[ValueTracking] add logic for known-never-nan with minnum/maxnum

From the LangRef: "Returns NaN only if both operands are NaN."

llvm-svn: 360206

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 7c16b21..5457544 100644 (file)
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -3136,6 +3136,11 @@ bool llvm::isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI,
     case Intrinsic::sqrt:
       return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) &&
              CannotBeOrderedLessThanZero(II->getArgOperand(0), TLI);
+    case Intrinsic::minnum:
+    case Intrinsic::maxnum:
+      // If either operand is not NaN, the result is not NaN.
+      return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) ||
+             isKnownNeverNaN(II->getArgOperand(1), TLI, Depth + 1);
     default:
       return false;
     }

diff --git a/llvm/test/Transforms/InstSimplify/floating-point-compare.ll b/llvm/test/Transforms/InstSimplify/floating-point-compare.ll
index a2785fa..1a1afbe 100644 (file)
--- a/llvm/test/Transforms/InstSimplify/floating-point-compare.ll
+++ b/llvm/test/Transforms/InstSimplify/floating-point-compare.ll
@@ -487,9 +487,7 @@ define i1 @orderedLessZeroMaximum(float, float) {
 
 define i1 @minnum_non_nan(float %x) {
 ; CHECK-LABEL: @minnum_non_nan(
-; CHECK-NEXT:    [[MIN:%.*]] = call float @llvm.minnum.f32(float 5.000000e-01, float [[X:%.*]])
-; CHECK-NEXT:    [[CMP:%.*]] = fcmp ord float [[MIN]], 1.000000e+00
-; CHECK-NEXT:    ret i1 [[CMP]]
+; CHECK-NEXT:    ret i1 true
 ;
   %min = call float @llvm.minnum.f32(float 0.5, float %x)
   %cmp = fcmp ord float %min, 1.0
@@ -498,9 +496,7 @@ define i1 @minnum_non_nan(float %x) {
 
 define i1 @maxnum_non_nan(float %x) {
 ; CHECK-LABEL: @maxnum_non_nan(
-; CHECK-NEXT:    [[MIN:%.*]] = call float @llvm.maxnum.f32(float [[X:%.*]], float 4.200000e+01)
-; CHECK-NEXT:    [[CMP:%.*]] = fcmp uno float [[MIN]], 1.200000e+01
-; CHECK-NEXT:    ret i1 [[CMP]]
+; CHECK-NEXT:    ret i1 false
 ;
   %min = call float @llvm.maxnum.f32(float %x, float 42.0)
   %cmp = fcmp uno float %min, 12.0