Add support for fast-math flags to the FCmp instruction.

FCmp behaves a lot like a floating-point binary operator in many ways,
and can benefit from fast-math information. Flags such as nsz and nnan
can affect if this fcmp (in combination with a select) can be treated
as a fminnum/fmaxnum operation.

This adds backwards-compatible bitcode support, IR parsing and writing,
LangRef changes and IRBuilder changes. I'll need to audit InstSimplify
and InstCombine in a followup to find places where flags should be
copied.

llvm-svn: 241901

1 files changed, 20 insertions, 2 deletions

diff --git a/llvm/unittests/IR/IRBuilderTest.cpp b/llvm/unittests/IR/IRBuilderTest.cpp
index f3db68feacc..093cbbfc779 100644
--- a/llvm/unittests/IR/IRBuilderTest.cpp
+++ b/llvm/unittests/IR/IRBuilderTest.cpp
@@ -130,8 +130,8 @@ TEST_F(IRBuilderTest, GetIntTy) {
 
 TEST_F(IRBuilderTest, FastMathFlags) {
   IRBuilder<> Builder(BB);
-  Value *F;
-  Instruction *FDiv, *FAdd;
+  Value *F, *FC;
+  Instruction *FDiv, *FAdd, *FCmp;
 
   F = Builder.CreateLoad(GV);
   F = Builder.CreateFAdd(F, F);
@@ -190,6 +190,24 @@ TEST_F(IRBuilderTest, FastMathFlags) {
 
   Builder.clearFastMathFlags();
 
+  FC = Builder.CreateFCmpOEQ(F, F);
+  ASSERT_TRUE(isa<Instruction>(FC));
+  FCmp = cast<Instruction>(FC);
+  EXPECT_FALSE(FCmp->hasAllowReciprocal());
+
+  FMF.clear();
+  FMF.setAllowReciprocal();
+  Builder.SetFastMathFlags(FMF);
+
+  FC = Builder.CreateFCmpOEQ(F, F);
+  EXPECT_TRUE(Builder.getFastMathFlags().any());
+  EXPECT_TRUE(Builder.getFastMathFlags().AllowReciprocal);
+  ASSERT_TRUE(isa<Instruction>(FC));
+  FCmp = cast<Instruction>(FC);
+  EXPECT_TRUE(FCmp->hasAllowReciprocal());
+
+  Builder.clearFastMathFlags();
+
   // To test a copy, make sure that a '0' and a '1' change state. 
   F = Builder.CreateFDiv(F, F);
   ASSERT_TRUE(isa<Instruction>(F));