[PATCH][v2] Introduce TARGET_SUPPORTS_ALIASES

["Martin Liška" <mliska@suse.cz>]

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On 07/31/2017 11:57 AM, Yuri Gribov wrote:
> On Mon, Jul 31, 2017 at 9:04 AM, Martin Liška <mliska@suse.cz> wrote:
>> Hi.
>>
>> Doing the transformation suggested by Honza.
>>
>> Patch can bootstrap on ppc64le-redhat-linux and x86_64-linux-gnu and survives regression tests.
>> And I also verified that works on hppa2.0w-hp-hpux11.11 (target w/o aliasing support).
>>
>> Ready to be installed?
> 
> A nit - you can probly get rid of ATTRIBUTE_UNUSED in note_mangling_alias now.
> 
> -Y
> 

Sure.

Done in v2.

Martin

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From 78ee08b25d22125cb1fa248bac98ef1e84504761 Mon Sep 17 00:00:00 2001
From: marxin <mliska@suse.cz>
Date: Tue, 25 Jul 2017 13:11:28 +0200
Subject: [PATCH] Introduce TARGET_SUPPORTS_ALIASES

gcc/c-family/ChangeLog:

2017-07-25  Martin Liska  <mliska@suse.cz>

	* c-opts.c (c_common_post_options): Replace ASM_OUTPUT_DEF with
	TARGET_SUPPORTS_ALIASES.

gcc/ChangeLog:

2017-07-25  Martin Liska  <mliska@suse.cz>

	* asan.c (asan_protect_global): Replace ASM_OUTPUT_DEF with
	TARGET_SUPPORTS_ALIASES.
	* cgraph.c (cgraph_node::create_same_body_alias): Likewise.
	* ipa-visibility.c (can_replace_by_local_alias): Likewise.
	(optimize_weakref): Likewise.
	* symtab.c (symtab_node::noninterposable_alias): Likewise.
	* varpool.c (varpool_node::create_extra_name_alias): Likewise.
	* defaults.h: Introduce TARGET_SUPPORTS_ALIASES.

gcc/cp/ChangeLog:

2017-07-25  Martin Liska  <mliska@suse.cz>

	* decl2.c (get_tls_init_fn): Replace ASM_OUTPUT_DEF with
	TARGET_SUPPORTS_ALIASES.
	(handle_tls_init): Likewise.
	(note_mangling_alias): Likewise.  Remove ATTRIBUTE_UNUSED for
	both arguments.
	* optimize.c (can_alias_cdtor): Likewise.
---
 gcc/asan.c            |  4 +---
 gcc/c-family/c-opts.c | 22 ++++++++++++----------
 gcc/cgraph.c          |  7 ++++---
 gcc/cp/decl2.c        | 25 +++++++++++--------------
 gcc/cp/optimize.c     |  6 +++---
 gcc/defaults.h        |  9 +++++++++
 gcc/ipa-visibility.c  | 15 +++++----------
 gcc/symtab.c          |  6 +++---
 gcc/varpool.c         |  6 +++---
 9 files changed, 51 insertions(+), 49 deletions(-)

diff --git a/gcc/asan.c b/gcc/asan.c
index 5f9275f6425..d8cb2b52c8b 100644
--- a/gcc/asan.c
+++ b/gcc/asan.c
@@ -1663,10 +1663,8 @@ asan_protect_global (tree decl)
   if (lookup_attribute ("weakref", DECL_ATTRIBUTES (decl)))
     return false;
 
-#ifndef ASM_OUTPUT_DEF
-  if (asan_needs_local_alias (decl))
+  if (!TARGET_SUPPORTS_ALIASES && asan_needs_local_alias (decl))
     return false;
-#endif
 
   return true;
 }
diff --git a/gcc/c-family/c-opts.c b/gcc/c-family/c-opts.c
index 1657e7a4390..0b13a188c1b 100644
--- a/gcc/c-family/c-opts.c
+++ b/gcc/c-family/c-opts.c
@@ -957,16 +957,18 @@ c_common_post_options (const char **pfilename)
 
