479 lines
15 KiB
C
479 lines
15 KiB
C
/* Target-dependent code for the Mitsubishi m32r for GDB, the GNU debugger.
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Copyright 1996, Free Software Foundation, Inc.
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This file is part of GDB.
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This program 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 of the License, or
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(at your option) any later version.
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This program 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 this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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#include "defs.h"
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#include "frame.h"
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#include "inferior.h"
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#include "obstack.h"
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#include "target.h"
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#include "value.h"
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#include "bfd.h"
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#include "gdb_string.h"
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#include "gdbcore.h"
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#include "symfile.h"
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/* Function: frame_find_saved_regs
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Return the frame_saved_regs structure for the frame.
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Doesn't really work for dummy frames, but it does pass back
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an empty frame_saved_regs, so I guess that's better than total failure */
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void
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m32r_frame_find_saved_regs (fi, regaddr)
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struct frame_info *fi;
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struct frame_saved_regs *regaddr;
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{
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memcpy(regaddr, &fi->fsr, sizeof(struct frame_saved_regs));
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}
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/* Function: skip_prologue
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Find end of function prologue */
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CORE_ADDR
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m32r_skip_prologue (pc)
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CORE_ADDR pc;
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{
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CORE_ADDR func_addr, func_end;
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struct symtab_and_line sal;
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/* See what the symbol table says */
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if (find_pc_partial_function (pc, NULL, &func_addr, &func_end))
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{
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sal = find_pc_line (func_addr, 0);
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if (sal.line != 0 && sal.end < func_end)
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return sal.end;
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else
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/* Either there's no line info, or the line after the prologue is after
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the end of the function. In this case, there probably isn't a
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prologue. */
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return pc;
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}
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/* We can't find the start of this function, so there's nothing we can do. */
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return pc;
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}
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/* Function: scan_prologue
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This function decodes the target function prologue to determine
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1) the size of the stack frame, and 2) which registers are saved on it.
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It saves the offsets of saved regs in the frame_saved_regs argument,
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and returns the frame size. */
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static unsigned long
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m32r_scan_prologue (fi, fsr)
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struct frame_info *fi;
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struct frame_saved_regs *fsr;
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{
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struct symtab_and_line sal;
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CORE_ADDR prologue_start, prologue_end, current_pc;
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unsigned long framesize;
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/* this code essentially duplicates skip_prologue,
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but we need the start address below. */
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if (find_pc_partial_function (fi->pc, NULL, &prologue_start, &prologue_end))
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{
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sal = find_pc_line (prologue_start, 0);
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if (sal.line == 0) /* no line info, use current PC */
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if (prologue_start != entry_point_address ())
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prologue_end = fi->pc;
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else
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return 0; /* _start has no frame or prologue */
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else if (sal.end < prologue_end) /* next line begins after fn end */
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prologue_end = sal.end; /* (probably means no prologue) */
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}
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else
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prologue_end = prologue_start + 40; /* We're in the boondocks: allow for */
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/* 16 pushes, an add, and "mv fp,sp" */
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prologue_end = min (prologue_end, fi->pc);
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/* Now, search the prologue looking for instructions that setup fp, save
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rp (and other regs), adjust sp and such. */
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framesize = 0;
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for (current_pc = prologue_start; current_pc < prologue_end; current_pc += 2)
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{
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int insn;
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int regno;
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insn = read_memory_unsigned_integer (current_pc, 2);
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if (insn & 0x8000) /* Four byte instruction? */
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current_pc += 2;
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if ((insn & 0xf0ff) == 0x207f) { /* st reg, @-sp */
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framesize += 4;
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regno = ((insn >> 8) & 0xf);
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if (fsr) /* save_regs offset */
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fsr->regs[regno] = framesize;
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}
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else if ((insn >> 8) == 0x4f) /* addi sp, xx */
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/* add 8 bit sign-extended offset */
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framesize += -((char) (insn & 0xff));
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else if (insn == 0x8faf) /* add3 sp, sp, xxxx */
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/* add 16 bit sign-extended offset */
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framesize += -((short) read_memory_unsigned_integer (current_pc, 2));
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else if (((insn >> 8) == 0xe4) && /* ld24 r4, xxxxxx ; sub sp, r4 */
