From 5c12507f5d0bc080e4f346af99824e039236e61c Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Thu, 20 Jan 2022 14:25:51 +0100 Subject: [PATCH] middle-end/100786 - constant folding from incompatible alias The following avoids us ICEing doing constant folding from variables with aliases of different types. The issue appears both in folding and CCP and FRE can do more fancy stuff to still constant fold cases where the load is smaller than the initializer so defer it to there. 2022-01-20 Richard Biener PR middle-end/100786 * gimple-fold.cc (get_symbol_constant_value): Only return values of compatible type to the symbol. * gcc.dg/torture/pr100786.c: New testcase. --- gcc/gimple-fold.cc | 4 +++- gcc/testsuite/gcc.dg/torture/pr100786.c | 9 +++++++++ 2 files changed, 12 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/torture/pr100786.c diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc index 08d3cc2..3639aa2 100644 --- a/gcc/gimple-fold.cc +++ b/gcc/gimple-fold.cc @@ -291,7 +291,9 @@ get_symbol_constant_value (tree sym) if (val) { val = canonicalize_constructor_val (unshare_expr (val), sym); - if (val && is_gimple_min_invariant (val)) + if (val + && is_gimple_min_invariant (val) + && useless_type_conversion_p (TREE_TYPE (sym), TREE_TYPE (val))) return val; else return NULL_TREE; diff --git a/gcc/testsuite/gcc.dg/torture/pr100786.c b/gcc/testsuite/gcc.dg/torture/pr100786.c new file mode 100644 index 0000000..42f4e48 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr100786.c @@ -0,0 +1,9 @@ +/* { dg-do compile } */ + +const double a = 0; +extern int b __attribute__((alias("a"))); +void inc() { b++; } + +const int a2 = 0; +extern double b2 __attribute__((alias("a2"))); +void inc2() { b2+=1; } -- 2.7.4