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.

2017-04-18  Denys Vlasenko  <dvlas...@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));    \

Reply via email to