[llvm] 74e9952 - [X86][SSE] splitAndLowerShuffle - use splitVector helper. NFC.

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2020-05-03T11:26:51+01:00
New Revision: 74e9952c8ecdf7c4869b945470f8f89978a879ca

URL: https://github.com/llvm/llvm-project/commit/74e9952c8ecdf7c4869b945470f8f89978a879ca
DIFF: https://github.com/llvm/llvm-project/commit/74e9952c8ecdf7c4869b945470f8f89978a879ca.diff

LOG: [X86][SSE] splitAndLowerShuffle - use splitVector helper. NFC.

The splitVector helper uses extractSubVector which splits build vectors like we do here, so avoid reimplementing it.

splitVector could easily be extended to peek through bitcasts as well but I'd prefer to keep this commit NFC.

Added: 
    

Modified: 
    llvm/lib/Target/X86/X86ISelLowering.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index ed1fd966a22b..3db6a9173fb2 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -15138,37 +15138,13 @@ static SDValue splitAndLowerShuffle(const SDLoc &DL, MVT VT, SDValue V1,
   int NumElements = VT.getVectorNumElements();
   int SplitNumElements = NumElements / 2;
   MVT ScalarVT = VT.getVectorElementType();
-  MVT SplitVT = MVT::getVectorVT(ScalarVT, NumElements / 2);
+  MVT SplitVT = MVT::getVectorVT(ScalarVT, SplitNumElements);
 
-  // Rather than splitting build-vectors, just build two narrower build
-  // vectors. This helps shuffling with splats and zeros.
+  // Use splitVector/extractSubVector so that split build-vectors just build two
+  // narrower build vectors. This helps shuffling with splats and zeros.
   auto SplitVector = [&](SDValue V) {
-    V = peekThroughBitcasts(V);
-
-    MVT OrigVT = V.getSimpleValueType();
-    int OrigNumElements = OrigVT.getVectorNumElements();
-    int OrigSplitNumElements = OrigNumElements / 2;
-    MVT OrigScalarVT = OrigVT.getVectorElementType();
-    MVT OrigSplitVT = MVT::getVectorVT(OrigScalarVT, OrigNumElements / 2);
-
     SDValue LoV, HiV;
-
-    auto *BV = dyn_cast<BuildVectorSDNode>(V);
-    if (!BV) {
-      LoV = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, OrigSplitVT, V,
-                        DAG.getIntPtrConstant(0, DL));
-      HiV = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, OrigSplitVT, V,
-                        DAG.getIntPtrConstant(OrigSplitNumElements, DL));
-    } else {
-
-      SmallVector<SDValue, 16> LoOps, HiOps;
-      for (int i = 0; i < OrigSplitNumElements; ++i) {
-        LoOps.push_back(BV->getOperand(i));
-        HiOps.push_back(BV->getOperand(i + OrigSplitNumElements));
-      }
-      LoV = DAG.getBuildVector(OrigSplitVT, DL, LoOps);
-      HiV = DAG.getBuildVector(OrigSplitVT, DL, HiOps);
-    }
+    std::tie(LoV, HiV) = splitVector(peekThroughBitcasts(V), DAG, DL);
     return std::make_pair(DAG.getBitcast(SplitVT, LoV),
                           DAG.getBitcast(SplitVT, HiV));
   };