[llvm] [InstCombine] Use `canIgnoreSignBitOfZero` in `spf->minmax` fold (PR #141914)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Yingwei Zheng (dtcxzyw)

<details>
<summary>Changes</summary>

Alive2: https://alive2.llvm.org/ce/z/dCZBB_
Fix remaining regressions caused by https://github.com/llvm/llvm-project/pull/141010.


---
Full diff: https://github.com/llvm/llvm-project/pull/141914.diff


3 Files Affected:

- (modified) llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp (+4-1) 
- (modified) llvm/test/Transforms/InstCombine/minmax-fp.ll (+1-2) 
- (added) minmax () 


``````````diff
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 3882d4cb59e01..a791fc5db6698 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -3929,7 +3929,10 @@ Instruction *InstCombinerImpl::visitSelectInst(SelectInst &SI) {
 
     // Canonicalize select of FP values where NaN and -0.0 are not valid as
     // minnum/maxnum intrinsics.
-    if (SIFPOp->hasNoNaNs() && SIFPOp->hasNoSignedZeros()) {
+    if (SIFPOp->hasNoNaNs() &&
+        (SIFPOp->hasNoSignedZeros() ||
+         (SIFPOp->hasOneUse() &&
+          canIgnoreSignBitOfZero(*SIFPOp->use_begin())))) {
       Value *X, *Y;
       if (match(&SI, m_OrdOrUnordFMax(m_Value(X), m_Value(Y)))) {
         Value *BinIntr =
diff --git a/llvm/test/Transforms/InstCombine/minmax-fp.ll b/llvm/test/Transforms/InstCombine/minmax-fp.ll
index a8470a20365e9..4ae6905404bbd 100644
--- a/llvm/test/Transforms/InstCombine/minmax-fp.ll
+++ b/llvm/test/Transforms/InstCombine/minmax-fp.ll
@@ -174,8 +174,7 @@ define i8 @t11(float %a, float %b) {
 ; Either operand could be NaN, but nnan modifier applied.
 define i8 @t12(float %a, float %b) {
 ; CHECK-LABEL: @t12(
-; CHECK-NEXT:    [[DOTINV:%.*]] = fcmp nnan oge float [[B:%.*]], [[A:%.*]]
-; CHECK-NEXT:    [[DOTV:%.*]] = select nnan i1 [[DOTINV]], float [[A]], float [[B]]
+; CHECK-NEXT:    [[DOTV:%.*]] = call nnan float @llvm.minnum.f32(float [[B:%.*]], float [[A:%.*]])
 ; CHECK-NEXT:    [[TMP1:%.*]] = fptosi float [[DOTV]] to i8
 ; CHECK-NEXT:    ret i8 [[TMP1]]
 ;
diff --git a/minmax b/minmax
new file mode 100644
index 0000000000000..e69de29bb2d1d

``````````

</details>


https://github.com/llvm/llvm-project/pull/141914