Skip to content

[SelectionDAG] Fix NaN regression in fma dag-combine. #146592

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jul 1, 2025
+13 −2
Merged

[SelectionDAG] Fix NaN regression in fma dag-combine. #146592

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 1 addition & 2 deletions llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -18087,8 +18087,7 @@ template <class MatchContextClass> SDValue DAGCombiner::visitFMA(SDNode *N) {

// FIXME: use fast math flags instead of Options.UnsafeFPMath
// TODO: Finally migrate away from global TargetOptions.
if (Options.AllowFPOpFusion == FPOpFusion::Fast ||
(Options.NoNaNsFPMath && Options.NoInfsFPMath) ||
if ((Options.NoNaNsFPMath && Options.NoInfsFPMath) ||
(N->getFlags().hasNoNaNs() && N->getFlags().hasNoInfs())) {
if (Options.NoSignedZerosFPMath || N->getFlags().hasNoSignedZeros() ||
(N2CFP && !N2CFP->isExactlyValue(-0.0))) {
Expand Down
12 changes: 12 additions & 0 deletions llvm/test/CodeGen/X86/dag-combiner-fma-folding.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
; RUN: llc -mtriple=x86_64-- --start-before=x86-isel -mattr=+avx,+fma %s -o - | FileCheck %s
; RUN: llc -mtriple=x86_64-- --start-before=x86-isel -mattr=+avx,+fma %s -o - -fp-contract=fast | FileCheck %s

define double @fma_folding(double %x) {
; CHECK-LABEL: fma_folding:
Expand All @@ -20,3 +21,14 @@ define double @fma_no_folding(double %x) {
%fused = call contract nnan ninf double @llvm.fma.f64(double %x, double 0.0, double -0.0)
ret double %fused
}

define double @fma_no_fold_potential_nan(double %x) {
; CHECK-LABEL: fma_no_fold_potential_nan:
; CHECK: # %bb.0:
; CHECK-NEXT: vxorpd %xmm1, %xmm1, %xmm1
; CHECK-NEXT: vfmadd213sd {{.*#+}} xmm0 = (xmm1 * xmm0) + mem
; CHECK-NEXT: retq
%fused = call contract double @llvm.fma.f64(double %x, double 0.0, double 1.0)
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Doesn't need contract flag?

ret double %fused
}

Loading