Allow constant folding of round function whenever feasible

llvm-svn: 203198

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index ff1124ad878..8ff79d6f625 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -1196,6 +1196,7 @@ bool llvm::canConstantFoldCallTo(const Function *F) {
   case Intrinsic::fma:
   case Intrinsic::fmuladd:
   case Intrinsic::copysign:
+  case Intrinsic::round:
   case Intrinsic::sadd_with_overflow:
   case Intrinsic::uadd_with_overflow:
   case Intrinsic::ssub_with_overflow:
@@ -1345,6 +1346,12 @@ static Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID,
       if (!Ty->isHalfTy() && !Ty->isFloatTy() && !Ty->isDoubleTy())
         return 0;
 
+      if (IntrinsicID == Intrinsic::round) {
+        APFloat V = Op->getValueAPF();
+        V.roundToIntegral(APFloat::rmNearestTiesToAway);
+        return ConstantFP::get(Ty->getContext(), V);
+      }
+
       /// We only fold functions with finite arguments. Folding NaN and inf is
       /// likely to be aborted with an exception anyway, and some host libms
       /// have known errors raising exceptions.