[X86] Move splat addends from the gather/scatter index operand to the base address

[pengfei]

Summary

This can avoid a vector add and a constant pool load. Or an explicit broadcast in case of non-constant.

Also reverse the transform any time we encounter a constant index addend that can't be moved to base. In that case pull the constant from base into the index. This reduces code size needed for the displacement since we needed the index add anyway. Limit this to scale of 1 to avoid divisibility and wrap issues.

Authored by Craig.

[craig.topper]

llvm/lib/Target/X86/X86ISelDAGToDAG.cpp

2503

Please run clang-format

2526

"gather scatter" -> "gather/scatter" or "gather or scatter"

llvm/lib/Target/X86/X86ISelLowering.cpp

50268

Drop the comma after possible.

"case case" -> "case,"

[pengfei]

Address review comments. Thanks Craig.

[craig.topper]

LGTM

llvm/lib/Target/X86/X86ISelDAGToDAG.cpp

private:
     bool matchLoadInAddress(LoadSDNode *N, X86ISelAddressMode &AM,
                             bool AllowSegmentRegForX32 = false);
     bool matchWrapper(SDValue N, X86ISelAddressMode &AM);
     bool matchAddress(SDValue N, X86ISelAddressMode &AM);
     bool matchVectorAddress(SDValue N, X86ISelAddressMode &AM);
     bool matchAdd(SDValue &N, X86ISelAddressMode &AM, unsigned Depth);
     bool matchAddressRecursively(SDValue N, X86ISelAddressMode &AM,
                                  unsigned Depth);
+    bool matchVectorAddressRecursively(SDValue N, X86ISelAddressMode &AM,
+                                       unsigned Depth);
     bool matchAddressBase(SDValue N, X86ISelAddressMode &AM);
     bool selectAddr(SDNode *Parent, SDValue N, SDValue &Base,
                     SDValue &Scale, SDValue &Index, SDValue &Disp,
                     SDValue &Segment);
     bool selectVectorAddr(MemSDNode *Parent, SDValue BasePtr, SDValue IndexOp,
                           SDValue ScaleOp, SDValue &Base, SDValue &Scale,
                           SDValue &Index, SDValue &Disp, SDValue &Segment);
     bool selectMOV64Imm32(SDValue N, SDValue &Imm);
bool X86DAGToDAGISel::matchAddressBase(SDValue N, X86ISelAddressMode &AM) {
   }
 
   // Default, generate it as a register.
   AM.BaseType = X86ISelAddressMode::RegBase;
   AM.Base_Reg = N;
   return false;
 }
 
-/// Helper for selectVectorAddr. Handles things that can be folded into a
-/// gather scatter address. The index register and scale should have already
-/// been handled.
-bool X86DAGToDAGISel::matchVectorAddress(SDValue N, X86ISelAddressMode &AM) {
+bool X86DAGToDAGISel::matchVectorAddressRecursively(SDValue N,
+                                                    X86ISelAddressMode &AM,
+                                                    unsigned Depth) {
+  SDLoc dl(N);
+  LLVM_DEBUG({
+    dbgs() << "MatchVectorAddress: ";
+    AM.dump(CurDAG);
+  });
+  // Limit recursion.
+  if (Depth > 5)
+    return matchAddressBase(N, AM);
+
   // TODO: Support other operations.
   switch (N.getOpcode()) {
   case ISD::Constant: {
     uint64_t Val = cast<ConstantSDNode>(N)->getSExtValue();
     if (!foldOffsetIntoAddress(Val, AM))
       return false;
     break;
   }
   case X86ISD::Wrapper:
     if (!matchWrapper(N, AM))
       return false;
     break;
+  case ISD::ADD: {
+    // Add an artificial use to this node so that we can keep track of
+    // it if it gets CSE'd with a different node.
+    HandleSDNode Handle(N);
+
+    X86ISelAddressMode Backup = AM;
+    if (!matchVectorAddressRecursively(N.getOperand(0), AM,
+                                       Depth+1) &&
+        !matchVectorAddressRecursively(Handle.getValue().getOperand(1), AM,
+                                       Depth+1))
+      return false;
+    AM = Backup;
+
+    // Try again after commuting the operands.
+    if (!matchVectorAddressRecursively(Handle.getValue().getOperand(1), AM,
+                                       Depth+1) &&
+        !matchVectorAddressRecursively(Handle.getValue().getOperand(0), AM,
+                                       Depth+1))
+      return false;
+    AM = Backup;
+
+    N = Handle.getValue();
+  }
   }
 
