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re PR target/39942 (Nonoptimal code - leaveq; xchg %ax,%ax; retq)

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2009-05-18  H.J. Lu  <hongjiu.lu@intel.com>

	PR target/39942
	* config/i386/i386.c (ix86_avoid_jump_misspredicts): Replace
	gen_align with gen_pad.
	(ix86_reorg): Check ASM_OUTPUT_MAX_SKIP_PAD instead of
	#ifdef ASM_OUTPUT_MAX_SKIP_ALIGN.

	* config/i386/i386.h (ASM_OUTPUT_MAX_SKIP_PAD): New.
	* config/i386/x86-64.h (ASM_OUTPUT_MAX_SKIP_PAD): Likewise.

	* config/i386/i386.md (align): Renamed to ...
	(pad): This.  Replace ASM_OUTPUT_MAX_SKIP_ALIGN with
	ASM_OUTPUT_MAX_SKIP_PAD.

From-SVN: r147671
This commit is contained in:
H.J. Lu 2009-05-18 17:21:13 +00:00 committed by H.J. Lu
parent cf249b02ea
commit 6a90d232ab
5 changed files with 46 additions and 6 deletions
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15
gcc/ChangeLog
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@ -1,3 +1,18 @@
2009-05-18 H.J. Lu <hongjiu.lu@intel.com>
PR target/39942
* config/i386/i386.c (ix86_avoid_jump_misspredicts): Replace
gen_align with gen_pad.
(ix86_reorg): Check ASM_OUTPUT_MAX_SKIP_PAD instead of
#ifdef ASM_OUTPUT_MAX_SKIP_ALIGN.
* config/i386/i386.h (ASM_OUTPUT_MAX_SKIP_PAD): New.
* config/i386/x86-64.h (ASM_OUTPUT_MAX_SKIP_PAD): Likewise.
* config/i386/i386.md (align): Renamed to ...
(pad): This. Replace ASM_OUTPUT_MAX_SKIP_ALIGN with
ASM_OUTPUT_MAX_SKIP_PAD.
2009-05-18 Andreas Schwab <schwab@linux-m68k.org>
* config.gcc: Fix variable syntax.

4
gcc/config/i386/i386.c
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@ -27334,7 +27334,7 @@ ix86_avoid_jump_mispredicts (void)
if (dump_file)
fprintf (dump_file, "Padding insn %i by %i bytes!\n",
INSN_UID (insn), padsize);
emit_insn_before (gen_align (GEN_INT (padsize)), insn);
emit_insn_before (gen_pad (GEN_INT (padsize)), insn);
}
}
}
@ -27402,7 +27402,7 @@ ix86_reorg (void)
{
if (TARGET_PAD_RETURNS)
ix86_pad_returns ();
#ifdef ASM_OUTPUT_MAX_SKIP_ALIGN
#ifdef ASM_OUTPUT_MAX_SKIP_PAD
if (TARGET_FOUR_JUMP_LIMIT)
ix86_avoid_jump_mispredicts ();
#endif

16
gcc/config/i386/i386.h
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@ -2175,6 +2175,22 @@ do { \
#define ASM_OUTPUT_OPCODE(STREAM, PTR) \
ASM_OUTPUT_AVX_PREFIX ((STREAM), (PTR))
/* A C statement to output to the stdio stream FILE an assembler
command to pad the location counter to a multiple of 1<<LOG
bytes if it is within MAX_SKIP bytes. */
#ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
#undef ASM_OUTPUT_MAX_SKIP_PAD
#define ASM_OUTPUT_MAX_SKIP_PAD(FILE, LOG, MAX_SKIP) \
if ((LOG) != 0) \
{ \
if ((MAX_SKIP) == 0) \
fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
else \
fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \
}
#endif
/* Under some conditions we need jump tables in the text section,
because the assembler cannot handle label differences between
sections. This is the case for x86_64 on Mach-O for example. */

8
gcc/config/i386/i386.md
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@ -15519,16 +15519,16 @@
(set_attr "length_immediate" "0")
(set_attr "modrm" "0")])
;; Align to 16-byte boundary, max skip in op0. Used to avoid
;; Pad to 16-byte boundary, max skip in op0. Used to avoid
;; branch prediction penalty for the third jump in a 16-byte
;; block on K8.
(define_insn "align"
(define_insn "pad"
[(unspec_volatile [(match_operand 0 "" "")] UNSPECV_ALIGN)]
""
{
#ifdef ASM_OUTPUT_MAX_SKIP_ALIGN
ASM_OUTPUT_MAX_SKIP_ALIGN (asm_out_file, 4, (int)INTVAL (operands[0]));
#ifdef ASM_OUTPUT_MAX_SKIP_PAD
ASM_OUTPUT_MAX_SKIP_PAD (asm_out_file, 4, (int)INTVAL (operands[0]));
#else
/* It is tempting to use ASM_OUTPUT_ALIGN here, but we don't want to do that.
The align insn is used to avoid 3 jump instructions in the row to improve

9
gcc/config/i386/x86-64.h
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@ -81,6 +81,15 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
} \
} \
} while (0)
#undef ASM_OUTPUT_MAX_SKIP_PAD
#define ASM_OUTPUT_MAX_SKIP_PAD(FILE, LOG, MAX_SKIP) \
if ((LOG) != 0) \
{ \
if ((MAX_SKIP) == 0) \
fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
else \
fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \
}
#endif