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| author | Diego Novillo <dnovillo@redhat.com> | 2004-09-15 02:58:28 +0000 |
|---|---|---|
| committer | Diego Novillo <dnovillo@gcc.gnu.org> | 2004-09-14 22:58:28 -0400 |
| commit | 391f9afbd2d6ac8dd691c6d79a8817c63a637ca8 (patch) | |
| tree | 1e2d0774d13dac9492acaed1a577afad8dd177c7 | |
| parent | 67f236204409bd498339b92c65fdb031344e8e36 (diff) | |
| download | gcc-391f9afbd2d6ac8dd691c6d79a8817c63a637ca8.zip gcc-391f9afbd2d6ac8dd691c6d79a8817c63a637ca8.tar.gz gcc-391f9afbd2d6ac8dd691c6d79a8817c63a637ca8.tar.bz2 | |
re PR tree-optimization/17252 (not marking char types as aliasing anything)
PR tree-optimization/17252
* tree-ssa-alias.c (may_alias_p): Don't assume that a
pointer may not point to itself when using relaxed
aliasing rules.
testsuite/ChangeLog
PR tree-optimization/17252
* gcc.c-torture/execute/pr17252.c: New test.
From-SVN: r87529
| -rw-r--r-- | gcc/ChangeLog | 7 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.c-torture/execute/pr17252.c | 24 | ||||
| -rw-r--r-- | gcc/tree-ssa-alias.c | 3 |
4 files changed, 38 insertions, 1 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index ff7e392..a2f169c 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2004-09-14 Diego Novillo <dnovillo@redhat.com> + + PR tree-optimization/17252 + * tree-ssa-alias.c (may_alias_p): Don't assume that a + pointer may not point to itself when using relaxed + aliasing rules. + 2004-09-14 Richard Henderson <rth@redhat.com> PR middle-end/17397 diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 78de08e..61744bf 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2004-09-14 Diego Novillo <dnovillo@redhat.com> + + PR tree-optimization/17252 + * gcc.c-torture/execute/pr17252.c: New test. + 2004-09-14 Andrew Pinski <apinski@apple.com> * g++.dg/tree-ssa/pointer-reference-alias.C: New test. diff --git a/gcc/testsuite/gcc.c-torture/execute/pr17252.c b/gcc/testsuite/gcc.c-torture/execute/pr17252.c new file mode 100644 index 0000000..e31622f --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/execute/pr17252.c @@ -0,0 +1,24 @@ +/* PR 17252. When a char * pointer P takes its own address, storing + into *P changes P itself. */ + +char *a; + +main () +{ + int i; + + /* Make 'a' point to itself. */ + a = (char *)&a; + + /* Assign NULL to 'a' byte by byte. */ + for (i = 0; i < sizeof(char *); i++) + a[i] = 0; + + /* If a's memory tag does not contain 'a' in its alias set, we will + think that this predicate is superfluous and change it to + 'if (1)'. */ + if (a == (char *)&a) + abort (); + + return 0; +} diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c index 65b0d7b..801de5b 100644 --- a/gcc/tree-ssa-alias.c +++ b/gcc/tree-ssa-alias.c @@ -1558,7 +1558,8 @@ may_alias_p (tree ptr, HOST_WIDE_INT mem_alias_set, for PTR's alias set here, not its pointed-to type. We also can't do this check with relaxed aliasing enabled. */ if (POINTER_TYPE_P (TREE_TYPE (var)) - && var_alias_set != 0) + && var_alias_set != 0 + && mem_alias_set != 0) { HOST_WIDE_INT ptr_alias_set = get_alias_set (ptr); if (ptr_alias_set == var_alias_set) |