[PATCH] AIX visibility

[David Edelsohn <dje.gcc@gmail.com>]

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This patch enables visibility support for AIX.  AIX of course chose
different syntax, so the default machinery isn't usable.  AIX appends
the visibility to the .globl and .comm pseudo-ops.

Within the rs6000 port, this patch only affects AIX / XCOFF.

Also, because visibility support implicitly enables other features in
GCC, some of which conflict with AIX, I had to disable the additional
features.  Because AIX uses DWARF for EH but places the DWARF
information in the data section, the use of DWARF references and
force_constant_mem conflicts with the data section.  For this reason,
USE_LINKONCE_INDIRECT is disabled in dwarf2asm.c.

This patch also adjusts gcc/configure to set HAVE_GAS_HIDDEN. AIX ld
support for hidden is forced true because the assembler test will
catch if support is present.

A number of testsuite tweaks also are necessary to XFAIL some
visibility tests on AIX.

Bootstrapped on powerpc-ibm-aix7.2.0.0 and powerpc64le-ibm-linux-gnu.

Are the changes to configure and dwarf2asm.c okay?

* configure.ac (.hidden): Change to conftest_s string. Provide string
for AIX assembler.
(gcc_cv_ld_hidden): Yes for AIX.
* configure: Regenerate.

* dwarf2asm.c (USE_LINKONCE_INDIRECT): Don't set for AIX (XCOFF).

* config/rs6000/rs6000-protos.h
(rs6000_xcoff_asm_output_aligned_decl_common): Declare.
* config/rs6000/xcoff.h (TARGET_ASM_GLOBALIZE_DECL_NAME): Define.
(ASM_OUTPUT_ALIGNED_DECL_COMMON): Define.
(ASM_OUTPUT_ALIGNED_COMMON): Delete.
* config/rs6000/rs6000.c (rs6000_xcoff_visibility): New.
(rs6000_xcoff_declare_function_name): Add visibility support.
(rs6000_xcoff_asm_globalize_decl_name): New.
(rs6000_xcoff_asm_output_aligned_decl_common): New.
(rs6000_code_end): Disable HIDDEN_LINKONCE on XCOFF.

Thanks, David

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Index: configure.ac
===================================================================
--- configure.ac	(revision 241708)
+++ configure.ac	(working copy)
@@ -2537,10 +2537,17 @@ gcc_GAS_CHECK_FEATURE([.nsubspa comdat], gcc_cv_as
 # ld, we don't know its patchlevel version, so we set the baseline at 2.13
 # to be safe.
 # The gcc_GAS_CHECK_FEATURE call just sets a cache variable.
+case "${target}" in
+  *-*-aix*)
+    conftest_s='	.globl foobar,hidden'
+    ;;
+  *)
+    conftest_s='	.hidden foobar
+foobar:'
+    ;;
+esac
 gcc_GAS_CHECK_FEATURE([.hidden], gcc_cv_as_hidden,
- [elf,2,13,0],,
-[	.hidden foobar
-foobar:])
+ [elf,2,13,0],, [$conftest_s])
 case "${target}" in
   *-*-darwin*)
     # Darwin as has some visibility support, though with a different syntax.
@@ -2649,6 +2656,9 @@ else
     fi
   else
     case "${target}" in
+      *-*-aix[[789]]*)
+        gcc_cv_ld_hiden=yes
+        ;;
       *-*-darwin*)
 	# Darwin ld has some visibility support.
 	gcc_cv_ld_hidden=yes
Index: dwarf2asm.c
===================================================================
--- dwarf2asm.c	(revision 241720)
+++ dwarf2asm.c	(working copy)
@@ -824,7 +824,7 @@ static GTY(()) hash_map<const char *, tree> *indir
 
 static GTY(()) int dw2_const_labelno;
 
