AMDGPU: Fold fneg into fp_extend

llvm-svn: 291777

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp b/llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
index 94953440eeb..043f613b96c 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
@@ -2899,6 +2899,20 @@ SDValue AMDGPUTargetLowering::performFNegCombine(SDNode *N,
       DAG.ReplaceAllUsesWith(N0, DAG.getNode(ISD::FNEG, SL, VT, Res));
     return Res;
   }
+  case ISD::FP_EXTEND: {
+    SDValue CvtSrc = N0.getOperand(0);
+    if (CvtSrc.getOpcode() == ISD::FNEG) {
+      // (fneg (fp_extend (fneg x))) -> (fp_extend x)
+      return DAG.getNode(ISD::FP_EXTEND, SL, VT, CvtSrc.getOperand(0));
+    }
+
+    if (!N0.hasOneUse())
+      return SDValue();
+
+    // (fneg (fp_extend x)) -> (fp_extend (fneg x))
+    SDValue Neg = DAG.getNode(ISD::FNEG, SL, CvtSrc.getValueType(), CvtSrc);
+    return DAG.getNode(ISD::FP_EXTEND, SL, VT, Neg);
+  }
   default:
     return SDValue();
   }