From 654c733fa3f10531f3fd6b6d89e39f28c0075bd6 Mon Sep 17 00:00:00 2001 From: Roger Sayle Date: Sat, 7 Feb 2026 07:50:41 +0000 Subject: [PATCH] PR rtl-optimization/123833: Use of insn attributes in insn_costs corrupts recog_data. Thanks again to Jeff Law and Andrew Pinski. Here's a revised patch that addresses the true underlying cause of PR 128333. recog.cc's cancel_changes was not correctly updating the recog_data cache, which leads to strange (incorrect) behavior in fwprop and ifcvt. 2026-02-07 Roger Sayle Andrew Pinski Jeff Law gcc/ChangeLog PR rtl-optimization/123833 * recog.cc (cancel_changes): Update the recog_data cache if it holds the instruction being changed. gcc/testsuite PR rtl-optimization/123833 * gcc.target/mips/pr123833.c: New test case. Upstream: https://gcc.gnu.org/cgit/gcc/commit/?id=654c733fa3f10531f3fd6b6d89e39f28c0075bd6 Signed-off-by: Bernd Kuhls --- gcc/recog.cc | 6 +++++- gcc/testsuite/gcc.target/mips/pr123833.c | 26 ++++++++++++++++++++++++ 2 files changed, 31 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.target/mips/pr123833.c diff --git a/gcc/recog.cc b/gcc/recog.cc index 48f6b45ec6d..f37e548d6ab 100644 --- a/gcc/recog.cc +++ b/gcc/recog.cc @@ -608,7 +608,11 @@ cancel_changes (int num) else *changes[i].loc = changes[i].old; if (changes[i].object && !MEM_P (changes[i].object)) - INSN_CODE (changes[i].object) = changes[i].old_code; + { + INSN_CODE (changes[i].object) = changes[i].old_code; + if (recog_data.insn == changes[i].object) + recog_data.insn = nullptr; + } } num_changes = num; } diff --git a/gcc/testsuite/gcc.target/mips/pr123833.c b/gcc/testsuite/gcc.target/mips/pr123833.c new file mode 100644 index 00000000000..4d0c9e8eaec --- /dev/null +++ b/gcc/testsuite/gcc.target/mips/pr123833.c @@ -0,0 +1,26 @@ +/* { dg-do compile } */ +/* { dg-options "-O1 -mabi=64 -mhard-float" } */ + +typedef short int16_t; +typedef signed char int8_t; +typedef long long int64_t; +typedef unsigned char uint8_t; +typedef unsigned long long uint64_t; + +#define BS_VEC(type, num) type __attribute__((vector_size(num * sizeof(type)))) +BS_VEC(int8_t, 2) backsmith_pure_0(int64_t); +uint64_t backsmith_pure_4(int16_t BS_ARG_0) +{ + BS_VEC(int16_t, 16) + BS_VAR_0 = __builtin_convertvector( + __builtin_shufflevector(backsmith_pure_0(0), backsmith_pure_0(0), 0, 2, + 2, 3, 2, 1, 2, 3, 0, 2, 0, 0, 2, 2, 0, 1), + BS_VEC(int16_t, 16)); + for (;;) + { + if (__builtin_ctzg((uint8_t)BS_VAR_0[3], BS_ARG_0)) + for (;;); + return 0; + } +} + -- 2.47.3