From d45a7192a63eda89c771ab2caaca09e5cdd47a2a Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@intel.com>
Date: Fri, 9 Aug 2019 06:59:53 +0000
Subject: [PATCH] [X86] Remove code that expands truncating stores from
 combineStore.

We shouldn't form trunc stores that need to be expanded now that
we are using widening legalization.

llvm-svn: 368400
---
 lib/Target/X86/X86ISelLowering.cpp | 77 +-----------------------------
 1 file changed, 1 insertion(+), 76 deletions(-)

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index c89eff8ec2c..fa5f788ff9f 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -39922,82 +39922,7 @@ static SDValue combineStore(SDNode *N, SelectionDAG &DAG,
                              dl, Val, St->getBasePtr(),
                              St->getMemoryVT(), St->getMemOperand(), DAG);
 
-    unsigned NumElems = VT.getVectorNumElements();
-    assert(StVT != VT && "Cannot truncate to the same type");
-    unsigned FromSz = VT.getScalarSizeInBits();
-    unsigned ToSz = StVT.getScalarSizeInBits();
-
-    // The truncating store is legal in some cases. For example
-    // vpmovqb, vpmovqw, vpmovqd, vpmovdb, vpmovdw
-    // are designated for truncate store.
-    // In this case we don't need any further transformations.
-    if (TLI.isTruncStoreLegalOrCustom(VT, StVT))
-      return SDValue();
-
-    // From, To sizes and ElemCount must be pow of two
-    if (!isPowerOf2_32(NumElems * FromSz * ToSz)) return SDValue();
-    // We are going to use the original vector elt for storing.
-    // Accumulated smaller vector elements must be a multiple of the store size.
-    if (0 != (NumElems * FromSz) % ToSz) return SDValue();
-
-    unsigned SizeRatio  = FromSz / ToSz;
-
-    assert(SizeRatio * NumElems * ToSz == VT.getSizeInBits());
-
-    // Create a type on which we perform the shuffle
-    EVT WideVecVT = EVT::getVectorVT(*DAG.getContext(),
-            StVT.getScalarType(), NumElems*SizeRatio);
-
-    assert(WideVecVT.getSizeInBits() == VT.getSizeInBits());
-
-    SDValue WideVec = DAG.getBitcast(WideVecVT, St->getValue());
-    SmallVector<int, 8> ShuffleVec(NumElems * SizeRatio, -1);
-    for (unsigned i = 0; i != NumElems; ++i)
-      ShuffleVec[i] = i * SizeRatio;
-
-    // Can't shuffle using an illegal type.
-    if (!TLI.isTypeLegal(WideVecVT))
-      return SDValue();
-
-    SDValue Shuff = DAG.getVectorShuffle(WideVecVT, dl, WideVec,
-                                         DAG.getUNDEF(WideVecVT),
-                                         ShuffleVec);
-    // At this point all of the data is stored at the bottom of the
-    // register. We now need to save it to mem.
-
-    // Find the largest store unit
-    MVT StoreType = MVT::i8;
-    for (MVT Tp : MVT::integer_valuetypes()) {
-      if (TLI.isTypeLegal(Tp) && Tp.getSizeInBits() <= NumElems * ToSz)
-        StoreType = Tp;
-    }
-
-    // On 32bit systems, we can't save 64bit integers. Try bitcasting to F64.
-    if (TLI.isTypeLegal(MVT::f64) && StoreType.getSizeInBits() < 64 &&
-        (64 <= NumElems * ToSz))
-      StoreType = MVT::f64;
-
-    // Bitcast the original vector into a vector of store-size units
-    EVT StoreVecVT = EVT::getVectorVT(*DAG.getContext(),
-            StoreType, VT.getSizeInBits()/StoreType.getSizeInBits());
-    assert(StoreVecVT.getSizeInBits() == VT.getSizeInBits());
-    SDValue ShuffWide = DAG.getBitcast(StoreVecVT, Shuff);
-    SmallVector<SDValue, 8> Chains;
-    SDValue Ptr = St->getBasePtr();
-
-    // Perform one or more big stores into memory.
-    for (unsigned i=0, e=(ToSz*NumElems)/StoreType.getSizeInBits(); i!=e; ++i) {
-      SDValue SubVec = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl,
-                                   StoreType, ShuffWide,
-                                   DAG.getIntPtrConstant(i, dl));
-      SDValue Ch =
-          DAG.getStore(St->getChain(), dl, SubVec, Ptr, St->getPointerInfo(),
-                       St->getAlignment(), St->getMemOperand()->getFlags());
-      Ptr = DAG.getMemBasePlusOffset(Ptr, StoreType.getStoreSize(), dl);
-      Chains.push_back(Ch);
-    }
-
-    return DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Chains);
+    return SDValue();
   }
 
   // Turn load->store of MMX types into GPR load/stores.  This avoids clobbering