configure.in: Check whether assembler supports section merging.

	* configure.in: Check whether assembler supports section merging.
	* config.in: Rebuilt.
	* configure: Rebuilt.
	* varasm.c (variable_section, output_constant_pool): Pass alignment
	to SELECT_SECTION and SELECT_RTX_SECTION.
	(mergeable_string_section): New.
	(mergeable_constant_section): New.
	(default_elf_asm_named_section): Output SECTION_MERGE and
	SECTION_STRINGS flags plus SECTION_ENTSIZE entity size.
	* output.h (mergeable_string_section): New.
	(mergeable_constant_section): New.
	(SECTION_MERGE, SECTION_STRINGS, SECTION_ENTSIZE): Define.
	* toplev.c (flag_merge_constants): New.
	(f_options): Add -fmerge-constants and -fmerge-all-constants
	options.
	(toplev_main): Default to -fno-merge-constants if not optimizing.
	* flags.h (flag_merge_constants): Add extern.
	* invoke.texi (-fmerge-constants, -fmerge-all-constants): Document.
	* tm.texi (SELECT_SECTION, SELECT_RTX_SECTION): Document added third
	argument.
	* config/elfos.h (ASM_SECTION_START_OP, ASM_OUTPUT_SECTION_START):
	Define if assembler has working .subsection -1 support.
	(SELECT_RTX_SECTION, SELECT_SECTION): Add third macro argument.
	Put constant into special SHF_MERGE sections if the linker should
	attempt to merge duplicates.
	* config/ia64/sysv4.h (SELECT_RTX_SECTION, SELECT_SECTION): Add third
	macro argument.
	Put constant into special SHF_MERGE sections if the linker should
	attempt to merge duplicates.
	* config/alpha/elf.h: Likewise.
	(ASM_SECTION_START_OP, ASM_OUTPUT_SECTION_START): Define if assembler
	has working .subsection -1 support.
	* config/nextstep.h: Add third argument to SELECT_RTX_SECTION and
	SELECT_SECTION.
	* config/svr3.h: Likewise.
	* config/darwin.h: Likewise.
	* config/arm/aof.h: Likewise.
	* config/arm/linux-elf.h: Likewise.
	* config/avr/avr.h: Likewise.
	* config/c4x/c4x.h: Likewise.
	* config/d30v/d30v.h: Likewise.
	* config/i386/dgux.h: Likewise.
	* config/i386/osfrose.h: Likewise.
	* config/i386/sco5.h: Likewise.
	* config/i386/svr3gas.h: Likewise.
	* config/ia64/aix.h: Likewise.
	* config/m32r/m32r.h: Likewise.
	* config/m68k/m68k.h: Likewise.
	* config/m88k/dgux.h: Likewise.
	* config/m88k/m88k.h: Likewise.
	* config/mcore/mcore-pe.h: Likewise.
	* config/mips/mips.h: Likewise.
	* config/pa/pa.h: Likewise.
	* config/pa/pa-linux.h: Likewise.
	* config/romp/romp.h: Likewise.
	* config/rs6000/sysv4.h: Likewise.
	* config/rs6000/xcoff.h: Likewise.
	* config/s390/linux.h: Likewise.
	* config/sparc/sparc.h: Likewise.
	* config/sparc/sysv4.h: Likewise.
	* config/stormy16/stormy16.h: Likewise.
	* config/v850/v850.h: Likewise.
	* config/vax/vms.h: Likewise.
	* config/arm/arm.c (arm_elf_asm_named_section): Output SECTION_MERGE
	and SECTION_STRINGS flags plus SECTION_ENTSIZE entity size.
	* config/sparc/sparc.c (sparc_elf_asm_named_section): Use
	default_elf_asm_named_section for SHF_MERGE sections.

	* com.c (ffe_init_options): Default to -fmerge-all-constants
	if optimizing.

From-SVN: r45548

47 files changed, 489 insertions, 118 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b0463a40631..4fa939c9d96 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,73 @@
+2001-09-11  Jakub Jelinek  <jakub@redhat.com>
+
+	* configure.in: Check whether assembler supports section merging.
+	* config.in: Rebuilt.
+	* configure: Rebuilt.
+	* varasm.c (variable_section, output_constant_pool): Pass alignment
+	to SELECT_SECTION and SELECT_RTX_SECTION.
+	(mergeable_string_section): New.
+	(mergeable_constant_section): New.
+	(default_elf_asm_named_section): Output SECTION_MERGE and
+	SECTION_STRINGS flags plus SECTION_ENTSIZE entity size.
+	* output.h (mergeable_string_section): New.
+	(mergeable_constant_section): New.
+	(SECTION_MERGE, SECTION_STRINGS, SECTION_ENTSIZE): Define.
+	* toplev.c (flag_merge_constants): New.
+	(f_options): Add -fmerge-constants and -fmerge-all-constants
+	options.
+	(toplev_main): Default to -fno-merge-constants if not optimizing.
+	* flags.h (flag_merge_constants): Add extern.
+	* invoke.texi (-fmerge-constants, -fmerge-all-constants): Document.
+	* tm.texi (SELECT_SECTION, SELECT_RTX_SECTION): Document added third
+	argument.
+	* config/elfos.h (ASM_SECTION_START_OP, ASM_OUTPUT_SECTION_START):
+	Define if assembler has working .subsection -1 support.
+	(SELECT_RTX_SECTION, SELECT_SECTION): Add third macro argument.
+	Put constant into special SHF_MERGE sections if the linker should
+	attempt to merge duplicates.
+	* config/ia64/sysv4.h (SELECT_RTX_SECTION, SELECT_SECTION): Add third
+	macro argument.
+	Put constant into special SHF_MERGE sections if the linker should
+	attempt to merge duplicates.
+	* config/alpha/elf.h: Likewise.
+	(ASM_SECTION_START_OP, ASM_OUTPUT_SECTION_START): Define if assembler
+	has working .subsection -1 support.
+	* config/nextstep.h: Add third argument to SELECT_RTX_SECTION and
+	SELECT_SECTION.
+	* config/svr3.h: Likewise.
+	* config/darwin.h: Likewise.
+	* config/arm/aof.h: Likewise.
+	* config/arm/linux-elf.h: Likewise.
+	* config/avr/avr.h: Likewise.
+	* config/c4x/c4x.h: Likewise.
+	* config/d30v/d30v.h: Likewise.
+	* config/i386/dgux.h: Likewise.
+	* config/i386/osfrose.h: Likewise.
+	* config/i386/sco5.h: Likewise.
+	* config/i386/svr3gas.h: Likewise.
+	* config/ia64/aix.h: Likewise.
+	* config/m32r/m32r.h: Likewise.
+	* config/m68k/m68k.h: Likewise.
+	* config/m88k/dgux.h: Likewise.
+	* config/m88k/m88k.h: Likewise.
+	* config/mcore/mcore-pe.h: Likewise.
+	* config/mips/mips.h: Likewise.
+	* config/pa/pa.h: Likewise.
+	* config/pa/pa-linux.h: Likewise.
+	* config/romp/romp.h: Likewise.
+	* config/rs6000/sysv4.h: Likewise.
+	* config/rs6000/xcoff.h: Likewise.
+	* config/s390/linux.h: Likewise.
+	* config/sparc/sparc.h: Likewise.
+	* config/sparc/sysv4.h: Likewise.
+	* config/stormy16/stormy16.h: Likewise.
+	* config/v850/v850.h: Likewise.
+	* config/vax/vms.h: Likewise.
+	* config/arm/arm.c (arm_elf_asm_named_section): Output SECTION_MERGE
+	and SECTION_STRINGS flags plus SECTION_ENTSIZE entity size.
+	* config/sparc/sparc.c (sparc_elf_asm_named_section): Use
+	default_elf_asm_named_section for SHF_MERGE sections.
+
 Tue Sep 11 17:55:54 CEST 2001  Jan Hubicka  <jh@suse.cz>
 
 	* bb-reorder.c (fixup_reorder_chain): Fallthru edge to exit block
diff --git a/gcc/config.in b/gcc/config.in
index 88a751703c4..b9156619b5c 100644
--- a/gcc/config.in
+++ b/gcc/config.in
@@ -475,6 +475,9 @@
 /* Define if your assembler mis-optimizes .eh_frame data. */
 #undef USE_AS_TRADITIONAL_FORMAT
 
+/* Define if your assembler supports marking sections with SHF_MERGE flag. */
+#undef HAVE_GAS_SHF_MERGE
+
 /* Define if your assembler supports .register. */
 #undef HAVE_AS_REGISTER_PSEUDO_OP
 
diff --git a/gcc/config/alpha/elf.h b/gcc/config/alpha/elf.h
index 3bb51cca6b2..7c2ad236b44 100644
--- a/gcc/config/alpha/elf.h
+++ b/gcc/config/alpha/elf.h
@@ -1,5 +1,6 @@
 /* Definitions of target machine for GNU compiler, for DEC Alpha w/ELF.
-   Copyright (C) 1996, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
+   Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001
+   Free Software Foundation, Inc.
    Contributed by Richard Henderson (rth@tamu.edu).
 