   return matchAddressBase(N, AM);
 }
 
+/// Helper for selectVectorAddr. Handles things that can be folded into a
+/// gather scatter address. The index register and scale should have already
+/// been handled.
+bool X86DAGToDAGISel::matchVectorAddress(SDValue N, X86ISelAddressMode &AM) {
+  return matchVectorAddressRecursively(N, AM, 0);
+}
+
 bool X86DAGToDAGISel::selectVectorAddr(MemSDNode *Parent, SDValue BasePtr,
                                        SDValue IndexOp, SDValue ScaleOp,
                                        SDValue &Base, SDValue &Scale,
                                        SDValue &Index, SDValue &Disp,
                                        SDValue &Segment) {
   X86ISelAddressMode AM;
   AM.IndexReg = IndexOp;
   AM.Scale = cast<ConstantSDNode>(ScaleOp)->getZExtValue();

llvm/lib/Target/X86/X86ISelLowering.cpp

         Index.getOperand(0).getScalarValueSizeInBits() <= 32 &&
         DAG.ComputeNumSignBits(Index) > (IndexWidth - 32)) {
       EVT NewVT = Index.getValueType().changeVectorElementType(MVT::i32);
       Index = DAG.getNode(ISD::TRUNCATE, DL, NewVT, Index);
       return rebuildGatherScatter(GorS, Index, Base, Scale, DAG);
     }
   }
 
+  const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+  EVT PtrVT = TLI.getPointerTy(DAG.getDataLayout());
+  // Try to move splat constant adders from the index operand to the base
+  // pointer operand. Taking care to multiply by the scale. We can only do
+  // this when index element type is the same as the pointer type.
+  // Otherwise we need to be sure the math doesn't wrap before the scale.
+  if (Index.getOpcode() == ISD::ADD &&
+      Index.getValueType().getVectorElementType() == PtrVT &&
+      isa<ConstantSDNode>(Scale)) {
+    uint64_t ScaleAmt = cast<ConstantSDNode>(Scale)->getZExtValue();
+    if (auto *BV = dyn_cast<BuildVectorSDNode>(Index.getOperand(1))) {
+      BitVector UndefElts;
+      if (ConstantSDNode *C = BV->getConstantSplatNode(&UndefElts)) {
+        // FIXME: Allow non-constant?
+        if (UndefElts.none()) {
+          // Apply the scale.
+          APInt Adder = C->getAPIntValue() * ScaleAmt;
+          // Add it to the existing base.
+          Base = DAG.getNode(ISD::ADD, DL, PtrVT, Base,
+                             DAG.getConstant(Adder, DL, PtrVT));
+          Index = Index.getOperand(0);
+          return rebuildGatherScatter(GorS, Index, Base, Scale, DAG);
+        }
+      }
+
+      // It's also possible, base is just a constant. In that case case just
+      // replace it with 0 and move the displacement into the index.
+      if (BV->isConstant() && isa<ConstantSDNode>(Base) &&
+          isOneConstant(Scale)) {
+        SDValue Splat = DAG.getSplatBuildVector(Index.getValueType(), DL, Base);
+        // Combine the constant build_vector and the constant base.
+        Splat = DAG.getNode(ISD::ADD, DL, Index.getValueType(),
+                            Index.getOperand(1), Splat);
+        // Add to the LHS of the original Index add.
+        Index = DAG.getNode(ISD::ADD, DL, Index.getValueType(),
+                            Index.getOperand(0), Splat);
+        Base = DAG.getConstant(0, DL, Base.getValueType());
+        return rebuildGatherScatter(GorS, Index, Base, Scale, DAG);
+      }
+    }
+  }
+
   if (DCI.isBeforeLegalizeOps()) {
     unsigned IndexWidth = Index.getScalarValueSizeInBits();
 
