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[PATCH 2/3] Temporary remove "at least 8 byte alignment" code from x86
- From: Denys Vlasenko <dvlasenk at redhat dot com>
- To: gcc-patches at gcc dot gnu dot org
- Cc: Denys Vlasenko <dvlasenk at redhat dot com>, Andrew Pinski <pinskia at gmail dot com>, Uros Bizjak <ubizjak at gmail dot com>, Bernd Schmidt <bschmidt at redhat dot com>
- Date: Mon, 17 Apr 2017 17:57:15 +0200
- Subject: [PATCH 2/3] Temporary remove "at least 8 byte alignment" code from x86
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- References: <20170417155716.26171-1-dvlasenk@redhat.com>
This change drops forced alignment to 8 if requested alignment is higher
than 8: before the patch, -falign-functions=9 was generating
.p2align 4,,8
.p2align 3
which means: "align to 16 if the skip is 8 bytes or less; else align to 8".
After this change, ".p2align 3" is not emitted.
This behavior will be implemented differently by the next patch.
The new SUBALIGN_LOG define will be used by the next patch.
While we are here, avoid generating ".p2align N,,2^N-1" -
it is functionally equivalent to ".p2align N". In this case, use the latter.
2016-09-27 Denys Vlasenko <dvlasenk@redhat.com>
* config/i386/dragonfly.h: (ASM_OUTPUT_MAX_SKIP_ALIGN):
Use a simpler align directive also if MAXSKIP = ALIGN-1.
* config/i386/gas.h (ASM_OUTPUT_MAX_SKIP_ALIGN): Likewise.
* config/i386/lynx.h (ASM_OUTPUT_MAX_SKIP_ALIGN): Likewise.
* config/i386/netbsd-elf.h (ASM_OUTPUT_MAX_SKIP_ALIGN): Likewise.
* config/i386/i386.h (ASM_OUTPUT_MAX_SKIP_PAD): Likewise.
* config/i386/freebsd.h (ASM_OUTPUT_MAX_SKIP_ALIGN): Remove "If N
is large, do at least 8 byte alignment" code. Add SUBALIGN_LOG
define. Use a simpler align directive also if MAXSKIP = ALIGN-1.
* config/i386/gnu-user.h (ASM_OUTPUT_MAX_SKIP_ALIGN): Likewise.
* config/i386/iamcu.h (ASM_OUTPUT_MAX_SKIP_ALIGN): Likewise.
* config/i386/openbsdelf.h (ASM_OUTPUT_MAX_SKIP_ALIGN): Likewise.
* config/i386/x86-64.h (ASM_OUTPUT_MAX_SKIP_ALIGN): Likewise.
Index: gcc/config/i386/dragonfly.h
===================================================================
--- gcc/config/i386/dragonfly.h (revision 239860)
+++ gcc/config/i386/dragonfly.h (working copy)
@@ -69,10 +69,12 @@ see the files COPYING3 and COPYING.RUNTIME respect
#ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
#undef ASM_OUTPUT_MAX_SKIP_ALIGN
-#define ASM_OUTPUT_MAX_SKIP_ALIGN(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)); \
+#define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE, LOG, MAX_SKIP) \
+ if ((LOG) != 0) { \
+ if ((MAX_SKIP) == 0 || (MAX_SKIP) >= (1<<(LOG))-1) \
+ fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
+ else \
+ fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \
}
#endif
Index: gcc/config/i386/freebsd.h
===================================================================
--- gcc/config/i386/freebsd.h (revision 239860)
+++ gcc/config/i386/freebsd.h (working copy)
@@ -92,9 +92,9 @@ along with GCC; see the file COPYING3. If not see
/* A C statement to output to the stdio stream FILE an assembler
command to advance the location counter to a multiple of 1<<LOG
- bytes if it is within MAX_SKIP bytes.