 This file is part of GNU CC.
@@ -222,6 +223,16 @@ do {									\
 #undef  FINI_SECTION_ASM_OP
 #define FINI_SECTION_ASM_OP	"\t.section\t.fini"
 
+#ifdef HAVE_GAS_SUBSECTION_ORDERING
+
+#define ASM_SECTION_START_OP	"\t.subsection\t-1"
+
+/* Output assembly directive to move to the beginning of current section.  */
+#define ASM_OUTPUT_SECTION_START(FILE)	\
+  fprintf ((FILE), "%s\n", ASM_SECTION_START_OP)
+
+#endif
+
 /* A default list of other sections which we might be "in" at any given
    time.  For targets that use additional sections (e.g. .tdesc) you
    should override this definition in the target-specific file which
@@ -240,8 +251,6 @@ do {									\
   SECTION_FUNCTION_TEMPLATE(sbss_section, in_sbss, SBSS_SECTION_ASM_OP)	\
   SECTION_FUNCTION_TEMPLATE(sdata_section, in_sdata, SDATA_SECTION_ASM_OP)
 
-extern void ctors_section		PARAMS ((void));
-extern void dtors_section		PARAMS ((void));
 extern void sbss_section		PARAMS ((void));
 extern void sdata_section		PARAMS ((void));
 
@@ -300,6 +309,8 @@ void FN ()					\
 	 {							\
 	   if (flag_writable_strings)				\
 	     SECNUM = 2;					\
+	   else							\
+	     SECNUM = 0x101;					\
 	 }							\
        else if (TREE_CODE (DECL) == VAR_DECL)			\
 	 {							\
@@ -311,6 +322,17 @@ void FN ()					\
 		    || TREE_SIDE_EFFECTS (DECL)			\
 		    || ! TREE_CONSTANT (DECL_INITIAL (DECL)))	\
 	     SECNUM = 2;					\
+	  else if (flag_merge_constants >= 2)			\
+	    {							\
+	      /* C and C++ don't allow different variables to	\
+		 share the same location.  -fmerge-all-constants\
+		 allows even that (at the expense of not	\
+		 conforming).  */				\
+	      if (TREE_CODE (DECL_INITIAL (DECL)) == STRING_CST)\
+		SECNUM = 0x201;					\
+	      else						\
+		SECNUM = 0x301;					\
+	    }							\
 	 }							\
        else if (TREE_CODE (DECL) == CONSTRUCTOR)		\
 	 {							\
@@ -322,7 +344,7 @@ void FN ()					\
 	 }							\
 								\
        /* Select small data sections based on size.  */		\
-       if (SECNUM >= 2)						\
+       if ((SECNUM & 0xff) >= 2)				\
 	 {							\
 	   int size = int_size_in_bytes (TREE_TYPE (DECL));	\
 	   if (size >= 0 && size <= g_switch_value)		\
@@ -332,26 +354,42 @@ void FN ()					\
    while (0)
 
 #undef  SELECT_SECTION
-#define SELECT_SECTION(DECL, RELOC)		\
-  do						\
-    {						\
-      typedef void (*sec_fn) PARAMS ((void));	\
-      static sec_fn const sec_functions[6] =	\
-      {						\
-	text_section,				\
-	const_section,				\
-	data_section,				\
-	sdata_section,				\
-	bss_section,				\
-	sbss_section				\
-      };					\
-						\
-      int sec;					\
-						\
-      DO_SELECT_SECTION (sec, DECL, RELOC);	\
-						\
-      (*sec_functions[sec]) ();			\
-    }						\
+#define SELECT_SECTION(DECL, RELOC, ALIGN)		\
+  do							\
+    {							\
+      typedef void (*sec_fn) PARAMS ((void));		\
+      static sec_fn const sec_functions[6] =		\
+      {							\
+	text_section,					\
+	const_section,					\
+	data_section,					\
+	sdata_section,					\
+	bss_section,					\
+	sbss_section					\
+      };						\
+							\
+      int sec;						\
+							\
+      DO_SELECT_SECTION (sec, DECL, RELOC);		\
+							\
+      switch (sec)					\
+	{						\
+	case 0x101:					\
+	  mergeable_string_section (DECL, ALIGN, 0);	\
+	  break;					\
+	case 0x201:					\
+	  mergeable_string_section (DECL_INITIAL (DECL),\
+				    ALIGN, 0);		\
+	  break;					\
+	case 0x301:					\
+	  mergeable_constant_section (DECL_MODE (DECL),	\
+				      ALIGN, 0);	\
+	  break;					\
+	default:					\
+	  (*sec_functions[sec]) ();			\
+	  break;					\
+	}						\
+    }							\
   while (0)
 
 #define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
@@ -380,7 +418,7 @@ void FN ()					\
       STRIP_NAME_ENCODING (name, name);					\
       nlen = strlen (name);						\
 									\
-      prefix = prefixes[sec][DECL_ONE_ONLY(DECL)];			\
+      prefix = prefixes[sec & 0xff][DECL_ONE_ONLY(DECL)];		\
       plen = strlen (prefix);						\
 									\
       string = alloca (nlen + plen + 1);				\
@@ -399,8 +437,8 @@ void FN ()					\
    go into the const section.  */
 
 #undef  SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(MODE, RTX) \
-   const_section()
+#define SELECT_RTX_SECTION(MODE, RTX, ALIGN) \
+   mergeable_constant_section((MODE), (ALIGN), 0)
 
 /* Define the strings used for the special svr4 .type and .size directives.
    These strings generally do not vary from one system running svr4 to
diff --git a/gcc/config/arm/aof.h b/gcc/config/arm/aof.h
index 2721b8bbdeb..55b8eefda2d 100644
--- a/gcc/config/arm/aof.h
+++ b/gcc/config/arm/aof.h
@@ -55,7 +55,7 @@ Boston, MA 02111-1307, USA.  */
 char *aof_text_section ();
 #define TEXT_SECTION_ASM_OP aof_text_section ()
 
-#define SELECT_RTX_SECTION(MODE,RTX) text_section ();
+#define SELECT_RTX_SECTION(MODE,RTX,ALIGN) text_section ();
 
 char *aof_data_section ();
 #define DATA_SECTION_ASM_OP aof_data_section ()
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index c3f4e2eadef..725864c54a0 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -10860,6 +10860,10 @@ arm_elf_asm_named_section (name, flags)
     *f++ = 'x';
   if (flags & SECTION_SMALL)
     *f++ = 's';
+  if (flags & SECTION_MERGE)
+    *f++ = 'M';
+  if (flags & SECTION_STRINGS)
+    *f++ = 'S';
   *f = '\0';
 
   if (flags & SECTION_BSS)
@@ -10867,6 +10871,10 @@ arm_elf_asm_named_section (name, flags)
   else
     type = "progbits";
 
-  fprintf (asm_out_file, "\t.section\t%s,\"%s\",%%%s\n",
-	   name, flagchars, type);
+  if (flags & SECTION_ENTSIZE)
+    fprintf (asm_out_file, "\t.section\t%s,\"%s\",%%%s,%d\n",
+	     name, flagchars, type, flags & SECTION_ENTSIZE);
+  else
+    fprintf (asm_out_file, "\t.section\t%s,\"%s\",%%%s\n",
+	     name, flagchars, type);
 }
diff --git a/gcc/config/arm/linux-elf.h b/gcc/config/arm/linux-elf.h
index 06519604ff0..cb9014ce741 100644
--- a/gcc/config/arm/linux-elf.h
+++ b/gcc/config/arm/linux-elf.h
@@ -139,7 +139,7 @@ const_section ()							\
    section for output of DECL.  DECL is either a `VAR_DECL' node
    or a constant of some sort.  RELOC indicates whether forming
    the initial value of DECL requires link-time relocations.  */
-#define SELECT_SECTION(DECL,RELOC)					\
+#define SELECT_SECTION(DECL,RELOC,ALIGN)				\
 {									\
   if (TREE_CODE (DECL) == STRING_CST)					\
     {									\
@@ -204,7 +204,7 @@ const_section ()							\
    of constant in RTL.  The argument MODE is redundant except
    in the case of a `const_int' rtx.  Currently, these always
    go into the const section.  */
-#define SELECT_RTX_SECTION(MODE,RTX) const_section ()
+#define SELECT_RTX_SECTION(MODE,RTX,ALIGN) const_section ()
 
