From 5c95bf945c632925efba86dd5dceccdb9da8884c Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Wed, 29 Nov 2023 12:26:50 +0100 Subject: fold-const: Fix up multiple_of_p [PR112733] We ICE on the following testcase when wi::multiple_of_p is called on widest_int 1 and -128 with UNSIGNED. I still need to work on the actual wide-int.cc issue, the latest patch attached to the PR regressed bitint-{38,39}.c, so will need to debug that, but there is a clear bug on the fold-const.cc side as well - widest_int is a signed representation by definition, using UNSIGNED with it certainly doesn't match what was intended, because -128 as the second operand effectively means unsigned 131072 bit 0xfffff............ffff80 integer, not the signed char -128 that appeared in the source. In the INTEGER_CST case a few lines above this we already use case INTEGER_CST: if (TREE_CODE (bottom) != INTEGER_CST || integer_zerop (bottom)) return false; return wi::multiple_of_p (wi::to_widest (top), wi::to_widest (bottom), SIGNED); so I think using SIGNED with widest_int is best there (compared to the other choices in the PR). 2023-11-29 Jakub Jelinek PR middle-end/112733 * fold-const.cc (multiple_of_p): Pass SIGNED rather than UNSIGNED for wi::multiple_of_p on widest_int arguments. * gcc.dg/pr112733.c: New test. --- gcc/fold-const.cc | 2 +- gcc/testsuite/gcc.dg/pr112733.c | 16 ++++++++++++++++ 2 files changed, 17 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/pr112733.c diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc index dff09b8..2692b98 100644 --- a/gcc/fold-const.cc +++ b/gcc/fold-const.cc @@ -14563,7 +14563,7 @@ multiple_of_p (tree type, const_tree top, const_tree bottom, bool nowrap) && TREE_CODE (op2) == INTEGER_CST && integer_pow2p (bottom) && wi::multiple_of_p (wi::to_widest (op2), - wi::to_widest (bottom), UNSIGNED)) + wi::to_widest (bottom), SIGNED)) return true; op1 = gimple_assign_rhs1 (stmt); diff --git a/gcc/testsuite/gcc.dg/pr112733.c b/gcc/testsuite/gcc.dg/pr112733.c new file mode 100644 index 0000000..d6f99f7 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr112733.c @@ -0,0 +1,16 @@ +/* PR middle-end/112733 */ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +signed char a, c; +short b; + +void +foo (void) +{ + signed char *e = &a; + c = foo != 0; + *e &= c; + for (; b; --b) + *e &= -128; +} -- cgit v1.1