From 4653cae5b8dc090912f262572d0105f27ec2c83b Mon Sep 17 00:00:00 2001
From: Richard Guenther <rguenther@suse.de>
Date: Wed, 11 Jun 2008 18:19:28 +0000
Subject: [PATCH] alias.c (get_alias_set): Use the element alias-set for
arrays.
2008-06-11 Richard Guenther <rguenther@suse.de>
* alias.c (get_alias_set): Use the element alias-set for arrays.
(record_component_aliases): For arrays and vectors do nothing.
* c-common.c (strict_aliasing_warning): Handle the cases
of alias set zero explicitly.
* Makefile.in (dfp.o-warn): Add -Wno-error.
From-SVN: r136679
---
gcc/ChangeLog | 8 ++++++++
gcc/Makefile.in | 2 ++
gcc/alias.c | 20 +++++++++++++++-----
gcc/c-common.c | 3 ++-
4 files changed, 27 insertions(+), 6 deletions(-)
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b5c210ccae53..95a86b0d398c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2008-06-11 Richard Guenther <rguenther@suse.de>
+
+ * alias.c (get_alias_set): Use the element alias-set for arrays.
+ (record_component_aliases): For arrays and vectors do nothing.
+ * c-common.c (strict_aliasing_warning): Handle the cases
+ of alias set zero explicitly.
+ * Makefile.in (dfp.o-warn): Add -Wno-error.
+
2008-06-11 Joseph Myers <joseph@codesourcery.com>
* config.gcc (all_defaults): Add arch_32 arch_64 cpu_32 cpu_64
diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 7069728a1289..47a45a1f4a2e 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -187,6 +187,8 @@ GCC_WARN_CFLAGS = $(LOOSE_WARN) $($(@D)-warn) $(NOCOMMON_FLAG) $($@-warn)
build/gengtype-lex.o-warn = -Wno-error
# SYSCALLS.c misses prototypes
SYSCALLS.c.X-warn = -Wno-strict-prototypes -Wno-error
+# dfp.c contains alias violations
+dfp.o-warn = -Wno-error
# All warnings have to be shut off in stage1 if the compiler used then
# isn't gcc; configure determines that. WARN_CFLAGS will be either
diff --git a/gcc/alias.c b/gcc/alias.c
index 06ad867d3035..ec2d053362c3 100644
--- a/gcc/alias.c
+++ b/gcc/alias.c
@@ -640,6 +640,18 @@ get_alias_set (tree t)
else if (TREE_CODE (t) == VECTOR_TYPE)
set = get_alias_set (TREE_TYPE (t));
+ /* Unless the language specifies otherwise, treat array types the
+ same as their components. This avoids the asymmetry we get
+ through recording the components. Consider accessing a
+ character(kind=1) through a reference to a character(kind=1)[1:1].
+ Or consider if we want to assign integer(kind=4)[0:D.1387] and
+ integer(kind=4)[4] the same alias set or not.
+ Just be pragmatic here and make sure the array and its element
+ type get the same alias set assigned. */
+ else if (TREE_CODE (t) == ARRAY_TYPE
+ && !TYPE_NONALIASED_COMPONENT (t))
+ set = get_alias_set (TREE_TYPE (t));
+
else
/* Otherwise make a new alias set for this type. */
set = new_alias_set ();
@@ -747,11 +759,6 @@ record_component_aliases (tree type)
switch (TREE_CODE (type))
{
- case ARRAY_TYPE:
- if (!TYPE_NONALIASED_COMPONENT (type))
- record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
- break;
-
case RECORD_TYPE:
case UNION_TYPE:
case QUAL_UNION_TYPE:
@@ -775,6 +782,9 @@ record_component_aliases (tree type)
record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
break;
+ /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
+ element type. */
+
default:
break;
}
diff --git a/gcc/c-common.c b/gcc/c-common.c
index 377db5708d06..b783c5340123 100644
--- a/gcc/c-common.c
+++ b/gcc/c-common.c
@@ -1093,7 +1093,8 @@ strict_aliasing_warning (tree otype, tree type, tree expr)
get_alias_set (TREE_TYPE (TREE_OPERAND (expr, 0)));
alias_set_type set2 = get_alias_set (TREE_TYPE (type));
- if (!alias_sets_conflict_p (set1, set2))
+ if (set1 != set2 && set2 != 0
+ && (set1 == 0 || !alias_sets_conflict_p (set1, set2)))
{
warning (OPT_Wstrict_aliasing, "dereferencing type-punned "
"pointer will break strict-aliasing rules");
--
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