 /* On svr4, we *do* have support for the .init and .fini sections, and we
    can put stuff in there to be executed before and after `main'.  We let
diff --git a/gcc/config/avr/avr.h b/gcc/config/avr/avr.h
index 3fd1e5652eb..8ae9302f5e1 100644
--- a/gcc/config/avr/avr.h
+++ b/gcc/config/avr/avr.h
@@ -1890,7 +1890,7 @@ progmem_section (void)							      \
    If these items should be placed in the text section, this macro
    should not be defined.  */
 
-/* `SELECT_SECTION (EXP, RELOC)'
+/* `SELECT_SECTION (EXP, RELOC, ALIGN)'
    A C statement or statements to switch to the appropriate section
    for output of EXP.  You can assume that EXP is either a `VAR_DECL'
    node or a constant of some sort.  RELOC indicates whether the
@@ -1901,7 +1901,7 @@ progmem_section (void)							      \
    Do not define this macro if you put all read-only variables and
    constants in the read-only data section (usually the text section).  */
 
-/* `SELECT_RTX_SECTION (MODE, RTX)'
+/* `SELECT_RTX_SECTION (MODE, RTX, ALIGN)'
    A C statement or statements to switch to the appropriate section
    for output of RTX in mode MODE.  You can assume that RTX is some
    kind of constant in RTL.  The argument MODE is redundant except in
diff --git a/gcc/config/c4x/c4x.h b/gcc/config/c4x/c4x.h
index cdc39db30c3..e8052c6b68c 100644
--- a/gcc/config/c4x/c4x.h
+++ b/gcc/config/c4x/c4x.h
@@ -2030,7 +2030,7 @@ const_section ()							\
    or a constant of some sort.  RELOC indicates whether forming
    the initial value of DECL requires link-time relocations.  */
 
-#define SELECT_SECTION(DECL, RELOC)					\
+#define SELECT_SECTION(DECL, RELOC, ALIGN)				\
 {									\
   if (TREE_CODE (DECL) == STRING_CST)					\
     {									\
@@ -2075,7 +2075,7 @@ const_section ()							\
    in the case of a `const_int' rtx.  Currently, these always
    go into the const section.  */
 
-#define SELECT_RTX_SECTION(MODE, RTX) const_section()
+#define SELECT_RTX_SECTION(MODE, RTX, ALIGN) const_section()
 
 
 /* Overall Framework of an Assembler File.  */
diff --git a/gcc/config/d30v/d30v.h b/gcc/config/d30v/d30v.h
index 82598fd659b..abf2d4736f0 100644
--- a/gcc/config/d30v/d30v.h
+++ b/gcc/config/d30v/d30v.h
@@ -3698,7 +3698,7 @@ extern const char *d30v_branch_cost_string;
    the read-only data section (usually the text section).
 
    Defined in svr4.h.  */
-/* #define SELECT_SECTION(EXP, RELOC) */
+/* #define SELECT_SECTION(EXP, RELOC, ALIGN) */
 
 /* A C statement or statements to switch to the appropriate section for output
    of RTX in mode MODE.  You can assume that RTX is some kind of constant in
@@ -3710,7 +3710,7 @@ extern const char *d30v_branch_cost_string;
    section.
 
    Defined in svr4.h.  */
-/* #define SELECT_RTX_SECTION(MODE, RTX) */
+/* #define SELECT_RTX_SECTION(MODE, RTX, ALIGN) */
 
 /* Define this macro if jump tables (for `tablejump' insns) should be output in
    the text section, along with the assembler instructions.  Otherwise, the
diff --git a/gcc/config/darwin.h b/gcc/config/darwin.h
index 9124307755c..5c49d113193 100644
--- a/gcc/config/darwin.h
+++ b/gcc/config/darwin.h
@@ -509,7 +509,7 @@ void alias_section (name, alias)			\
 #define READONLY_DATA_SECTION const_section
 
 #undef	SELECT_SECTION
-#define SELECT_SECTION(exp,reloc)				\
+#define SELECT_SECTION(exp,reloc,align)				\
   do								\
     {								\
       if (TREE_CODE (exp) == STRING_CST)			\
@@ -633,7 +633,7 @@ void alias_section (name, alias)			\
   while (0)
 
 #undef	SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(mode, rtx)					\
+#define SELECT_RTX_SECTION(mode, rtx, align)				\
   do									\
     {									\
       if (GET_MODE_SIZE (mode) == 8)					\
diff --git a/gcc/config/elfos.h b/gcc/config/elfos.h
index d813678682e..d2ae669a83f 100644
--- a/gcc/config/elfos.h
+++ b/gcc/config/elfos.h
@@ -262,6 +262,16 @@ Boston, MA 02111-1307, USA.  */
 #define INIT_SECTION_ASM_OP	"\t.section\t.init"
 #define FINI_SECTION_ASM_OP	"\t.section\t.fini"
 
+#ifdef HAVE_GAS_SUBSECTION_ORDERING
+
+#define ASM_SECTION_START_OP	"\t.subsection\t-1"
+
+/* Output assembly directive to move to the beginning of current section.  */
+#define ASM_OUTPUT_SECTION_START(FILE)	\
+  fprintf ((FILE), "%s\n", ASM_SECTION_START_OP)
+
+#endif
+
 /* A default list of other sections which we might be "in" at any given
    time.  For targets that use additional sections (e.g. .tdesc) you
    should override this definition in the target-specific file which
@@ -340,11 +350,14 @@ const_section ()						\
 /* A C statement or statements to switch to the appropriate
    section for output of RTX in mode MODE.  RTX is some kind
    of constant in RTL.  The argument MODE is redundant except
-   in the case of a `const_int' rtx.  Currently, these always
-   go into the const section.  */
+   in the case of a `const_int' rtx.
+   If assembler supports SHF_MERGE sections, put it into
+   a .rodata.cstN section where N is size of the constant,
+   otherwise into const section.  */
 
 #undef  SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(MODE, RTX) const_section ()
+#define SELECT_RTX_SECTION(MODE, RTX, ALIGN)	\
+  mergeable_constant_section ((MODE), (ALIGN), 0)
 
 /* A C statement or statements to switch to the appropriate
    section for output of DECL.  DECL is either a `VAR_DECL' node
@@ -352,12 +365,12 @@ const_section ()						\
    the initial value of DECL requires link-time relocations.  */
 
 #undef SELECT_SECTION
-#define SELECT_SECTION(DECL, RELOC)				\
+#define SELECT_SECTION(DECL, RELOC, ALIGN)			\
 {								\
   if (TREE_CODE (DECL) == STRING_CST)				\
     {								\
       if (! flag_writable_strings)				\
-	const_section ();					\
+	mergeable_string_section ((DECL), (ALIGN), 0);		\
       else							\
 	data_section ();					\
     }								\
@@ -369,8 +382,17 @@ const_section ()						\
 	  || (DECL_INITIAL (DECL) != error_mark_node		\
 	      && !TREE_CONSTANT (DECL_INITIAL (DECL))))		\
 	data_section ();					\
-      else							\
+      else if (flag_merge_constants < 2)			\
+	/* C and C++ don't allow different variables to share	\
+	   the same location.  -fmerge-all-constants allows	\
+	   even that (at the expense of not conforming).  */	\
 	const_section ();					\
+      else if (TREE_CODE (DECL_INITIAL (DECL)) == STRING_CST)	\
+	mergeable_string_section (DECL_INITIAL (DECL), (ALIGN),	\
+				  0);				\
+      else							\
+	mergeable_constant_section (DECL_MODE (DECL), (ALIGN),	\
+				    0);				\
     }								\
   else if (TREE_CODE (DECL) == CONSTRUCTOR)			\
     {								\
diff --git a/gcc/config/i386/dgux.h b/gcc/config/i386/dgux.h
index 04a29001291..5d7a6aa0d4f 100644
--- a/gcc/config/i386/dgux.h
+++ b/gcc/config/i386/dgux.h
@@ -27,7 +27,7 @@ Boston, MA 02111-1307, USA.  */
 #include "i386/sysv4.h"
 
 #ifndef VERSION_INFO2
-#define VERSION_INFO2   "$Revision: 1.12 $"
+#define VERSION_INFO2   "$Revision: 1.13 $"
 #endif
 
 #ifndef VERSION_STRING
@@ -232,7 +232,7 @@ Boston, MA 02111-1307, USA.  */
 
 /* Must use data section for relocatable constants when pic.  */
 #undef SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(MODE,RTX)            \
+#define SELECT_RTX_SECTION(MODE,RTX,ALIGN)      \
 {                                               \
   if (flag_pic && symbolic_operand (RTX, VOIDmode)) \
     data_section ();                            \
diff --git a/gcc/config/i386/osfrose.h b/gcc/config/i386/osfrose.h
index 7d74f7ac1bc..785aa4fe7a6 100644
--- a/gcc/config/i386/osfrose.h
+++ b/gcc/config/i386/osfrose.h
@@ -506,7 +506,7 @@ while (0)
    and select that section.  */
 
