re PR middle-end/71002 (-fstrict-aliasing breaks Boost's short string optimization...

2016-06-29  Richard Biener  <rguenther@suse.de>

	PR middle-end/71002
	* alias.c (component_uses_parent_alias_set_from): Handle
	type punning through union accesses by using the union alias set.
	* gimple.c (gimple_get_alias_set): Remove union type punning case.

	c-family/
	* c-common.c (c_common_get_alias_set): Remove union type punning case.

	fortran/
	* f95-lang.c (LANG_HOOKS_GET_ALIAS_SET): Remove (un-)define.
	(gfc_get_alias_set): Remove.

	* g++.dg/torture/pr71002.C: Adjust testcase.

From-SVN: r237839

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 109ff1c8bd2df8ef5e50adccac26b4cdfebe4834..e57c1a9b8340594fc02f9ce17aff49fdf7797ebe 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2016-06-29  Richard Biener  <rguenther@suse.de>
+
+       PR middle-end/71002
+       * alias.c (component_uses_parent_alias_set_from): Handle
+       type punning through union accesses by using the union alias set.
+       * gimple.c (gimple_get_alias_set): Remove union type punning case.
+
 2016-07-29  Richard Biener  <rguenther@suse.de>
 
        * match.pd ((T)(T2)x -> (T)x): Remove restriction on final

diff --git a/gcc/alias.c b/gcc/alias.c
index 1e4c4d19e69a35cfffd0a92fe529f9e74845959f..dd1dfd3892034d8622bcc176d38d9947f443b824 100644 (file)
--- a/gcc/alias.c
+++ b/gcc/alias.c
@@ -619,6 +619,14 @@ component_uses_parent_alias_set_from (const_tree t)
        case COMPONENT_REF:
          if (DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1)))
            found = t;
+         /* Permit type-punning when accessing a union, provided the access
+            is directly through the union.  For example, this code does not
+            permit taking the address of a union member and then storing
+            through it.  Even the type-punning allowed here is a GCC
+            extension, albeit a common and useful one; the C standard says
+            that such accesses have implementation-defined behavior.  */
+         else if (TREE_CODE (TREE_TYPE (TREE_OPERAND (t, 0))) == UNION_TYPE)
+           found = t;
          break;
 
        case ARRAY_REF:

diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 86ce14a968eec909c49265413d03b17e434f0ac8..d5b839594ce339dcf203414ac49f478ec3fb0c42 100644 (file)
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,8 @@
+2016-06-29  Richard Biener  <rguenther@suse.de>
+
+       PR middle-end/71002
+       * c-common.c (c_common_get_alias_set): Remove union type punning case.
+
 2016-06-24  Jason Merrill  <jason@redhat.com>
 
        P0145R2: Refining Expression Order for C++.

diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 3301c313998de42ba60e7ac97317b8687e25df1d..936ddfb87e59d152e0c77deca869565f90e4717e 100644 (file)
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -4736,8 +4736,6 @@ static GTY(()) hash_table<c_type_hasher> *type_hash_table;
 alias_set_type
 c_common_get_alias_set (tree t)
 {
-  tree u;
-
   /* For VLAs, use the alias set of the element type rather than the
      default of alias set 0 for types compared structurally.  */
   if (TYPE_P (t) && TYPE_STRUCTURAL_EQUALITY_P (t))
@@ -4747,19 +4745,6 @@ c_common_get_alias_set (tree t)
       return -1;
     }
 
-  /* Permit type-punning when accessing a union, provided the access
-     is directly through the union.  For example, this code does not
-     permit taking the address of a union member and then storing
-     through it.  Even the type-punning allowed here is a GCC
-     extension, albeit a common and useful one; the C standard says
-     that such accesses have implementation-defined behavior.  */
-  for (u = t;
-       TREE_CODE (u) == COMPONENT_REF || TREE_CODE (u) == ARRAY_REF;
-       u = TREE_OPERAND (u, 0))
-    if (TREE_CODE (u) == COMPONENT_REF
-       && TREE_CODE (TREE_TYPE (TREE_OPERAND (u, 0))) == UNION_TYPE)
-      return 0;
-
   /* That's all the expressions we handle specially.  */
   if (!TYPE_P (t))
     return -1;

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index b8cadceb5910c64d11bf1a461349b9fad4025de3..68e1f34edb54d4bf0ef2c87a2b7479a5a50bcfaf 100644 (file)
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,9 @@
+2016-06-29  Richard Biener  <rguenther@suse.de>
+
+       PR middle-end/71002
+       * f95-lang.c (LANG_HOOKS_GET_ALIAS_SET): Remove (un-)define.
+       (gfc_get_alias_set): Remove.
+
 2016-06-25  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
 
        PR fortran/71649

diff --git a/gcc/fortran/f95-lang.c b/gcc/fortran/f95-lang.c
index b89a291e7615c6b5b576a6fbd2a7fe518b226186..5849073b66e4148f78195a66f5e0dfb90484ef02 100644 (file)
--- a/gcc/fortran/f95-lang.c
+++ b/gcc/fortran/f95-lang.c
@@ -74,7 +74,6 @@ static bool global_bindings_p (void);
 static bool gfc_init (void);
 static void gfc_finish (void);
 static void gfc_be_parse_file (void);
-static alias_set_type gfc_get_alias_set (tree);
 static void gfc_init_ts (void);
 static tree gfc_builtin_function (tree);
 
