tree lhs = PHI_RESULT (phi);
|
|
tree rhs = NULL;
|
|
int i;
|
|
|
|
for (i = 0; i < PHI_NUM_ARGS (phi); i++)
|
|
{
|
|
tree t = PHI_ARG_DEF (phi, i);
|
|
|
|
/* Ignore alternatives which are the same as our LHS. Since
|
|
LHS is a PHI_RESULT, it is known to be a SSA_NAME, so we
|
|
can simply compare pointers. */
|
|
if (lhs == t)
|
|
continue;
|
|
|
|
/* If we have not processed an alternative yet, then set
|
|
RHS to this alternative. */
|
|
if (rhs == NULL)
|
|
rhs = t;
|
|
/* If we have processed an alternative (stored in RHS), then
|
|
see if it is equal to this one. If it isn't, then stop
|
|
the search. */
|
|
else if (! operand_equal_for_phi_arg_p (rhs, t))
|
|
break;
|
|
}
|
|
|
|
/* If we had no interesting alternatives, then all the RHS alternatives
|
|
must have been the same as LHS. */
|
|
if (!rhs)
|
|
rhs = lhs;
|
|
|
|
/* If we managed to iterate through each PHI alternative without
|
|
breaking out of the loop, then we have a PHI which may create
|
|
a useful equivalence. We do not need to record unwind data for
|
|
this, since this is a true assignment and not an equivalence
|
|
inferred from a comparison. All uses of this ssa name are dominated
|
|
by this assignment, so unwinding just costs time and space. */
|
|
if (i == PHI_NUM_ARGS (phi)
|
|
&& may_propagate_copy (lhs, rhs))
|
|
SSA_NAME_VALUE (lhs) = rhs;
|
|
|
|
/* Now see if we know anything about the nonzero property for the
|
|
result of this PHI. */
|
|
for (i = 0; i < PHI_NUM_ARGS (phi); i++)
|
|
{
|
|
if (!PHI_ARG_NONZERO (phi, i))
|
|
break;
|
|
}
|
|
|
|
if (i == PHI_NUM_ARGS (phi))
|
|
bitmap_set_bit (nonzero_vars, SSA_NAME_VERSION (PHI_RESULT (phi)));
|
|
}
|
|
}
|
|
|
|
/* Ignoring loop backedges, if BB has precisely one incoming edge then
|
|
return that edge. Otherwise return NULL. */
|
|
static edge
|
|
single_incoming_edge_ignoring_loop_edges (basic_block bb)
|
|
{
|
|
edge retval = NULL;
|
|
edge e;
|
|
edge_iterator ei;
|
|
|
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
|
{
|
|
/* A loop back edge can be identified by the destination of
|
|
the edge dominating the source of the edge. */
|
|
if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest))
|
|
continue;
|
|
|
|
/* If we have already seen a non-loop edge, then we must have
|
|
multiple incoming non-loop edges and thus we return NULL. */
|
|
if (retval)
|
|
return NULL;
|
|
|
|
/* This is the first non-loop incoming edge we have found. Record
|
|
it. */
|
|
retval = e;
|
|
}
|
|
|
|
return retval;
|
|
}
|
|
|
|
/* Record any equivalences created by the incoming edge to BB. If BB
|
|
has more than one incoming edge, then no equivalence is created. */
|
|
|
|
static void
|
|
record_equivalences_from_incoming_edge (basic_block bb)
|
|
{
|
|
edge e;
|
|
basic_block parent;
|
|
struct edge_info *edge_info;
|
|
|
|
/* If our parent block ended with a control statement, then we may be
|
|
able to record some equivalences based on which outgoing edge from
|
|
the parent was followed. */
|
|
parent = get_immediate_dominator (CDI_DOMINATORS, bb);
|
|
|
|
e = single_incoming_edge_ignoring_loop_edges (bb);
|
|
|
|
/* If we had a single incoming edge from our parent block, then enter
|
|
any data associated with the edge into our tables. */
|
|
if (e && e->src == parent)
|
|
{
|
|
unsigned int i;
|
|
|
|
edge_info = e->aux;
|
|
|
|
if (edge_info)
|
|
{
|
|
tree lhs = edge_info->lhs;
|
|
tree rhs = edge_info->rhs;
|
|
tree *cond_equivalences = edge_info->cond_equivalences;
|
|
|
|
if (lhs)
|
|
record_equality (lhs, rhs);
|
|
|
|
if (cond_equivalences)
|
|
{
|
|
bool recorded_range = false;
|
|
for (i = 0; i < edge_info->max_cond_equivalences; i += 2)
|
|
{
|
|
tree expr = cond_equivalences[i];
|
|
tree value = cond_equivalences[i + 1];
|
|
|
|
record_cond (expr, value);
|
|
|
|
/* For the first true equivalence, record range
|
|
information. We only do this for the first
|
|
true equivalence as it should dominate any
|
|
later true equivalences. */
|
|
if (! recorded_range
|
|
&& COMPARISON_CLASS_P (expr)
|
|
&& value == boolean_true_node
|
|
&& TREE_CONSTANT (TREE_OPERAND (expr, 1)))
|
|
{
|
|
record_range (expr, bb);
|
|
recorded_range = true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Dump SSA statistics on FILE. */
|
|
|
|
void
|
|
dump_dominator_optimization_stats (FILE *file)
|
|
{
|
|
long n_exprs;
|
|
|
|
fprintf (file, "Total number of statements: %6ld\n\n",
|
|
opt_stats.num_stmts);
|
|
fprintf (file, "Exprs considered for dominator optimizations: %6ld\n",
|
|
opt_stats.num_exprs_considered);
|
|
|
|
n_exprs = opt_stats.num_exprs_considered;
|
|
if (n_exprs == 0)
|
|
n_exprs = 1;
|
|
|
|
fprintf (file, " Redundant expressions eliminated: %6ld (%.0f%%)\n",
|
|
opt_stats.num_re, PERCENT (opt_stats.num_re,
|
|
n_exprs));
|
|
fprintf (file, " Constants propagated: %6ld\n",
|
|
opt_stats.num_const_prop);
|
|
fprintf (file, " Copies propagated: %6ld\n",
|
|
opt_stats.num_copy_prop);
|
|
|
|
fprintf (file, "\nTotal number of DOM iterations: %6ld\n",
|
|
opt_stats.num_iterations);
|
|
|
|
fprintf (file, "\nHash table statistics:\n");
|
|
|
|
fprintf (file, " avail_exprs: ");
|
|
htab_statistics (file, avail_exprs);
|
|
}
|
|
|
|
|
|
/* Dump SSA statistics on stderr. */
|
|
|
|
void
|
|
debug_dominator_optimization_stats (void)
|
|
{
|
|
dump_dominator_optimization_stats (stderr);
|
|
}
|
|
|
|
|
|
/* Dump statistics for the hash table HTAB. */
|
|
|
|
static void
|
|
htab_statistics (FILE *file, htab_t htab)
|
|
{
|
|
fprintf (file, "size %ld, %ld elements, %f collision/search ratio\n",
|
|
(long) htab_size (htab),
|
|
(long) htab_elements (htab),
|
|
htab_collisions (htab));
|
|
}
|
|
|
|
/* Record the fact that VAR has a nonzero value, though we may not know
|
|
its exact value. Note that if VAR is already known to have a nonzero
|
|
value, then we do nothing. */
|
|
|
|
static void
|
|
record_var_is_nonzero (tree var)
|
|
{
|
|
int indx = SSA_NAME_VERSION (var);
|
|
|
|
if (bitmap_bit_p (nonzero_vars, indx))
|
|
return;
|
|
|
|
/* Mark it in the global table. */
|
|
bitmap_set_bit (nonzero_vars, indx);
|
|
|
|
/* Record this SSA_NAME so that we can reset the global table
|
|
when we leave this block. */
|
|
VEC_safe_push (tree, heap, nonzero_vars_stack, var);
|
|
}
|
|
|
|
/* Enter a statement into the true/false expression hash table indicating
|
|
that the condition COND has the value VALUE. */
|
|
|
|
static void
|
|
record_cond (tree cond, tree value)
|
|
{
|
|
struct expr_hash_elt *element = xmalloc (sizeof (struct expr_hash_elt));
|
|
void **slot;
|
|
|
|
initialize_hash_element (cond, value, element);
|
|
|
|
slot = htab_find_slot_with_hash (avail_exprs, (void *)element,
|
|
element->hash, INSERT);
|
|
if (*slot == NULL)
|
|
{
|
|
*slot = (void *) element;
|
|
VEC_safe_push (tree, heap, avail_exprs_stack, cond);
|
|
}
|
|
else
|
|
free (element);
|
|
}
|
|
|
|
/* Build a new conditional using NEW_CODE, OP0 and OP1 and store
|
|
the new conditional into *p, then store a boolean_true_node
|
|
into *(p + 1). */
|
|
|
|
static void
|
|
build_and_record_new_cond (enum tree_code new_code, tree op0, tree op1, tree *p)
|
|
{
|
|
*p = build2 (new_code, boolean_type_node, op0, op1);
|
|
p++;
|
|
*p = boolean_true_node;
|
|
}
|
|
|
|
/* Record that COND is true and INVERTED is false into the edge information
|
|
structure. Also record that any conditions dominated by COND are true
|
|
as well.
