copyFastMathFlags utility and test case

llvm-svn: 168943

llvm/include/llvm/Instruction.h

@@ -227,6 +227,9 @@ public:
   /// these flats.
   FastMathFlags getFastMathFlags() const;
 
+  /// Copy I's fast-math flags
+  void copyFastMathFlags(const Instruction *I);
+
 private:
   /// hasMetadataHashEntry - Return true if we have an entry in the on-the-side
   /// metadata hash.

llvm/lib/VMCore/Instruction.cpp

@@ -177,6 +177,12 @@ FastMathFlags Instruction::getFastMathFlags() const {
   return cast<FPMathOperator>(this)->getFastMathFlags();
 }
 
+/// Copy I's fast-math flags
+void Instruction::copyFastMathFlags(const Instruction *I) {
+  setFastMathFlags(I->getFastMathFlags());
+}
+
+
 const char *Instruction::getOpcodeName(unsigned OpCode) {
   switch (OpCode) {
   // Terminators

llvm/unittests/VMCore/IRBuilderTest.cpp

@@ -164,6 +164,15 @@ TEST_F(IRBuilderTest, FastMathFlags) {
   FDiv = cast<Instruction>(F);
   EXPECT_TRUE(FDiv->hasAllowReciprocal());
 
+  Builder.clearFastMathFlags();
+
+  F = Builder.CreateFDiv(F, F);
+  ASSERT_TRUE(isa<Instruction>(F));
+  FDiv = cast<Instruction>(F);
+  EXPECT_FALSE(FDiv->getFastMathFlags().any());
+  FDiv->copyFastMathFlags(FAdd);
+  EXPECT_TRUE(FDiv->hasNoNaNs());
+
 }
 
 }