tree.c (free_lang_data_in_type): Do not call get_alias_set.

2009-10-28  Richard Guenther  <rguenther@suse.de>

	* tree.c (free_lang_data_in_type): Do not call get_alias_set.
	(free_lang_data): Unconditionally compute alias sets for all
	standard integer types.  Bail out if gate bailed out previously.
	Do not reset the types_compatible_p langhook.
	(gate_free_lang_data): Remove.
	(struct pass_ipa_free_lang_data): Enable unconditionally.
	* gimple.c (gimple_get_alias_set): Use the same alias-set for
	all pointer types.

From-SVN: r153659

3 files changed, 60 insertions, 38 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9a7155f..65ca8c2 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,16 @@
 2009-10-28  Richard Guenther  <rguenther@suse.de>
 
+	* tree.c (free_lang_data_in_type): Do not call get_alias_set.
+	(free_lang_data): Unconditionally compute alias sets for all
+	standard integer types.  Bail out if gate bailed out previously.
+	Do not reset the types_compatible_p langhook.
+	(gate_free_lang_data): Remove.
+	(struct pass_ipa_free_lang_data): Enable unconditionally.
+	* gimple.c (gimple_get_alias_set): Use the same alias-set for
+	all pointer types.
+
+2009-10-28  Richard Guenther  <rguenther@suse.de>
+
 	PR middle-end/41855
 	* tree-ssa-alias.c (refs_may_alias_p_1): Deal with CONST_DECLs
 	(ref_maybe_used_by_call_p_1): Fix bcopy handling.
diff --git a/gcc/gimple.c b/gcc/gimple.c
index 0b76677..24ac0b8 100644
--- a/gcc/gimple.c
+++ b/gcc/gimple.c
@@ -4131,7 +4131,6 @@ gimple_signed_type (tree type)
 alias_set_type
 gimple_get_alias_set (tree t)
 {
-  static bool recursing_p;
   tree u;
 
   /* Permit type-punning when accessing a union, provided the access
@@ -4171,15 +4170,9 @@ gimple_get_alias_set (tree t)
     }
   else if (POINTER_TYPE_P (t))
     {
-      tree t1;
+      /* From the common C and C++ langhook implementation:
 
-      /* ???  We can end up creating cycles with TYPE_MAIN_VARIANT
-	 and TYPE_CANONICAL.  Avoid recursing endlessly between
-	 this langhook and get_alias_set.  */
-      if (recursing_p)
-	return -1;
-
-      /* Unfortunately, there is no canonical form of a pointer type.
+	 Unfortunately, there is no canonical form of a pointer type.
 	 In particular, if we have `typedef int I', then `int *', and
 	 `I *' are different types.  So, we have to pick a canonical
 	 representative.  We do this below.
@@ -4201,15 +4194,36 @@ gimple_get_alias_set (tree t)
 	 can dereference IPP and CIPP.  So, we ignore cv-qualifiers on
 	 the pointed-to types.  This issue has been reported to the
 	 C++ committee.  */
-      t1 = build_type_no_quals (t);
-      if (t1 != t)
-	{
-	  alias_set_type set;
-	  recursing_p = true;
-	  set = get_alias_set (t1);
-	  recursing_p = false;
-	  return set;
-	}
+
+      /* In addition to the above canonicalization issue with LTO
+         we should also canonicalize `T (*)[]' to `T *' avoiding
+	 alias issues with pointer-to element types and pointer-to
+	 array types.
+
+	 Likewise we need to deal with the situation of incomplete
+	 pointed-to types and make `*(struct X **)&a' and
+	 `*(struct X {} **)&a' alias.  Otherwise we will have to
+	 guarantee that all pointer-to incomplete type variants
+	 will be replaced by pointer-to complete type variants if
+	 they are available.
+
+	 With LTO the convenient situation of using `void *' to
+	 access and store any pointer type will also become
+	 more appearant (and `void *' is just another pointer-to
+	 incomplete type).  Assigning alias-set zero to `void *'
+	 and all pointer-to incomplete types is a not appealing
+	 solution.  Assigning an effective alias-set zero only
+	 affecting pointers might be - by recording proper subset
+	 relationships of all pointer alias-sets.
+
+	 Pointer-to function types are another grey area which
+	 needs caution.  Globbing them all into one alias-set
+	 or the above effective zero set would work.  */
+
+      /* For now just assign the same alias-set to all pointers.
+         That's simple and avoids all the above problems.  */
+      if (t != ptr_type_node)
+	return get_alias_set (ptr_type_node);
     }
 
   return -1;
diff --git a/gcc/tree.c b/gcc/tree.c
index 4343415..6079725 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -4171,11 +4171,6 @@ free_lang_data_in_type (tree type)
 {
   gcc_assert (TYPE_P (type));
 
-  /* Fill in the alias-set.  We need to at least track zeroness here
-     for correctness.  */
-  if (lang_hooks.get_alias_set (type) == 0)
-    TYPE_ALIAS_SET (type) = 0;
-
   /* Give the FE a chance to remove its own data first.  */
   lang_hooks.free_lang_data (type);
 
@@ -4924,6 +4919,20 @@ free_lang_data_in_cgraph (void)
 static unsigned
 free_lang_data (void)
 {
+  unsigned i;
+
+  /* Allocate and assign alias sets to the standard integer types
+     while the slots are still in the way the frontends generated them.  */
+  for (i = 0; i < itk_none; ++i)
+    if (integer_types[i])
+      TYPE_ALIAS_SET (integer_types[i]) = get_alias_set (integer_types[i]);
+
+  /* FIXME.  Remove after save_debug_info is working.  */
+  if (!(flag_generate_lto
+	|| (!in_lto_p
+	    && !flag_gtoggle && debug_info_level <= DINFO_LEVEL_TERSE)))
+    return 0;
+
   /* Traverse the IL resetting language specific information for
      operands, expressions, etc.  */
   free_lang_data_in_cgraph ();
@@ -4951,9 +4960,9 @@ free_lang_data (void)
   else
     signed_char_type_node = char_type_node;
 
-  /* Reset some langhooks.  */
+  /* Reset some langhooks.  Do not reset types_compatible_p, it may
+     still be used indirectly via the get_alias_set langhook.  */
   lang_hooks.callgraph.analyze_expr = NULL;
-  lang_hooks.types_compatible_p = NULL;
   lang_hooks.dwarf_name = lhd_dwarf_name;
   lang_hooks.decl_printable_name = gimple_decl_printable_name;
   lang_hooks.set_decl_assembler_name = lhd_set_decl_assembler_name;
@@ -4975,24 +4984,12 @@ free_lang_data (void)
 }
 
 
-/* Gate function for free_lang_data.  */
-
-static bool
-gate_free_lang_data (void)
-{
-  /* FIXME.  Remove after save_debug_info is working.  */
-  return (flag_generate_lto
-	  || (!in_lto_p
-	      && !flag_gtoggle && debug_info_level <= DINFO_LEVEL_TERSE));
-}
-
-
 struct simple_ipa_opt_pass pass_ipa_free_lang_data = 
 {
  {
   SIMPLE_IPA_PASS,
   NULL,					/* name */
-  gate_free_lang_data,			/* gate */
+  NULL,					/* gate */
   free_lang_data,			/* execute */
   NULL,					/* sub */
   NULL,					/* next */