Add a roundToIntegral method to APFloat, which can be parameterized over various rounding modes. Use this to implement SelectionDAG constant folding of FFLOOR, FCEIL, and FTRUNC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161807 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 0 deletions

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index d96f275d50..f4fe8927f6 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2483,6 +2483,24 @@ SDValue SelectionDAG::getNode(unsigned Opcode, DebugLoc DL,
       case ISD::FABS:
         V.clearSign();
         return getConstantFP(V, VT);
+      case ISD::FCEIL: {
+        APFloat::opStatus fs = V.roundToIntegral(APFloat::rmTowardPositive);
+        if (fs == APFloat::opOK || fs == APFloat::opInexact)
+          return getConstantFP(V, VT);
+        break;
+      }
+      case ISD::FTRUNC: {
+        APFloat::opStatus fs = V.roundToIntegral(APFloat::rmTowardZero);
+        if (fs == APFloat::opOK || fs == APFloat::opInexact)
+          return getConstantFP(V, VT);
+        break;
+      }
+      case ISD::FFLOOR: {
+        APFloat::opStatus fs = V.roundToIntegral(APFloat::rmTowardNegative);
+        if (fs == APFloat::opOK || fs == APFloat::opInexact)
+          return getConstantFP(V, VT);
+        break;
+      }
       case ISD::FP_EXTEND: {
         bool ignored;
         // This can return overflow, underflow, or inexact; we don't care.