+ bytes if it is within MAX_SKIP bytes. */
- This is used to align code labels according to Intel recommendations. */
+#define SUBALIGN_LOG 3
#ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
#undef ASM_OUTPUT_MAX_SKIP_ALIGN
@@ -101,16 +101,10 @@ along with GCC; see the file COPYING3. If not see
#define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE,LOG,MAX_SKIP) \
do { \
if ((LOG) != 0) { \
- if ((MAX_SKIP) == 0) fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
- else { \
+ if ((MAX_SKIP) == 0 || (MAX_SKIP) >= (1<<(LOG))-1) \
+ fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
+ else \
fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \
- /* Make sure that we have at least 8 byte alignment if > 8 byte \
- alignment is preferred. */ \
- if ((LOG) > 3 \
- && (1 << (LOG)) > ((MAX_SKIP) + 1) \
- && (MAX_SKIP) >= 7) \
- fputs ("\t.p2align 3\n", (FILE)); \
- } \
} \
} while (0)
#endif
Index: gcc/config/i386/gas.h
===================================================================
--- gcc/config/i386/gas.h (revision 239860)
+++ gcc/config/i386/gas.h (working copy)
@@ -72,10 +72,12 @@ along with GCC; see the file COPYING3. If not see
#ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
# define ASM_OUTPUT_MAX_SKIP_ALIGN(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)); \
- }
+ if ((LOG) != 0) { \
+ if ((MAX_SKIP) == 0 || (MAX_SKIP) >= (1<<(LOG))-1) \
+ fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
+ else \
+ fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \
+ }
#endif
/* A C statement or statements which output an assembler instruction
Index: gcc/config/i386/gnu-user.h
===================================================================
--- gcc/config/i386/gnu-user.h (revision 239860)
+++ gcc/config/i386/gnu-user.h (working copy)
@@ -94,24 +94,18 @@ along with GCC; see the file COPYING3. If not see
/* A C statement to output to the stdio stream FILE an assembler
command to advance the location counter to a multiple of 1<<LOG
- bytes if it is within MAX_SKIP bytes.
+ bytes if it is within MAX_SKIP bytes. */
- This is used to align code labels according to Intel recommendations. */
+#define SUBALIGN_LOG 3
#ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
#define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE,LOG,MAX_SKIP) \
do { \
if ((LOG) != 0) { \
- if ((MAX_SKIP) == 0) fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
- else { \
+ if ((MAX_SKIP) == 0 || (MAX_SKIP) >= (1<<(LOG))-1) \
+ fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
+ else \
fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \
- /* Make sure that we have at least 8 byte alignment if > 8 byte \
- alignment is preferred. */ \
- if ((LOG) > 3 \
- && (1 << (LOG)) > ((MAX_SKIP) + 1) \
- && (MAX_SKIP) >= 7) \
- fputs ("\t.p2align 3\n", (FILE)); \
- } \
} \
} while (0)
#endif
Index: gcc/config/i386/i386.h
===================================================================
--- gcc/config/i386/i386.h (revision 239860)
+++ gcc/config/i386/i386.h (working copy)
@@ -2271,7 +2271,7 @@ do { \
#define ASM_OUTPUT_MAX_SKIP_PAD(FILE, LOG, MAX_SKIP) \
if ((LOG) != 0) \
{ \
- if ((MAX_SKIP) == 0) \
+ if ((MAX_SKIP) == 0 || (MAX_SKIP) >= (1<<(LOG))-1) \
fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
else \
fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \
Index: gcc/config/i386/iamcu.h
===================================================================
--- gcc/config/i386/iamcu.h (revision 239860)
+++ gcc/config/i386/iamcu.h (working copy)
@@ -62,23 +62,17 @@ see the files COPYING3 and COPYING.RUNTIME respect
/* A C statement to output to the stdio stream FILE an assembler
command to advance the location counter to a multiple of 1<<LOG
- bytes if it is within MAX_SKIP bytes.