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read_memory_unsigned_integer (current_pc + 2, 2) == 0x0f24)
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{ /* subtract 24 bit sign-extended negative-offset */
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insn = read_memory_unsigned_integer (current_pc - 2, 4);
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if (insn & 0x00800000) /* sign extend */
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insn |= 0xff000000; /* negative */
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else
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insn &= 0x00ffffff; /* positive */
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framesize += insn;
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}
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else if (insn == 0x1d8f) { /* mv fp, sp */
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fi->using_frame_pointer = 1; /* fp is now valid */
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break; /* end of stack adjustments */
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}
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else
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break; /* anything else isn't prologue */
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}
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return framesize;
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}
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/* Function: init_extra_frame_info
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This function actually figures out the frame address for a given pc and
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sp. This is tricky on the m32r because we sometimes don't use an explicit
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frame pointer, and the previous stack pointer isn't necessarily recorded
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on the stack. The only reliable way to get this info is to
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examine the prologue. */
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void
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m32r_init_extra_frame_info (fi)
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struct frame_info *fi;
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{
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int reg;
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if (fi->next)
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fi->pc = FRAME_SAVED_PC (fi->next);
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memset (fi->fsr.regs, '\000', sizeof fi->fsr.regs);
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if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame))
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{
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/* We need to setup fi->frame here because run_stack_dummy gets it wrong
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by assuming it's always FP. */
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fi->frame = generic_read_register_dummy (fi->pc, fi->frame, SP_REGNUM);
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fi->framesize = 0;
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return;
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}
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else
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{
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fi->using_frame_pointer = 0;
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fi->framesize = m32r_scan_prologue (fi, &fi->fsr);
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if (!fi->next)
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if (fi->using_frame_pointer)
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fi->frame = read_register (FP_REGNUM);
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else
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fi->frame = read_register (SP_REGNUM);
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else /* fi->next means this is not the innermost frame */
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if (fi->using_frame_pointer) /* we have an FP */
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if (fi->next->fsr.regs[FP_REGNUM] != 0) /* caller saved our FP */
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fi->frame = read_memory_integer (fi->next->fsr.regs[FP_REGNUM], 4);
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for (reg = 0; reg < NUM_REGS; reg++)
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if (fi->fsr.regs[reg] != 0)
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fi->fsr.regs[reg] = fi->frame + fi->framesize - fi->fsr.regs[reg];
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}
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}
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/* Function: find_callers_reg
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Find REGNUM on the stack. Otherwise, it's in an active register. One thing
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we might want to do here is to check REGNUM against the clobber mask, and
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somehow flag it as invalid if it isn't saved on the stack somewhere. This
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would provide a graceful failure mode when trying to get the value of
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caller-saves registers for an inner frame. */
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CORE_ADDR
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m32r_find_callers_reg (fi, regnum)
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struct frame_info *fi;
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int regnum;
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{
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for (; fi; fi = fi->next)
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if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame))
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return generic_read_register_dummy (fi->pc, fi->frame, regnum);
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else if (fi->fsr.regs[regnum] != 0)
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return read_memory_integer (fi->fsr.regs[regnum],
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REGISTER_RAW_SIZE(regnum));
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return read_register (regnum);
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}
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/* Function: frame_chain
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Given a GDB frame, determine the address of the calling function's frame.
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This will be used to create a new GDB frame struct, and then
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INIT_EXTRA_FRAME_INFO and INIT_FRAME_PC will be called for the new frame.
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For m32r, we save the frame size when we initialize the frame_info. */
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CORE_ADDR
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m32r_frame_chain (fi)
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struct frame_info *fi;
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{
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CORE_ADDR fn_start, callers_pc, fp;
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/* is this a dummy frame? */
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if (PC_IN_CALL_DUMMY(fi->pc, fi->frame, fi->frame))
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return fi->frame; /* dummy frame same as caller's frame */
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/* is caller-of-this a dummy frame? */
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callers_pc = FRAME_SAVED_PC(fi); /* find out who called us: */
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fp = m32r_find_callers_reg (fi, FP_REGNUM);
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if (PC_IN_CALL_DUMMY(callers_pc, fp, fp))
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return fp; /* dummy frame's frame may bear no relation to ours */
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if (find_pc_partial_function (fi->pc, 0, &fn_start, 0))
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if (fn_start == entry_point_address ())
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return 0; /* in _start fn, don't chain further */
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return fi->frame + fi->framesize;
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}
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/* Function: push_return_address (pc)
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Set up the return address for the inferior function call.
