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| author | Richard Guenther <rguenther@suse.de> | 2008-05-24 09:27:47 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2008-05-24 09:27:47 +0000 |
| commit | 7c88f67af2a876e108a5fa1abd64e87e9e3019bc (patch) | |
| tree | b4e6538253993decb91c5f31f992ce1e251da9bb /gcc/tree-dfa.c | |
| parent | 32101f99491da036f466cd6ba1eed7a2586983af (diff) | |
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tree-dfa.c (refs_may_alias_p): Re-instantiate case that a scalar variable can be only accessed through a...
2008-05-24 Richard Guenther <rguenther@suse.de>
* tree-dfa.c (refs_may_alias_p): Re-instantiate case that
a scalar variable can be only accessed through a pointer
or a union.
From-SVN: r135846
Diffstat (limited to 'gcc/tree-dfa.c')
| -rw-r--r-- | gcc/tree-dfa.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/gcc/tree-dfa.c b/gcc/tree-dfa.c index 02d2139..7e4bb76 100644 --- a/gcc/tree-dfa.c +++ b/gcc/tree-dfa.c @@ -1078,8 +1078,23 @@ refs_may_alias_p (tree ref1, tree ref2) /* If one base is a ref-all pointer weird things are allowed. */ strict_aliasing_applies = (flag_strict_aliasing - && get_alias_set (base1) != 0 - && get_alias_set (base2) != 0); + && (!INDIRECT_REF_P (base1) + || get_alias_set (base1) != 0) + && (!INDIRECT_REF_P (base2) + || get_alias_set (base2) != 0)); + + /* If strict aliasing applies the only way to access a scalar variable + is through a pointer dereference or through a union (gcc extension). */ + if (strict_aliasing_applies + && ((SSA_VAR_P (ref2) + && !AGGREGATE_TYPE_P (TREE_TYPE (ref2)) + && !INDIRECT_REF_P (ref1) + && TREE_CODE (TREE_TYPE (base1)) != UNION_TYPE) + || (SSA_VAR_P (ref1) + && !AGGREGATE_TYPE_P (TREE_TYPE (ref1)) + && !INDIRECT_REF_P (ref2) + && TREE_CODE (TREE_TYPE (base2)) != UNION_TYPE))) + return false; /* If both references are through the same type, or if strict aliasing doesn't apply they are through two same pointers, they do not alias |