|
|
|
|
For example, if a < b is true, then a <= b must also be true. */
|
|
|
|
static void
|
|
record_conditions (struct edge_info *edge_info, tree cond, tree inverted)
|
|
{
|
|
tree op0, op1;
|
|
|
|
if (!COMPARISON_CLASS_P (cond))
|
|
return;
|
|
|
|
op0 = TREE_OPERAND (cond, 0);
|
|
op1 = TREE_OPERAND (cond, 1);
|
|
|
|
switch (TREE_CODE (cond))
|
|
{
|
|
case LT_EXPR:
|
|
case GT_EXPR:
|
|
edge_info->max_cond_equivalences = 12;
|
|
edge_info->cond_equivalences = xmalloc (12 * sizeof (tree));
|
|
build_and_record_new_cond ((TREE_CODE (cond) == LT_EXPR
|
|
? LE_EXPR : GE_EXPR),
|
|
op0, op1, &edge_info->cond_equivalences[4]);
|
|
build_and_record_new_cond (ORDERED_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[6]);
|
|
build_and_record_new_cond (NE_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[8]);
|
|
build_and_record_new_cond (LTGT_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[10]);
|
|
break;
|
|
|
|
case GE_EXPR:
|
|
case LE_EXPR:
|
|
edge_info->max_cond_equivalences = 6;
|
|
edge_info->cond_equivalences = xmalloc (6 * sizeof (tree));
|
|
build_and_record_new_cond (ORDERED_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[4]);
|
|
break;
|
|
|
|
case EQ_EXPR:
|
|
edge_info->max_cond_equivalences = 10;
|
|
edge_info->cond_equivalences = xmalloc (10 * sizeof (tree));
|
|
build_and_record_new_cond (ORDERED_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[4]);
|
|
build_and_record_new_cond (LE_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[6]);
|
|
build_and_record_new_cond (GE_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[8]);
|
|
break;
|
|
|
|
case UNORDERED_EXPR:
|
|
edge_info->max_cond_equivalences = 16;
|
|
edge_info->cond_equivalences = xmalloc (16 * sizeof (tree));
|
|
build_and_record_new_cond (NE_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[4]);
|
|
build_and_record_new_cond (UNLE_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[6]);
|
|
build_and_record_new_cond (UNGE_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[8]);
|
|
build_and_record_new_cond (UNEQ_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[10]);
|
|
build_and_record_new_cond (UNLT_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[12]);
|
|
build_and_record_new_cond (UNGT_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[14]);
|
|
break;
|
|
|
|
case UNLT_EXPR:
|
|
case UNGT_EXPR:
|
|
edge_info->max_cond_equivalences = 8;
|
|
edge_info->cond_equivalences = xmalloc (8 * sizeof (tree));
|
|
build_and_record_new_cond ((TREE_CODE (cond) == UNLT_EXPR
|
|
? UNLE_EXPR : UNGE_EXPR),
|
|
op0, op1, &edge_info->cond_equivalences[4]);
|
|
build_and_record_new_cond (NE_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[6]);
|
|
break;
|
|
|
|
case UNEQ_EXPR:
|
|
edge_info->max_cond_equivalences = 8;
|
|
edge_info->cond_equivalences = xmalloc (8 * sizeof (tree));
|
|
build_and_record_new_cond (UNLE_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[4]);
|
|
build_and_record_new_cond (UNGE_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[6]);
|
|
break;
|
|
|
|
case LTGT_EXPR:
|
|
edge_info->max_cond_equivalences = 8;
|
|
edge_info->cond_equivalences = xmalloc (8 * sizeof (tree));
|
|
build_and_record_new_cond (NE_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[4]);
|
|
build_and_record_new_cond (ORDERED_EXPR, op0, op1,
|
|
&edge_info->cond_equivalences[6]);
|
|
break;
|
|
|
|
default:
|
|
edge_info->max_cond_equivalences = 4;
|
|
edge_info->cond_equivalences = xmalloc (4 * sizeof (tree));
|
|
break;
|
|
}
|
|
|
|
/* Now store the original true and false conditions into the first
|
|
two slots. */
|
|
edge_info->cond_equivalences[0] = cond;
|
|
edge_info->cond_equivalences[1] = boolean_true_node;
|
|
edge_info->cond_equivalences[2] = inverted;
|
|
edge_info->cond_equivalences[3] = boolean_false_node;
|
|
}
|
|
|
|
/* A helper function for record_const_or_copy and record_equality.
|
|
Do the work of recording the value and undo info. */
|
|
|
|
static void
|
|
record_const_or_copy_1 (tree x, tree y, tree prev_x)
|
|
{
|
|
SSA_NAME_VALUE (x) = y;
|
|
|
|
VEC_reserve (tree, heap, const_and_copies_stack, 2);
|
|
VEC_quick_push (tree, const_and_copies_stack, prev_x);
|
|
VEC_quick_push (tree, const_and_copies_stack, x);
|
|
}
|
|
|
|
|
|
/* Return the loop depth of the basic block of the defining statement of X.
|
|
This number should not be treated as absolutely correct because the loop
|
|
information may not be completely up-to-date when dom runs. However, it
|
|
will be relatively correct, and as more passes are taught to keep loop info
|
|
up to date, the result will become more and more accurate. */
|
|
|
|
int
|
|
loop_depth_of_name (tree x)
|
|
{
|
|
tree defstmt;
|
|
basic_block defbb;
|
|
|
|
/* If it's not an SSA_NAME, we have no clue where the definition is. */
|
|
if (TREE_CODE (x) != SSA_NAME)
|
|
return 0;
|
|
|
|
/* Otherwise return the loop depth of the defining statement's bb.
|
|
Note that there may not actually be a bb for this statement, if the
|
|
ssa_name is live on entry. */
|
|
defstmt = SSA_NAME_DEF_STMT (x);
|
|
defbb = bb_for_stmt (defstmt);
|
|
if (!defbb)
|
|
return 0;
|
|
|
|
return defbb->loop_depth;
|
|
}
|
|
|
|
|
|
/* Record that X is equal to Y in const_and_copies. Record undo
|
|
information in the block-local vector. */
|
|
|
|
static void
|
|
record_const_or_copy (tree x, tree y)
|
|
{
|
|
tree prev_x = SSA_NAME_VALUE (x);
|
|
|
|
if (TREE_CODE (y) == SSA_NAME)
|
|
{
|
|
tree tmp = SSA_NAME_VALUE (y);
|
|
if (tmp)
|
|
y = tmp;
|
|
}
|
|
|
|
record_const_or_copy_1 (x, y, prev_x);
|
|
}
|
|
|
|
/* Similarly, but assume that X and Y are the two operands of an EQ_EXPR.
|
|
This constrains the cases in which we may treat this as assignment. */
|
|
|
|
static void
|
|
record_equality (tree x, tree y)
|
|
{
|
|
tree prev_x = NULL, prev_y = NULL;
|
|
|
|
if (TREE_CODE (x) == SSA_NAME)
|
|
prev_x = SSA_NAME_VALUE (x);
|
|
if (TREE_CODE (y) == SSA_NAME)
|
|
prev_y = SSA_NAME_VALUE (y);
|
|
|
|
/* If one of the previous values is invariant, or invariant in more loops
|
|
(by depth), then use that.
|
|
Otherwise it doesn't matter which value we choose, just so
|
|
long as we canonicalize on one value. */
|
|
if (TREE_INVARIANT (y))
|
|
;
|
|
else if (TREE_INVARIANT (x) || (loop_depth_of_name (x) <= loop_depth_of_name (y)))
|
|
prev_x = x, x = y, y = prev_x, prev_x = prev_y;
|
|
else if (prev_x && TREE_INVARIANT (prev_x))
|
|
x = y, y = prev_x, prev_x = prev_y;
|
|
else if (prev_y && TREE_CODE (prev_y) != VALUE_HANDLE)
|
|
y = prev_y;
|
|
|
|
/* After the swapping, we must have one SSA_NAME. */
|
|
if (TREE_CODE (x) != SSA_NAME)
|
|
return;
|
|
|
|
/* For IEEE, -0.0 == 0.0, so we don't necessarily know the sign of a
|
|
variable compared against zero. If we're honoring signed zeros,
|
|
then we cannot record this value unless we know that the value is
|
|
nonzero. */
|
|
if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (x)))
|
|
&& (TREE_CODE (y) != REAL_CST
|
|
|| REAL_VALUES_EQUAL (dconst0, TREE_REAL_CST (y))))
|
|
return;
|
|
|
|
record_const_or_copy_1 (x, y, prev_x);
|
|
}
|
|
|
|
/* Return true, if it is ok to do folding of an associative expression.
|
|
EXP is the tree for the associative expression. */
|
|
|
|
static inline bool
|
|
unsafe_associative_fp_binop (tree exp)
|
|
{
|
|
enum tree_code code = TREE_CODE (exp);
|
|
return !(!flag_unsafe_math_optimizations
|
|
&& (code == MULT_EXPR || code == PLUS_EXPR
|
|
|| code == MINUS_EXPR)
|
|
&& FLOAT_TYPE_P (TREE_TYPE (exp)));
|
|
}
|
|
|
|
/* Returns true when STMT is a simple iv increment. It detects the
|
|
following situation:
|
|
|
|
i_1 = phi (..., i_2)
|
|
i_2 = i_1 +/- ... */
|
|
|
|
static bool
|
|
simple_iv_increment_p (tree stmt)
|
|
{
|
|
tree lhs, rhs, preinc, phi;
|
|
unsigned i;
|
|
|
|
if (TREE_CODE (stmt) != MODIFY_EXPR)
|
|
return false;
|
|
|
|
lhs = TREE_OPERAND (stmt, 0);
|
|
if (TREE_CODE (lhs) != SSA_NAME)
|
|
return false;
|
|
|
|
rhs = TREE_OPERAND (stmt, 1);
|
|
|
|
if (TREE_CODE (rhs) != PLUS_EXPR
|
|
&& TREE_CODE (rhs) != MINUS_EXPR)
|
|
return false;
|
|
|
|
preinc = TREE_OPERAND (rhs, 0);
|
|
if (TREE_CODE (preinc) != SSA_NAME)
|
|
return false;
|
|
|
|
phi = SSA_NAME_DEF_STMT (preinc);
|
|
if (TREE_CODE (phi) != PHI_NODE)
|
|
return false;
|
|
|
|
for (i = 0; i < (unsigned) PHI_NUM_ARGS (phi); i++)
|
|
if (PHI_ARG_DEF (phi, i) == lhs)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/* STMT is a MODIFY_EXPR for which we were unable to find RHS in the
|
|
hash tables. Try to simplify the RHS using whatever equivalences
|
|
we may have recorded.
|
|
|
|
If we are able to simplify the RHS, then lookup the simplified form in
|
|
the hash table and return the result. Otherwise return NULL. */
|
|
|
|
static tree
|
|
simplify_rhs_and_lookup_avail_expr (tree stmt, int insert)
|
|
{
|
|
tree rhs = TREE_OPERAND (stmt, 1);
|
|
enum tree_code rhs_code = TREE_CODE (rhs);
|
|
tree result = NULL;
|
|
|
|
/* If we have lhs = ~x, look and see if we earlier had x = ~y.
|
|
In which case we can change this statement to be lhs = y.
|
|
Which can then be copy propagated.
|
|
|
|
Similarly for negation. */
|
|
if ((rhs_code == BIT_NOT_EXPR || rhs_code == NEGATE_EXPR)
|
|
&& TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
|
|
{
|
|
/* Get the definition statement for our RHS. */
|
|
tree rhs_def_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0));
|
|
|
|
/* See if the RHS_DEF_STMT has the same form as our statement. */
|
|
if (TREE_CODE (rhs_def_stmt) == MODIFY_EXPR
|
|
&& TREE_CODE (TREE_OPERAND (rhs_def_stmt, 1)) == rhs_code)
|
|
{
|
|
tree rhs_def_operand;
|
|
|
|
rhs_def_operand = TREE_OPERAND (TREE_OPERAND (rhs_def_stmt, 1), 0);
|
|
|
|
/* Verify that RHS_DEF_OPERAND is a suitable SSA variable. */
|
|
if (TREE_CODE (rhs_def_operand) == SSA_NAME
|
|
&& ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs_def_operand))
|
|
result = update_rhs_and_lookup_avail_expr (stmt,
|
|
rhs_def_operand,
|
|
insert);
|
|
}
|
|
}
|
|
|
|
/* If we have z = (x OP C1), see if we earlier had x = y OP C2.
