[build] Support COMDAT group with Sun as (PR target/40483), final version

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -8768,6 +8768,10 @@  ix86_code_end (void)
   rtx xops[2];
   int regno;
 
+#ifdef TARGET_SOLARIS
+  solaris_code_end ();
+#endif
+
   for (regno = AX_REG; regno <= SP_REG; regno++)
     {
       char name[32];
@@ -32148,9 +32152,10 @@  void ix86_emit_swsqrtsf (rtx res, rtx a,
 			  gen_rtx_MULT (mode, e2, e3)));
 }
 
+#ifdef TARGET_SOLARIS
 /* Solaris implementation of TARGET_ASM_NAMED_SECTION.  */
 
-static void ATTRIBUTE_UNUSED
+static void
 i386_solaris_elf_named_section (const char *name, unsigned int flags,
 				tree decl)
 {
@@ -32164,8 +32169,18 @@  i386_solaris_elf_named_section (const ch
 	       flags & SECTION_WRITE ? "aw" : "a");
       return;
     }
+
+#ifndef USE_GAS
+  if (HAVE_COMDAT_GROUP && flags & SECTION_LINKONCE)
+    {
+      solaris_elf_asm_comdat_section (name, flags, decl);
+      return;
+    }
+#endif
+
   default_elf_asm_named_section (name, flags, decl);
 }
+#endif /* TARGET_SOLARIS */
 
 /* Return the mangling of TYPE if it is an extended fundamental type.  */
 
diff --git a/gcc/config/i386/sol2-10.h b/gcc/config/i386/sol2-10.h
--- a/gcc/config/i386/sol2-10.h
+++ b/gcc/config/i386/sol2-10.h
@@ -133,6 +133,3 @@  along with GCC; see the file COPYING3.  
 
 /* We do not need to search a special directory for startup files.  */
 #undef MD_STARTFILE_PREFIX
-
-#undef TARGET_ASM_NAMED_SECTION
-#define TARGET_ASM_NAMED_SECTION i386_solaris_elf_named_section
diff --git a/gcc/config/i386/sol2.h b/gcc/config/i386/sol2.h
--- a/gcc/config/i386/sol2.h
+++ b/gcc/config/i386/sol2.h
@@ -154,6 +154,9 @@  along with GCC; see the file COPYING3.  
     }								\
   while (0)
 
+#undef TARGET_ASM_NAMED_SECTION
+#define TARGET_ASM_NAMED_SECTION i386_solaris_elf_named_section
+
 /* We do not need NT_VERSION notes.  */
 #undef X86_FILE_START_VERSION_DIRECTIVE
 #define X86_FILE_START_VERSION_DIRECTIVE false
diff --git a/gcc/config/sol2-protos.h b/gcc/config/sol2-protos.h
--- a/gcc/config/sol2-protos.h
+++ b/gcc/config/sol2-protos.h
@@ -22,3 +22,5 @@  extern void solaris_insert_attributes (t
 extern void solaris_register_pragmas (void);
 extern void solaris_output_init_fini (FILE *, tree);
 extern void solaris_assemble_visibility (tree, int);
+extern void solaris_elf_asm_comdat_section (const char *, unsigned int, tree);
+extern void solaris_code_end (void);
diff --git a/gcc/config/sol2.c b/gcc/config/sol2.c
--- a/gcc/config/sol2.c
+++ b/gcc/config/sol2.c
@@ -29,6 +29,7 @@  along with GCC; see the file COPYING3.  
 #include "tm_p.h"
 #include "diagnostic-core.h"
 #include "ggc.h"
+#include "hashtab.h"
 
 tree solaris_pending_aligns, solaris_pending_inits, solaris_pending_finis;
 
@@ -106,14 +107,14 @@  solaris_output_init_fini (FILE *file, tr
 {
   if (lookup_attribute ("init", DECL_ATTRIBUTES (decl)))
     {
-      fprintf (file, PUSHSECTION_FORMAT, ".init");
+      fprintf (file, "\t.pushsection\t" SECTION_NAME_FORMAT "\n", ".init");
       ASM_OUTPUT_CALL (file, decl);
       fprintf (file, "\t.popsection\n");
     }
 
