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i386.c (ix86_emit_restore_regs_using_mov): Break out from ... 

* i386.c (ix86_emit_restore_regs_using_mov): Break out from ...
	(ix86_expand_epilogue): ... here. Use mov instead of add to restore
	stack pointer in functions w/o saved registers, output LEAVE more often
	on TARGET_USE_LEAVE machines.

From-SVN: r31941
This commit is contained in:
Jan Hubicka 2000-02-12 01:49:11 +01:00 committed by Jan Hubicka
parent 28ec5077d7
commit da2d1d3a8f
2 changed files with 58 additions and 14 deletions
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7
gcc/ChangeLog
View File

@ -1,3 +1,10 @@
Sat Feb 12 01:44:26 MET 2000 Jan Hubicka <jh@suse.cz>
* i386.c (ix86_emit_restore_regs_using_mov): Break out from ...
(ix86_expand_epilogue): ... here. Use mov instead of add to restore
stack pointer in functions w/o saved registers, output LEAVE more often
on TARGET_USE_LEAVE machines.
2000-02-07 Dmitri Makarov <dim@wrs.com> & Bernd Schmidt <bernds@redhat.com>
* config/arm/arm.c (arm_init_cumulative_args); New function:

65
gcc/config/i386/i386.c
View File

@ -401,6 +401,7 @@ static HOST_WIDE_INT ix86_compute_frame_size PARAMS((HOST_WIDE_INT,
int *, int *, int *));
static int ix86_nsaved_regs PARAMS((void));
static void ix86_emit_save_regs PARAMS((void));
static void ix86_emit_restore_regs_using_mov PARAMS ((rtx, int));
static void ix86_emit_epilogue_esp_adjustment PARAMS((int));
static void ix86_sched_reorder_pentium PARAMS((rtx *, rtx *));
static void ix86_sched_reorder_ppro PARAMS((rtx *, rtx *));
@ -1963,6 +1964,31 @@ ix86_emit_epilogue_esp_adjustment (tsize)
}
}
/* Emit code to restore saved registers using MOV insns. First register
is restored from POINTER + OFFSET. */
static void
ix86_emit_restore_regs_using_mov (pointer, offset)
rtx pointer;
int offset;
{
int regno;
int pic_reg_used = flag_pic && (current_function_uses_pic_offset_table
|| current_function_uses_const_pool);
int limit = (frame_pointer_needed
? HARD_FRAME_POINTER_REGNUM : STACK_POINTER_REGNUM);
for (regno = 0; regno < limit; regno++)
if ((regs_ever_live[regno] && !call_used_regs[regno])
|| (regno == PIC_OFFSET_TABLE_REGNUM && pic_reg_used))
{
emit_move_insn (gen_rtx_REG (SImode, regno),
adj_offsettable_operand (gen_rtx_MEM (SImode,
pointer),
offset));
offset += 4;
}
}
/* Restore function stack, frame, and registers. */
void
@ -1991,23 +2017,34 @@ ix86_expand_epilogue ()
/* If we're only restoring one register and sp is not valid then
using a move instruction to restore the register since it's
less work than reloading sp and popping the register. */
if (!sp_valid && nregs <= 1)
less work than reloading sp and popping the register.
The default code result in stack adjustment using add/lea instruction,
while this code results in LEAVE instruction (or discrete equivalent),
so it is profitable in some other cases as well. Especially when there
are no registers to restore. We also use this code when TARGET_USE_LEAVE
and there is exactly one register to pop. This heruistic may need some
tuning in future. */
if ((!sp_valid && nregs <= 1)
|| (frame_pointer_needed && !nregs && tsize)
|| (frame_pointer_needed && TARGET_USE_LEAVE && !optimize_size
&& nregs == 1))
{
/* Restore registers. We can use ebp or esp to address the memory
locations. If both are available, default to ebp, since offsets
are known to be small. Only exception is esp pointing directly to the
end of block of saved registers, where we may simplify addressing
mode. */
if (!frame_pointer_needed || (sp_valid && !tsize))
ix86_emit_restore_regs_using_mov (stack_pointer_rtx, tsize);
else
ix86_emit_restore_regs_using_mov (hard_frame_pointer_rtx, offset);
if (!frame_pointer_needed)
abort();
for (regno = 0; regno < HARD_FRAME_POINTER_REGNUM; regno++)
if ((regs_ever_live[regno] && ! call_used_regs[regno])
|| (regno == PIC_OFFSET_TABLE_REGNUM && pic_reg_used))
{
emit_move_insn (gen_rtx_REG (SImode, regno),
adj_offsettable_operand (AT_BP (Pmode), offset));
offset += 4;
}
ix86_emit_epilogue_esp_adjustment (tsize + nregs * UNITS_PER_WORD);
/* If not an i386, mov & pop is faster than "leave". */
if (TARGET_USE_LEAVE || optimize_size)
else if (TARGET_USE_LEAVE || optimize_size)
emit_insn (gen_leave ());
else
{