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| author | Richard Biener <rguenther@suse.de> | 2022-06-15 11:27:31 +0200 |
|---|---|---|
| committer | Richard Biener <rguenther@suse.de> | 2022-06-15 13:15:11 +0200 |
| commit | 8c2733e16ec1c0cdda3db4cdc5ad158a96a658e8 (patch) | |
| tree | 89f4994f3979b631a0717a5766d87d18dfe8fc07 | |
| parent | edb9330c29fe8a0a0b76df6fafd6a223a4d0e41f (diff) | |
| download | gcc-8c2733e16ec1c0cdda3db4cdc5ad158a96a658e8.zip gcc-8c2733e16ec1c0cdda3db4cdc5ad158a96a658e8.tar.gz gcc-8c2733e16ec1c0cdda3db4cdc5ad158a96a658e8.tar.bz2 | |
tree-optimization/105971 - less surprising refs_may_alias_p_2
When DSE asks whether __real a is using __imag a it gets a surprising
result when a is a FUNCTION_DECL. The following makes sure this case
is less surprising to callers but keeping the bail-out for the
non-decl case where it is true that PTA doesn't track aliases to code
correctly.
2022-06-15 Richard Biener <rguenther@suse.de>
PR tree-optimization/105971
* tree-ssa-alias.cc (refs_may_alias_p_2): Put bail-out for
FUNCTION_DECL and LABEL_DECL refs after decl-decl disambiguation
to leak less surprising alias results.
* gcc.dg/torture/pr106971.c: New testcase.
| -rw-r--r-- | gcc/testsuite/gcc.dg/torture/pr106971.c | 12 | ||||
| -rw-r--r-- | gcc/tree-ssa-alias.cc | 18 |
2 files changed, 21 insertions, 9 deletions
diff --git a/gcc/testsuite/gcc.dg/torture/pr106971.c b/gcc/testsuite/gcc.dg/torture/pr106971.c new file mode 100644 index 0000000..33f2105 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr106971.c @@ -0,0 +1,12 @@ +/* { dg-do compile } */ + +void a() +{ + int b; + int c; + int d = (__INTPTR_TYPE__)a; + _Complex float *e = (_Complex float *)a; + for (;;) { + (*e += d) / b ?: 0; + } +} diff --git a/gcc/tree-ssa-alias.cc b/gcc/tree-ssa-alias.cc index 063f189..b1e7a2d 100644 --- a/gcc/tree-ssa-alias.cc +++ b/gcc/tree-ssa-alias.cc @@ -2397,15 +2397,6 @@ refs_may_alias_p_2 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p) || CONSTANT_CLASS_P (base2)) return false; - /* We can end up referring to code via function and label decls. - As we likely do not properly track code aliases conservatively - bail out. */ - if (TREE_CODE (base1) == FUNCTION_DECL - || TREE_CODE (base1) == LABEL_DECL - || TREE_CODE (base2) == FUNCTION_DECL - || TREE_CODE (base2) == LABEL_DECL) - return true; - /* Two volatile accesses always conflict. */ if (ref1->volatile_p && ref2->volatile_p) @@ -2432,6 +2423,15 @@ refs_may_alias_p_2 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p) ref2ref, base2, offset2, max_size2, ref2->size); + /* We can end up referring to code via function and label decls. + As we likely do not properly track code aliases conservatively + bail out. */ + if (TREE_CODE (base1) == FUNCTION_DECL + || TREE_CODE (base1) == LABEL_DECL + || TREE_CODE (base2) == FUNCTION_DECL + || TREE_CODE (base2) == LABEL_DECL) + return true; + /* Handle restrict based accesses. ??? ao_ref_base strips inner MEM_REF [&decl], recover from that here. */ |