   if (lookup_attribute ("fini", DECL_ATTRIBUTES (decl)))
     {
-      fprintf (file, PUSHSECTION_FORMAT, ".fini");
+      fprintf (file, "\t.pushsection\t" SECTION_NAME_FORMAT "\n", ".fini");
       ASM_OUTPUT_CALL (file, decl);
       fprintf (file, "\t.popsection\n");
     }
@@ -155,3 +156,129 @@  solaris_assemble_visibility (tree decl A
 	   "in this configuration; ignored");
 #endif
 }
+
+/* Hash table of group signature symbols.  */
+
+static htab_t solaris_comdat_htab;
+
+/* Group section information entry stored in solaris_comdat_htab.  */
+
+typedef struct comdat_entry
+{
+  const char *name;
+  unsigned int flags;
+  tree decl;
+  const char *sig;
+} comdat_entry;
+
+/* Helper routines for maintaining solaris_comdat_htab.  */
+
+static hashval_t
+comdat_hash (const void *p)
+{
+  const comdat_entry *entry = (const comdat_entry *) p;
+
+  return htab_hash_string (entry->sig);
+}
+
+static int
+comdat_eq (const void *p1, const void *p2)
+{
+  const comdat_entry *entry1 = (const comdat_entry *) p1;
+  const comdat_entry *entry2 = (const comdat_entry *) p2;
+
+  return strcmp (entry1->sig, entry2->sig) == 0;
+}
+
+/* Output assembly to switch to COMDAT group section NAME with attributes
+   FLAGS and group signature symbol DECL, using Sun as syntax.  */
+
+void
+solaris_elf_asm_comdat_section (const char *name, unsigned int flags, tree decl)
+{
+  const char *signature;
+  char *section;
+  comdat_entry entry, **slot;
+
+  if (TREE_CODE (decl) == IDENTIFIER_NODE)
+    signature = IDENTIFIER_POINTER (decl);
+  else
+    signature = IDENTIFIER_POINTER (DECL_COMDAT_GROUP (decl));
+
+  /* Sun as requires group sections to be fragmented, i.e. to have names of
+     the form <section>%<fragment>.  Strictly speaking this is only
+     necessary to support cc -xF, but is enforced globally in violation of
+     the ELF gABI.  We keep the section names generated by GCC (generally
+     of the form .text.<signature>) and append %<signature> to pacify as,
+     despite the redundancy.  */
+  section = concat (name, "%", signature, NULL);
+
+  /* Clear SECTION_LINKONCE flag so targetm.asm_out.named_section only
+     emits this as a regular section.  Emit section before .group
+     directive since Sun as treats undeclared sections as @progbits,
+     which conflicts with .bss* sections which are @nobits.  */
+  targetm.asm_out.named_section (section, flags & ~SECTION_LINKONCE, decl);
+  
+  /* Sun as separates declaration of a group section and of the group
+     itself, using the .group directive and the #comdat flag.  */
+  fprintf (asm_out_file, "\t.group\t%s," SECTION_NAME_FORMAT ",#comdat\n",
+	   signature, section);
+
+  /* Unlike GNU as, group signature symbols need to be defined explicitly
+     for Sun as.  With a few exceptions, this is already the case.  To
+     identify the missing ones without changing the affected frontents,
+     remember the signature symbols and emit those not marked
+     TREE_SYMBOL_REFERENCED in solaris_code_end.  */
+  if (solaris_comdat_htab == NULL)
+    solaris_comdat_htab = htab_create_alloc (37, comdat_hash, comdat_eq, NULL,
+					     xcalloc, free);
+
+  entry.sig = signature;
+  slot = (comdat_entry **) htab_find_slot (solaris_comdat_htab, &entry, INSERT);
+
+  if (*slot == NULL)
+    {
+      *slot = XCNEW (comdat_entry);
+      /* Remember fragmented section name.  */
+      (*slot)->name = section;
+      /* Emit as regular section, .group declaration has already been done.  */
+      (*slot)->flags = flags & ~SECTION_LINKONCE;
+      (*slot)->decl = decl;
+      (*slot)->sig = signature;
+    }
+}
+
+/* Define unreferenced COMDAT group signature symbol corresponding to SLOT.  */
+
+static int
+solaris_define_comdat_signature (void **slot, void *aux ATTRIBUTE_UNUSED)
+{
+  comdat_entry *entry = *(comdat_entry **) slot;
+  tree decl = entry->decl;
+
+  if (TREE_CODE (decl) != IDENTIFIER_NODE)
+    decl = DECL_COMDAT_GROUP (decl);
+
+  if (!TREE_SYMBOL_REFERENCED (decl))
+    {
+      /* Switch to group section, otherwise Sun as complains
+	 `Group Id symbol defined outside of group'.  */
+      switch_to_section (get_section (entry->name, entry->flags, entry->decl));
+
+      ASM_OUTPUT_LABEL (asm_out_file, entry->sig);
+    }
+
+  /* Continue with scan.  */
+  return 1;
+}
+
+/* Emit unreferenced COMDAT group signature symbols for Sun as.  */
+
+void
+solaris_code_end (void)
+{
+  if (solaris_comdat_htab == NULL)
+    return;
+
+  htab_traverse (solaris_comdat_htab, solaris_define_comdat_signature, NULL);
+}
diff --git a/gcc/config/sol2.h b/gcc/config/sol2.h
--- a/gcc/config/sol2.h
+++ b/gcc/config/sol2.h
@@ -19,6 +19,9 @@  You should have received a copy of the G
 along with GCC; see the file COPYING3.  If not see
 <http://www.gnu.org/licenses/>.  */
 
