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i386.h (machine_function): New fields use_fast_prologue_epilogue.

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* i386.h (machine_function): New fields use_fast_prologue_epilogue.
	* i386.c (use_fast_prologue_epilogue): Remove.
	(ix86_frame): New field save_regs-using_mov;
	(ix86_compute_frame_layout):  Decide on fast prologues;
	allocate saved registers in red zone.
	(ix86_expand_epilogue, ix86_expand_prolgoues): Obey new parameters.

From-SVN: r64579
This commit is contained in:
Jan Hubicka 2003-03-19 13:51:28 +01:00 committed by Jan Hubicka
parent 38b2a9713f
commit d9b40e8dbe
3 changed files with 66 additions and 39 deletions
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9
gcc/ChangeLog
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@ -1,3 +1,12 @@
Wed Mar 19 11:28:45 CET 2003 Jan Hubicka <jh@suse.cz>
* i386.h (machine_function): New fields use_fast_prologue_epilogue.
* i386.c (use_fast_prologue_epilogue): Remove.
(ix86_frame): New field save_regs-using_mov;
(ix86_compute_frame_layout): Decide on fast prologues;
allocate saved registers in red zone.
(ix86_expand_epilogue, ix86_expand_prolgoues): Obey new parameters.
2003-03-19 Nick Clifton <nickc@redhat.com>
* config/mcore/mcore.h (CPP_SPEC): Remove trailing semi-colon.