-#if defined(HAVE_GAS_HIDDEN)
+#if defined(HAVE_GAS_HIDDEN) && !defined(XCOFF_DEBUGGING_INFO)
 # define USE_LINKONCE_INDIRECT (SUPPORTS_ONE_ONLY)
 #else
 # define USE_LINKONCE_INDIRECT 0
Index: config/rs6000/rs6000-protos.h
===================================================================
--- config/rs6000/rs6000-protos.h	(revision 241720)
+++ config/rs6000/rs6000-protos.h	(working copy)
@@ -189,6 +189,10 @@ extern int function_ok_for_sibcall (tree);
 extern int rs6000_reg_parm_stack_space (tree, bool);
 extern void rs6000_xcoff_declare_function_name (FILE *, const char *, tree);
 extern void rs6000_xcoff_declare_object_name (FILE *, const char *, tree);
+extern void rs6000_xcoff_asm_output_aligned_decl_common (FILE *, tree,
+							 const char *,
+							 unsigned HOST_WIDE_INT,
+							 unsigned HOST_WIDE_INT);
 extern void rs6000_elf_declare_function_name (FILE *, const char *, tree);
 extern bool rs6000_elf_in_small_data_p (const_tree);
 #ifdef ARGS_SIZE_RTX
Index: config/rs6000/xcoff.h
===================================================================
--- config/rs6000/xcoff.h	(revision 241720)
+++ config/rs6000/xcoff.h	(working copy)
@@ -89,6 +89,7 @@
 #undef TARGET_DEBUG_UNWIND_INFO
 #define TARGET_DEBUG_UNWIND_INFO  rs6000_xcoff_debug_unwind_info
 #define TARGET_ASM_OUTPUT_ANCHOR  rs6000_xcoff_asm_output_anchor
+#define TARGET_ASM_GLOBALIZE_DECL_NAME  rs6000_xcoff_asm_globalize_decl_name
 #define TARGET_ASM_GLOBALIZE_LABEL  rs6000_xcoff_asm_globalize_label
 #define TARGET_ASM_INIT_SECTIONS  rs6000_xcoff_asm_init_sections
 #define TARGET_ASM_RELOC_RW_MASK  rs6000_xcoff_reloc_rw_mask
@@ -102,6 +103,7 @@
 #ifdef HAVE_AS_TLS
 #define TARGET_ENCODE_SECTION_INFO rs6000_xcoff_encode_section_info
 #endif
+#define ASM_OUTPUT_ALIGNED_DECL_COMMON  rs6000_xcoff_asm_output_aligned_decl_common
 
 /* FP save and restore routines.  */
 #define	SAVE_FP_PREFIX "._savef"
@@ -217,18 +219,6 @@
 
 #define COMMON_ASM_OP "\t.comm "
 
-#define ASM_OUTPUT_ALIGNED_COMMON(FILE, NAME, SIZE, ALIGN)	\
-  do { fputs (COMMON_ASM_OP, (FILE));			\
-       RS6000_OUTPUT_BASENAME ((FILE), (NAME));		\
-       if ((ALIGN) > 32)				\
-	 fprintf ((FILE), "," HOST_WIDE_INT_PRINT_UNSIGNED",%u\n", (SIZE), \
-		  floor_log2 ((ALIGN) / BITS_PER_UNIT)); \
-       else if ((SIZE) > 4)				\
-         fprintf ((FILE), "," HOST_WIDE_INT_PRINT_UNSIGNED",3\n", (SIZE)); \
-       else						\
-	 fprintf ((FILE), "," HOST_WIDE_INT_PRINT_UNSIGNED"\n", (SIZE)); \
-  } while (0)
-
 /* This says how to output an assembler line
    to define a local common symbol.
    The assembler in AIX 6.1 and later supports an alignment argument.
Index: config/rs6000/rs6000.c
===================================================================
--- config/rs6000/rs6000.c	(revision 241720)
+++ config/rs6000/rs6000.c	(working copy)
@@ -35316,6 +35316,31 @@ rs6000_declare_alias (struct symtab_node *n, void
   return false;
 }
 