+/* We are compiling for Solaris 2 now.  */
+#define TARGET_SOLARIS 1
+
 /* We use stabs-in-elf for debugging, because that is what the native
    toolchain uses.  */
 #undef PREFERRED_DEBUGGING_TYPE
@@ -257,9 +260,8 @@  __enable_execute_stack (void *addr)					
   { "init",      0, 0, true,  false,  false, NULL, false },		\
   { "fini",      0, 0, true,  false,  false, NULL, false }
 
-/* Solaris/x86 as and gas support the common ELF .section/.pushsection
-   syntax.  */
-#define PUSHSECTION_FORMAT	"\t.pushsection\t%s\n"
+/* Solaris/x86 as and gas support unquoted section names.  */
+#define SECTION_NAME_FORMAT	"%s"
 
 /* This is how to declare the size of a function.  For Solaris, we output
    any .init or .fini entries here.  */
diff --git a/gcc/config/sparc/sol2.h b/gcc/config/sparc/sol2.h
--- a/gcc/config/sparc/sol2.h
+++ b/gcc/config/sparc/sol2.h
@@ -188,9 +188,16 @@  along with GCC; see the file COPYING3.  
 #undef TARGET_ASM_NAMED_SECTION
 #define TARGET_ASM_NAMED_SECTION sparc_solaris_elf_asm_named_section
 
-/* And SPARC non-standard pushsection syntax.  */
-#undef PUSHSECTION_FORMAT
-#define PUSHSECTION_FORMAT "\t.pushsection\t\"%s\"\n"
+/* Emit COMDAT group signature symbols for Sun as.  */
+#undef TARGET_ASM_CODE_END
+#define TARGET_ASM_CODE_END solaris_code_end
+
+/* Solaris/SPARC as requires doublequoted section names.  While gas
+   supports that, too, we prefer the standard variant.  */
+#ifndef USE_GAS
+#undef SECTION_NAME_FORMAT
+#define SECTION_NAME_FORMAT	"\"%s\""
+#endif
 
 /* Static stack checking is supported by means of probes.  */
 #define STACK_CHECK_STATIC_BUILTIN 1
diff --git a/gcc/config/sparc/sparc.c b/gcc/config/sparc/sparc.c
--- a/gcc/config/sparc/sparc.c
+++ b/gcc/config/sparc/sparc.c
@@ -8537,12 +8537,19 @@  sparc_profile_hook (int labelno)
     }
 }
 
+#ifdef TARGET_SOLARIS
 /* Solaris implementation of TARGET_ASM_NAMED_SECTION.  */
 
 static void
 sparc_solaris_elf_asm_named_section (const char *name, unsigned int flags,
 				     tree decl ATTRIBUTE_UNUSED)
 {
+  if (HAVE_COMDAT_GROUP && flags & SECTION_LINKONCE)
+    {
+      solaris_elf_asm_comdat_section (name, flags, decl);
+      return;
+    }
+
   fprintf (asm_out_file, "\t.section\t\"%s\"", name);
 
   if (!(flags & SECTION_DEBUG))
@@ -8558,6 +8565,7 @@  sparc_solaris_elf_asm_named_section (con
 
   fputc ('\n', asm_out_file);
 }
+#endif /* TARGET_SOLARIS */
 
 /* We do not allow indirect calls to be optimized into sibling calls.
 
diff --git a/gcc/configure.ac b/gcc/configure.ac
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -2589,15 +2589,48 @@  AC_DEFINE_UNQUOTED(HAVE_GAS_SHF_MERGE,
   [`if test $gcc_cv_as_shf_merge = yes; then echo 1; else echo 0; fi`],
 [Define 0/1 if your assembler supports marking sections with SHF_MERGE flag.])
 