     // Make sure the index is either i32 or i64
     if (IndexWidth != 32 && IndexWidth != 64) {
       MVT EltVT = IndexWidth > 32 ? MVT::i64 : MVT::i32;
       EVT IndexVT = Index.getValueType().changeVectorElementType(EltVT);
       Index = DAG.getSExtOrTrunc(Index, DL, IndexVT);

llvm/test/CodeGen/X86/masked_gather_scatter.ll

 ; KNL_64-NEXT:    vpmuludq %zmm3, %zmm0, %zmm4
 ; KNL_64-NEXT:    vpsrlq $32, %zmm0, %zmm0
 ; KNL_64-NEXT:    vpmuludq %zmm3, %zmm0, %zmm0
 ; KNL_64-NEXT:    vpsllq $32, %zmm0, %zmm0
 ; KNL_64-NEXT:    vpaddq %zmm2, %zmm0, %zmm0
 ; KNL_64-NEXT:    vpmovzxdq {{.*#+}} zmm1 = ymm1[0],zero,ymm1[1],zero,ymm1[2],zero,ymm1[3],zero,ymm1[4],zero,ymm1[5],zero,ymm1[6],zero,ymm1[7],zero
 ; KNL_64-NEXT:    vpmuldq {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %zmm1, %zmm1
 ; KNL_64-NEXT:    vpaddq %zmm1, %zmm0, %zmm0
-; KNL_64-NEXT:    vpaddq %zmm0, %zmm4, %zmm0
-; KNL_64-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %zmm0, %zmm1
+; KNL_64-NEXT:    vpaddq %zmm0, %zmm4, %zmm1
 ; KNL_64-NEXT:    kxnorw %k0, %k0, %k1
-; KNL_64-NEXT:    vpgatherqd (,%zmm1), %ymm0 {%k1}
+; KNL_64-NEXT:    vpgatherqd 72(,%zmm1), %ymm0 {%k1}
 ; KNL_64-NEXT:    retq
 ;
 ; KNL_32-LABEL: test9:
 ; KNL_32:       # %bb.0: # %entry
 ; KNL_32-NEXT:    vpbroadcastd {{[0-9]+}}(%esp), %ymm2
 ; KNL_32-NEXT:    vpbroadcastd {{.*#+}} ymm3 = [80,80,80,80,80,80,80,80]
 ; KNL_32-NEXT:    vpmulld %ymm3, %ymm1, %ymm1
 ; KNL_32-NEXT:    vpmovqd %zmm0, %ymm0
 ; KNL_32-NEXT:    vpbroadcastd {{.*#+}} ymm3 = [820,820,820,820,820,820,820,820]
 ; KNL_32-NEXT:    vpmulld %ymm3, %ymm0, %ymm0
 ; KNL_32-NEXT:    vpaddd %ymm1, %ymm0, %ymm0
-; KNL_32-NEXT:    vpbroadcastd {{.*#+}} ymm1 = [68,68,68,68,68,68,68,68]
-; KNL_32-NEXT:    vpaddd %ymm1, %ymm0, %ymm0
 ; KNL_32-NEXT:    vpaddd %ymm0, %ymm2, %ymm1
 ; KNL_32-NEXT:    movw $255, %ax
 ; KNL_32-NEXT:    kmovw %eax, %k1
-; KNL_32-NEXT:    vpgatherdd (,%zmm1), %zmm0 {%k1}
+; KNL_32-NEXT:    vpgatherdd 68(,%zmm1), %zmm0 {%k1}
 ; KNL_32-NEXT:    # kill: def $ymm0 killed $ymm0 killed $zmm0
 ; KNL_32-NEXT:    retl
 ;
 ; SKX_SMALL-LABEL: test9:
 ; SKX_SMALL:       # %bb.0: # %entry
 ; SKX_SMALL-NEXT:    vpbroadcastq %rdi, %zmm2
 ; SKX_SMALL-NEXT:    vpmullq {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %zmm0, %zmm0
 ; SKX_SMALL-NEXT:    vpmovzxdq {{.*#+}} zmm1 = ymm1[0],zero,ymm1[1],zero,ymm1[2],zero,ymm1[3],zero,ymm1[4],zero,ymm1[5],zero,ymm1[6],zero,ymm1[7],zero