@@ -110,7 +109,6 @@ static const struct attribute_spec gfc_attribute_table[] =
 #undef LANG_HOOKS_MARK_ADDRESSABLE
 #undef LANG_HOOKS_TYPE_FOR_MODE
 #undef LANG_HOOKS_TYPE_FOR_SIZE
-#undef LANG_HOOKS_GET_ALIAS_SET
 #undef LANG_HOOKS_INIT_TS
 #undef LANG_HOOKS_OMP_PRIVATIZE_BY_REFERENCE
 #undef LANG_HOOKS_OMP_PREDETERMINED_SHARING
@@ -142,7 +140,6 @@ static const struct attribute_spec gfc_attribute_table[] =
 #define LANG_HOOKS_PARSE_FILE           gfc_be_parse_file
 #define LANG_HOOKS_TYPE_FOR_MODE       gfc_type_for_mode
 #define LANG_HOOKS_TYPE_FOR_SIZE       gfc_type_for_size
-#define LANG_HOOKS_GET_ALIAS_SET       gfc_get_alias_set
 #define LANG_HOOKS_INIT_TS             gfc_init_ts
 #define LANG_HOOKS_OMP_PRIVATIZE_BY_REFERENCE  gfc_omp_privatize_by_reference
 #define LANG_HOOKS_OMP_PREDETERMINED_SHARING   gfc_omp_predetermined_sharing
@@ -503,24 +500,6 @@ gfc_init_decl_processing (void)
 }
 
 
-/* Return the typed-based alias set for T, which may be an expression
-   or a type.  Return -1 if we don't do anything special.  */
-
-static alias_set_type
-gfc_get_alias_set (tree t)
-{
-  tree u;
-
-  /* Permit type-punning when accessing an EQUIVALENCEd variable or
-     mixed type entry master's return value.  */
-  for (u = t; handled_component_p (u); u = TREE_OPERAND (u, 0))
-    if (TREE_CODE (u) == COMPONENT_REF
-       && TREE_CODE (TREE_TYPE (TREE_OPERAND (u, 0))) == UNION_TYPE)
-      return 0;
-
-  return -1;
-}
-
 /* Builtin function initialization.  */
 
 static tree

diff --git a/gcc/gimple.c b/gcc/gimple.c
index 677c56070904f82d77aa8a6e4de7a2e664ecda76..e275dfc3c520d247565362b7e48f9de0230f91f4 100644 (file)
--- a/gcc/gimple.c
+++ b/gcc/gimple.c
@@ -2400,21 +2400,6 @@ gimple_signed_type (tree type)
 alias_set_type
 gimple_get_alias_set (tree t)
 {
-  tree u;
-
-  /* Permit type-punning when accessing a union, provided the access
-     is directly through the union.  For example, this code does not
-     permit taking the address of a union member and then storing
-     through it.  Even the type-punning allowed here is a GCC
-     extension, albeit a common and useful one; the C standard says
-     that such accesses have implementation-defined behavior.  */
-  for (u = t;
-       TREE_CODE (u) == COMPONENT_REF || TREE_CODE (u) == ARRAY_REF;
-       u = TREE_OPERAND (u, 0))
-    if (TREE_CODE (u) == COMPONENT_REF
-       && TREE_CODE (TREE_TYPE (TREE_OPERAND (u, 0))) == UNION_TYPE)
-      return 0;
-
   /* That's all the expressions we handle specially.  */
   if (!TYPE_P (t))
     return -1;

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 171e616d04523cd10dbdb6c806309b36c9c64107..70e90482ba09a4d56fcca742546008fb286ae033 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-06-29  Richard Biener  <rguenther@suse.de>
+
+       PR middle-end/71002
+       * g++.dg/torture/pr71002.C: Adjust testcase.
+
 2016-06-29  Jakub Jelinek  <jakub@redhat.com>
 
        PR c/71685

diff --git a/gcc/testsuite/g++.dg/torture/pr71002.C b/gcc/testsuite/g++.dg/torture/pr71002.C
index 8a726809217037a2ce503c3a4d23bcaeceb3e4d2..666da0215a118ef0f6f2db16ed060b416e3f79e5 100644 (file)
--- a/gcc/testsuite/g++.dg/torture/pr71002.C
+++ b/gcc/testsuite/g++.dg/torture/pr71002.C
@@ -16,11 +16,6 @@ struct long_t
   char* pointer;
 };
 
-union long_raw_t {
-  unsigned char data[sizeof(long_t)];
-  struct __attribute__((aligned(alignof(long_t)))) { } align;
-};
-
 struct short_header
 {
   unsigned char is_short : 1;
@@ -35,20 +30,20 @@ struct short_t
 
 union repr_t
 {
-  long_raw_t  r;
+  long_t      r;
   short_t     s;
 
   const short_t& short_repr() const
   { return s; }
 
   const long_t& long_repr() const
-  { return *static_cast<const long_t*>(static_cast<const void*>(&r)); }
+  { return r; }
 
   short_t& short_repr()
   { return s;  }
 
   long_t& long_repr()
-  { return *static_cast<long_t*>(static_cast<void*>(&r)); }
+  { return r; }
 };
 
 class string