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, 5 insertions, 1 deletions

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 622f7eaf0784..8a3ed18ffebb 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -1759,13 +1759,17 @@ static void WriteInstruction(const Instruction &I, unsigned InstID,
     pushValue(I.getOperand(2), InstID, Vals, VE);
     break;
   case Instruction::ICmp:
-  case Instruction::FCmp:
+  case Instruction::FCmp: {
     // compare returning Int1Ty or vector of Int1Ty
     Code = bitc::FUNC_CODE_INST_CMP2;
     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
     pushValue(I.getOperand(1), InstID, Vals, VE);
     Vals.push_back(cast<CmpInst>(I).getPredicate());
+    uint64_t Flags = GetOptimizationFlags(&I);
+    if (Flags != 0)
+      Vals.push_back(Flags);
     break;
+  }
 
   case Instruction::Ret:
     {