+
+#ifdef HAVE_GAS_HIDDEN
+/* Helper function to calculate visibility of a DECL
+   and return the value as a const string.  */
+
+static const char *
+rs6000_xcoff_visibility (tree decl)
+{
+  static const char * const visibility_types[] = {
+    "", ",protected", ",hidden", ",internal"
+  };
+
+  enum symbol_visibility vis = DECL_VISIBILITY (decl);
+
+  if (TREE_CODE (decl) == FUNCTION_DECL
+      && cgraph_node::get (decl)
+      && cgraph_node::get (decl)->instrumentation_clone
+      && cgraph_node::get (decl)->instrumented_version)
+    vis = DECL_VISIBILITY (cgraph_node::get (decl)->instrumented_version->decl);
+
+  return visibility_types[vis];
+}
+#endif
+
+
 /* This macro produces the initial definition of a function name.
    On the RS/6000, we need to place an extra '.' in the function name and
    output the function descriptor.
@@ -35355,6 +35380,9 @@ rs6000_xcoff_declare_function_name (FILE *file, co
 	    }
 	  fputs ("\t.globl .", file);
 	  RS6000_OUTPUT_BASENAME (file, buffer);
+#ifdef HAVE_GAS_HIDDEN
+	  fputs (rs6000_xcoff_visibility (decl), file);
+#endif
 	  putc ('\n', file);
 	}
     }
@@ -35399,6 +35427,52 @@ rs6000_xcoff_declare_function_name (FILE *file, co
   return;
 }
 
+
+/* Output assembly language to globalize a symbol from a DECL,
+   possibly with visibility.  */
+
+void
+rs6000_xcoff_asm_globalize_decl_name (FILE *stream, tree decl)
+{
+  const char *name = XSTR (XEXP (DECL_RTL (decl), 0), 0);
+  fputs (GLOBAL_ASM_OP, stream);
+  RS6000_OUTPUT_BASENAME (stream, name);
+#ifdef HAVE_GAS_HIDDEN
+  fputs (rs6000_xcoff_visibility (decl), stream);
+#endif
+  putc ('\n', stream);
+}
+
+/* Output assembly language to define a symbol as COMMON from a DECL,
+   possibly with visibility.  */
+
+void
+rs6000_xcoff_asm_output_aligned_decl_common (FILE *stream,
+					     tree decl ATTRIBUTE_UNUSED,
+					     const char *name,
+					     unsigned HOST_WIDE_INT size,
+					     unsigned HOST_WIDE_INT align)
+{
+  unsigned HOST_WIDE_INT align2 = 2;
+
+  if (align > 32)
+    align2 = floor_log2 (align / BITS_PER_UNIT);
+  else if (size > 4)
+    align2 = 3;
+
+  fputs (COMMON_ASM_OP, stream);
+  RS6000_OUTPUT_BASENAME (stream, name);
+
+  fprintf (stream,
+	   "," HOST_WIDE_INT_PRINT_UNSIGNED "," HOST_WIDE_INT_PRINT_UNSIGNED,
+	   size, align2);
+
+#ifdef HAVE_GAS_HIDDEN
+  fputs (rs6000_xcoff_visibility (decl), stream);
+#endif
+  putc ('\n', stream);
+}
+
 /* This macro produces the initial definition of a object (variable) name.
    Because AIX assembler's .set command has unexpected semantics, we output
    all aliases as alternative labels in front of the definition.  */
@@ -38651,7 +38725,7 @@ rs6000_code_end (void)
   TREE_STATIC (decl) = 1;
 
 #if RS6000_WEAK
-  if (USE_HIDDEN_LINKONCE)
+  if (USE_HIDDEN_LINKONCE && !TARGET_XCOFF)
     {
       cgraph_node::create (decl)->set_comdat_group (DECL_ASSEMBLER_NAME (decl));
       targetm.asm_out.unique_section (decl, 0);