From 8804e5b5b127b27d099d0c361fa2161d0b13edef Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Thu, 12 Jun 2025 20:22:39 +0200 Subject: [PATCH] recip: Reset range info when replacing sqrt with rsqrt [PR120638] This pass reuses a SSA_NAME on the lhs of sqrt etc. call as lhs of .RSQRT etc. call. The following testcase is miscompiled since my recent ranger cast changes, because we compute (correct) range for sqrtf argument as well as result but then recip pass keeps using that range for the .RQSRT call which returns 1. / sqrt, so the function then returns 0.5f unconditionally. Note, on foo this is a regression from GCC 15, but on bar it regressed already with the r14-536 change. 2025-06-12 Jakub Jelinek PR tree-optimization/120638 * tree-ssa-math-opts.cc (pass_cse_reciprocals::execute): Call reset_flow_sensitive_info on arg1. * gcc.dg/pr120638.c: New test. --- gcc/testsuite/gcc.dg/pr120638.c | 31 +++++++++++++++++++++++++++++++ gcc/tree-ssa-math-opts.cc | 1 + 2 files changed, 32 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/pr120638.c diff --git a/gcc/testsuite/gcc.dg/pr120638.c b/gcc/testsuite/gcc.dg/pr120638.c new file mode 100644 index 00000000000..4a057a02847 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr120638.c @@ -0,0 +1,31 @@ +/* PR tree-optimization/120638 */ +/* { dg-do run } */ +/* { dg-options "-O2 -ffast-math" } */ + +extern float sqrtf (float x); + +__attribute__((noipa)) float +foo (unsigned int s) +{ + return 0.5f / sqrtf (1.f + s); +} + +__attribute__((noipa)) float +bar (float s) +{ + if (s < 0.0 || s > 65535.0f) + __builtin_unreachable (); + return 0.5f / sqrtf (1.f + s); +} + +int +main () +{ + if (__builtin_fabsf (foo (3) - 0.25f) > 0.00390625f + || __builtin_fabsf (foo (15) - 0.125f) > 0.00390625f + || __builtin_fabsf (foo (63) - 0.0625f) > 0.00390625f + || __builtin_fabsf (bar (3.0f) - 0.25f) > 0.00390625f + || __builtin_fabsf (bar (15.0f) - 0.125f) > 0.00390625f + || __builtin_fabsf (bar (63.0f) - 0.0625f) > 0.00390625f) + __builtin_abort (); +} diff --git a/gcc/tree-ssa-math-opts.cc b/gcc/tree-ssa-math-opts.cc index 7e819f37446..4cfcc420fea 100644 --- a/gcc/tree-ssa-math-opts.cc +++ b/gcc/tree-ssa-math-opts.cc @@ -1053,6 +1053,7 @@ pass_cse_reciprocals::execute (function *fun) continue; gimple_replace_ssa_lhs (call, arg1); + reset_flow_sensitive_info (arg1); if (gimple_call_internal_p (call) != (ifn != IFN_LAST)) { auto_vec args; -- 2.47.2