 ; SKX_SMALL-NEXT:    vpmuldq {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %zmm1, %zmm1
 ; SKX_SMALL-NEXT:    vpaddq %zmm1, %zmm0, %zmm0
-; SKX_SMALL-NEXT:    vpaddq %zmm0, %zmm2, %zmm0
-; SKX_SMALL-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %zmm0, %zmm1
+; SKX_SMALL-NEXT:    vpaddq %zmm0, %zmm2, %zmm1
 ; SKX_SMALL-NEXT:    kxnorw %k0, %k0, %k1
-; SKX_SMALL-NEXT:    vpgatherqd (,%zmm1), %ymm0 {%k1}
+; SKX_SMALL-NEXT:    vpgatherqd 72(,%zmm1), %ymm0 {%k1}
 ; SKX_SMALL-NEXT:    retq
 ;
 ; SKX_LARGE-LABEL: test9:
 ; SKX_LARGE:       # %bb.0: # %entry
 ; SKX_LARGE-NEXT:    vpbroadcastq %rdi, %zmm2
 ; SKX_LARGE-NEXT:    vpmovzxdq {{.*#+}} zmm1 = ymm1[0],zero,ymm1[1],zero,ymm1[2],zero,ymm1[3],zero,ymm1[4],zero,ymm1[5],zero,ymm1[6],zero,ymm1[7],zero
 ; SKX_LARGE-NEXT:    movabsq ${{\.?LCPI[0-9]+_[0-9]+}}, %rax
 ; SKX_LARGE-NEXT:    vpmuldq (%rax){1to8}, %zmm1, %zmm1
 ; SKX_LARGE-NEXT:    movabsq ${{\.?LCPI[0-9]+_[0-9]+}}, %rax
 ; SKX_LARGE-NEXT:    vpmullq (%rax){1to8}, %zmm0, %zmm0
 ; SKX_LARGE-NEXT:    vpaddq %zmm1, %zmm0, %zmm0
-; SKX_LARGE-NEXT:    vpaddq %zmm0, %zmm2, %zmm0
-; SKX_LARGE-NEXT:    movabsq ${{\.?LCPI[0-9]+_[0-9]+}}, %rax
-; SKX_LARGE-NEXT:    vpaddq (%rax){1to8}, %zmm0, %zmm1
+; SKX_LARGE-NEXT:    vpaddq %zmm0, %zmm2, %zmm1
 ; SKX_LARGE-NEXT:    kxnorw %k0, %k0, %k1
-; SKX_LARGE-NEXT:    vpgatherqd (,%zmm1), %ymm0 {%k1}
+; SKX_LARGE-NEXT:    vpgatherqd 72(,%zmm1), %ymm0 {%k1}
 ; SKX_LARGE-NEXT:    retq
 ;
 ; SKX_32-LABEL: test9:
 ; SKX_32:       # %bb.0: # %entry
 ; SKX_32-NEXT:    vpmulld {{\.?LCPI[0-9]+_[0-9]+}}{1to8}, %ymm1, %ymm1
 ; SKX_32-NEXT:    vpmovqd %zmm0, %ymm0
 ; SKX_32-NEXT:    vpmulld {{\.?LCPI[0-9]+_[0-9]+}}{1to8}, %ymm0, %ymm0
 ; SKX_32-NEXT:    vpaddd {{[0-9]+}}(%esp){1to8}, %ymm0, %ymm0
-; SKX_32-NEXT:    vpaddd %ymm1, %ymm0, %ymm0
-; SKX_32-NEXT:    vpaddd {{\.?LCPI[0-9]+_[0-9]+}}{1to8}, %ymm0, %ymm1
+; SKX_32-NEXT:    vpaddd %ymm1, %ymm0, %ymm1
 ; SKX_32-NEXT:    kxnorw %k0, %k0, %k1
-; SKX_32-NEXT:    vpgatherdd (,%ymm1), %ymm0 {%k1}
+; SKX_32-NEXT:    vpgatherdd 68(,%ymm1), %ymm0 {%k1}
 ; SKX_32-NEXT:    retl
 entry:
   %broadcast.splatinsert = insertelement <8 x %struct.ST*> undef, %struct.ST* %base, i32 0
   %broadcast.splat = shufflevector <8 x %struct.ST*> %broadcast.splatinsert, <8 x %struct.ST*> undef, <8 x i32> zeroinitializer
 