   if (flag_extern_tls_init)
     {
-#if !defined (ASM_OUTPUT_DEF) || !SUPPORTS_WEAK
-      /* Lazy TLS initialization for a variable in another TU requires
-	 alias and weak reference support. */
-      if (flag_extern_tls_init > 0)
-	sorry ("external TLS initialization functions not supported "
-	       "on this target");
-      flag_extern_tls_init = 0;
-#else
-      flag_extern_tls_init = 1;
-#endif
+      if (!TARGET_SUPPORTS_ALIASES || !SUPPORTS_WEAK)
+	{
+	  /* Lazy TLS initialization for a variable in another TU requires
+	     alias and weak reference support.  */
+	  if (flag_extern_tls_init > 0)
+	    sorry ("external TLS initialization functions not supported "
+		   "on this target");
+
+	  flag_extern_tls_init = 0;
+	}
+      else
+	flag_extern_tls_init = 1;
     }
 
   if (num_in_fnames > 1)
diff --git a/gcc/cgraph.c b/gcc/cgraph.c
index d7c9ba61795..849989443b1 100644
--- a/gcc/cgraph.c
+++ b/gcc/cgraph.c
@@ -582,10 +582,11 @@ cgraph_node *
 cgraph_node::create_same_body_alias (tree alias, tree decl)
 {
   cgraph_node *n;
-#ifndef ASM_OUTPUT_DEF
+
   /* If aliases aren't supported by the assembler, fail.  */
-  return NULL;
-#endif
+  if (!TARGET_SUPPORTS_ALIASES)
+    return NULL;
+
   /* Langhooks can create same body aliases of symbols not defined.
      Those are useless. Drop them on the floor.  */
   if (symtab->global_info_ready)
diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index 2a52f8ca3e2..29a2e3cf02d 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -3156,11 +3156,9 @@ get_tls_init_fn (tree var)
   if (!flag_extern_tls_init && DECL_EXTERNAL (var))
     return NULL_TREE;
 
-#ifdef ASM_OUTPUT_DEF
   /* If the variable is internal, or if we can't generate aliases,
      call the local init function directly.  */
-  if (!TREE_PUBLIC (var))
-#endif
+  if (!TREE_PUBLIC (var) || !TARGET_SUPPORTS_ALIASES)
     return get_local_tls_init_fn ();
 
   tree sname = mangle_tls_init_fn (var);
@@ -4241,9 +4239,8 @@ handle_tls_init (void)
       tree init = TREE_PURPOSE (vars);
       one_static_initialization_or_destruction (var, init, true);
 
-#ifdef ASM_OUTPUT_DEF
       /* Output init aliases even with -fno-extern-tls-init.  */
-      if (TREE_PUBLIC (var))
+      if (TARGET_SUPPORTS_ALIASES && TREE_PUBLIC (var))
 	{
           tree single_init_fn = get_tls_init_fn (var);
 	  if (single_init_fn == NULL_TREE)
@@ -4253,7 +4250,6 @@ handle_tls_init (void)
 		(single_init_fn, fn);
 	  gcc_assert (alias != NULL);
 	}
-#endif
     }
 
   finish_then_clause (if_stmt);
@@ -4298,17 +4294,18 @@ generate_mangling_alias (tree decl, tree id2)
    implementation.  */
 
 void
-note_mangling_alias (tree decl ATTRIBUTE_UNUSED, tree id2 ATTRIBUTE_UNUSED)
+note_mangling_alias (tree decl, tree id2)
 {
-#ifdef ASM_OUTPUT_DEF
-  if (!defer_mangling_aliases)
-    generate_mangling_alias (decl, id2);
-  else
+  if (TARGET_SUPPORTS_ALIASES)
     {
-      vec_safe_push (mangling_aliases, decl);
-      vec_safe_push (mangling_aliases, id2);
+      if (!defer_mangling_aliases)
+	generate_mangling_alias (decl, id2);
+      else
+	{
+	  vec_safe_push (mangling_aliases, decl);
+	  vec_safe_push (mangling_aliases, id2);
+	}
     }
-#endif
 }
 