|
|
If OP is associative, create and fold (y OP C2) OP C1 which
|
|
should result in (y OP C3), use that as the RHS for the
|
|
assignment. Add minus to this, as we handle it specially below. */
|
|
if ((associative_tree_code (rhs_code) || rhs_code == MINUS_EXPR)
|
|
&& TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
|
|
&& has_single_use (TREE_OPERAND (rhs, 0))
|
|
&& is_gimple_min_invariant (TREE_OPERAND (rhs, 1)))
|
|
{
|
|
tree rhs_def_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0));
|
|
|
|
/* If the statement defines an induction variable, do not propagate
|
|
its value, so that we do not create overlapping life ranges. */
|
|
if (simple_iv_increment_p (rhs_def_stmt))
|
|
goto dont_fold_assoc;
|
|
|
|
/* See if the RHS_DEF_STMT has the same form as our statement. */
|
|
if (TREE_CODE (rhs_def_stmt) == MODIFY_EXPR)
|
|
{
|
|
tree rhs_def_rhs = TREE_OPERAND (rhs_def_stmt, 1);
|
|
enum tree_code rhs_def_code = TREE_CODE (rhs_def_rhs);
|
|
|
|
if ((rhs_code == rhs_def_code && unsafe_associative_fp_binop (rhs))
|
|
|| (rhs_code == PLUS_EXPR && rhs_def_code == MINUS_EXPR)
|
|
|| (rhs_code == MINUS_EXPR && rhs_def_code == PLUS_EXPR))
|
|
{
|
|
tree def_stmt_op0 = TREE_OPERAND (rhs_def_rhs, 0);
|
|
tree def_stmt_op1 = TREE_OPERAND (rhs_def_rhs, 1);
|
|
|
|
if (TREE_CODE (def_stmt_op0) == SSA_NAME
|
|
&& ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def_stmt_op0)
|
|
&& is_gimple_min_invariant (def_stmt_op1))
|
|
{
|
|
tree outer_const = TREE_OPERAND (rhs, 1);
|
|
tree type = TREE_TYPE (TREE_OPERAND (stmt, 0));
|
|
tree t;
|
|
|
|
/* If we care about correct floating point results, then
|
|
don't fold x + c1 - c2. Note that we need to take both
|
|
the codes and the signs to figure this out. */
|
|
if (FLOAT_TYPE_P (type)
|
|
&& !flag_unsafe_math_optimizations
|
|
&& (rhs_def_code == PLUS_EXPR
|
|
|| rhs_def_code == MINUS_EXPR))
|
|
{
|
|
bool neg = false;
|
|
|
|
neg ^= (rhs_code == MINUS_EXPR);
|
|
neg ^= (rhs_def_code == MINUS_EXPR);
|
|
neg ^= real_isneg (TREE_REAL_CST_PTR (outer_const));
|
|
neg ^= real_isneg (TREE_REAL_CST_PTR (def_stmt_op1));
|
|
|
|
if (neg)
|
|
goto dont_fold_assoc;
|
|
}
|
|
|
|
/* Ho hum. So fold will only operate on the outermost
|
|
thingy that we give it, so we have to build the new
|
|
expression in two pieces. This requires that we handle
|
|
combinations of plus and minus. */
|
|
if (rhs_def_code != rhs_code)
|
|
{
|
|
if (rhs_def_code == MINUS_EXPR)
|
|
t = build (MINUS_EXPR, type, outer_const, def_stmt_op1);
|
|
else
|
|
t = build (MINUS_EXPR, type, def_stmt_op1, outer_const);
|
|
rhs_code = PLUS_EXPR;
|
|
}
|
|
else if (rhs_def_code == MINUS_EXPR)
|
|
t = build (PLUS_EXPR, type, def_stmt_op1, outer_const);
|
|
else
|
|
t = build (rhs_def_code, type, def_stmt_op1, outer_const);
|
|
t = local_fold (t);
|
|
t = build (rhs_code, type, def_stmt_op0, t);
|
|
t = local_fold (t);
|
|
|
|
/* If the result is a suitable looking gimple expression,
|
|
then use it instead of the original for STMT. */
|
|
if (TREE_CODE (t) == SSA_NAME
|
|
|| (UNARY_CLASS_P (t)
|
|
&& TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME)
|
|
|| ((BINARY_CLASS_P (t) || COMPARISON_CLASS_P (t))
|
|
&& TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME
|
|
&& is_gimple_val (TREE_OPERAND (t, 1))))
|
|
result = update_rhs_and_lookup_avail_expr (stmt, t, insert);
|
|
}
|
|
}
|
|
}
|
|
dont_fold_assoc:;
|
|
}
|
|
|
|
/* Optimize *"foo" into 'f'. This is done here rather than
|
|
in fold to avoid problems with stuff like &*"foo". */
|
|
if (TREE_CODE (rhs) == INDIRECT_REF || TREE_CODE (rhs) == ARRAY_REF)
|
|
{
|
|
tree t = fold_read_from_constant_string (rhs);
|
|
|
|
if (t)
|
|
result = update_rhs_and_lookup_avail_expr (stmt, t, insert);
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/* COND is a condition of the form:
|
|
|
|
x == const or x != const
|
|
|
|
Look back to x's defining statement and see if x is defined as
|
|
|
|
x = (type) y;
|
|
|
|
If const is unchanged if we convert it to type, then we can build
|
|
the equivalent expression:
|
|
|
|
|
|
y == const or y != const
|
|
|
|
Which may allow further optimizations.
|
|
|
|
Return the equivalent comparison or NULL if no such equivalent comparison
|
|
was found. */
|
|
|
|
static tree
|
|
find_equivalent_equality_comparison (tree cond)
|
|
{
|
|
tree op0 = TREE_OPERAND (cond, 0);
|
|
tree op1 = TREE_OPERAND (cond, 1);
|
|
tree def_stmt = SSA_NAME_DEF_STMT (op0);
|
|
|
|
/* OP0 might have been a parameter, so first make sure it
|
|
was defined by a MODIFY_EXPR. */
|
|
if (def_stmt && TREE_CODE (def_stmt) == MODIFY_EXPR)
|
|
{
|
|
tree def_rhs = TREE_OPERAND (def_stmt, 1);
|
|
|
|
|
|
/* If either operand to the comparison is a pointer to
|
|
a function, then we can not apply this optimization
|
|
as some targets require function pointers to be
|
|
canonicalized and in this case this optimization would
|
|
eliminate a necessary canonicalization. */
|
|
if ((POINTER_TYPE_P (TREE_TYPE (op0))
|
|
&& TREE_CODE (TREE_TYPE (TREE_TYPE (op0))) == FUNCTION_TYPE)
|
|
|| (POINTER_TYPE_P (TREE_TYPE (op1))
|
|
&& TREE_CODE (TREE_TYPE (TREE_TYPE (op1))) == FUNCTION_TYPE))
|
|
return NULL;
|
|
|
|
/* Now make sure the RHS of the MODIFY_EXPR is a typecast. */
|
|
if ((TREE_CODE (def_rhs) == NOP_EXPR
|
|
|| TREE_CODE (def_rhs) == CONVERT_EXPR)
|
|
&& TREE_CODE (TREE_OPERAND (def_rhs, 0)) == SSA_NAME)
|
|
{
|
|
tree def_rhs_inner = TREE_OPERAND (def_rhs, 0);
|
|
tree def_rhs_inner_type = TREE_TYPE (def_rhs_inner);
|
|
tree new;
|
|
|
|
if (TYPE_PRECISION (def_rhs_inner_type)
|
|
> TYPE_PRECISION (TREE_TYPE (def_rhs)))
|
|
return NULL;
|
|
|
|
/* If the inner type of the conversion is a pointer to
|
|
a function, then we can not apply this optimization
|
|
as some targets require function pointers to be
|
|
canonicalized. This optimization would result in
|
|
canonicalization of the pointer when it was not originally
|
|
needed/intended. */
|
|
if (POINTER_TYPE_P (def_rhs_inner_type)
|
|
&& TREE_CODE (TREE_TYPE (def_rhs_inner_type)) == FUNCTION_TYPE)
|
|
return NULL;
|
|
|
|
/* What we want to prove is that if we convert OP1 to
|
|
the type of the object inside the NOP_EXPR that the
|
|
result is still equivalent to SRC.
|
|
|
|
If that is true, the build and return new equivalent
|
|
condition which uses the source of the typecast and the
|
|
new constant (which has only changed its type). */
|
|
new = build1 (TREE_CODE (def_rhs), def_rhs_inner_type, op1);
|
|
new = local_fold (new);
|
|
if (is_gimple_val (new) && tree_int_cst_equal (new, op1))
|
|
return build (TREE_CODE (cond), TREE_TYPE (cond),
|
|
def_rhs_inner, new);
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/* STMT is a COND_EXPR for which we could not trivially determine its
|
|
result. This routine attempts to find equivalent forms of the
|
|
condition which we may be able to optimize better. It also
|
|
uses simple value range propagation to optimize conditionals. */
|
|
|
|
static tree
|
|
simplify_cond_and_lookup_avail_expr (tree stmt,
|
|
stmt_ann_t ann,
|
|
int insert)
|
|
{
|
|
tree cond = COND_EXPR_COND (stmt);
|
|
|
|
if (COMPARISON_CLASS_P (cond))
|
|
{
|
|
tree op0 = TREE_OPERAND (cond, 0);
|
|
tree op1 = TREE_OPERAND (cond, 1);
|
|
|
|
if (TREE_CODE (op0) == SSA_NAME && is_gimple_min_invariant (op1))
|
|
{
|
|
int limit;
|
|
tree low, high, cond_low, cond_high;
|
|
int lowequal, highequal, swapped, no_overlap, subset, cond_inverted;
|
|
VEC(vrp_element_p,heap) **vrp_records;
|
|
struct vrp_element *element;
|
|
struct vrp_hash_elt vrp_hash_elt, *vrp_hash_elt_p;
|
|
void **slot;
|
|
|
|
/* First see if we have test of an SSA_NAME against a constant
|
|
where the SSA_NAME is defined by an earlier typecast which
|
|
is irrelevant when performing tests against the given
|
|
constant. */
|
|
if (TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
|
|
{
|
|
tree new_cond = find_equivalent_equality_comparison (cond);
|
|
|
|
if (new_cond)
|
|
{
|
|
/* Update the statement to use the new equivalent
|
|
condition. */
|
|
COND_EXPR_COND (stmt) = new_cond;
|
|
|
|
/* If this is not a real stmt, ann will be NULL and we
|
|
avoid processing the operands. */
|
|
if (ann)
|
|
mark_stmt_modified (stmt);
|
|
|
|
/* Lookup the condition and return its known value if it
|
|
exists. */
|
|
new_cond = lookup_avail_expr (stmt, insert);
|
|
if (new_cond)
|
|
return new_cond;
|
|
|
|
/* The operands have changed, so update op0 and op1. */
|
|
op0 = TREE_OPERAND (cond, 0);
|
|
op1 = TREE_OPERAND (cond, 1);
|
|
}
|
|
}
|
|
|
|
/* Consult the value range records for this variable (if they exist)
|
|
to see if we can eliminate or simplify this conditional.
|
|
|
|
Note two tests are necessary to determine no records exist.
|
|
First we have to see if the virtual array exists, if it
|
|
exists, then we have to check its active size.