   %arrayidx = getelementptr  %struct.ST, <8 x %struct.ST*> %broadcast.splat, <8 x i64> %ind1, <8 x i32> <i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2>, <8 x i32><i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>, <8 x i32> %ind5, <8 x i64> <i64 13, i64 13, i64 13, i64 13, i64 13, i64 13, i64 13, i64 13>
   %res = call <8 x i32 >  @llvm.masked.gather.v8i32.v8p0i32(<8 x i32*>%arrayidx, i32 4, <8 x i1> <i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true>, <8 x i32> undef)
   ret <8 x i32> %res
 }
 
 define <8 x i32> @test10(%struct.ST* %base, <8 x i64> %i1, <8 x i32>%ind5) {
 ; KNL_64-LABEL: test10:
 ; KNL_64:       # %bb.0: # %entry
 ; KNL_64-NEXT:    vpbroadcastq %rdi, %zmm2
 ; KNL_64-NEXT:    vpbroadcastq {{.*#+}} zmm3 = [824,824,824,824,824,824,824,824]
 ; KNL_64-NEXT:    vpmuludq %zmm3, %zmm0, %zmm4
 ; KNL_64-NEXT:    vpsrlq $32, %zmm0, %zmm0
 ; KNL_64-NEXT:    vpmuludq %zmm3, %zmm0, %zmm0
 ; KNL_64-NEXT:    vpsllq $32, %zmm0, %zmm0
 ; KNL_64-NEXT:    vpaddq %zmm2, %zmm0, %zmm0
 ; KNL_64-NEXT:    vpmovzxdq {{.*#+}} zmm1 = ymm1[0],zero,ymm1[1],zero,ymm1[2],zero,ymm1[3],zero,ymm1[4],zero,ymm1[5],zero,ymm1[6],zero,ymm1[7],zero
 ; KNL_64-NEXT:    vpmuldq {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %zmm1, %zmm1
 ; KNL_64-NEXT:    vpaddq %zmm1, %zmm0, %zmm0
-; KNL_64-NEXT:    vpaddq %zmm0, %zmm4, %zmm0
-; KNL_64-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %zmm0, %zmm1
+; KNL_64-NEXT:    vpaddq %zmm0, %zmm4, %zmm1
 ; KNL_64-NEXT:    kxnorw %k0, %k0, %k1
-; KNL_64-NEXT:    vpgatherqd (,%zmm1), %ymm0 {%k1}
+; KNL_64-NEXT:    vpgatherqd 72(,%zmm1), %ymm0 {%k1}
 ; KNL_64-NEXT:    retq
 ;
 ; KNL_32-LABEL: test10:
 ; KNL_32:       # %bb.0: # %entry
 ; KNL_32-NEXT:    vpbroadcastd {{[0-9]+}}(%esp), %ymm2
 ; KNL_32-NEXT:    vpbroadcastd {{.*#+}} ymm3 = [80,80,80,80,80,80,80,80]
 ; KNL_32-NEXT:    vpmulld %ymm3, %ymm1, %ymm1
 ; KNL_32-NEXT:    vpmovqd %zmm0, %ymm0
 ; KNL_32-NEXT:    vpbroadcastd {{.*#+}} ymm3 = [820,820,820,820,820,820,820,820]
 ; KNL_32-NEXT:    vpmulld %ymm3, %ymm0, %ymm0
 ; KNL_32-NEXT:    vpaddd %ymm1, %ymm0, %ymm0
-; KNL_32-NEXT:    vpbroadcastd {{.*#+}} ymm1 = [68,68,68,68,68,68,68,68]
-; KNL_32-NEXT:    vpaddd %ymm1, %ymm0, %ymm0
 ; KNL_32-NEXT:    vpaddd %ymm0, %ymm2, %ymm1
 ; KNL_32-NEXT:    movw $255, %ax
 ; KNL_32-NEXT:    kmovw %eax, %k1
-; KNL_32-NEXT:    vpgatherdd (,%zmm1), %zmm0 {%k1}
+; KNL_32-NEXT:    vpgatherdd 68(,%zmm1), %zmm0 {%k1}
 ; KNL_32-NEXT:    # kill: def $ymm0 killed $ymm0 killed $zmm0
 ; KNL_32-NEXT:    retl
 ;
 ; SKX_SMALL-LABEL: test10:
 ; SKX_SMALL:       # %bb.0: # %entry