 #undef	SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(MODE, RTX)					\
+#define SELECT_RTX_SECTION(MODE, RTX, ALIGN)				\
 do									\
   {									\
     if (MODE == Pmode && HALF_PIC_P () && HALF_PIC_ADDRESS_P (RTX))	\
@@ -517,7 +517,7 @@ do									\
 while (0)
 
 #undef	SELECT_SECTION
-#define SELECT_SECTION(DECL, RELOC)					\
+#define SELECT_SECTION(DECL, RELOC, ALIGN)				\
 {									\
   if (RELOC && HALF_PIC_P ())						\
     data_section ();							\
diff --git a/gcc/config/i386/sco5.h b/gcc/config/i386/sco5.h
index a8184270821..56bc2879e6c 100644
--- a/gcc/config/i386/sco5.h
+++ b/gcc/config/i386/sco5.h
@@ -371,7 +371,7 @@ do {									\
 
 /* Must use data section for relocatable constants when pic.  */
 #undef SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(MODE,RTX)					\
+#define SELECT_RTX_SECTION(MODE,RTX,ALIGN)				\
 {									\
   if (TARGET_ELF) {							\
     if (flag_pic && symbolic_operand (RTX, VOIDmode))			\
@@ -565,7 +565,7 @@ init_section ()								\
    : 0))
 
 #undef SELECT_SECTION
-#define SELECT_SECTION(DECL,RELOC)					\
+#define SELECT_SECTION(DECL,RELOC,ALIGN)				\
 {									\
   if (TARGET_ELF && flag_pic && RELOC)					\
      data_section ();							\
diff --git a/gcc/config/i386/svr3gas.h b/gcc/config/i386/svr3gas.h
index 8733ba72724..08ada117284 100644
--- a/gcc/config/i386/svr3gas.h
+++ b/gcc/config/i386/svr3gas.h
@@ -177,7 +177,7 @@ const_section ()							\
    or a constant of some sort.  RELOC indicates whether forming
    the initial value of DECL requires link-time relocations.  */
 
-#define SELECT_SECTION(DECL,RELOC)					\
+#define SELECT_SECTION(DECL,RELOC,ALIGN)				\
 {									\
   if (TREE_CODE (DECL) == STRING_CST)					\
     {									\
@@ -207,4 +207,4 @@ const_section ()							\
    in the case of a `const_int' rtx.  Currently, these always
    go into the const section.  */
 
-#define SELECT_RTX_SECTION(MODE,RTX) const_section()
+#define SELECT_RTX_SECTION(MODE,RTX,ALIGN) const_section()
diff --git a/gcc/config/ia64/aix.h b/gcc/config/ia64/aix.h
index cf1f4b0874a..0c632111b5a 100644
--- a/gcc/config/ia64/aix.h
+++ b/gcc/config/ia64/aix.h
@@ -150,7 +150,7 @@ do {							\
    the initial value of DECL requires link-time relocations.  */
 
 #undef SELECT_SECTION
-#define SELECT_SECTION(DECL,RELOC)					\
+#define SELECT_SECTION(DECL,RELOC,ALIGN)				\
 {									\
   if (TREE_CODE (DECL) == STRING_CST)					\
     {									\
@@ -184,7 +184,7 @@ do {							\
 
 extern unsigned int ia64_section_threshold;
 #undef SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(MODE, RTX)					\
+#define SELECT_RTX_SECTION(MODE, RTX, ALIGN)				\
 {									\
   if (GET_MODE_SIZE (MODE) > 0						\
       && GET_MODE_SIZE (MODE) <= ia64_section_threshold)		\
diff --git a/gcc/config/ia64/sysv4.h b/gcc/config/ia64/sysv4.h
index 0abb7e8cd7e..54b5167363e 100644
--- a/gcc/config/ia64/sysv4.h
+++ b/gcc/config/ia64/sysv4.h
@@ -138,12 +138,12 @@ do {									\
 /* We override svr4.h so that we can support the sdata section.  */
 
 #undef SELECT_SECTION
-#define SELECT_SECTION(DECL,RELOC)					\
+#define SELECT_SECTION(DECL,RELOC,ALIGN)				\
 {									\
   if (TREE_CODE (DECL) == STRING_CST)					\
     {									\
       if (! flag_writable_strings)					\
-	const_section ();						\
+	mergeable_string_section ((DECL), (ALIGN), 0);			\
       else								\
 	data_section ();						\
     }									\
@@ -152,13 +152,20 @@ do {									\
       if (XSTR (XEXP (DECL_RTL (DECL), 0), 0)[0]			\
 	  == SDATA_NAME_FLAG_CHAR)					\
         sdata_section ();						\
-      /* ??? We need the extra ! RELOC check, because the default is to \
+      /* ??? We need the extra RELOC check, because the default is to	\
 	 only check RELOC if flag_pic is set, and we don't set flag_pic \
 	 (yet?).  */							\
-      else if (DECL_READONLY_SECTION (DECL, RELOC) && ! (RELOC))	\
+      else if (!DECL_READONLY_SECTION (DECL, RELOC) || (RELOC))		\
+	data_section ();						\
+      else if (flag_merge_constants < 2)				\
+	/* C and C++ don't allow different variables to share		\
+	   the same location.  -fmerge-all-constants allows		\
+	   even that (at the expense of not conforming).  */		\
 	const_section ();						\
+      else if (TREE_CODE (DECL_INITIAL (DECL)) == STRING_CST)		\
+	mergeable_string_section (DECL_INITIAL (DECL), (ALIGN), 0);	\
       else								\
-	data_section ();						\
+	mergeable_constant_section (DECL_MODE (DECL), (ALIGN), 0);	\
     }									\
   /* This could be a CONSTRUCTOR containing ADDR_EXPR of a VAR_DECL,	\
      in which case we can't put it in a shared library rodata.  */	\
@@ -172,7 +179,7 @@ do {									\
 
 extern unsigned int ia64_section_threshold;
 #undef SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(MODE, RTX)					\
+#define SELECT_RTX_SECTION(MODE, RTX, ALIGN)				\
 {									\
   if (GET_MODE_SIZE (MODE) > 0						\
       && GET_MODE_SIZE (MODE) <= ia64_section_threshold)		\
@@ -180,7 +187,7 @@ extern unsigned int ia64_section_threshold;
   else if (flag_pic && symbolic_operand ((RTX), (MODE)))		\
     data_section ();							\
   else									\
-    const_section ();							\
+    mergeable_constant_section ((MODE), (ALIGN), 0);			\
 }
 
 #undef EXTRA_SECTIONS
diff --git a/gcc/config/m32r/m32r.h b/gcc/config/m32r/m32r.h
index 5ef9951cd6b..4cb379e34be 100644
--- a/gcc/config/m32r/m32r.h
+++ b/gcc/config/m32r/m32r.h
@@ -1534,7 +1534,8 @@ sbss_section ()								\
    or a constant of some sort.  RELOC indicates whether the initial value
    of EXP requires link-time relocations.  */
 #undef  SELECT_SECTION
-#define SELECT_SECTION(EXP, RELOC) m32r_select_section ((EXP), (RELOC))
+#define SELECT_SECTION(EXP, RELOC, ALIGN) \
+  m32r_select_section ((EXP), (RELOC))
 
 /* A C statement or statements to switch to the appropriate section for
    output of RTX in mode MODE.  You can assume that RTX
diff --git a/gcc/config/m68k/m68k.h b/gcc/config/m68k/m68k.h
index 14bcaa25c14..9607a920c59 100644
--- a/gcc/config/m68k/m68k.h
+++ b/gcc/config/m68k/m68k.h
@@ -359,7 +359,7 @@ extern int target_flags;
 /* This is how to align an instruction for optimal branching. */
 #define LABEL_ALIGN_AFTER_BARRIER(LABEL) (m68k_align_jumps)
 
-#define SELECT_RTX_SECTION(MODE, X)					\
+#define SELECT_RTX_SECTION(MODE, X, ALIGN)				\
 {									\
   if (!flag_pic)							\
     readonly_data_section();						\
diff --git a/gcc/config/m88k/dgux.h b/gcc/config/m88k/dgux.h
index ab8e3710e1e..1d91168a5a4 100644
--- a/gcc/config/m88k/dgux.h
+++ b/gcc/config/m88k/dgux.h
@@ -294,7 +294,7 @@ func_ptr __DTOR_END__[1] = { (func_ptr) (-1) }
 