+ bytes if it is within MAX_SKIP bytes. */
- This is used to align code labels according to Intel recommendations. */
+#define SUBALIGN_LOG 3
#define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE,LOG,MAX_SKIP) \
do { \
if ((LOG) != 0) { \
- if ((MAX_SKIP) == 0) fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
- else { \
+ if ((MAX_SKIP) == 0 || (MAX_SKIP) >= (1<<(LOG))-1) \
+ fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
+ else \
fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \
- /* Make sure that we have at least 8 byte alignment if > 8 byte \
- alignment is preferred. */ \
- if ((LOG) > 3 \
- && (1 << (LOG)) > ((MAX_SKIP) + 1) \
- && (MAX_SKIP) >= 7) \
- fputs ("\t.p2align 3\n", (FILE)); \
- } \
} \
} while (0)
Index: gcc/config/i386/lynx.h
===================================================================
--- gcc/config/i386/lynx.h (revision 239860)
+++ gcc/config/i386/lynx.h (working copy)
@@ -61,8 +61,10 @@ along with GCC; see the file COPYING3. If not see
#define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE,LOG,MAX_SKIP) \
do { \
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)); \
+ if ((MAX_SKIP) == 0 || (MAX_SKIP) >= (1<<(LOG))-1) \
+ fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
+ else \
+ fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \
} \
} while (0)
#endif
Index: gcc/config/i386/netbsd-elf.h
===================================================================
--- gcc/config/i386/netbsd-elf.h (revision 239860)
+++ gcc/config/i386/netbsd-elf.h (working copy)
@@ -104,8 +104,10 @@ along with GCC; see the file COPYING3. If not see
#ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
#define ASM_OUTPUT_MAX_SKIP_ALIGN(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)); \
+ if ((MAX_SKIP) == 0 || (MAX_SKIP) >= (1<<(LOG))-1) \
+ fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
+ else \
+ fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \
}
#endif
Index: gcc/config/i386/openbsdelf.h
===================================================================
--- gcc/config/i386/openbsdelf.h (revision 239860)
+++ gcc/config/i386/openbsdelf.h (working copy)
@@ -63,24 +63,18 @@ along with GCC; see the file COPYING3. If not see
/* A C statement to output to the stdio stream FILE an assembler
command to advance the location counter to a multiple of 1<<LOG
- bytes if it is within MAX_SKIP bytes.
+ bytes if it is within MAX_SKIP bytes. */
- This is used to align code labels according to Intel recommendations. */
+#define SUBALIGN_LOG 3
#ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
#define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE,LOG,MAX_SKIP) \
do { \
if ((LOG) != 0) { \
- if ((MAX_SKIP) == 0) fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
- else { \
+ if ((MAX_SKIP) == 0 || (MAX_SKIP) >= (1<<(LOG))-1) \
+ fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
+ else \
fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \
- /* Make sure that we have at least 8 byte alignment if > 8 byte \
- alignment is preferred. */ \
- if ((LOG) > 3 \
- && (1 << (LOG)) > ((MAX_SKIP) + 1) \
- && (MAX_SKIP) >= 7) \
- fputs ("\t.p2align 3\n", (FILE)); \
- } \
} \
} while (0)
#endif
Index: gcc/config/i386/x86-64.h
===================================================================
--- gcc/config/i386/x86-64.h (revision 239860)
+++ gcc/config/i386/x86-64.h (working copy)
@@ -61,20 +61,16 @@ see the files COPYING3 and COPYING.RUNTIME respect
/* This is used to align code labels according to Intel recommendations. */
+#define SUBALIGN_LOG 3
+
#ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
#define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE,LOG,MAX_SKIP) \
do { \
if ((LOG) != 0) { \
- if ((MAX_SKIP) == 0) fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
- else { \
+ if ((MAX_SKIP) == 0 || (MAX_SKIP) >= (1<<(LOG))-1) \
+ fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
+ else \
fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \
- /* Make sure that we have at least 8 byte alignment if > 8 byte \
- alignment is preferred. */ \
- if ((LOG) > 3 \
- && (1 << (LOG)) > ((MAX_SKIP) + 1) \
- && (MAX_SKIP) >= 7) \
- fputs ("\t.p2align 3\n", (FILE)); \
- } \
} \
} while (0)
#undef ASM_OUTPUT_MAX_SKIP_PAD
@@ -81,7 +77,7 @@ see the files COPYING3 and COPYING.RUNTIME respect
#define ASM_OUTPUT_MAX_SKIP_PAD(FILE, LOG, MAX_SKIP) \
if ((LOG) != 0) \
{ \
- if ((MAX_SKIP) == 0) \
+ if ((MAX_SKIP) == 0 || (MAX_SKIP) >= (1<<(LOG))-1) \
fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
else \
fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP)); \