93
gcc/config/i386/i386.c
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@ -530,10 +530,6 @@ const int x86_ext_80387_constants = m_K6 | m_ATHLON | m_PENT4 | m_PPRO;
epilogue code. */
#define FAST_PROLOGUE_INSN_COUNT 20
/* Set by prologue expander and used by epilogue expander to determine
the style used. */
static int use_fast_prologue_epilogue;
/* Names for 8 (low), 8 (high), and 16-bit registers, respectively. */
static const char *const qi_reg_name[] = QI_REGISTER_NAMES;
static const char *const qi_high_reg_name[] = QI_HIGH_REGISTER_NAMES;
@ -724,6 +720,10 @@ struct ix86_frame
HOST_WIDE_INT frame_pointer_offset;
HOST_WIDE_INT hard_frame_pointer_offset;
HOST_WIDE_INT stack_pointer_offset;
/* When save_regs_using_mov is set, emit prologue using
move instead of push instructions. */
bool save_regs_using_mov;
};
/* Used to enable/disable debugging features. */
@ -4914,6 +4914,37 @@ ix86_compute_frame_layout (frame)
frame->nregs = ix86_nsaved_regs ();
total_size = size;
if (!optimize_size && !reload_completed)
{
int count = frame->nregs;
/* The fast prologue uses move instead of push to save registers. This
is significantly longer, but also executes faster as modern hardware
can execute the moves in parallel, but can't do that for push/pop.
Be careful about choosing what prologue to emit: When function takes
many instructions to execute we may use slow version as well as in
case function is known to be outside hot spot (this is known with
feedback only). Weight the size of function by number of registers
to save as it is cheap to use one or two push instructions but very
slow to use many of them. */
if (count)
count = (count - 1) * FAST_PROLOGUE_INSN_COUNT;
if (cfun->function_frequency < FUNCTION_FREQUENCY_NORMAL
|| (flag_branch_probabilities
&& cfun->function_frequency < FUNCTION_FREQUENCY_HOT))
cfun->machine->use_fast_prologue_epilogue = false;
else
cfun->machine->use_fast_prologue_epilogue
= !expensive_function_p (count);
}
if (TARGET_PROLOGUE_USING_MOVE
&& cfun->machine->use_fast_prologue_epilogue)
frame->save_regs_using_mov = true;
else
frame->save_regs_using_mov = false;
/* Skip return address and saved base pointer. */
offset = frame_pointer_needed ? UNITS_PER_WORD * 2 : UNITS_PER_WORD;
@ -4986,10 +5017,15 @@ ix86_compute_frame_layout (frame)
(size + frame->padding1 + frame->padding2
+ frame->outgoing_arguments_size + frame->va_arg_size);
if (!frame->to_allocate && frame->nregs <= 1)
frame->save_regs_using_mov = false;
if (TARGET_64BIT && TARGET_RED_ZONE && current_function_sp_is_unchanging
&& current_function_is_leaf)
{
frame->red_zone_size = frame->to_allocate;
if (frame->save_regs_using_mov)
frame->red_zone_size += frame->nregs * UNITS_PER_WORD;
if (frame->red_zone_size > RED_ZONE_SIZE - RED_ZONE_RESERVE)
frame->red_zone_size = RED_ZONE_SIZE - RED_ZONE_RESERVE;
}
@ -5058,35 +5094,9 @@ ix86_expand_prologue ()
rtx insn;
bool pic_reg_used;
struct ix86_frame frame;
int use_mov = 0;
HOST_WIDE_INT allocate;
ix86_compute_frame_layout (&frame);
if (!optimize_size)
{
int count = frame.nregs;
/* The fast prologue uses move instead of push to save registers. This
is significantly longer, but also executes faster as modern hardware
can execute the moves in parallel, but can't do that for push/pop.
Be careful about choosing what prologue to emit: When function takes
many instructions to execute we may use slow version as well as in
case function is known to be outside hot spot (this is known with
feedback only). Weight the size of function by number of registers
to save as it is cheap to use one or two push instructions but very
slow to use many of them. */
if (count)
count = (count - 1) * FAST_PROLOGUE_INSN_COUNT;
if (cfun->function_frequency < FUNCTION_FREQUENCY_NORMAL
|| (flag_branch_probabilities
&& cfun->function_frequency < FUNCTION_FREQUENCY_HOT))
use_fast_prologue_epilogue = 0;
else
use_fast_prologue_epilogue = !expensive_function_p (count);
if (TARGET_PROLOGUE_USING_MOVE)
use_mov = use_fast_prologue_epilogue;
}
/* Note: AT&T enter does NOT have reversed args. Enter is probably
slower on all targets. Also sdb doesn't like it. */
@ -5101,16 +5111,19 @@ ix86_expand_prologue ()
}
allocate = frame.to_allocate;
/* In case we are dealing only with single register and empty frame,
push is equivalent of the mov+add sequence. */
if (allocate == 0 && frame.nregs <= 1)
use_mov = 0;
if (!use_mov)
if (!frame.save_regs_using_mov)
ix86_emit_save_regs ();
else
allocate += frame.nregs * UNITS_PER_WORD;
/* When using red zone we may start register saving before allocating
the stack frame saving one cycle of the prologue. */
if (TARGET_RED_ZONE && frame.save_regs_using_mov)
ix86_emit_save_regs_using_mov (frame_pointer_needed ? hard_frame_pointer_rtx
: stack_pointer_rtx,
-frame.nregs * UNITS_PER_WORD);
if (allocate == 0)
;
else if (! TARGET_STACK_PROBE || allocate < CHECK_STACK_LIMIT)
@ -5144,7 +5157,7 @@ ix86_expand_prologue ()
call. */
emit_insn (gen_blockage (const0_rtx));
}
if (use_mov)
if (frame.save_regs_using_mov && !TARGET_RED_ZONE)
{
if (!frame_pointer_needed || !frame.to_allocate)
ix86_emit_save_regs_using_mov (stack_pointer_rtx, frame.to_allocate);
@ -5243,11 +5256,12 @@ ix86_expand_epilogue (style)
tuning in future. */
if ((!sp_valid && frame.nregs <= 1)
|| (TARGET_EPILOGUE_USING_MOVE
&& use_fast_prologue_epilogue
&& cfun->machine->use_fast_prologue_epilogue
&& (frame.nregs > 1 || frame.to_allocate))
|| (frame_pointer_needed && !frame.nregs && frame.to_allocate)
|| (frame_pointer_needed && TARGET_USE_LEAVE
&& use_fast_prologue_epilogue && frame.nregs == 1)
&& cfun->machine->use_fast_prologue_epilogue
&& frame.nregs == 1)
|| current_function_calls_eh_return)
{
/* Restore registers. We can use ebp or esp to address the memory
@ -5294,7 +5308,8 @@ ix86_expand_epilogue (style)
GEN_INT (frame.to_allocate
+ frame.nregs * UNITS_PER_WORD)));
/* If not an i386, mov & pop is faster than "leave". */
else if (TARGET_USE_LEAVE || optimize_size || !use_fast_prologue_epilogue)
else if (TARGET_USE_LEAVE || optimize_size
|| !cfun->machine->use_fast_prologue_epilogue)
emit_insn (TARGET_64BIT ? gen_leave_rex64 () : gen_leave ());
else
{

3
gcc/config/i386/i386.h
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@ -3220,6 +3220,9 @@ struct machine_function GTY(())
int save_varrargs_registers;
int accesses_prev_frame;
int optimize_mode_switching;
/* Set by ix86_compute_frame_layout and used by prologue/epilogue expander to
determine the style used. */
int use_fast_prologue_epilogue;
};
#define ix86_stack_locals (cfun->machine->stack_locals)