 ; SKX_SMALL-NEXT:    vpbroadcastq %rdi, %zmm2
 ; SKX_SMALL-NEXT:    vpmullq {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %zmm0, %zmm0
 ; SKX_SMALL-NEXT:    vpmovzxdq {{.*#+}} zmm1 = ymm1[0],zero,ymm1[1],zero,ymm1[2],zero,ymm1[3],zero,ymm1[4],zero,ymm1[5],zero,ymm1[6],zero,ymm1[7],zero
 ; SKX_SMALL-NEXT:    vpmuldq {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %zmm1, %zmm1
 ; SKX_SMALL-NEXT:    vpaddq %zmm1, %zmm0, %zmm0
-; SKX_SMALL-NEXT:    vpaddq %zmm0, %zmm2, %zmm0
-; SKX_SMALL-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %zmm0, %zmm1
+; SKX_SMALL-NEXT:    vpaddq %zmm0, %zmm2, %zmm1
 ; SKX_SMALL-NEXT:    kxnorw %k0, %k0, %k1
-; SKX_SMALL-NEXT:    vpgatherqd (,%zmm1), %ymm0 {%k1}
+; SKX_SMALL-NEXT:    vpgatherqd 72(,%zmm1), %ymm0 {%k1}
 ; SKX_SMALL-NEXT:    retq
 ;
 ; SKX_LARGE-LABEL: test10:
 ; SKX_LARGE:       # %bb.0: # %entry
 ; SKX_LARGE-NEXT:    vpbroadcastq %rdi, %zmm2
 ; SKX_LARGE-NEXT:    vpmovzxdq {{.*#+}} zmm1 = ymm1[0],zero,ymm1[1],zero,ymm1[2],zero,ymm1[3],zero,ymm1[4],zero,ymm1[5],zero,ymm1[6],zero,ymm1[7],zero
 ; SKX_LARGE-NEXT:    movabsq ${{\.?LCPI[0-9]+_[0-9]+}}, %rax
 ; SKX_LARGE-NEXT:    vpmuldq (%rax){1to8}, %zmm1, %zmm1
 ; SKX_LARGE-NEXT:    movabsq ${{\.?LCPI[0-9]+_[0-9]+}}, %rax
 ; SKX_LARGE-NEXT:    vpmullq (%rax){1to8}, %zmm0, %zmm0
 ; SKX_LARGE-NEXT:    vpaddq %zmm1, %zmm0, %zmm0
-; SKX_LARGE-NEXT:    vpaddq %zmm0, %zmm2, %zmm0
-; SKX_LARGE-NEXT:    movabsq ${{\.?LCPI[0-9]+_[0-9]+}}, %rax
-; SKX_LARGE-NEXT:    vpaddq (%rax){1to8}, %zmm0, %zmm1
+; SKX_LARGE-NEXT:    vpaddq %zmm0, %zmm2, %zmm1
 ; SKX_LARGE-NEXT:    kxnorw %k0, %k0, %k1
-; SKX_LARGE-NEXT:    vpgatherqd (,%zmm1), %ymm0 {%k1}
+; SKX_LARGE-NEXT:    vpgatherqd 72(,%zmm1), %ymm0 {%k1}
 ; SKX_LARGE-NEXT:    retq
 ;
 ; SKX_32-LABEL: test10:
 ; SKX_32:       # %bb.0: # %entry
 ; SKX_32-NEXT:    vpmulld {{\.?LCPI[0-9]+_[0-9]+}}{1to8}, %ymm1, %ymm1
 ; SKX_32-NEXT:    vpmovqd %zmm0, %ymm0
 ; SKX_32-NEXT:    vpmulld {{\.?LCPI[0-9]+_[0-9]+}}{1to8}, %ymm0, %ymm0
 ; SKX_32-NEXT:    vpaddd {{[0-9]+}}(%esp){1to8}, %ymm0, %ymm0
-; SKX_32-NEXT:    vpaddd %ymm1, %ymm0, %ymm0
-; SKX_32-NEXT:    vpaddd {{\.?LCPI[0-9]+_[0-9]+}}{1to8}, %ymm0, %ymm1
+; SKX_32-NEXT:    vpaddd %ymm1, %ymm0, %ymm1
 ; SKX_32-NEXT:    kxnorw %k0, %k0, %k1
-; SKX_32-NEXT:    vpgatherdd (,%ymm1), %ymm0 {%k1}
+; SKX_32-NEXT:    vpgatherdd 68(,%ymm1), %ymm0 {%k1}
 ; SKX_32-NEXT:    retl
 entry:
   %broadcast.splatinsert = insertelement <8 x %struct.ST*> undef, %struct.ST* %base, i32 0
   %broadcast.splat = shufflevector <8 x %struct.ST*> %broadcast.splatinsert, <8 x %struct.ST*> undef, <8 x i32> zeroinitializer
 