|
|
|
|
Also note the vast majority of conditionals are not testing
|
|
a variable which has had its range constrained by an earlier
|
|
conditional. So this filter avoids a lot of unnecessary work. */
|
|
vrp_hash_elt.var = op0;
|
|
vrp_hash_elt.records = NULL;
|
|
slot = htab_find_slot (vrp_data, &vrp_hash_elt, NO_INSERT);
|
|
if (slot == NULL)
|
|
return NULL;
|
|
|
|
vrp_hash_elt_p = (struct vrp_hash_elt *) *slot;
|
|
vrp_records = &vrp_hash_elt_p->records;
|
|
|
|
limit = VEC_length (vrp_element_p, *vrp_records);
|
|
|
|
/* If we have no value range records for this variable, or we are
|
|
unable to extract a range for this condition, then there is
|
|
nothing to do. */
|
|
if (limit == 0
|
|
|| ! extract_range_from_cond (cond, &cond_high,
|
|
&cond_low, &cond_inverted))
|
|
return NULL;
|
|
|
|
/* We really want to avoid unnecessary computations of range
|
|
info. So all ranges are computed lazily; this avoids a
|
|
lot of unnecessary work. i.e., we record the conditional,
|
|
but do not process how it constrains the variable's
|
|
potential values until we know that processing the condition
|
|
could be helpful.
|
|
|
|
However, we do not want to have to walk a potentially long
|
|
list of ranges, nor do we want to compute a variable's
|
|
range more than once for a given path.
|
|
|
|
Luckily, each time we encounter a conditional that can not
|
|
be otherwise optimized we will end up here and we will
|
|
compute the necessary range information for the variable
|
|
used in this condition.
|
|
|
|
Thus you can conclude that there will never be more than one
|
|
conditional associated with a variable which has not been
|
|
processed. So we never need to merge more than one new
|
|
conditional into the current range.
|
|
|
|
These properties also help us avoid unnecessary work. */
|
|
element = VEC_last (vrp_element_p, *vrp_records);
|
|
|
|
if (element->high && element->low)
|
|
{
|
|
/* The last element has been processed, so there is no range
|
|
merging to do, we can simply use the high/low values
|
|
recorded in the last element. */
|
|
low = element->low;
|
|
high = element->high;
|
|
}
|
|
else
|
|
{
|
|
tree tmp_high, tmp_low;
|
|
int dummy;
|
|
|
|
/* The last element has not been processed. Process it now.
|
|
record_range should ensure for cond inverted is not set.
|
|
This call can only fail if cond is x < min or x > max,
|
|
which fold should have optimized into false.
|
|
If that doesn't happen, just pretend all values are
|
|
in the range. */
|
|
if (! extract_range_from_cond (element->cond, &tmp_high,
|
|
&tmp_low, &dummy))
|
|
gcc_unreachable ();
|
|
else
|
|
gcc_assert (dummy == 0);
|
|
|
|
/* If this is the only element, then no merging is necessary,
|
|
the high/low values from extract_range_from_cond are all
|
|
we need. */
|
|
if (limit == 1)
|
|
{
|
|
low = tmp_low;
|
|
high = tmp_high;
|
|
}
|
|
else
|
|
{
|
|
/* Get the high/low value from the previous element. */
|
|
struct vrp_element *prev
|
|
= VEC_index (vrp_element_p, *vrp_records, limit - 2);
|
|
low = prev->low;
|
|
high = prev->high;
|
|
|
|
/* Merge in this element's range with the range from the
|
|
previous element.
|
|
|
|
The low value for the merged range is the maximum of
|
|
the previous low value and the low value of this record.
|
|
|
|
Similarly the high value for the merged range is the
|
|
minimum of the previous high value and the high value of
|
|
this record. */
|
|
low = (low && tree_int_cst_compare (low, tmp_low) == 1
|
|
? low : tmp_low);
|
|
high = (high && tree_int_cst_compare (high, tmp_high) == -1
|
|
? high : tmp_high);
|
|
}
|
|
|
|
/* And record the computed range. */
|
|
element->low = low;
|
|
element->high = high;
|
|
|
|
}
|
|
|
|
/* After we have constrained this variable's potential values,
|
|
we try to determine the result of the given conditional.
|
|
|
|
To simplify later tests, first determine if the current
|
|
low value is the same low value as the conditional.
|
|
Similarly for the current high value and the high value
|
|
for the conditional. */
|
|
lowequal = tree_int_cst_equal (low, cond_low);
|
|
highequal = tree_int_cst_equal (high, cond_high);
|
|
|
|
if (lowequal && highequal)
|
|
return (cond_inverted ? boolean_false_node : boolean_true_node);
|
|
|
|
/* To simplify the overlap/subset tests below we may want
|
|
to swap the two ranges so that the larger of the two
|
|
ranges occurs "first". */
|
|
swapped = 0;
|
|
if (tree_int_cst_compare (low, cond_low) == 1
|
|
|| (lowequal
|
|
&& tree_int_cst_compare (cond_high, high) == 1))
|
|
{
|
|
tree temp;
|
|
|
|
swapped = 1;
|
|
temp = low;
|
|
low = cond_low;
|
|
cond_low = temp;
|
|
temp = high;
|
|
high = cond_high;
|
|
cond_high = temp;
|
|
}
|
|
|
|
/* Now determine if there is no overlap in the ranges
|
|
or if the second range is a subset of the first range. */
|
|
no_overlap = tree_int_cst_lt (high, cond_low);
|
|
subset = tree_int_cst_compare (cond_high, high) != 1;
|
|
|
|
/* If there was no overlap in the ranges, then this conditional
|
|
always has a false value (unless we had to invert this
|
|
conditional, in which case it always has a true value). */
|
|
if (no_overlap)
|
|
return (cond_inverted ? boolean_true_node : boolean_false_node);
|
|
|
|
/* If the current range is a subset of the condition's range,
|
|
then this conditional always has a true value (unless we
|
|
had to invert this conditional, in which case it always
|
|
has a true value). */
|
|
if (subset && swapped)
|
|
return (cond_inverted ? boolean_false_node : boolean_true_node);
|
|
|
|
/* We were unable to determine the result of the conditional.
|
|
However, we may be able to simplify the conditional. First
|
|
merge the ranges in the same manner as range merging above. */
|
|
low = tree_int_cst_compare (low, cond_low) == 1 ? low : cond_low;
|
|
high = tree_int_cst_compare (high, cond_high) == -1 ? high : cond_high;
|
|
|
|
/* If the range has converged to a single point, then turn this
|
|
into an equality comparison. */
|
|
if (TREE_CODE (cond) != EQ_EXPR
|
|
&& TREE_CODE (cond) != NE_EXPR
|
|
&& tree_int_cst_equal (low, high))
|
|
{
|
|
TREE_SET_CODE (cond, EQ_EXPR);
|
|
TREE_OPERAND (cond, 1) = high;
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* STMT is a SWITCH_EXPR for which we could not trivially determine its
|
|
result. This routine attempts to find equivalent forms of the
|
|
condition which we may be able to optimize better. */
|
|
|
|
static tree
|
|
simplify_switch_and_lookup_avail_expr (tree stmt, int insert)
|
|
{
|
|
tree cond = SWITCH_COND (stmt);
|
|
tree def, to, ti;
|
|
|
|
/* The optimization that we really care about is removing unnecessary
|
|
casts. That will let us do much better in propagating the inferred
|
|
constant at the switch target. */
|
|
if (TREE_CODE (cond) == SSA_NAME)
|
|
{
|
|
def = SSA_NAME_DEF_STMT (cond);
|
|
if (TREE_CODE (def) == MODIFY_EXPR)
|
|
{
|
|
def = TREE_OPERAND (def, 1);
|
|
if (TREE_CODE (def) == NOP_EXPR)
|
|
{
|
|
int need_precision;
|
|
bool fail;
|
|
|
|
def = TREE_OPERAND (def, 0);
|
|
|
|
#ifdef ENABLE_CHECKING
|
|
/* ??? Why was Jeff testing this? We are gimple... */
|
|
gcc_assert (is_gimple_val (def));
|
|
#endif
|
|
|
|
to = TREE_TYPE (cond);
|
|
ti = TREE_TYPE (def);
|
|
|
|
/* If we have an extension that preserves value, then we
|
|
can copy the source value into the switch. */
|
|
|
|
need_precision = TYPE_PRECISION (ti);
|
|
fail = false;
|
|
if (! INTEGRAL_TYPE_P (ti))
|
|
fail = true;
|
|
else if (TYPE_UNSIGNED (to) && !TYPE_UNSIGNED (ti))
|
|
fail = true;
|
|
else if (!TYPE_UNSIGNED (to) && TYPE_UNSIGNED (ti))
|
|
need_precision += 1;
|
|
if (TYPE_PRECISION (to) < need_precision)
|
|
fail = true;
|
|
|
|
if (!fail)
|
|
{
|
|
SWITCH_COND (stmt) = def;
|
|
mark_stmt_modified (stmt);
|
|
|
|
return lookup_avail_expr (stmt, insert);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
/* CONST_AND_COPIES is a table which maps an SSA_NAME to the current
|
|
known value for that SSA_NAME (or NULL if no value is known).
|
|
|
|
NONZERO_VARS is the set SSA_NAMES known to have a nonzero value,
|
|
even if we don't know their precise value.