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Necessary for targets that don't actually execute a JSR/BSR instruction
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(ie. when using an empty CALL_DUMMY) */
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CORE_ADDR
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m32r_push_return_address (pc, sp)
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CORE_ADDR pc;
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CORE_ADDR sp;
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{
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write_register (RP_REGNUM, CALL_DUMMY_ADDRESS ());
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return sp;
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}
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/* Function: pop_frame
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Discard from the stack the innermost frame,
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restoring all saved registers. */
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struct frame_info *
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m32r_pop_frame (frame)
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struct frame_info *frame;
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{
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int regnum;
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if (PC_IN_CALL_DUMMY (frame->pc, frame->frame, frame->frame))
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generic_pop_dummy_frame ();
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else
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{
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for (regnum = 0; regnum < NUM_REGS; regnum++)
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if (frame->fsr.regs[regnum] != 0)
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write_register (regnum,
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read_memory_integer (frame->fsr.regs[regnum], 4));
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write_register (PC_REGNUM, FRAME_SAVED_PC (frame));
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write_register (SP_REGNUM, read_register (FP_REGNUM));
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if (read_register (PSW_REGNUM) & 0x80)
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write_register (SPU_REGNUM, read_register (SP_REGNUM));
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else
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write_register (SPI_REGNUM, read_register (SP_REGNUM));
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}
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flush_cached_frames ();
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return NULL;
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}
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/* Function: frame_saved_pc
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Find the caller of this frame. We do this by seeing if RP_REGNUM is saved
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in the stack anywhere, otherwise we get it from the registers. */
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CORE_ADDR
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m32r_frame_saved_pc (fi)
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struct frame_info *fi;
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{
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if (PC_IN_CALL_DUMMY(fi->pc, fi->frame, fi->frame))
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return generic_read_register_dummy(fi->pc, fi->frame, PC_REGNUM);
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else
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return m32r_find_callers_reg (fi, RP_REGNUM);
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}
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/* Function: push_arguments
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Setup the function arguments for calling a function in the inferior.
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On the Mitsubishi M32R architecture, there are four registers (R0 to R3)
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which are dedicated for passing function arguments. Up to the first
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four arguments (depending on size) may go into these registers.
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The rest go on the stack.
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Arguments that are smaller than 4 bytes will still take up a whole
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register or a whole 32-bit word on the stack, and will be
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right-justified in the register or the stack word. This includes
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chars, shorts, and small aggregate types.
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Arguments of 8 bytes size are split between two registers, if
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available. If only one register is available, the argument will
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be split between the register and the stack. Otherwise it is
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passed entirely on the stack. Aggregate types with sizes between
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4 and 8 bytes are passed entirely on the stack, and are left-justified
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within the double-word (as opposed to aggregates smaller than 4 bytes
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which are right-justified).
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Aggregates of greater than 8 bytes are first copied onto the stack,
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and then a pointer to the copy is passed in the place of the normal
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argument (either in a register if available, or on the stack).
