[llvm] 7f4429c - ValueTracking: Teach CannotBeOrderedLessThanZero about copysign

[Matt Arsenault via llvm-commits]

Author: Matt Arsenault
Date: 2022-12-06T09:01:39-05:00
New Revision: 7f4429c0e48b9c7d31ff587604707cf10d3acdf0

URL: https://github.com/llvm/llvm-project/commit/7f4429c0e48b9c7d31ff587604707cf10d3acdf0
DIFF: https://github.com/llvm/llvm-project/commit/7f4429c0e48b9c7d31ff587604707cf10d3acdf0.diff

LOG: ValueTracking: Teach CannotBeOrderedLessThanZero about copysign

Added: 
    

Modified: 
    llvm/lib/Analysis/ValueTracking.cpp
    llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index bc63368bcc2d2..8e97637a858a3 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -3694,7 +3694,10 @@ static bool cannotBeOrderedLessThanZeroImpl(const Value *V,
     case Intrinsic::exp2:
     case Intrinsic::fabs:
       return true;
-
+    case Intrinsic::copysign:
+      // Only the sign operand matters.
+      return cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, true,
+                                             Depth + 1);
     case Intrinsic::sqrt:
       // sqrt(x) is always >= -0 or NaN.  Moreover, sqrt(x) == -0 iff x == -0.
       if (!SignBitOnly)

diff  --git a/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll b/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll
index 0c0f7b6b509fb..a2aac2d723d9a 100644
--- a/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll
+++ b/llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll
@@ -279,6 +279,7 @@ define float @PR22688(float %x) {
 declare float @llvm.fabs.f32(float)
 declare float @llvm.canonicalize.f32(float)
 declare float @llvm.arithmetic.fence.f32(float)
+declare float @llvm.copysign.f32(float, float)
 declare <2 x float> @llvm.fabs.v2f32(<2 x float>)
 declare float @llvm.sqrt.f32(float)
 declare float @llvm.maxnum.f32(float, float)
@@ -955,3 +956,37 @@ define i1 @arithmetic_fence_unknown_positive(float %unknown) {
   %cmp = fcmp nnan oge float %known.positive, 0.0
   ret i1 %cmp
 }
+
+define i1 @copysign_known_positive_maybe_neg0(float %unknown, float %sign) {
+; CHECK-LABEL: @copysign_known_positive_maybe_neg0(
+; CHECK-NEXT:    [[SQRT:%.*]] = call nnan ninf float @llvm.sqrt.f32(float [[SIGN:%.*]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[UNKNOWN:%.*]], float [[SQRT]])
+; CHECK-NEXT:    [[CMP:%.*]] = fcmp nnan oge float [[COPYSIGN]], 0.000000e+00
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %sqrt = call ninf nnan float @llvm.sqrt.f32(float %sign)
+  %copysign = call float @llvm.copysign.f32(float %unknown, float %sqrt)
+  %cmp = fcmp nnan oge float %copysign, 0.0
+  ret i1 %cmp
+}
+
+define i1 @copysign_known_positive(float %unknown, float %sign) {
+; CHECK-LABEL: @copysign_known_positive(
+; CHECK-NEXT:    ret i1 true
+;
+  %sqrt = call ninf nnan nsz float @llvm.sqrt.f32(float %sign)
+  %copysign = call float @llvm.copysign.f32(float %unknown, float %sqrt)
+  %cmp = fcmp nnan oge float %copysign, 0.0
+  ret i1 %cmp
+}
+
+define i1 @copysign_unknown_positive(float %unknown, float %unknown.sign) {
+; CHECK-LABEL: @copysign_unknown_positive(
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[UNKNOWN:%.*]], float [[UNKNOWN_SIGN:%.*]])
+; CHECK-NEXT:    [[CMP:%.*]] = fcmp nnan oge float [[COPYSIGN]], 0.000000e+00
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %copysign = call float @llvm.copysign.f32(float %unknown, float %unknown.sign)
+  %cmp = fcmp nnan oge float %copysign, 0.0
+  ret i1 %cmp
+}