|
|
|
|
Propagate values from CONST_AND_COPIES and NONZERO_VARS into the PHI
|
|
nodes of the successors of BB. */
|
|
|
|
static void
|
|
cprop_into_successor_phis (basic_block bb, bitmap nonzero_vars)
|
|
{
|
|
edge e;
|
|
edge_iterator ei;
|
|
|
|
FOR_EACH_EDGE (e, ei, bb->succs)
|
|
{
|
|
tree phi;
|
|
int indx;
|
|
|
|
/* If this is an abnormal edge, then we do not want to copy propagate
|
|
into the PHI alternative associated with this edge. */
|
|
if (e->flags & EDGE_ABNORMAL)
|
|
continue;
|
|
|
|
phi = phi_nodes (e->dest);
|
|
if (! phi)
|
|
continue;
|
|
|
|
indx = e->dest_idx;
|
|
for ( ; phi; phi = PHI_CHAIN (phi))
|
|
{
|
|
tree new;
|
|
use_operand_p orig_p;
|
|
tree orig;
|
|
|
|
/* The alternative may be associated with a constant, so verify
|
|
it is an SSA_NAME before doing anything with it. */
|
|
orig_p = PHI_ARG_DEF_PTR (phi, indx);
|
|
orig = USE_FROM_PTR (orig_p);
|
|
if (TREE_CODE (orig) != SSA_NAME)
|
|
continue;
|
|
|
|
/* If the alternative is known to have a nonzero value, record
|
|
that fact in the PHI node itself for future use. */
|
|
if (bitmap_bit_p (nonzero_vars, SSA_NAME_VERSION (orig)))
|
|
PHI_ARG_NONZERO (phi, indx) = true;
|
|
|
|
/* If we have *ORIG_P in our constant/copy table, then replace
|
|
ORIG_P with its value in our constant/copy table. */
|
|
new = SSA_NAME_VALUE (orig);
|
|
if (new
|
|
&& new != orig
|
|
&& (TREE_CODE (new) == SSA_NAME
|
|
|| is_gimple_min_invariant (new))
|
|
&& may_propagate_copy (orig, new))
|
|
propagate_value (orig_p, new);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* We have finished optimizing BB, record any information implied by
|
|
taking a specific outgoing edge from BB. */
|
|
|
|
static void
|
|
record_edge_info (basic_block bb)
|
|
{
|
|
block_stmt_iterator bsi = bsi_last (bb);
|
|
struct edge_info *edge_info;
|
|
|
|
if (! bsi_end_p (bsi))
|
|
{
|
|
tree stmt = bsi_stmt (bsi);
|
|
|
|
if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
|
|
{
|
|
tree cond = SWITCH_COND (stmt);
|
|
|
|
if (TREE_CODE (cond) == SSA_NAME)
|
|
{
|
|
tree labels = SWITCH_LABELS (stmt);
|
|
int i, n_labels = TREE_VEC_LENGTH (labels);
|
|
tree *info = xcalloc (last_basic_block, sizeof (tree));
|
|
edge e;
|
|
edge_iterator ei;
|
|
|
|
for (i = 0; i < n_labels; i++)
|
|
{
|
|
tree label = TREE_VEC_ELT (labels, i);
|
|
basic_block target_bb = label_to_block (CASE_LABEL (label));
|
|
|
|
if (CASE_HIGH (label)
|
|
|| !CASE_LOW (label)
|
|
|| info[target_bb->index])
|
|
info[target_bb->index] = error_mark_node;
|
|
else
|
|
info[target_bb->index] = label;
|
|
}
|
|
|
|
FOR_EACH_EDGE (e, ei, bb->succs)
|
|
{
|
|
basic_block target_bb = e->dest;
|
|
tree node = info[target_bb->index];
|
|
|
|
if (node != NULL && node != error_mark_node)
|
|
{
|
|
tree x = fold_convert (TREE_TYPE (cond), CASE_LOW (node));
|
|
edge_info = allocate_edge_info (e);
|
|
edge_info->lhs = cond;
|
|
edge_info->rhs = x;
|
|
}
|
|
}
|
|
free (info);
|
|
}
|
|
}
|
|
|
|
/* A COND_EXPR may create equivalences too. */
|
|
if (stmt && TREE_CODE (stmt) == COND_EXPR)
|
|
{
|
|
tree cond = COND_EXPR_COND (stmt);
|
|
edge true_edge;
|
|
edge false_edge;
|
|
|
|
extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
|
|
|
|
/* If the conditional is a single variable 'X', record 'X = 1'
|
|
for the true edge and 'X = 0' on the false edge. */
|
|
if (SSA_VAR_P (cond))
|
|
{
|
|
struct edge_info *edge_info;
|
|
|
|
edge_info = allocate_edge_info (true_edge);
|
|
edge_info->lhs = cond;
|
|
edge_info->rhs = constant_boolean_node (1, TREE_TYPE (cond));
|
|
|
|
edge_info = allocate_edge_info (false_edge);
|
|
edge_info->lhs = cond;
|
|
edge_info->rhs = constant_boolean_node (0, TREE_TYPE (cond));
|
|
}
|
|
/* Equality tests may create one or two equivalences. */
|
|
else if (COMPARISON_CLASS_P (cond))
|
|
{
|
|
tree op0 = TREE_OPERAND (cond, 0);
|
|
tree op1 = TREE_OPERAND (cond, 1);
|
|
|
|
/* Special case comparing booleans against a constant as we
|
|
know the value of OP0 on both arms of the branch. i.e., we
|
|
can record an equivalence for OP0 rather than COND. */
|
|
if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
|
|
&& TREE_CODE (op0) == SSA_NAME
|
|
&& TREE_CODE (TREE_TYPE (op0)) == BOOLEAN_TYPE
|
|
&& is_gimple_min_invariant (op1))
|
|
{
|
|
if (TREE_CODE (cond) == EQ_EXPR)
|
|
{
|
|
edge_info = allocate_edge_info (true_edge);
|
|
edge_info->lhs = op0;
|
|
edge_info->rhs = (integer_zerop (op1)
|
|
? boolean_false_node
|
|
: boolean_true_node);
|
|
|
|
edge_info = allocate_edge_info (false_edge);
|
|
edge_info->lhs = op0;
|
|
edge_info->rhs = (integer_zerop (op1)
|
|
? boolean_true_node
|
|
: boolean_false_node);
|
|
}
|
|
else
|
|
{
|
|
edge_info = allocate_edge_info (true_edge);
|
|
edge_info->lhs = op0;
|
|
edge_info->rhs = (integer_zerop (op1)
|
|
? boolean_true_node
|
|
: boolean_false_node);
|
|
|
|
edge_info = allocate_edge_info (false_edge);
|
|
edge_info->lhs = op0;
|
|
edge_info->rhs = (integer_zerop (op1)
|
|
? boolean_false_node
|
|
: boolean_true_node);
|
|
}
|
|
}
|
|
|
|
else if (is_gimple_min_invariant (op0)
|
|
&& (TREE_CODE (op1) == SSA_NAME
|
|
|| is_gimple_min_invariant (op1)))
|
|
{
|
|
tree inverted = invert_truthvalue (cond);
|
|
struct edge_info *edge_info;
|
|
|
|
edge_info = allocate_edge_info (true_edge);
|
|
record_conditions (edge_info, cond, inverted);
|
|
|
|
if (TREE_CODE (cond) == EQ_EXPR)
|
|
{
|
|
edge_info->lhs = op1;
|
|
edge_info->rhs = op0;
|
|
}
|
|
|
|
edge_info = allocate_edge_info (false_edge);
|
|
record_conditions (edge_info, inverted, cond);
|
|
|
|
if (TREE_CODE (cond) == NE_EXPR)
|
|
{
|
|
edge_info->lhs = op1;
|
|
edge_info->rhs = op0;
|
|
}
|
|
}
|
|
|
|
else if (TREE_CODE (op0) == SSA_NAME
|
|
&& (is_gimple_min_invariant (op1)
|
|
|| TREE_CODE (op1) == SSA_NAME))
|
|
{
|
|
tree inverted = invert_truthvalue (cond);
|
|
struct edge_info *edge_info;
|
|
|
|
edge_info = allocate_edge_info (true_edge);
|
|
record_conditions (edge_info, cond, inverted);
|
|
|
|
if (TREE_CODE (cond) == EQ_EXPR)
|
|
{
|
|
edge_info->lhs = op0;
|
|
edge_info->rhs = op1;
|
|
}
|
|
|
|
edge_info = allocate_edge_info (false_edge);
|
|
record_conditions (edge_info, inverted, cond);
|
|
|
|
if (TREE_CODE (cond) == NE_EXPR)
|
|
{
|
|
edge_info->lhs = op0;
|
|
edge_info->rhs = op1;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* ??? TRUTH_NOT_EXPR can create an equivalence too. */
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Propagate information from BB to its outgoing edges.
|
|
|
|
This can include equivalency information implied by control statements
|
|
at the end of BB and const/copy propagation into PHIs in BB's
|
|
successor blocks. */
|
|
|
|
static void
|
|
propagate_to_outgoing_edges (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
|
|
basic_block bb)
|
|
{
|
|
record_edge_info (bb);
|
|
cprop_into_successor_phis (bb, nonzero_vars);
|
|
}
|
|
|
|
/* Search for redundant computations in STMT. If any are found, then
|
|
replace them with the variable holding the result of the computation.
|
|
|
|
If safe, record this expression into the available expression hash
|
|
table. */
|
|
|
|
static bool
|
|
eliminate_redundant_computations (tree stmt, stmt_ann_t ann)
|
|
{
|
|
tree *expr_p, def = NULL_TREE;
|
|
bool insert = true;
|
|
tree cached_lhs;
|
|
bool retval = false;
|
|
bool modify_expr_p = false;
|
|
|
|
if (TREE_CODE (stmt) == MODIFY_EXPR)
|
|
def = TREE_OPERAND (stmt, 0);
|
|
|
|
/* Certain expressions on the RHS can be optimized away, but can not
|
|
themselves be entered into the hash tables. */
|
|
if (ann->makes_aliased_stores
|
|
|| ! def
|
|
|| TREE_CODE (def) != SSA_NAME
|
|
|| SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def)
|
|
|| !ZERO_SSA_OPERANDS (stmt, SSA_OP_VMAYDEF)
|
|
/* Do not record equivalences for increments of ivs. This would create
|
|
overlapping live ranges for a very questionable gain. */
|
|
|| simple_iv_increment_p (stmt))
|
|
insert = false;
|
|
|
|
/* Check if the expression has been computed before. */
|
|
cached_lhs = lookup_avail_expr (stmt, insert);
|
|
|
|
/* If this is an assignment and the RHS was not in the hash table,
|
|
then try to simplify the RHS and lookup the new RHS in the
|
|
hash table. */
|
|
if (! cached_lhs && TREE_CODE (stmt) == MODIFY_EXPR)
|
|
cached_lhs = simplify_rhs_and_lookup_avail_expr (stmt, insert);
|
|
/* Similarly if this is a COND_EXPR and we did not find its
|
|
expression in the hash table, simplify the condition and
|
|
try again. */
|
|
else if (! cached_lhs && TREE_CODE (stmt) == COND_EXPR)
|
|
cached_lhs = simplify_cond_and_lookup_avail_expr (stmt, ann, insert);
|
|
/* Similarly for a SWITCH_EXPR. */
|
|
else if (!cached_lhs && TREE_CODE (stmt) == SWITCH_EXPR)
|
|
cached_lhs = simplify_switch_and_lookup_avail_expr (stmt, insert);
|
|
|
|
opt_stats.num_exprs_considered++;
|
|
|
|
/* Get a pointer to the expression we are trying to optimize. */
|
|
if (TREE_CODE (stmt) == COND_EXPR)
|
|
expr_p = &COND_EXPR_COND (stmt);
|
|
else if (TREE_CODE (stmt) == SWITCH_EXPR)
|
|
expr_p = &SWITCH_COND (stmt);
|
|
else if (TREE_CODE (stmt) == RETURN_EXPR && TREE_OPERAND (stmt, 0))
|
|
{
|
|
expr_p = &TREE_OPERAND (TREE_OPERAND (stmt, 0), 1);
|
|
modify_expr_p = true;
|
|
}
|
|
else
|
|
{
|
|
expr_p = &TREE_OPERAND (stmt, 1);
|
|
modify_expr_p = true;
|
|
}
|
|
|
|
/* It is safe to ignore types here since we have already done
|
|
type checking in the hashing and equality routines. In fact
|
|
type checking here merely gets in the way of constant
|
|
propagation. Also, make sure that it is safe to propagate
|
|
CACHED_LHS into *EXPR_P. */
|
|
if (cached_lhs
|
|
&& ((TREE_CODE (cached_lhs) != SSA_NAME
|
|
&& (modify_expr_p
|
|
|| tree_ssa_useless_type_conversion_1 (TREE_TYPE (*expr_p),
|
|
TREE_TYPE (cached_lhs))))
|
|
|| may_propagate_copy (*expr_p, cached_lhs)))
|
|
{
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
{
|
|
fprintf (dump_file, " Replaced redundant expr '");
|
|
print_generic_expr (dump_file, *expr_p, dump_flags);
|
|
fprintf (dump_file, "' with '");
|
|
print_generic_expr (dump_file, cached_lhs, dump_flags);
|
|
fprintf (dump_file, "'\n");
|
|
}
|
|
|
|
opt_stats.num_re++;
|
|
|
|
#if defined ENABLE_CHECKING
|
|
gcc_assert (TREE_CODE (cached_lhs) == SSA_NAME
|
|
|| is_gimple_min_invariant (cached_lhs));
|
|
#endif
|
|
|
|
if (TREE_CODE (cached_lhs) == ADDR_EXPR
|
|
|| (POINTER_TYPE_P (TREE_TYPE (*expr_p))
|
|
&& is_gimple_min_invariant (cached_lhs)))
|
|
retval = true;
|
|
|
|
if (modify_expr_p
|
|
&& !tree_ssa_useless_type_conversion_1 (TREE_TYPE (*expr_p),
|
|
TREE_TYPE (cached_lhs)))
|
|
cached_lhs = fold_convert (TREE_TYPE (*expr_p), cached_lhs);
|
|
|
|
propagate_tree_value (expr_p, cached_lhs);
|
|
mark_stmt_modified (stmt);
|
|
}
|
|
return retval;
|
|
}
|
|
|
|
/* STMT, a MODIFY_EXPR, may create certain equivalences, in either
|
|
the available expressions table or the const_and_copies table.
