From 565e0e80660dac24e5193873ca07542b99cd8bc3 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Wed, 26 Jul 2023 09:28:10 +0200 Subject: [PATCH] tree-optimization/110799 - fix bug in code hoisting Code hoisting part of GIMPLE PRE failed to adjust the TBAA behavior of common loads in the case the alias set of the ref was the same but the base alias set was not. It also failed to adjust the base behavior, assuming it would match. The following plugs this hole. PR tree-optimization/110799 * tree-ssa-pre.cc (compute_avail): More thoroughly match up TBAA behavior of redundant loads. * gcc.dg/torture/pr110799.c: New testcase. --- gcc/testsuite/gcc.dg/torture/pr110799.c | 46 +++++++++++++++++++++++++ gcc/tree-ssa-pre.cc | 15 +++++--- 2 files changed, 56 insertions(+), 5 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/torture/pr110799.c diff --git a/gcc/testsuite/gcc.dg/torture/pr110799.c b/gcc/testsuite/gcc.dg/torture/pr110799.c new file mode 100644 index 000000000000..53f06f079e12 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr110799.c @@ -0,0 +1,46 @@ +/* { dg-do run { target { { *-*-linux* *-*-gnu* *-*-uclinux* } && mmap } } } */ + +#include +#include +#include + +struct S { + int a; +}; +struct M { + int a, b; +}; + +int __attribute__((noipa)) +f(struct S *p, int c, int d) +{ + int r; + if (c) + { + if (d) + r = p->a; + else + r = ((struct M*)p)->a; + } + else + r = ((struct M*)p)->b; + return r; +} + +int main () +{ + long pgsz = sysconf(_SC_PAGESIZE); + if (pgsz < sizeof (struct M)) + return 0; + char *p = mmap ((void *) 0, 2 * pgsz, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, + -1, 0); + if (p == MAP_FAILED) + return 0; + if (mprotect (p, pgsz, PROT_READ | PROT_WRITE)) + return 0; + struct S *q = (struct S *)(p + pgsz) - 1; + q->a = 42; + if (f (q, 1, 1) != 42) + abort (); + return 0; +} diff --git a/gcc/tree-ssa-pre.cc b/gcc/tree-ssa-pre.cc index e33c5ba80e27..0f2e458395c8 100644 --- a/gcc/tree-ssa-pre.cc +++ b/gcc/tree-ssa-pre.cc @@ -4217,8 +4217,10 @@ compute_avail (function *fun) /* TBAA behavior is an obvious part so make sure that the hashtable one covers this as well by adjusting the ref alias set and its base. */ - if (ref->set == set - || alias_set_subset_of (set, ref->set)) + if ((ref->set == set + || alias_set_subset_of (set, ref->set)) + && (ref->base_set == base_set + || alias_set_subset_of (base_set, ref->base_set))) ; else if (ref1->opcode != ref2->opcode || (ref1->opcode != MEM_REF @@ -4230,16 +4232,19 @@ compute_avail (function *fun) operands.release (); continue; } - else if (alias_set_subset_of (ref->set, set)) + else if (ref->set == set + || alias_set_subset_of (ref->set, set)) { + tree reft = reference_alias_ptr_type (rhs1); ref->set = set; + ref->base_set = set; if (ref1->opcode == MEM_REF) ref1->op0 - = wide_int_to_tree (TREE_TYPE (ref2->op0), + = wide_int_to_tree (reft, wi::to_wide (ref1->op0)); else ref1->op2 - = wide_int_to_tree (TREE_TYPE (ref2->op2), + = wide_int_to_tree (reft, wi::to_wide (ref1->op2)); } else -- 2.47.2