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Functions that must return an aggregate type can return it in the
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normal return value registers (R0 and R1) if its size is 8 bytes or
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less. For larger return values, the caller must allocate space for
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the callee to copy the return value to. A pointer to this space is
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passed as an implicit first argument, always in R0. */
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CORE_ADDR
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m32r_push_arguments (nargs, args, sp, struct_return, struct_addr)
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int nargs;
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value_ptr *args;
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CORE_ADDR sp;
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unsigned char struct_return;
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CORE_ADDR struct_addr;
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{
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int stack_offset, stack_alloc;
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int argreg;
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int argnum;
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struct type *type;
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CORE_ADDR regval;
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char *val;
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char valbuf[4];
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int len;
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int odd_sized_struct;
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/* first force sp to a 4-byte alignment */
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sp = sp & ~3;
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argreg = ARG0_REGNUM;
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/* The "struct return pointer" pseudo-argument goes in R0 */
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if (struct_return)
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write_register (argreg++, struct_addr);
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/* Now make sure there's space on the stack */
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for (argnum = 0, stack_alloc = 0;
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argnum < nargs; argnum++)
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stack_alloc += ((TYPE_LENGTH(VALUE_TYPE(args[argnum])) + 3) & ~3);
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sp -= stack_alloc; /* make room on stack for args */
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/* Now load as many as possible of the first arguments into
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registers, and push the rest onto the stack. There are 16 bytes
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in four registers available. Loop thru args from first to last. */
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argreg = ARG0_REGNUM;
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for (argnum = 0, stack_offset = 0; argnum < nargs; argnum++)
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{
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type = VALUE_TYPE (args[argnum]);
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len = TYPE_LENGTH (type);
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memset(valbuf, 0, sizeof(valbuf));
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if (len < 4)
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{ /* value gets right-justified in the register or stack word */
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memcpy(valbuf + (4 - len),
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(char *) VALUE_CONTENTS (args[argnum]), len);
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val = valbuf;
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}
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else
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val = (char *) VALUE_CONTENTS (args[argnum]);
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if (len > 4 && (len & 3) != 0)
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odd_sized_struct = 1; /* such structs go entirely on stack */
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else
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odd_sized_struct = 0;
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while (len > 0)
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{
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if (argreg > ARGLAST_REGNUM || odd_sized_struct)
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{ /* must go on the stack */
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write_memory (sp + stack_offset, val, 4);
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stack_offset += 4;
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}
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/* NOTE WELL!!!!! This is not an "else if" clause!!!
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That's because some *&^%$ things get passed on the stack
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AND in the registers! */
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if (argreg <= ARGLAST_REGNUM)
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{ /* there's room in a register */
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regval = extract_address (val, REGISTER_RAW_SIZE(argreg));
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write_register (argreg++, regval);
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}
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/* Store the value 4 bytes at a time. This means that things
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larger than 4 bytes may go partly in registers and partly
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on the stack. */
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len -= REGISTER_RAW_SIZE(argreg);
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val += REGISTER_RAW_SIZE(argreg);
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}
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}
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return sp;
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}
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/* Function: fix_call_dummy
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If there is real CALL_DUMMY code (eg. on the stack), this function
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has the responsability to insert the address of the actual code that
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is the target of the target function call. */
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int
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m32r_fix_call_dummy (dummy, pc, fun, nargs, args, type, gcc_p)
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char *dummy;
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CORE_ADDR pc;
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CORE_ADDR fun;
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int nargs;
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value_ptr *args;
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struct type *type;
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int gcc_p;
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{
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/* ld24 r8, <(imm24) fun> */
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*(unsigned long *) (dummy) = (fun & 0x00ffffff) | 0xe8000000;
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}
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/* Function: get_saved_register
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Just call the generic_get_saved_register function. */
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void
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get_saved_register (raw_buffer, optimized, addrp, frame, regnum, lval)
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char *raw_buffer;
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int *optimized;
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CORE_ADDR *addrp;
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struct frame_info *frame;
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int regnum;
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enum lval_type *lval;
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{
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generic_get_saved_register (raw_buffer, optimized, addrp,
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frame, regnum, lval);
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}
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/* Function: m32r_write_sp
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Because SP is really a read-only register that mirrors either SPU or SPI,
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we must actually write one of those two as well, depending on PSW. */
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void
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m32r_write_sp (val)
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CORE_ADDR val;
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{
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unsigned long psw = read_register (PSW_REGNUM);
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if (psw & 0x80) /* stack mode: user or interrupt */
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write_register (SPU_REGNUM, val);
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else
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write_register (SPI_REGNUM, val);
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write_register (SP_REGNUM, val);
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}
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void
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_initialize_m32r_tdep ()
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{
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tm_print_insn = print_insn_m32r;
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}
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