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Remove code duplication in ix86_expand_epilogue.

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Union the undo of the frame pointer between the pop and move
code paths.

Combine the local frame stack deallocation with the one for
ix86_static_chain_on_stack, if possible.

From-SVN: r162890
This commit is contained in:
Richard Henderson 2010-08-04 16:58:33 -07:00 committed by Richard Henderson
parent c9f4c45115
commit 87ec2632b8
2 changed files with 45 additions and 86 deletions
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4
gcc/ChangeLog
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@ -1,5 +1,9 @@
2010-08-04 Richard Henderson <rth@redhat.com>
* config/i386/i386.c (ix86_expand_epilogue): Eliminate code
duplication deconstructing the frame pointer. Simplify
deallocation of the local stack frame.
* reg-notes.def (CFA_EXPRESSION): New.
* dwarf2out.c (dwarf2out_frame_debug): Handle it.
(dwarf2out_frame_debug_cfa_expression): New.

127
gcc/config/i386/i386.c
View File

@ -10101,49 +10101,11 @@ ix86_expand_epilogue (int style)
}
m->fs.sp_offset = UNITS_PER_WORD;
}
else if (!frame_pointer_needed)
{
pro_epilogue_adjust_stack (stack_pointer_rtx, stack_pointer_rtx,
GEN_INT (m->fs.sp_offset
- frame.reg_save_offset
+ frame.nregs * UNITS_PER_WORD),
style, !using_drap);
}
else
{
if (stack_realign_fp)
{
/* We're re-defining what it means to be the local stack
frame. Thus the FP is suddenly valid and the SP isn't. */
m->fs.fp_valid = true;
m->fs.sp_valid = false;
m->fs.realigned = false;
}
/* Leave results in shorter dependency chains on CPUs that are
able to grok it fast. */
if (TARGET_USE_LEAVE
|| optimize_function_for_size_p (cfun)
|| !cfun->machine->use_fast_prologue_epilogue)
ix86_emit_leave ();
else
{
pro_epilogue_adjust_stack (stack_pointer_rtx,
hard_frame_pointer_rtx,
const0_rtx, style, !using_drap);
ix86_emit_restore_reg_using_pop (hard_frame_pointer_rtx);
}
}
}
else
{
/* First step is to deallocate the stack frame so that we can
pop the registers.
If we realign stack with frame pointer, then stack pointer
won't be able to recover via lea $offset(%bp), %sp, because
there is a padding area between bp and sp for realign.
"add $to_allocate, %sp" must be used instead. */
pop the registers. */
if (!m->fs.sp_valid)
{
pro_epilogue_adjust_stack (stack_pointer_rtx, hard_frame_pointer_rtx,
@ -10161,34 +10123,38 @@ ix86_expand_epilogue (int style)
}
ix86_emit_restore_regs_using_pop ();
}
if (frame_pointer_needed)
/* If we used a stack pointer and haven't already got rid of it,
then do so now. */
if (m->fs.fp_valid || stack_realign_fp)
{
if (stack_realign_fp)
{
if (stack_realign_fp)
{
/* We're re-defining what it means to be the local stack
frame. Thus the FP is suddenly valid and the SP isn't. */
m->fs.fp_valid = true;
m->fs.sp_valid = false;
m->fs.realigned = false;
}
/* Leave results in shorter dependency chains on CPUs that are
able to grok it fast. */
if (TARGET_USE_LEAVE
|| (stack_realign_fp
&& (optimize_function_for_size_p (cfun)
|| !cfun->machine->use_fast_prologue_epilogue)))
ix86_emit_leave ();
else
{
if (stack_realign_fp)
pro_epilogue_adjust_stack (stack_pointer_rtx,
hard_frame_pointer_rtx,
const0_rtx, style, !using_drap);
ix86_emit_restore_reg_using_pop (hard_frame_pointer_rtx);
}
/* We're re-defining what it means to be the local stack
frame. Thus the FP is suddenly valid and the SP isn't. */
m->fs.fp_valid = true;
m->fs.sp_valid = false;
m->fs.realigned = false;
}
/* If the stack pointer is valid and pointing at the frame
pointer store address, then we only need a pop. */
if (m->fs.sp_valid && m->fs.sp_offset == frame.hard_frame_pointer_offset)
ix86_emit_restore_reg_using_pop (hard_frame_pointer_rtx);
/* Leave results in shorter dependency chains on CPUs that are
able to grok it fast. */
else if (TARGET_USE_LEAVE
|| optimize_function_for_size_p (cfun)
|| !cfun->machine->use_fast_prologue_epilogue)
ix86_emit_leave ();
else
{
pro_epilogue_adjust_stack (stack_pointer_rtx,
hard_frame_pointer_rtx,
const0_rtx, style, !using_drap);
ix86_emit_restore_reg_using_pop (hard_frame_pointer_rtx);
}
}
if (using_drap)
@ -10222,31 +10188,20 @@ ix86_expand_epilogue (int style)
ix86_emit_restore_reg_using_pop (crtl->drap_reg);
}
/* Remove the saved static chain from the stack. The use of ECX is
merely as a scratch register, not as the actual static chain. */
if (ix86_static_chain_on_stack)
{
rtx r, insn;
gcc_assert (m->fs.cfa_reg == stack_pointer_rtx);
m->fs.cfa_offset -= UNITS_PER_WORD;
m->fs.sp_offset -= UNITS_PER_WORD;
r = gen_rtx_REG (Pmode, CX_REG);
insn = emit_insn (ix86_gen_pop1 (r));
r = plus_constant (stack_pointer_rtx, UNITS_PER_WORD);
r = gen_rtx_SET (VOIDmode, stack_pointer_rtx, r);
add_reg_note (insn, REG_CFA_ADJUST_CFA, r);
RTX_FRAME_RELATED_P (insn) = 1;
}
/* At this point we should have de-allocated the entire stack frame,
so the stack pointer points to the return address. */
gcc_assert (m->fs.sp_offset == UNITS_PER_WORD);
/* At this point the stack pointer must be valid, and we must have
restored all of the registers. We may not have deallocated the
entire stack frame. We've delayed this until now because it may
be possible to merge the local stack deallocation with the
deallocation forced by ix86_static_chain_on_stack. */
gcc_assert (m->fs.sp_valid);
gcc_assert (!m->fs.fp_valid);
gcc_assert (!m->fs.realigned);
if (m->fs.sp_offset != UNITS_PER_WORD)
{
pro_epilogue_adjust_stack (stack_pointer_rtx, stack_pointer_rtx,
GEN_INT (m->fs.sp_offset - UNITS_PER_WORD),
style, true);
}
/* Sibcall epilogues don't want a return instruction. */
if (style == 0)