|
|
Detect and record those equivalences. */
|
|
|
|
static void
|
|
record_equivalences_from_stmt (tree stmt,
|
|
int may_optimize_p,
|
|
stmt_ann_t ann)
|
|
{
|
|
tree lhs = TREE_OPERAND (stmt, 0);
|
|
enum tree_code lhs_code = TREE_CODE (lhs);
|
|
int i;
|
|
|
|
if (lhs_code == SSA_NAME)
|
|
{
|
|
tree rhs = TREE_OPERAND (stmt, 1);
|
|
|
|
/* Strip away any useless type conversions. */
|
|
STRIP_USELESS_TYPE_CONVERSION (rhs);
|
|
|
|
/* If the RHS of the assignment is a constant or another variable that
|
|
may be propagated, register it in the CONST_AND_COPIES table. We
|
|
do not need to record unwind data for this, since this is a true
|
|
assignment and not an equivalence inferred from a comparison. All
|
|
uses of this ssa name are dominated by this assignment, so unwinding
|
|
just costs time and space. */
|
|
if (may_optimize_p
|
|
&& (TREE_CODE (rhs) == SSA_NAME
|
|
|| is_gimple_min_invariant (rhs)))
|
|
SSA_NAME_VALUE (lhs) = rhs;
|
|
|
|
if (tree_expr_nonzero_p (rhs))
|
|
record_var_is_nonzero (lhs);
|
|
}
|
|
|
|
/* Look at both sides for pointer dereferences. If we find one, then
|
|
the pointer must be nonnull and we can enter that equivalence into
|
|
the hash tables. */
|
|
if (flag_delete_null_pointer_checks)
|
|
for (i = 0; i < 2; i++)
|
|
{
|
|
tree t = TREE_OPERAND (stmt, i);
|
|
|
|
/* Strip away any COMPONENT_REFs. */
|
|
while (TREE_CODE (t) == COMPONENT_REF)
|
|
t = TREE_OPERAND (t, 0);
|
|
|
|
/* Now see if this is a pointer dereference. */
|
|
if (INDIRECT_REF_P (t))
|
|
{
|
|
tree op = TREE_OPERAND (t, 0);
|
|
|
|
/* If the pointer is a SSA variable, then enter new
|
|
equivalences into the hash table. */
|
|
while (TREE_CODE (op) == SSA_NAME)
|
|
{
|
|
tree def = SSA_NAME_DEF_STMT (op);
|
|
|
|
record_var_is_nonzero (op);
|
|
|
|
/* And walk up the USE-DEF chains noting other SSA_NAMEs
|
|
which are known to have a nonzero value. */
|
|
if (def
|
|
&& TREE_CODE (def) == MODIFY_EXPR
|
|
&& TREE_CODE (TREE_OPERAND (def, 1)) == NOP_EXPR)
|
|
op = TREE_OPERAND (TREE_OPERAND (def, 1), 0);
|
|
else
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* A memory store, even an aliased store, creates a useful
|
|
equivalence. By exchanging the LHS and RHS, creating suitable
|
|
vops and recording the result in the available expression table,
|
|
we may be able to expose more redundant loads. */
|
|
if (!ann->has_volatile_ops
|
|
&& (TREE_CODE (TREE_OPERAND (stmt, 1)) == SSA_NAME
|
|
|| is_gimple_min_invariant (TREE_OPERAND (stmt, 1)))
|
|
&& !is_gimple_reg (lhs))
|
|
{
|
|
tree rhs = TREE_OPERAND (stmt, 1);
|
|
tree new;
|
|
|
|
/* FIXME: If the LHS of the assignment is a bitfield and the RHS
|
|
is a constant, we need to adjust the constant to fit into the
|
|
type of the LHS. If the LHS is a bitfield and the RHS is not
|
|
a constant, then we can not record any equivalences for this
|
|
statement since we would need to represent the widening or
|
|
narrowing of RHS. This fixes gcc.c-torture/execute/921016-1.c
|
|
and should not be necessary if GCC represented bitfields
|
|
properly. */
|
|
if (lhs_code == COMPONENT_REF
|
|
&& DECL_BIT_FIELD (TREE_OPERAND (lhs, 1)))
|
|
{
|
|
if (TREE_CONSTANT (rhs))
|
|
rhs = widen_bitfield (rhs, TREE_OPERAND (lhs, 1), lhs);
|
|
else
|
|
rhs = NULL;
|
|
|
|
/* If the value overflowed, then we can not use this equivalence. */
|
|
if (rhs && ! is_gimple_min_invariant (rhs))
|
|
rhs = NULL;
|
|
}
|
|
|
|
if (rhs)
|
|
{
|
|
/* Build a new statement with the RHS and LHS exchanged. */
|
|
new = build (MODIFY_EXPR, TREE_TYPE (stmt), rhs, lhs);
|
|
|
|
create_ssa_artficial_load_stmt (new, stmt);
|
|
|
|
/* Finally enter the statement into the available expression
|
|
table. */
|
|
lookup_avail_expr (new, true);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Replace *OP_P in STMT with any known equivalent value for *OP_P from
|
|
CONST_AND_COPIES. */
|
|
|
|
static bool
|
|
cprop_operand (tree stmt, use_operand_p op_p)
|
|
{
|
|
bool may_have_exposed_new_symbols = false;
|
|
tree val;
|
|
tree op = USE_FROM_PTR (op_p);
|
|
|
|
/* If the operand has a known constant value or it is known to be a
|
|
copy of some other variable, use the value or copy stored in
|
|
CONST_AND_COPIES. */
|
|
val = SSA_NAME_VALUE (op);
|
|
if (val && val != op && TREE_CODE (val) != VALUE_HANDLE)
|
|
{
|
|
tree op_type, val_type;
|
|
|
|
/* Do not change the base variable in the virtual operand
|
|
tables. That would make it impossible to reconstruct
|
|
the renamed virtual operand if we later modify this
|
|
statement. Also only allow the new value to be an SSA_NAME
|
|
for propagation into virtual operands. */
|
|
if (!is_gimple_reg (op)
|
|
&& (TREE_CODE (val) != SSA_NAME
|
|
|| is_gimple_reg (val)
|
|
|| get_virtual_var (val) != get_virtual_var (op)))
|
|
return false;
|
|
|
|
/* Do not replace hard register operands in asm statements. */
|
|
if (TREE_CODE (stmt) == ASM_EXPR
|
|
&& !may_propagate_copy_into_asm (op))
|
|
return false;
|
|
|
|
/* Get the toplevel type of each operand. */
|
|
op_type = TREE_TYPE (op);
|
|
val_type = TREE_TYPE (val);
|
|
|
|
/* While both types are pointers, get the type of the object
|
|
pointed to. */
|
|
while (POINTER_TYPE_P (op_type) && POINTER_TYPE_P (val_type))
|
|
{
|
|
op_type = TREE_TYPE (op_type);
|
|
val_type = TREE_TYPE (val_type);
|
|
}
|
|
|
|
/* Make sure underlying types match before propagating a constant by
|
|
converting the constant to the proper type. Note that convert may
|
|
return a non-gimple expression, in which case we ignore this
|
|
propagation opportunity. */
|
|
if (TREE_CODE (val) != SSA_NAME)
|
|
{
|
|
if (!lang_hooks.types_compatible_p (op_type, val_type))
|
|
{
|
|
val = fold_convert (TREE_TYPE (op), val);
|
|
if (!is_gimple_min_invariant (val))
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/* Certain operands are not allowed to be copy propagated due
|
|
to their interaction with exception handling and some GCC
|
|
extensions. */
|
|
else if (!may_propagate_copy (op, val))
|
|
return false;
|
|
|
|
/* Do not propagate copies if the propagated value is at a deeper loop
|
|
depth than the propagatee. Otherwise, this may move loop variant
|
|
variables outside of their loops and prevent coalescing
|
|
opportunities. If the value was loop invariant, it will be hoisted
|
|
by LICM and exposed for copy propagation. */
|
|
if (loop_depth_of_name (val) > loop_depth_of_name (op))
|
|
return false;
|
|
|
|
/* Dump details. */
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
{
|
|
fprintf (dump_file, " Replaced '");
|
|
print_generic_expr (dump_file, op, dump_flags);
|
|
fprintf (dump_file, "' with %s '",
|
|
(TREE_CODE (val) != SSA_NAME ? "constant" : "variable"));
|
|
print_generic_expr (dump_file, val, dump_flags);
|
|
fprintf (dump_file, "'\n");
|
|
}
|
|
|
|
/* If VAL is an ADDR_EXPR or a constant of pointer type, note
|
|
that we may have exposed a new symbol for SSA renaming. */
|
|
if (TREE_CODE (val) == ADDR_EXPR
|
|
|| (POINTER_TYPE_P (TREE_TYPE (op))
|
|
&& is_gimple_min_invariant (val)))
|
|
may_have_exposed_new_symbols = true;
|
|
|
|
if (TREE_CODE (val) != SSA_NAME)
|
|
opt_stats.num_const_prop++;
|
|
else
|
|
opt_stats.num_copy_prop++;
|
|
|
|
propagate_value (op_p, val);
|
|
|
|
/* And note that we modified this statement. This is now
|
|
safe, even if we changed virtual operands since we will
|
|
rescan the statement and rewrite its operands again. */
|
|
mark_stmt_modified (stmt);
|
|
}
|
|
return may_have_exposed_new_symbols;
|
|
}
|
|
|
|
/* CONST_AND_COPIES is a table which maps an SSA_NAME to the current
|
|
known value for that SSA_NAME (or NULL if no value is known).