 /* Must use data section for relocatable constants when pic.  */
 #undef SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(MODE,RTX)            \
+#define SELECT_RTX_SECTION(MODE,RTX,ALIGN)      \
 {                                               \
   if (flag_pic && symbolic_operand (RTX))       \
     data_section ();                            \
diff --git a/gcc/config/m88k/m88k.h b/gcc/config/m88k/m88k.h
index c30c81891f4..881acd88be0 100644
--- a/gcc/config/m88k/m88k.h
+++ b/gcc/config/m88k/m88k.h
@@ -2480,7 +2480,7 @@ sdata_section ()							\
 
    For strings, the section is selected before the segment info is encoded.  */
 #undef	SELECT_SECTION
-#define SELECT_SECTION(DECL,RELOC)					\
+#define SELECT_SECTION(DECL,RELOC,ALIGN)				\
 {									\
   if (TREE_CODE (DECL) == STRING_CST)					\
     {									\
diff --git a/gcc/config/mcore/mcore-pe.h b/gcc/config/mcore/mcore-pe.h
index 2362b521a18..e08b337c194 100644
--- a/gcc/config/mcore/mcore-pe.h
+++ b/gcc/config/mcore/mcore-pe.h
@@ -81,7 +81,7 @@ rdata_section ()						\
    or a constant of some sort.  RELOC indicates whether forming
    the initial value of DECL requires link-time relocations.  */
 #undef  SELECT_SECTION
-#define SELECT_SECTION(DECL, RELOC)					\
+#define SELECT_SECTION(DECL, RELOC, ALIGN)				\
 {									\
   if (TREE_CODE (DECL) == STRING_CST)					\
     {									\
@@ -111,7 +111,7 @@ rdata_section ()						\
    in the case of a `const_int' rtx.  Currently, these always
    go into the const section.  */
 #undef  SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(MODE, RTX) rdata_section ()
+#define SELECT_RTX_SECTION(MODE, RTX, ALIGN) rdata_section ()
 
 #define MCORE_EXPORT_NAME(STREAM, NAME)			\
   do							\
diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
index 81f675cd06a..fb54bcd605d 100644
--- a/gcc/config/mips/mips.h
+++ b/gcc/config/mips/mips.h
@@ -4477,10 +4477,12 @@ rdata_section ()							\
    and select that section.  */
 
 #undef SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(MODE,RTX)	mips_select_rtx_section (MODE, RTX)
+#define SELECT_RTX_SECTION(MODE, RTX, ALIGN) \
+  mips_select_rtx_section (MODE, RTX)
 
 #undef SELECT_SECTION
-#define SELECT_SECTION(DECL, RELOC)	mips_select_section (DECL, RELOC)
+#define SELECT_SECTION(DECL, RELOC, ALIGN) \
+  mips_select_section (DECL, RELOC)
 
 
 /* Store in OUTPUT a string (made with alloca) containing
diff --git a/gcc/config/nextstep.h b/gcc/config/nextstep.h
index 7bb96814634..956b9e27d42 100644
--- a/gcc/config/nextstep.h
+++ b/gcc/config/nextstep.h
@@ -445,7 +445,7 @@ objc_section_init ()				\
 #define READONLY_DATA_SECTION const_section
 
 #undef	SELECT_SECTION
-#define SELECT_SECTION(exp,reloc)				\
+#define SELECT_SECTION(exp,reloc,align)				\
   do								\
     {								\
       if (TREE_CODE (exp) == STRING_CST)			\
@@ -563,7 +563,7 @@ objc_section_init ()				\
   while (0)
 
 #undef	SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(mode, rtx)					\
+#define SELECT_RTX_SECTION(mode, rtx, align)				\
   do									\
     {									\
       if (GET_MODE_SIZE(mode) == 8)					\
diff --git a/gcc/config/pa/pa-linux.h b/gcc/config/pa/pa-linux.h
index baa1cf5b4a5..f290802bf34 100644
--- a/gcc/config/pa/pa-linux.h
+++ b/gcc/config/pa/pa-linux.h
@@ -55,7 +55,7 @@ Boston, MA 02111-1307, USA.  */
 
 /* Put plabels into the data section so we can relocate them.  */
 #undef SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(MODE,RTX)	\
+#define SELECT_RTX_SECTION(MODE,RTX,ALIGN)	\
   if (flag_pic && function_label_operand (RTX, MODE))	\
     data_section ();					\
   else							\
diff --git a/gcc/config/pa/pa.h b/gcc/config/pa/pa.h
index 4385914347d..fa892f1421b 100644
--- a/gcc/config/pa/pa.h
+++ b/gcc/config/pa/pa.h
@@ -1403,7 +1403,7 @@ do { 									\
    library.  Since we can't know at compile time if a symbol will be
    satisfied by a shared library or main program we put any symbolic
    constant into the normal data section.  */
-#define SELECT_RTX_SECTION(MODE,RTX)	\
+#define SELECT_RTX_SECTION(MODE,RTX,ALIGN)	\
   if (symbolic_operand (RTX, MODE))	\
     data_section ();			\
   else					\
@@ -1413,7 +1413,7 @@ do { 									\
    in the read-only data section to a symbol defined in a shared
    library.  Therefore, expressions that might require a reloc can
    not be placed in the read-only data section.  */
-#define SELECT_SECTION(EXP,RELOC) \
+#define SELECT_SECTION(EXP,RELOC,ALIGN) \
   if (TREE_CODE (EXP) == VAR_DECL \
       && TREE_READONLY (EXP) \
       && !TREE_THIS_VOLATILE (EXP) \
diff --git a/gcc/config/romp/romp.h b/gcc/config/romp/romp.h
index 4f920cc574d..2e517a19cb5 100644
--- a/gcc/config/romp/romp.h
+++ b/gcc/config/romp/romp.h
@@ -717,7 +717,7 @@ struct rt_cargs {int gregs, fregs; };
 
    On ROMP, all constants are in the data area.  */
 
-#define SELECT_RTX_SECTION(MODE, X)	data_section ()
+#define SELECT_RTX_SECTION(MODE, X, ALIGN)	data_section ()
 
 /* Output assembler code to FILE to increment profiler label # LABELNO
    for profiling a function entry.  */
diff --git a/gcc/config/rs6000/sysv4.h b/gcc/config/rs6000/sysv4.h
index b8158ccf15b..1b2051d82c4 100644
--- a/gcc/config/rs6000/sysv4.h
+++ b/gcc/config/rs6000/sysv4.h
@@ -566,7 +566,7 @@ fini_section ()								\
 
 /* Override elfos.h definition.  */
 #undef	SELECT_RTX_SECTION
-#define	SELECT_RTX_SECTION(MODE, X) rs6000_select_rtx_section (MODE, X)
+#define	SELECT_RTX_SECTION(MODE, X, ALIGN) rs6000_select_rtx_section (MODE, X)
 
 /* A C statement or statements to switch to the appropriate
    section for output of DECL.  DECL is either a `VAR_DECL' node
@@ -575,7 +575,7 @@ fini_section ()								\
 
 /* Override elfos.h definition.  */
 #undef	SELECT_SECTION
-#define	SELECT_SECTION(DECL, RELOC) rs6000_select_section (DECL, RELOC)
+#define	SELECT_SECTION(DECL, RELOC, ALIGN) rs6000_select_section (DECL, RELOC)
 
 /* A C statement to build up a unique section name, expressed as a
    STRING_CST node, and assign it to DECL_SECTION_NAME (decl).
diff --git a/gcc/config/rs6000/xcoff.h b/gcc/config/rs6000/xcoff.h
index c120e643c94..fbb74360bad 100644
--- a/gcc/config/rs6000/xcoff.h
+++ b/gcc/config/rs6000/xcoff.h
@@ -144,7 +144,7 @@ toc_section ()						\
    On the RS/6000, we have a special section for all variables except those
    that are static.  */
 
-#define SELECT_SECTION(EXP,RELOC)			\
+#define SELECT_SECTION(EXP,RELOC,ALIGN)			\
 {							\
   if ((TREE_CODE (EXP) == STRING_CST			\
        && ! flag_writable_strings)			\
@@ -199,7 +199,7 @@ toc_section ()						\
    However, if this is being placed in the TOC it must be output as a
    toc entry.  */
 
-#define SELECT_RTX_SECTION(MODE, X)			\
+#define SELECT_RTX_SECTION(MODE, X, ALIGN)		\
 { if (ASM_OUTPUT_SPECIAL_POOL_ENTRY_P (X, MODE))	\
     toc_section ();					\
   else							\
diff --git a/gcc/config/s390/linux.h b/gcc/config/s390/linux.h
index 31b657ce78d..efe13777623 100644
--- a/gcc/config/s390/linux.h
+++ b/gcc/config/s390/linux.h
@@ -295,7 +295,7 @@ do {                                                                    \
  */
 
 #undef SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(MODE, X)
+#define SELECT_RTX_SECTION(MODE, X, ALIGN)
 
