[AArch64] Add DAG combine for extract extend pattern

[oota-llvm.git] / lib / Target / AArch64 / AArch64ISelLowering.cpp

diff --git a/lib/Target/AArch64/AArch64ISelLowering.cpp b/lib/Target/AArch64/AArch64ISelLowering.cpp
index 9f5beff121002a5e9103f31b57af3f3762c0406f..2ede39eb7f22dc252387943ea81559d95612563b 100644 (file)
--- a/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -8450,6 +8450,25 @@ static SDValue performExtendCombine(SDNode *N,
     }
   }
 
+  const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+
+  // If we see (any_extend (extract_vector_element v, i)), we can potentially
+  // remove the extend and promote the extract. We can do this if the vector
+  // type is legal and if the result is sign extended from the element type.
+  if (DCI.isAfterLegalizeVectorOps() && N->getOpcode() == ISD::ANY_EXTEND &&
+      N->hasOneUse() && N->use_begin()->getOpcode() == ISD::SIGN_EXTEND_INREG) {
+    const SDValue &M = N->getOperand(0);
+    if (M.getNode()->hasOneUse() && M.getOpcode() == ISD::EXTRACT_VECTOR_ELT) {
+      EVT DstTy = N->getValueType(0);
+      EVT SrcTy = cast<VTSDNode>(N->use_begin()->getOperand(1))->getVT();
+      EVT VecTy = M.getOperand(0).getValueType();
+      EVT ElmTy = VecTy.getScalarType();
+      if (TLI.isTypeLegal(VecTy) && SrcTy == ElmTy)
+        return DAG.getNode(ISD::EXTRACT_VECTOR_ELT, SDLoc(N), DstTy,
+                           M.getOperand(0), M.getOperand(1));
+    }
+  }
+
   // This is effectively a custom type legalization for AArch64.
   //
   // Type legalization will split an extend of a small, legal, type to a larger
@@ -8480,7 +8499,6 @@ static SDValue performExtendCombine(SDNode *N,
   // We're only interested in cleaning things up for non-legal vector types
   // here. If both the source and destination are legal, things will just
   // work naturally without any fiddling.
-  const TargetLowering &TLI = DAG.getTargetLoweringInfo();
   EVT ResVT = N->getValueType(0);
   if (!ResVT.isVector() || TLI.isTypeLegal(ResVT))
     return SDValue();