|
|
|
|
Propagate values from CONST_AND_COPIES into the uses, vuses and
|
|
v_may_def_ops of STMT. */
|
|
|
|
static bool
|
|
cprop_into_stmt (tree stmt)
|
|
{
|
|
bool may_have_exposed_new_symbols = false;
|
|
use_operand_p op_p;
|
|
ssa_op_iter iter;
|
|
|
|
FOR_EACH_SSA_USE_OPERAND (op_p, stmt, iter, SSA_OP_ALL_USES)
|
|
{
|
|
if (TREE_CODE (USE_FROM_PTR (op_p)) == SSA_NAME)
|
|
may_have_exposed_new_symbols |= cprop_operand (stmt, op_p);
|
|
}
|
|
|
|
return may_have_exposed_new_symbols;
|
|
}
|
|
|
|
|
|
/* Optimize the statement pointed to by iterator SI.
|
|
|
|
We try to perform some simplistic global redundancy elimination and
|
|
constant propagation:
|
|
|
|
1- To detect global redundancy, we keep track of expressions that have
|
|
been computed in this block and its dominators. If we find that the
|
|
same expression is computed more than once, we eliminate repeated
|
|
computations by using the target of the first one.
|
|
|
|
2- Constant values and copy assignments. This is used to do very
|
|
simplistic constant and copy propagation. When a constant or copy
|
|
assignment is found, we map the value on the RHS of the assignment to
|
|
the variable in the LHS in the CONST_AND_COPIES table. */
|
|
|
|
static void
|
|
optimize_stmt (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
|
|
basic_block bb, block_stmt_iterator si)
|
|
{
|
|
stmt_ann_t ann;
|
|
tree stmt, old_stmt;
|
|
bool may_optimize_p;
|
|
bool may_have_exposed_new_symbols = false;
|
|
|
|
old_stmt = stmt = bsi_stmt (si);
|
|
|
|
update_stmt_if_modified (stmt);
|
|
ann = stmt_ann (stmt);
|
|
opt_stats.num_stmts++;
|
|
may_have_exposed_new_symbols = false;
|
|
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
{
|
|
fprintf (dump_file, "Optimizing statement ");
|
|
print_generic_stmt (dump_file, stmt, TDF_SLIM);
|
|
}
|
|
|
|
/* Const/copy propagate into USES, VUSES and the RHS of V_MAY_DEFs. */
|
|
may_have_exposed_new_symbols = cprop_into_stmt (stmt);
|
|
|
|
/* If the statement has been modified with constant replacements,
|
|
fold its RHS before checking for redundant computations. */
|
|
if (ann->modified)
|
|
{
|
|
tree rhs;
|
|
|
|
/* Try to fold the statement making sure that STMT is kept
|
|
up to date. */
|
|
if (fold_stmt (bsi_stmt_ptr (si)))
|
|
{
|
|
stmt = bsi_stmt (si);
|
|
ann = stmt_ann (stmt);
|
|
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
{
|
|
fprintf (dump_file, " Folded to: ");
|
|
print_generic_stmt (dump_file, stmt, TDF_SLIM);
|
|
}
|
|
}
|
|
|
|
rhs = get_rhs (stmt);
|
|
if (rhs && TREE_CODE (rhs) == ADDR_EXPR)
|
|
recompute_tree_invarant_for_addr_expr (rhs);
|
|
|
|
/* Constant/copy propagation above may change the set of
|
|
virtual operands associated with this statement. Folding
|
|
may remove the need for some virtual operands.
|
|
|
|
Indicate we will need to rescan and rewrite the statement. */
|
|
may_have_exposed_new_symbols = true;
|
|
}
|
|
|
|
/* Check for redundant computations. Do this optimization only
|
|
for assignments that have no volatile ops and conditionals. */
|
|
may_optimize_p = (!ann->has_volatile_ops
|
|
&& ((TREE_CODE (stmt) == RETURN_EXPR
|
|
&& TREE_OPERAND (stmt, 0)
|
|
&& TREE_CODE (TREE_OPERAND (stmt, 0)) == MODIFY_EXPR
|
|
&& ! (TREE_SIDE_EFFECTS
|
|
(TREE_OPERAND (TREE_OPERAND (stmt, 0), 1))))
|
|
|| (TREE_CODE (stmt) == MODIFY_EXPR
|
|
&& ! TREE_SIDE_EFFECTS (TREE_OPERAND (stmt, 1)))
|
|
|| TREE_CODE (stmt) == COND_EXPR
|
|
|| TREE_CODE (stmt) == SWITCH_EXPR));
|
|
|
|
if (may_optimize_p)
|
|
may_have_exposed_new_symbols
|
|
|= eliminate_redundant_computations (stmt, ann);
|
|
|
|
/* Record any additional equivalences created by this statement. */
|
|
if (TREE_CODE (stmt) == MODIFY_EXPR)
|
|
record_equivalences_from_stmt (stmt,
|
|
may_optimize_p,
|
|
ann);
|
|
|
|
/* If STMT is a COND_EXPR and it was modified, then we may know
|
|
where it goes. If that is the case, then mark the CFG as altered.
|
|
|
|
This will cause us to later call remove_unreachable_blocks and
|
|
cleanup_tree_cfg when it is safe to do so. It is not safe to
|
|
clean things up here since removal of edges and such can trigger
|
|
the removal of PHI nodes, which in turn can release SSA_NAMEs to
|
|
the manager.
|
|
|
|
That's all fine and good, except that once SSA_NAMEs are released
|
|
to the manager, we must not call create_ssa_name until all references
|
|
to released SSA_NAMEs have been eliminated.
|
|
|
|
All references to the deleted SSA_NAMEs can not be eliminated until
|
|
we remove unreachable blocks.
|
|
|
|
We can not remove unreachable blocks until after we have completed
|
|
any queued jump threading.
|
|
|
|
We can not complete any queued jump threads until we have taken
|
|
appropriate variables out of SSA form. Taking variables out of
|
|
SSA form can call create_ssa_name and thus we lose.
|
|
|
|
Ultimately I suspect we're going to need to change the interface
|
|
into the SSA_NAME manager. */
|
|
|
|
if (ann->modified)
|
|
{
|
|
tree val = NULL;
|
|
|
|
if (TREE_CODE (stmt) == COND_EXPR)
|
|
val = COND_EXPR_COND (stmt);
|
|
else if (TREE_CODE (stmt) == SWITCH_EXPR)
|
|
val = SWITCH_COND (stmt);
|
|
|
|
if (val && TREE_CODE (val) == INTEGER_CST && find_taken_edge (bb, val))
|
|
cfg_altered = true;
|
|
|
|
/* If we simplified a statement in such a way as to be shown that it
|
|
cannot trap, update the eh information and the cfg to match. */
|
|
if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
|
|
{
|
|
bitmap_set_bit (need_eh_cleanup, bb->index);
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
fprintf (dump_file, " Flagged to clear EH edges.\n");
|
|
}
|
|
}
|
|
|
|
if (may_have_exposed_new_symbols)
|
|
VEC_safe_push (tree, heap, stmts_to_rescan, bsi_stmt (si));
|
|
}
|
|
|
|
/* Replace the RHS of STMT with NEW_RHS. If RHS can be found in the
|
|
available expression hashtable, then return the LHS from the hash
|
|
table.
|
|
|
|
If INSERT is true, then we also update the available expression
|
|
hash table to account for the changes made to STMT. */
|
|
|
|
static tree
|
|
update_rhs_and_lookup_avail_expr (tree stmt, tree new_rhs, bool insert)
|
|
{
|
|
tree cached_lhs = NULL;
|
|
|
|
/* Remove the old entry from the hash table. */
|
|
if (insert)
|
|
{
|
|
struct expr_hash_elt element;
|
|
|
|
initialize_hash_element (stmt, NULL, &element);
|
|
htab_remove_elt_with_hash (avail_exprs, &element, element.hash);
|
|
}
|
|
|
|
/* Now update the RHS of the assignment. */
|
|
TREE_OPERAND (stmt, 1) = new_rhs;
|
|
|
|
/* Now lookup the updated statement in the hash table. */
|
|
cached_lhs = lookup_avail_expr (stmt, insert);
|
|
|
|
/* We have now called lookup_avail_expr twice with two different
|
|
versions of this same statement, once in optimize_stmt, once here.
|
|
|
|
We know the call in optimize_stmt did not find an existing entry
|
|
in the hash table, so a new entry was created. At the same time
|
|
this statement was pushed onto the AVAIL_EXPRS_STACK vector.
|
|
|
|
If this call failed to find an existing entry on the hash table,
|
|
then the new version of this statement was entered into the
|
|
hash table. And this statement was pushed onto BLOCK_AVAIL_EXPR
|
|
for the second time. So there are two copies on BLOCK_AVAIL_EXPRs
|
|
|
|
If this call succeeded, we still have one copy of this statement
|
|
on the BLOCK_AVAIL_EXPRs vector.
|
|
|
|
For both cases, we need to pop the most recent entry off the
|
|
BLOCK_AVAIL_EXPRs vector. For the case where we never found this
|
|
statement in the hash tables, that will leave precisely one
|
|
copy of this statement on BLOCK_AVAIL_EXPRs. For the case where
|
|
we found a copy of this statement in the second hash table lookup
|
|
we want _no_ copies of this statement in BLOCK_AVAIL_EXPRs. */
|
|
if (insert)
|
|
VEC_pop (tree, avail_exprs_stack);
|
|
|
|
/* And make sure we record the fact that we modified this
|
|
statement. */
|
|
mark_stmt_modified (stmt);
|
|
|
|
return cached_lhs;
|
|
}
|
|
|
|
/* Search for an existing instance of STMT in the AVAIL_EXPRS table. If
|
|
found, return its LHS. Otherwise insert STMT in the table and return
|
|
NULL_TREE.
|
|
|
|
Also, when an expression is first inserted in the AVAIL_EXPRS table, it
|
|
is also added to the stack pointed to by BLOCK_AVAIL_EXPRS_P, so that they
|
|
can be removed when we finish processing this block and its children.
|
|
|
|
NOTE: This function assumes that STMT is a MODIFY_EXPR node that
|
|
contains no CALL_EXPR on its RHS and makes no volatile nor
|
|
aliased references. */
|
|
|
|
static tree
|
|
lookup_avail_expr (tree stmt, bool insert)
|
|
{
|
|
void **slot;
|
|
tree lhs;
|
|
tree temp;
|
|
struct expr_hash_elt *element = xmalloc (sizeof (struct expr_hash_elt));
|
|
|
|
lhs = TREE_CODE (stmt) == MODIFY_EXPR ? TREE_OPERAND (stmt, 0) : NULL;
|
|
|
|
initialize_hash_element (stmt, lhs, element);
|
|
|
|
/* Don't bother remembering constant assignments and copy operations.