-gcc_GAS_CHECK_FEATURE(COMDAT group support, gcc_cv_as_comdat_group,
+gcc_GAS_CHECK_FEATURE([COMDAT group support (GNU as)],
+ gcc_cv_as_comdat_group,
  [elf,2,16,0], [--fatal-warnings],
  [.section .text,"axG",@progbits,.foo,comdat])
 if test $gcc_cv_as_comdat_group = yes; then
   gcc_cv_as_comdat_group_percent=no
+  gcc_cv_as_comdat_group_group=no
 else
- gcc_GAS_CHECK_FEATURE(COMDAT group support, gcc_cv_as_comdat_group_percent,
+ gcc_GAS_CHECK_FEATURE([COMDAT group support (GNU as, %type)],
+   gcc_cv_as_comdat_group_percent,
    [elf,2,16,0], [--fatal-warnings],
    [.section .text,"axG",%progbits,.foo,comdat])
+ if test $gcc_cv_as_comdat_group_percent = yes; then
+   gcc_cv_as_comdat_group_group=no
+ else
+   case "${target}" in
+     # Sun as uses a completely different syntax.
+     *-*-solaris2*)
+       case "${target}" in
+         sparc*-*-solaris2*)
+           conftest_s='
+               .group foo,".text%foo",#comdat
+               .section ".text%foo", #alloc,#execinstr,#progbits
+               .globl foo
+             foo:
+	     '
+           ;;
+         i?86-*-solaris2*)
+	   conftest_s='
+               .group foo,.text%foo,#comdat
+               .section .text%foo, "ax", @progbits
+               .globl  foo
+             foo:
+	     '
+	   ;;
+       esac
+       gcc_GAS_CHECK_FEATURE([COMDAT group support (Sun as, .group)],
+         gcc_cv_as_comdat_group_group,
+         ,, [$conftest_s])
+       ;;
+   esac
+ fi
 fi
 if test x"$ld_is_gold" = xyes; then
   comdat_group=yes
@@ -2623,16 +2656,19 @@  else
 changequote(,)dnl
   case "${target}" in
     *-*-solaris2.1[1-9]*)
+      comdat_group=no
       # Sun ld has COMDAT group support since Solaris 9, but it doesn't
       # interoperate with GNU as until Solaris 11 build 130, i.e. ld
       # version 1.688.
       #
-      # FIXME: Maybe need to refine later when COMDAT group support with
-      # Sun as is implemented.
-      if test "$ld_vers_major" -gt 1 || test "$ld_vers_minor" -ge 1688; then
+      # If using Sun as for COMDAT group as emitted by GCC, one needs at
+      # least ld version 1.2267.
+      if test "$ld_vers_major" -gt 1; then
         comdat_group=yes
-      else
-        comdat_group=no
+      elif test "x$gas_flag" = xyes && test "$ld_vers_minor" -ge 1688; then
+	comdat_group=yes
+      elif test "$ld_vers_minor" -ge 2267; then
+	comdat_group=yes
       fi
       ;;
     *)
@@ -2649,9 +2685,12 @@  AC_ARG_ENABLE(comdat,
 if test $comdat_group = no; then
   gcc_cv_as_comdat_group=no
   gcc_cv_as_comdat_group_percent=no
+  gcc_cv_as_comdat_group_group=no
 fi
 AC_DEFINE_UNQUOTED(HAVE_COMDAT_GROUP,
-  [`if test $gcc_cv_as_comdat_group = yes || test $gcc_cv_as_comdat_group_percent = yes; then echo 1; else echo 0; fi`],
+  [`if test $gcc_cv_as_comdat_group = yes \
+    || test $gcc_cv_as_comdat_group_percent = yes \
+    || test $gcc_cv_as_comdat_group_group = yes; then echo 1; else echo 0; fi`],
 [Define 0/1 if your assembler and linker support COMDAT groups.])
 
 gcc_GAS_CHECK_FEATURE([line table discriminator support],