From bb406a6aea336966681927a27f54ee89c4fd4ea1 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Mon, 24 Apr 2023 13:31:07 +0200 Subject: [PATCH] rtl-optimization/109585 - alias analysis typo When r10-514-gc6b84edb6110dd2b4fb improved access path analysis it introduced a typo that triggers when there's an access to a trailing array in the first access path leading to false disambiguation. PR rtl-optimization/109585 * tree-ssa-alias.cc (aliasing_component_refs_p): Fix typo. * gcc.dg/torture/pr109585.c: New testcase. (cherry picked from commit 6d4bd27a60447c7505cb4783e675e98a191a8904) --- gcc/testsuite/gcc.dg/torture/pr109585.c | 33 +++++++++++++++++++++++++ gcc/tree-ssa-alias.cc | 2 +- 2 files changed, 34 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/torture/pr109585.c --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr109585.c @@ -0,0 +1,33 @@ +/* { dg-do run } */ + +#include + +struct P { + long v; + struct P *n; +}; + +struct F { + long x; + struct P fam[]; +}; + +int __attribute__((noipa)) +f(struct F *f, int i) +{ + struct P *p = f->fam; + asm("" : "+r"(f): "r"(p)); + p->v = 0; + p->n = 0; + return f->fam->n != 0; +} + +int +main() +{ + struct F *m = malloc (sizeof (long) + 2 * sizeof (struct P)); + m->fam[0].n = &m->fam[1]; + if (f (m, 0)) + abort (); + return 0; +} --- a/gcc/tree-ssa-alias.cc +++ b/gcc/tree-ssa-alias.cc @@ -1330,7 +1330,7 @@ aliasing_component_refs_p (tree ref1, /* If we didn't find a common base, try the other way around. */ if (cmp_outer <= 0 || (end_struct_ref1 - && compare_type_sizes (TREE_TYPE (end_struct_ref1), type1) <= 0)) + && compare_type_sizes (TREE_TYPE (end_struct_ref1), type2) <= 0)) { int res = aliasing_component_refs_walk (ref2, type2, base2, offset2, max_size2,