 /* Emit all mangling aliases that were deferred up to this point.  */
diff --git a/gcc/cp/optimize.c b/gcc/cp/optimize.c
index a1c387092d4..09ffbda7ca8 100644
--- a/gcc/cp/optimize.c
+++ b/gcc/cp/optimize.c
@@ -184,10 +184,10 @@ cdtor_comdat_group (tree complete, tree base)
 static bool
 can_alias_cdtor (tree fn)
 {
-#ifndef ASM_OUTPUT_DEF
   /* If aliases aren't supported by the assembler, fail.  */
-  return false;
-#endif
+  if (!TARGET_SUPPORTS_ALIASES)
+    return false;
+
   /* We can't use an alias if there are virtual bases.  */
   if (CLASSTYPE_VBASECLASSES (DECL_CONTEXT (fn)))
     return false;
diff --git a/gcc/defaults.h b/gcc/defaults.h
index 7ad92d920f8..072ef6b6d17 100644
--- a/gcc/defaults.h
+++ b/gcc/defaults.h
@@ -863,6 +863,15 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #endif
 #endif
 
+/* Decide whether target supports aliases.  */
+#ifndef TARGET_SUPPORTS_ALIASES
+#ifdef ASM_OUTPUT_DEF
+#define TARGET_SUPPORTS_ALIASES 1
+#else
+#define TARGET_SUPPORTS_ALIASES 0
+#endif
+#endif
+
 /* Select a format to encode pointers in exception handling data.  We
    prefer those that result in fewer dynamic relocations.  Assume no
    special support here and encode direct references.  */
diff --git a/gcc/ipa-visibility.c b/gcc/ipa-visibility.c
index 3033f20e3f1..825b3fc36e9 100644
--- a/gcc/ipa-visibility.c
+++ b/gcc/ipa-visibility.c
@@ -337,10 +337,10 @@ varpool_node::externally_visible_p (void)
 static bool
 can_replace_by_local_alias (symtab_node *node)
 {
-#ifndef ASM_OUTPUT_DEF
   /* If aliases aren't supported, we can't do replacement.  */
-  return false;
-#endif
+  if (!TARGET_SUPPORTS_ALIASES)
+    return false;
+
   /* Weakrefs have a reason to be non-local.  Be sure we do not replace
      them.  */
   while (node->transparent_alias && node->definition && !node->weakref)
@@ -461,11 +461,6 @@ update_visibility_by_resolution_info (symtab_node * node)
 static void
 optimize_weakref (symtab_node *node)
 {
-#ifdef ASM_OUTPUT_DEF
-  bool aliases_supported = true;
-#else
-  bool aliases_supported = false;
-#endif
   bool strip_weakref = false;
   bool static_alias = false;
 
@@ -484,8 +479,8 @@ optimize_weakref (symtab_node *node)
 
   /* If we have definition of weakref's target and we know it binds locally,
      we can turn weakref to static alias.  */
-  if (target->definition && decl_binds_to_current_def_p (target->decl)
-      && aliases_supported)
+  if (TARGET_SUPPORTS_ALIASES
+      && target->definition && decl_binds_to_current_def_p (target->decl))
     strip_weakref = static_alias = true;
   /* Otherwise we can turn weakref into transparent alias.  This transformation
      may break asm statements which directly refers to symbol name and expect
diff --git a/gcc/symtab.c b/gcc/symtab.c
index 0145910023f..1affc1dce1d 100644
--- a/gcc/symtab.c
+++ b/gcc/symtab.c
@@ -1763,10 +1763,10 @@ symtab_node::noninterposable_alias (void)
 				   (void *)&new_node, true);
   if (new_node)
     return new_node;
-#ifndef ASM_OUTPUT_DEF
+
   /* If aliases aren't supported by the assembler, fail.  */
-  return NULL;
-#endif
+  if (!TARGET_SUPPORTS_ALIASES)
+    return NULL;
 
   /* Otherwise create a new one.  */
   new_decl = copy_node (node->decl);
diff --git a/gcc/varpool.c b/gcc/varpool.c
index ab59c80406b..db3dcee1af8 100644
--- a/gcc/varpool.c
+++ b/gcc/varpool.c
@@ -786,10 +786,10 @@ varpool_node::create_extra_name_alias (tree alias, tree decl)
 {
   varpool_node *alias_node;
 
-#ifndef ASM_OUTPUT_DEF
   /* If aliases aren't supported by the assembler, fail.  */
-  return NULL;
-#endif
+  if (!TARGET_SUPPORTS_ALIASES)
+    return NULL;
+
   alias_node = varpool_node::create_alias (alias, decl);
   alias_node->cpp_implicit_alias = true;
 
-- 
2.13.3