2 files changed, 15 insertions, 3 deletions
diff --git a/lib/IR/Constants.cpp b/lib/IR/Constants.cpp
index 4b58599..812692f 100644
--- a/lib/IR/Constants.cpp
+++ b/lib/IR/Constants.cpp
@@ -51,6 +51,15 @@ bool Constant::isNegativeZeroValue() const {
   return isNullValue();
 }
 
+bool Constant::isZeroValue() const {
+  // Floating point values have an explicit -0.0 value.
+  if (const ConstantFP *CFP = dyn_cast<ConstantFP>(this))
+    return CFP->isZero();
+
+  // Otherwise, just use +0.0.
+  return isNullValue();
+}
+
 bool Constant::isNullValue() const {
   // 0 is null.
   if (const ConstantInt *CI = dyn_cast<ConstantInt>(this))
diff --git a/lib/IR/Instructions.cpp b/lib/IR/Instructions.cpp
index 1b5d004..f2e9813 100644
--- a/lib/IR/Instructions.cpp
+++ b/lib/IR/Instructions.cpp
@@ -1926,11 +1926,14 @@ bool BinaryOperator::isNeg(const Value *V) {
   return false;
 }
 
-bool BinaryOperator::isFNeg(const Value *V) {
+bool BinaryOperator::isFNeg(const Value *V, bool IgnoreZeroSign) {
   if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(V))
     if (Bop->getOpcode() == Instruction::FSub)
-      if (Constant* C = dyn_cast<Constant>(Bop->getOperand(0)))
-        return C->isNegativeZeroValue();
+      if (Constant* C = dyn_cast<Constant>(Bop->getOperand(0))) {
+        if (!IgnoreZeroSign)
+          IgnoreZeroSign = cast<Instruction>(V)->hasNoSignedZeros();
+        return !IgnoreZeroSign ? C->isNegativeZeroValue() : C->isZeroValue();
+      }
   return false;
 }