|
|
Constants and copy operations are handled by the constant/copy propagator
|
|
in optimize_stmt. */
|
|
if (TREE_CODE (element->rhs) == SSA_NAME
|
|
|| is_gimple_min_invariant (element->rhs))
|
|
{
|
|
free (element);
|
|
return NULL_TREE;
|
|
}
|
|
|
|
/* If this is an equality test against zero, see if we have recorded a
|
|
nonzero value for the variable in question. */
|
|
if ((TREE_CODE (element->rhs) == EQ_EXPR
|
|
|| TREE_CODE (element->rhs) == NE_EXPR)
|
|
&& TREE_CODE (TREE_OPERAND (element->rhs, 0)) == SSA_NAME
|
|
&& integer_zerop (TREE_OPERAND (element->rhs, 1)))
|
|
{
|
|
int indx = SSA_NAME_VERSION (TREE_OPERAND (element->rhs, 0));
|
|
|
|
if (bitmap_bit_p (nonzero_vars, indx))
|
|
{
|
|
tree t = element->rhs;
|
|
free (element);
|
|
return constant_boolean_node (TREE_CODE (t) != EQ_EXPR,
|
|
TREE_TYPE (t));
|
|
}
|
|
}
|
|
|
|
/* Finally try to find the expression in the main expression hash table. */
|
|
slot = htab_find_slot_with_hash (avail_exprs, element, element->hash,
|
|
(insert ? INSERT : NO_INSERT));
|
|
if (slot == NULL)
|
|
{
|
|
free (element);
|
|
return NULL_TREE;
|
|
}
|
|
|
|
if (*slot == NULL)
|
|
{
|
|
*slot = (void *) element;
|
|
VEC_safe_push (tree, heap, avail_exprs_stack,
|
|
stmt ? stmt : element->rhs);
|
|
return NULL_TREE;
|
|
}
|
|
|
|
/* Extract the LHS of the assignment so that it can be used as the current
|
|
definition of another variable. */
|
|
lhs = ((struct expr_hash_elt *)*slot)->lhs;
|
|
|
|
/* See if the LHS appears in the CONST_AND_COPIES table. If it does, then
|
|
use the value from the const_and_copies table. */
|
|
if (TREE_CODE (lhs) == SSA_NAME)
|
|
{
|
|
temp = SSA_NAME_VALUE (lhs);
|
|
if (temp && TREE_CODE (temp) != VALUE_HANDLE)
|
|
lhs = temp;
|
|
}
|
|
|
|
free (element);
|
|
return lhs;
|
|
}
|
|
|
|
/* Given a condition COND, record into HI_P, LO_P and INVERTED_P the
|
|
range of values that result in the conditional having a true value.
|
|
|
|
Return true if we are successful in extracting a range from COND and
|
|
false if we are unsuccessful. */
|
|
|
|
static bool
|
|
extract_range_from_cond (tree cond, tree *hi_p, tree *lo_p, int *inverted_p)
|
|
{
|
|
tree op1 = TREE_OPERAND (cond, 1);
|
|
tree high, low, type;
|
|
int inverted;
|
|
|
|
type = TREE_TYPE (op1);
|
|
|
|
/* Experiments have shown that it's rarely, if ever useful to
|
|
record ranges for enumerations. Presumably this is due to
|
|
the fact that they're rarely used directly. They are typically
|
|
cast into an integer type and used that way. */
|
|
if (TREE_CODE (type) != INTEGER_TYPE)
|
|
return 0;
|
|
|
|
switch (TREE_CODE (cond))
|
|
{
|
|
case EQ_EXPR:
|
|
high = low = op1;
|
|
inverted = 0;
|
|
break;
|
|
|
|
case NE_EXPR:
|
|
high = low = op1;
|
|
inverted = 1;
|
|
break;
|
|
|
|
case GE_EXPR:
|
|
low = op1;
|
|
|
|
/* Get the highest value of the type. If not a constant, use that
|
|
of its base type, if it has one. */
|
|
high = TYPE_MAX_VALUE (type);
|
|
if (TREE_CODE (high) != INTEGER_CST && TREE_TYPE (type))
|
|
high = TYPE_MAX_VALUE (TREE_TYPE (type));
|
|
inverted = 0;
|
|
break;
|
|
|
|
case GT_EXPR:
|
|
high = TYPE_MAX_VALUE (type);
|
|
if (TREE_CODE (high) != INTEGER_CST && TREE_TYPE (type))
|
|
high = TYPE_MAX_VALUE (TREE_TYPE (type));
|
|
if (!tree_int_cst_lt (op1, high))
|
|
return 0;
|
|
low = int_const_binop (PLUS_EXPR, op1, integer_one_node, 1);
|
|
inverted = 0;
|
|
break;
|
|
|
|
case LE_EXPR:
|
|
high = op1;
|
|
low = TYPE_MIN_VALUE (type);
|
|
if (TREE_CODE (low) != INTEGER_CST && TREE_TYPE (type))
|
|
low = TYPE_MIN_VALUE (TREE_TYPE (type));
|
|
inverted = 0;
|
|
break;
|
|
|
|
case LT_EXPR:
|
|
low = TYPE_MIN_VALUE (type);
|
|
if (TREE_CODE (low) != INTEGER_CST && TREE_TYPE (type))
|
|
low = TYPE_MIN_VALUE (TREE_TYPE (type));
|
|
if (!tree_int_cst_lt (low, op1))
|
|
return 0;
|
|
high = int_const_binop (MINUS_EXPR, op1, integer_one_node, 1);
|
|
inverted = 0;
|
|
break;
|
|
|
|
default:
|
|
return 0;
|
|
}
|
|
|
|
*hi_p = high;
|
|
*lo_p = low;
|
|
*inverted_p = inverted;
|
|
return 1;
|
|
}
|
|
|
|
/* Record a range created by COND for basic block BB. */
|
|
|
|
static void
|
|
record_range (tree cond, basic_block bb)
|
|
{
|
|
enum tree_code code = TREE_CODE (cond);
|
|
|
|
/* We explicitly ignore NE_EXPRs and all the unordered comparisons.
|
|
They rarely allow for meaningful range optimizations and significantly
|
|
complicate the implementation. */
|
|
if ((code == LT_EXPR || code == LE_EXPR || code == GT_EXPR
|
|
|| code == GE_EXPR || code == EQ_EXPR)
|
|
&& TREE_CODE (TREE_TYPE (TREE_OPERAND (cond, 1))) == INTEGER_TYPE)
|
|
{
|
|
struct vrp_hash_elt *vrp_hash_elt;
|
|
struct vrp_element *element;
|
|
VEC(vrp_element_p,heap) **vrp_records_p;
|
|
void **slot;
|
|
|
|
|
|
vrp_hash_elt = xmalloc (sizeof (struct vrp_hash_elt));
|
|
vrp_hash_elt->var = TREE_OPERAND (cond, 0);
|
|
vrp_hash_elt->records = NULL;
|
|
slot = htab_find_slot (vrp_data, vrp_hash_elt, INSERT);
|
|
|
|
if (*slot == NULL)
|
|
*slot = (void *) vrp_hash_elt;
|
|
else
|
|
vrp_free (vrp_hash_elt);
|
|
|
|
vrp_hash_elt = (struct vrp_hash_elt *) *slot;
|
|
vrp_records_p = &vrp_hash_elt->records;
|
|
|
|
element = ggc_alloc (sizeof (struct vrp_element));
|
|
element->low = NULL;
|
|
element->high = NULL;
|
|
element->cond = cond;
|
|
element->bb = bb;
|
|
|
|
VEC_safe_push (vrp_element_p, heap, *vrp_records_p, element);
|
|
VEC_safe_push (tree, heap, vrp_variables_stack, TREE_OPERAND (cond, 0));
|
|
}
|
|
}
|
|
|
|
/* Hashing and equality functions for VRP_DATA.
|
|
|
|
Since this hash table is addressed by SSA_NAMEs, we can hash on
|
|
their version number and equality can be determined with a
|
|
pointer comparison. */
|
|
|
|
static hashval_t
|
|
vrp_hash (const void *p)
|
|
{
|
|
tree var = ((struct vrp_hash_elt *)p)->var;
|
|
|
|
return SSA_NAME_VERSION (var);
|
|
}
|
|
|
|
static int
|
|
vrp_eq (const void *p1, const void *p2)
|
|
{
|
|
tree var1 = ((struct vrp_hash_elt *)p1)->var;
|
|
tree var2 = ((struct vrp_hash_elt *)p2)->var;
|
|
|
|
return var1 == var2;
|
|
}
|
|
|
|
/* Hashing and equality functions for AVAIL_EXPRS. The table stores
|
|
MODIFY_EXPR statements. We compute a value number for expressions using
|
|
the code of the expression and the SSA numbers of its operands. */
|
|
|
|
static hashval_t
|
|
avail_expr_hash (const void *p)
|
|
{
|
|
tree stmt = ((struct expr_hash_elt *)p)->stmt;
|
|
tree rhs = ((struct expr_hash_elt *)p)->rhs;
|
|
tree vuse;
|
|
ssa_op_iter iter;
|
|
hashval_t val = 0;
|
|
|
|
/* iterative_hash_expr knows how to deal with any expression and
|
|
deals with commutative operators as well, so just use it instead
|
|
of duplicating such complexities here. */
|
|
val = iterative_hash_expr (rhs, val);
|
|
|
|
/* If the hash table entry is not associated with a statement, then we
|
|
can just hash the expression and not worry about virtual operands
|
|
and such. */
|
|
if (!stmt || !stmt_ann (stmt))
|
|
return val;
|
|
|
|
/* Add the SSA version numbers of every vuse operand. This is important
|
|
because compound variables like arrays are not renamed in the
|
|
operands. Rather, the rename is done on the virtual variable
|
|
representing all the elements of the array. */
|
|
FOR_EACH_SSA_TREE_OPERAND (vuse, stmt, iter, SSA_OP_VUSE)
|
|
val = iterative_hash_expr (vuse, val);
|
|
|
|
return val;
|
|
}
|
|
|
|
static hashval_t
|
|
real_avail_expr_hash (const void *p)
|
|
{
|
|
return ((const struct expr_hash_elt *)p)->hash;
|
|
}
|
|
|
|
static int
|
|
avail_expr_eq (const void *p1, const void *p2)
|
|
{
|
|
tree stmt1 = ((struct expr_hash_elt *)p1)->stmt;
|
|
tree rhs1 = ((struct expr_hash_elt *)p1)->rhs;
|
|
tree stmt2 = ((struct expr_hash_elt *)p2)->stmt;
|
|
tree rhs2 = ((struct expr_hash_elt *)p2)->rhs;
|
|
|
|
/* If they are the same physical expression, return true. */
|
|
if (rhs1 == rhs2 && stmt1 == stmt2)
|
|
return true;
|
|
|
|
/* If their codes are not equal, then quit now. */
|
|
if (TREE_CODE (rhs1) != TREE_CODE (rhs2))
|
|
return false;
|
|
|
|
/* In case of a collision, both RHS have to be identical and have the
|
|
same VUSE operands. */
|
|
if ((TREE_TYPE (rhs1) == TREE_TYPE (rhs2)
|
|
|| lang_hooks.types_compatible_p (TREE_TYPE (rhs1), TREE_TYPE (rhs2)))
|
|
&& operand_equal_p (rhs1, rhs2, OEP_PURE_SAME))
|
|
{
|
|
bool ret = compare_ssa_operands_equal (stmt1, stmt2, SSA_OP_VUSE);
|
|
gcc_assert (!ret || ((struct expr_hash_elt *)p1)->hash
|
|
== ((struct expr_hash_elt *)p2)->hash);
|
|
return ret;
|
|
}
|
|
|
|
return false;
|
|
}
|