 
 /* Output code to add DELTA to the first argument, and then jump to FUNCTION.
diff --git a/gcc/config/sparc/sparc.c b/gcc/config/sparc/sparc.c
index 9f51d989e5c..91deb4903d2 100644
--- a/gcc/config/sparc/sparc.c
+++ b/gcc/config/sparc/sparc.c
@@ -8765,6 +8765,14 @@ sparc_elf_asm_named_section (name, flags)
      const char *name;
      unsigned int flags;
 {
+  if (flags & SECTION_MERGE)
+    {
+      /* entsize cannot be expressed in this section attributes
+	 encoding style.  */
+      default_elf_asm_named_section (name, flags);
+      return;
+    }
+
   fprintf (asm_out_file, "\t.section\t\"%s\"", name);
 
   if (!(flags & SECTION_DEBUG))
diff --git a/gcc/config/sparc/sparc.h b/gcc/config/sparc/sparc.h
index 1b7ce2721c9..629286ed912 100644
--- a/gcc/config/sparc/sparc.h
+++ b/gcc/config/sparc/sparc.h
@@ -912,7 +912,7 @@ if (TARGET_ARCH64				\
 #endif
 
 /* This is defined differently for v9 in a cover file.  */
-#define SELECT_SECTION(T,RELOC)						\
+#define SELECT_SECTION(T,RELOC,ALIGN)					\
 {									\
   if (TREE_CODE (T) == VAR_DECL)					\
     {									\
@@ -945,7 +945,7 @@ if (TARGET_ARCH64				\
 /* Use text section for a constant
    unless we need more alignment than that offers.  */
 /* This is defined differently for v9 in a cover file.  */
-#define SELECT_RTX_SECTION(MODE, X)		\
+#define SELECT_RTX_SECTION(MODE, X, ALIGN)	\
 {						\
   if (GET_MODE_BITSIZE (MODE) <= MAX_TEXT_ALIGN \
       && ! (flag_pic && (symbolic_operand ((X), (MODE)) || SUNOS4_SHARED_LIBRARIES)))  \
diff --git a/gcc/config/sparc/sysv4.h b/gcc/config/sparc/sysv4.h
index 4cd0b396ca7..d9c0be7e208 100644
--- a/gcc/config/sparc/sysv4.h
+++ b/gcc/config/sparc/sysv4.h
@@ -79,7 +79,7 @@ Boston, MA 02111-1307, USA.  */
 
 /* Must use data section for relocatable constants when pic.  */
 #undef SELECT_RTX_SECTION
-#define SELECT_RTX_SECTION(MODE,RTX)		\
+#define SELECT_RTX_SECTION(MODE,RTX,ALIGN)	\
 {						\
   if (flag_pic && symbolic_operand ((RTX), (MODE))) \
     data_section ();				\
diff --git a/gcc/config/stormy16/stormy16.h b/gcc/config/stormy16/stormy16.h
index 8f2ee8094be..2258819306c 100644
--- a/gcc/config/stormy16/stormy16.h
+++ b/gcc/config/stormy16/stormy16.h
@@ -3470,7 +3470,7 @@ do {							\
    the read-only data section (usually the text section).
 
    Defined in svr4.h.  */
-/* #define SELECT_SECTION(EXP, RELOC) */
+/* #define SELECT_SECTION(EXP, RELOC, ALIGN) */
 
 /* A C statement or statements to switch to the appropriate section for output
    of RTX in mode MODE.  You can assume that RTX is some kind of constant in
@@ -3482,7 +3482,7 @@ do {							\
    section.
 
    Defined in svr4.h.  */
-/* #define SELECT_RTX_SECTION(MODE, RTX) */
+/* #define SELECT_RTX_SECTION(MODE, RTX, ALIGN) */
 
 /* Define this macro if jump tables (for `tablejump' insns) should be output in
    the text section, along with the assembler instructions.  Otherwise, the
diff --git a/gcc/config/svr3.h b/gcc/config/svr3.h
index 6f26fde8cd5..57f3ee333ed 100644
--- a/gcc/config/svr3.h
+++ b/gcc/config/svr3.h
@@ -301,7 +301,7 @@ const_section ()							\
    or a constant of some sort.  RELOC indicates whether forming
    the initial value of DECL requires link-time relocations.  */
 
-#define SELECT_SECTION(DECL,RELOC)					\
+#define SELECT_SECTION(DECL,RELOC,ALIGN)				\
 {									\
   if (TREE_CODE (DECL) == STRING_CST)					\
     {									\
@@ -331,4 +331,4 @@ const_section ()							\
    in the case of a `const_int' rtx.  Currently, these always
    go into the const section.  */
 
-#define SELECT_RTX_SECTION(MODE,RTX) const_section()
+#define SELECT_RTX_SECTION(MODE,RTX,ALIGN) const_section()
diff --git a/gcc/config/v850/v850.h b/gcc/config/v850/v850.h
index 5baef15e847..b077f6d72d9 100644
--- a/gcc/config/v850/v850.h
+++ b/gcc/config/v850/v850.h
@@ -1164,7 +1164,7 @@ zbss_section ()								\
    Do not define this macro if you put all read-only variables and
    constants in the read-only data section (usually the text section).  */
 #undef  SELECT_SECTION
-#define SELECT_SECTION(EXP, RELOC)					\
+#define SELECT_SECTION(EXP, RELOC, ALIGN)				\
 do {									\
   if (TREE_CODE (EXP) == VAR_DECL)					\
     {									\
@@ -1227,7 +1227,7 @@ do {									\
 
    Do not define this macro if you put all constants in the read-only
    data section.  */
-/* #define SELECT_RTX_SECTION(MODE, RTX) */
+/* #define SELECT_RTX_SECTION(MODE, RTX, ALIGN) */
 
 /* Output at beginning/end of assembler file.  */
 #undef ASM_FILE_START
diff --git a/gcc/config/vax/vms.h b/gcc/config/vax/vms.h
index 52f4d2750e3..133d1c3ba1a 100644
--- a/gcc/config/vax/vms.h
+++ b/gcc/config/vax/vms.h
@@ -218,7 +218,7 @@ const_section ()					\
    Since this macro is used in a number of places, we must also be able
    to decide where to place string constants.  */
 
-#define SELECT_SECTION(T,RELOC)						\
+#define SELECT_SECTION(T,RELOC,ALIGN)					\
 {									\
   if (TREE_CODE (T) == VAR_DECL)					\
     {									\
diff --git a/gcc/configure b/gcc/configure
index 640e5c2e8f9..169ba2cbb28 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -7164,6 +7164,29 @@ EOF
 fi
 echo "$ac_t""$gcc_cv_as_eh_frame" 1>&6
 
+echo $ac_n "checking assembler section merging support""... $ac_c" 1>&6
+echo "configure:6569: checking assembler section merging support" >&5
+gcc_cv_as_shf_merge=no
+if test x$gcc_cv_gas_major_version != x -a x$gcc_cv_gas_minor_version != x; then
+  if test "$gcc_cv_gas_major_version" -eq 2 -a "$gcc_cv_gas_minor_version" -ge 12 -o "$gcc_cv_gas_major_version" -gt 2 && grep 'obj_format = elf' ../gas/Makefile > /dev/null; then
+    gcc_cv_as_subsections="working SHF_MERGE support"
+  fi
+elif test x$gcc_cv_as != x; then
+	# Check if we support SHF_MERGE sections
+	echo '.section .rodata.str, "aMS", @progbits, 1' > conftest.s
+	if $gcc_cv_as -o conftest.o conftest.s > /dev/null 2>&1; then
+		gcc_cv_as_shf_merge=yes
+	fi
+	rm -f conftest.s conftest.o
+fi
+if test x"$gcc_cv_as_shf_merge" = xyes; then
+	cat >> confdefs.h <<\EOF
+#define HAVE_GAS_SHF_MERGE 1
+EOF
+
+fi
+echo "$ac_t""$gcc_cv_as_shf_merge" 1>&6
+
 case "$target" in 
   sparc*-*-*)
     echo $ac_n "checking assembler .register pseudo-op support""... $ac_c" 1>&6
diff --git a/gcc/configure.in b/gcc/configure.in
index f69250efd01..01a927e76a0 100644
--- a/gcc/configure.in
+++ b/gcc/configure.in
@@ -1484,6 +1484,26 @@ EOF
 fi
 AC_MSG_RESULT($gcc_cv_as_eh_frame)
 
+AC_MSG_CHECKING(assembler section merging support)
+gcc_cv_as_shf_merge=no
+if test x$gcc_cv_gas_major_version != x -a x$gcc_cv_gas_minor_version != x; then
+  if test "$gcc_cv_gas_major_version" -eq 2 -a "$gcc_cv_gas_minor_version" -ge 12 -o "$gcc_cv_gas_major_version" -gt 2 && grep 'obj_format = elf' ../gas/Makefile > /dev/null; then
+    gcc_cv_as_subsections="working SHF_MERGE support"
+  fi
+elif test x$gcc_cv_as != x; then
+	# Check if we support SHF_MERGE sections
+	echo '.section .rodata.str, "aMS", @progbits, 1' > conftest.s
+	if $gcc_cv_as -o conftest.o conftest.s > /dev/null 2>&1; then
+		gcc_cv_as_shf_merge=yes
+	fi
+	rm -f conftest.s conftest.o
+fi
+if test x"$gcc_cv_as_shf_merge" = xyes; then
+	AC_DEFINE(HAVE_GAS_SHF_MERGE, 1,
+[Define if your assembler supports marking sections with SHF_MERGE flag.])
+fi
+AC_MSG_RESULT($gcc_cv_as_shf_merge)
+
 case "$target" in 
   sparc*-*-*)
     AC_CACHE_CHECK([assembler .register pseudo-op support],
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 7991e8b42d6..d2b2afc8a80 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -262,8 +262,8 @@ in the following sections.
 -fforce-addr  -fforce-mem  -ffunction-sections @gol
 -fgcse  -fgcse-lm  -fgcse-sm @gol
 -finline-functions  -finline-limit=@var{n}  -fkeep-inline-functions @gol
--fkeep-static-consts  -fmove-all-movables @gol
--fno-default-inline  -fno-defer-pop @gol
+-fkeep-static-consts  -fmerge-constants  -fmerge-all-constants @gol
+-fmove-all-movables  -fno-default-inline  -fno-defer-pop @gol
 -fno-function-cse  -fno-guess-branch-probability @gol
 -fno-inline  -fno-math-errno  -fno-peephole  -fno-peephole2 @gol
 -funsafe-math-optimizations -fno-trapping-math @gol
@@ -3321,6 +3321,23 @@ GCC enables this option by default.  If you want to force the compiler to
 check if the variable was referenced, regardless of whether or not
 optimization is turned on, use the @option{-fno-keep-static-consts} option.
 
+@item -fmerge-constants
+Attempt to merge identical constants (string constants and floating point
+constants) accross compilation units.
+
+This option is default for optimized compilation if assembler and linker
+support it.  Use @option{-fno-merge-constants} to inhibit this behaviour.
+
+@item -fmerge-all-constants
+Attempt to merge identical constants and identical variables.
+
+This option implies @option{-fmerge-constants}.  In addition to
+@option{-fmerge-constants} this considers e.g. even constant initialized
+arrays or initialized constant variables with integral or floating point
+types.  Languages like C or C++ require each non-automatic variable to
+have distinct location, so using this option will result in non-conforming
+behaviour.
+
 @item -fno-function-cse
 @opindex fno-function-cse
 Do not put function addresses in registers; make each instruction that
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 80e8e75209d..edc2f3c342d 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -5650,25 +5650,26 @@ If these items should be placed in the text section, this macro should
 not be defined.
 
 @findex SELECT_SECTION
-@item SELECT_SECTION (@var{exp}, @var{reloc})
+@item SELECT_SECTION (@var{exp}, @var{reloc}, @var{align})
 A C statement or statements to switch to the appropriate section for
 output of @var{exp}.  You can assume that @var{exp} is either a
 @code{VAR_DECL} node or a constant of some sort.  @var{reloc}
 indicates whether the initial value of @var{exp} requires link-time
 relocations.  Select the section by calling @code{text_section} or one
-of the alternatives for other sections.
+of the alternatives for other sections.  @var{align} is the constant
+alignment in bits.
 
 Do not define this macro if you put all read-only variables and
 constants in the read-only data section (usually the text section).
 
 @findex SELECT_RTX_SECTION
-@item SELECT_RTX_SECTION (@var{mode}, @var{rtx})
+@item SELECT_RTX_SECTION (@var{mode}, @var{rtx}, @var{align})
 A C statement or statements to switch to the appropriate section for
 output of @var{rtx} in mode @var{mode}.  You can assume that @var{rtx}
 is some kind of constant in RTL@.  The argument @var{mode} is redundant
 except in the case of a @code{const_int} rtx.  Select the section by
 calling @code{text_section} or one of the alternatives for other
-sections.
+sections.  @var{align} is the constant alignment in bits.
 
 Do not define this macro if you put all constants in the read-only
 data section.
diff --git a/gcc/f/ChangeLog b/gcc/f/ChangeLog
index f33425ac4cb..04046af693b 100644
--- a/gcc/f/ChangeLog
+++ b/gcc/f/ChangeLog
@@ -1,3 +1,8 @@
+2001-09-11  Jakub Jelinek  <jakub@redhat.com>
+
+	* com.c (ffe_init_options): Default to -fmerge-all-constants
+	if optimizing.
+
 2000-08-14  Ulrich Weigand  <uweigand@de.ibm.com>
 
 	* target.h (FFETARGET_32bit_longs): Don't define
diff --git a/gcc/f/com.c b/gcc/f/com.c
index 5b4388f7997..137b72fa9ac 100644
--- a/gcc/f/com.c
+++ b/gcc/f/com.c
@@ -14657,6 +14657,7 @@ ffe_init_options ()
   flag_move_all_movables = 1;
   flag_reduce_all_givs = 1;
   flag_argument_noalias = 2;
+  flag_merge_constants = 2;
   flag_errno_math = 0;
   flag_complex_divide_method = 1;
 }
diff --git a/gcc/flags.h b/gcc/flags.h
index 89188c0283a..bd29cea1cde 100644
--- a/gcc/flags.h
+++ b/gcc/flags.h
@@ -544,6 +544,11 @@ extern int flag_bounded_pointers;
    For CHILL: defaults to off.  */
 extern int flag_bounds_check;
 
+/* This will attempt to merge constant section constants, if 1 only
+   string constants and constants from constant pool, if 2 also constant
+   variables.  */
+extern int flag_merge_constants;
+
 /* If one, renumber instruction UIDs to reduce the number of
    unused UIDs if there are a lot of instructions.  If greater than
    one, unconditionally renumber instruction UIDs.  */
diff --git a/gcc/output.h b/gcc/output.h
index 2edfb050794..f1722f146b6 100644
--- a/gcc/output.h
+++ b/gcc/output.h
@@ -207,6 +207,15 @@ extern void function_section		PARAMS ((tree));
 /* Tell assembler to switch to the section for the exception table.  */
 extern void exception_section		PARAMS ((void));
 
+/* Tell assembler to switch to the section for string merging.  */
+extern void mergeable_string_section	PARAMS ((tree, unsigned HOST_WIDE_INT,
+						 unsigned int));
+
+/* Tell assembler to switch to the section for constant merging.  */
+extern void mergeable_constant_section	PARAMS ((enum machine_mode,
+						 unsigned HOST_WIDE_INT,
+						 unsigned int));
+
 /* Declare DECL to be a weak symbol.  */
 extern void declare_weak		PARAMS ((tree));
 #endif /* TREE_CODE */
@@ -450,14 +459,18 @@ extern void default_function_pro_epilogue PARAMS ((FILE *, HOST_WIDE_INT));
 extern void no_asm_to_stream PARAMS ((FILE *));
 
 /* Flags controling properties of a section.  */
-#define SECTION_CODE	    1	/* contains code */
-#define SECTION_WRITE	    2	/* data is writable */
-#define SECTION_DEBUG	    4	/* contains debug data */
-#define SECTION_LINKONCE    8	/* is linkonce */
-#define SECTION_SMALL	   16	/* contains "small data" */
-#define SECTION_BSS	   32	/* contains zeros only */
-#define SECTION_FORGET	   64	/* forget that we've entered the section */
-#define SECTION_MACH_DEP  128	/* subsequent bits reserved for target */
+#define SECTION_ENTSIZE	 0x000ff	/* entity size in section */
+#define SECTION_CODE	 0x00100	/* contains code */
+#define SECTION_WRITE	 0x00200	/* data is writable */
+#define SECTION_DEBUG	 0x00400	/* contains debug data */
+#define SECTION_LINKONCE 0x00800	/* is linkonce */
+#define SECTION_SMALL	 0x01000	/* contains "small data" */
+#define SECTION_BSS	 0x02000	/* contains zeros only */
+#define SECTION_FORGET	 0x04000	/* forget that we've entered the section */
+#define SECTION_MERGE	 0x08000	/* contains mergeable data */
+#define SECTION_STRINGS  0x10000	/* contains zero terminated strings without
+					   embedded zeros */
+#define SECTION_MACH_DEP 0x20000	/* subsequent bits reserved for target */
 
 extern unsigned int get_named_section_flags PARAMS ((const char *));
 extern bool set_named_section_flags	PARAMS ((const char *, unsigned int));
diff --git a/gcc/toplev.c b/gcc/toplev.c
index 087a13a2cd8..925f06b3cde 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -898,6 +898,11 @@ int flag_bounded_pointers = 0;
    For CHILL: defaults to off.  */
 int flag_bounds_check = 0;
 
+/* This will attempt to merge constant section constants, if 1 only
+   string constants and constants from constant pool, if 2 also constant
+   variables.  */
+int flag_merge_constants = 1;
+
 /* If one, renumber instruction UIDs to reduce the number of
    unused UIDs if there are a lot of instructions.  If greater than
    one, unconditionally renumber instruction UIDs.  */
@@ -1139,6 +1144,10 @@ lang_independent_options f_options[] =
    N_("Align all labels") },
   {"align-functions", &align_functions, 0,
    N_("Align the start of functions") },
+  {"merge-constants", &flag_merge_constants, 1,
+   N_("Attempt to merge identical constants accross compilation units") },
+  {"merge-all-constants", &flag_merge_constants, 2,
+   N_("Attempt to merge identical constants and constant variables") },
   {"check-memory-usage", &flag_check_memory_usage, 1,
    N_("Generate code to check every memory access") },
   {"prefix-function-name", &flag_prefix_function_name, 1,
@@ -4680,6 +4689,11 @@ toplev_main (argc, argv)
 	}
     }
 
+  if (!optimize)
+    {
+      flag_merge_constants = 0;
+    }
+
   if (optimize >= 1)
     {
       flag_defer_pop = 1;
diff --git a/gcc/varasm.c b/gcc/varasm.c
index a95994ca237..defa0c6a4d8 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -560,7 +560,7 @@ variable_section (decl, reloc)
 	 for them.  */
 
 #ifdef SELECT_SECTION
-      SELECT_SECTION (decl, reloc);
+      SELECT_SECTION (decl, reloc, DECL_ALIGN (decl));
 #else
       if (DECL_READONLY_SECTION (decl, reloc))
 	readonly_data_section ();
@@ -587,6 +587,111 @@ exception_section ()
     readonly_data_section ();
 #endif
 }
+
+/* Tell assembler to switch to the section for string merging.  */
+
+void
+mergeable_string_section (decl, align, flags)
+  tree decl ATTRIBUTE_UNUSED;
+  unsigned HOST_WIDE_INT align ATTRIBUTE_UNUSED;
+  unsigned int flags ATTRIBUTE_UNUSED;
+{
+#ifdef HAVE_GAS_SHF_MERGE
+  if (flag_merge_constants
+      && TREE_CODE (decl) == STRING_CST
+      && TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE
+      && align <= 256
+      && TREE_STRING_LENGTH (decl) >= int_size_in_bytes (TREE_TYPE (decl)))
+    {
+      enum machine_mode mode;
+      unsigned int modesize;
+      const char *str;
+      int i, j, len, unit;
+      char name[30];
+
+      mode = TYPE_MODE (TREE_TYPE (TREE_TYPE (decl)));
+      modesize = GET_MODE_BITSIZE (mode);
+      if (modesize >= 8 && modesize <= 256
+	  && (modesize & (modesize - 1)) == 0)
+	{
+	  if (align < modesize)
+	    align = modesize;
+
+	  str = TREE_STRING_POINTER (decl);
+	  len = TREE_STRING_LENGTH (decl);
+	  unit = GET_MODE_SIZE (mode);
+
+	  /* Check for embedded NUL characters.  */
+	  for (i = 0; i < len; i += unit)
+	    {
+	      for (j = 0; j < unit; j++)
+		if (str [i + j] != '\0')
+		  break;
+	      if (j == unit)
+		break;
+	    }
+	  if (i == len - unit)
+	    {
+	      sprintf (name, ".rodata.str%d.%d", modesize / 8,
+		       (int) (align / 8));
+	      flags |= (modesize / 8) | SECTION_MERGE | SECTION_STRINGS;
+	      if (!i && modesize < align)
+		{
+		  /* A "" string with requested alignment greater than
+		     character size might cause a problem:
+		     if some other string required even bigger
+		     alignment than "", then linker might think the
+		     "" is just part of padding after some other string
+		     and not put it into the hash table initially.
+		     But this means "" could have smaller alignment
+		     than requested.  */
+#ifdef ASM_OUTPUT_SECTION_START
+		  named_section_flags (name, flags);
+		  ASM_OUTPUT_SECTION_START (asm_out_file);
+#else
+		  readonly_data_section ();
+#endif
+		  return;
+		}
+
+	      named_section_flags (name, flags);
+	      return;
+	    }
+	}
+    }
+#endif
+  readonly_data_section ();
+}  
+
+/* Tell assembler to switch to the section for constant merging.  */
+
+void
+mergeable_constant_section (mode, align, flags)
+  enum machine_mode mode ATTRIBUTE_UNUSED;
+  unsigned HOST_WIDE_INT align ATTRIBUTE_UNUSED;
+  unsigned int flags ATTRIBUTE_UNUSED;
+{
+#ifdef HAVE_GAS_SHF_MERGE
+  unsigned int modesize = GET_MODE_BITSIZE (mode);
+
+  if (flag_merge_constants
+      && mode != VOIDmode
+      && mode != BLKmode
+      && modesize <= align
+      && align >= 8
+      && align <= 256
+      && (align & (align - 1)) == 0)
+    {
+      char name[24];
+
+      sprintf (name, ".rodata.cst%d", (int) (align / 8));
+      flags |= (align / 8) | SECTION_MERGE;
+      named_section_flags (name, flags);
+      return;
+    }            
+#endif
+  readonly_data_section ();
+}
 
 /* Given NAME, a putative register name, discard any customary prefixes.  */
 
@@ -3305,13 +3410,19 @@ output_constant_def_contents (exp, reloc, labelno)
 {
   int align;
 
+  /* Align the location counter as required by EXP's data type.  */
+  align = TYPE_ALIGN (TREE_TYPE (exp));
+#ifdef CONSTANT_ALIGNMENT
+  align = CONSTANT_ALIGNMENT (exp, align);
+#endif
+
   if (IN_NAMED_SECTION (exp))
     named_section (exp, NULL, reloc);
   else
     {
       /* First switch to text section, except for writable strings.  */
 #ifdef SELECT_SECTION
-      SELECT_SECTION (exp, reloc);
+      SELECT_SECTION (exp, reloc, align);
 #else
       if (((TREE_CODE (exp) == STRING_CST) && flag_writable_strings)
 	  || (flag_pic && reloc))
@@ -3321,12 +3432,6 @@ output_constant_def_contents (exp, reloc, labelno)
 #endif
     }
 
-  /* Align the location counter as required by EXP's data type.  */
-  align = TYPE_ALIGN (TREE_TYPE (exp));
-#ifdef CONSTANT_ALIGNMENT
-  align = CONSTANT_ALIGNMENT (exp, align);
-#endif
-
   if (align > BITS_PER_UNIT)
     ASM_OUTPUT_ALIGN (asm_out_file, floor_log2 (align / BITS_PER_UNIT));
 
@@ -3877,7 +3982,7 @@ output_constant_pool (fnname, fndecl)
 
       /* First switch to correct section.  */
 #ifdef SELECT_RTX_SECTION
-      SELECT_RTX_SECTION (pool->mode, x);
+      SELECT_RTX_SECTION (pool->mode, x, pool->align);
 #else
       readonly_data_section ();
 #endif
@@ -5060,7 +5165,7 @@ default_elf_asm_named_section (name, flags)
      const char *name;
      unsigned int flags;
 {
-  char flagchars[8], *f = flagchars;
+  char flagchars[10], *f = flagchars;
   const char *type;
 
   if (!(flags & SECTION_DEBUG))
@@ -5071,6 +5176,10 @@ default_elf_asm_named_section (name, flags)
     *f++ = 'x';
   if (flags & SECTION_SMALL)
     *f++ = 's';
+  if (flags & SECTION_MERGE)
+    *f++ = 'M';
+  if (flags & SECTION_STRINGS)
+    *f++ = 'S';
   *f = '\0';
 
   if (flags & SECTION_BSS)
@@ -5078,8 +5187,12 @@ default_elf_asm_named_section (name, flags)
   else
     type = "progbits";
 
-  fprintf (asm_out_file, "\t.section\t%s,\"%s\",@%s\n",
-	   name, flagchars, type);
+  if (flags & SECTION_ENTSIZE)
+    fprintf (asm_out_file, "\t.section\t%s,\"%s\",@%s,%d\n",
+	     name, flagchars, type, flags & SECTION_ENTSIZE);
+  else
+    fprintf (asm_out_file, "\t.section\t%s,\"%s\",@%s\n",
+	     name, flagchars, type);
 }
 
 void