   %arrayidx = getelementptr  %struct.ST, <8 x %struct.ST*> %broadcast.splat, <8 x i64> %i1, i32 2, i32 1, <8 x i32> %ind5, i64 13
   %res = call <8 x i32 >  @llvm.masked.gather.v8i32.v8p0i32(<8 x i32*>%arrayidx, i32 4, <8 x i1> <i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true>, <8 x i32> undef)
   ret <8 x i32> %res

 ; cause an error in copyPhysReg.
 ;
 
 %struct.foo = type { i8*, i64, i16, i16, i32 }
 
 define <8 x i64> @pr45906(<8 x %struct.foo*> %ptr) {
 ; KNL_64-LABEL: pr45906:
 ; KNL_64:       # %bb.0: # %bb
-; KNL_64-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %zmm0, %zmm1
 ; KNL_64-NEXT:    kxnorw %k0, %k0, %k1
-; KNL_64-NEXT:    vpgatherqq (,%zmm1), %zmm0 {%k1}
+; KNL_64-NEXT:    vpgatherqq 8(,%zmm0), %zmm1 {%k1}
+; KNL_64-NEXT:    vmovdqa64 %zmm1, %zmm0
 ; KNL_64-NEXT:    retq
 ;
 ; KNL_32-LABEL: pr45906:
 ; KNL_32:       # %bb.0: # %bb
-; KNL_32-NEXT:    vpbroadcastd {{.*#+}} ymm1 = [4,4,4,4,4,4,4,4]
-; KNL_32-NEXT:    vpaddd %ymm1, %ymm0, %ymm1
 ; KNL_32-NEXT:    kxnorw %k0, %k0, %k1
-; KNL_32-NEXT:    vpgatherdq (,%ymm1), %zmm0 {%k1}
+; KNL_32-NEXT:    vpgatherdq 4(,%ymm0), %zmm1 {%k1}
+; KNL_32-NEXT:    vmovdqa64 %zmm1, %zmm0
 ; KNL_32-NEXT:    retl
 ;
-; SKX_SMALL-LABEL: pr45906:
-; SKX_SMALL:       # %bb.0: # %bb
-; SKX_SMALL-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %zmm0, %zmm1
-; SKX_SMALL-NEXT:    kxnorw %k0, %k0, %k1
-; SKX_SMALL-NEXT:    vpgatherqq (,%zmm1), %zmm0 {%k1}
-; SKX_SMALL-NEXT:    retq
-;
-; SKX_LARGE-LABEL: pr45906:
-; SKX_LARGE:       # %bb.0: # %bb
-; SKX_LARGE-NEXT:    movabsq ${{\.?LCPI[0-9]+_[0-9]+}}, %rax
-; SKX_LARGE-NEXT:    vpaddq (%rax){1to8}, %zmm0, %zmm1
-; SKX_LARGE-NEXT:    kxnorw %k0, %k0, %k1
-; SKX_LARGE-NEXT:    vpgatherqq (,%zmm1), %zmm0 {%k1}
-; SKX_LARGE-NEXT:    retq
+; SKX-LABEL: pr45906:
+; SKX:       # %bb.0: # %bb
+; SKX-NEXT:    kxnorw %k0, %k0, %k1
+; SKX-NEXT:    vpgatherqq 8(,%zmm0), %zmm1 {%k1}
+; SKX-NEXT:    vmovdqa64 %zmm1, %zmm0
+; SKX-NEXT:    retq
 ;
 ; SKX_32-LABEL: pr45906:
 ; SKX_32:       # %bb.0: # %bb
-; SKX_32-NEXT:    vpaddd {{\.?LCPI[0-9]+_[0-9]+}}{1to8}, %ymm0, %ymm1
 ; SKX_32-NEXT:    kxnorw %k0, %k0, %k1
-; SKX_32-NEXT:    vpgatherdq (,%ymm1), %zmm0 {%k1}
+; SKX_32-NEXT:    vpgatherdq 4(,%ymm0), %zmm1 {%k1}
+; SKX_32-NEXT:    vmovdqa64 %zmm1, %zmm0
 ; SKX_32-NEXT:    retl
 bb:
   %tmp = getelementptr inbounds %struct.foo, <8 x %struct.foo*> %ptr, i64 0, i32 1
   %tmp1 = call <8 x i64> @llvm.masked.gather.v8i64.v8p0i64(<8 x i64*> %tmp, i32 8, <8 x i1> <i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true>, <8 x i64> undef)
   ret <8 x i64> %tmp1
 }
 declare <8 x i64> @llvm.masked.gather.v8i64.v8p0i64(<8 x i64*>, i32, <8 x i1>, <8 x i64>)
+
+%struct.ST2 = type { i32, i32 }
+
+; Make sure we don't use a displacement on the gather. The constant from the
+; struct offset should be folded into the constant pool load for the vector
+; add.
+define <8 x i32> @test_const_fold(%struct.ST2* %base, <8 x i64> %i1) {
+; KNL_64-LABEL: test_const_fold:
+; KNL_64:       # %bb.0: # %entry
+; KNL_64-NEXT:    vpsllq $3, %zmm0, %zmm0
+; KNL_64-NEXT:    vpbroadcastq %rdi, %zmm1
+; KNL_64-NEXT:    vpaddq %zmm1, %zmm0, %zmm0
+; KNL_64-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %zmm0, %zmm1
+; KNL_64-NEXT:    kxnorw %k0, %k0, %k1
+; KNL_64-NEXT:    vpgatherqd (,%zmm1), %ymm0 {%k1}
+; KNL_64-NEXT:    retq
+;
+; KNL_32-LABEL: test_const_fold:
+; KNL_32:       # %bb.0: # %entry
+; KNL_32-NEXT:    vpmovqd %zmm0, %ymm0
+; KNL_32-NEXT:    vpslld $3, %ymm0, %ymm0
+; KNL_32-NEXT:    vpbroadcastd {{[0-9]+}}(%esp), %ymm1
+; KNL_32-NEXT:    vpaddd %ymm1, %ymm0, %ymm0
+; KNL_32-NEXT:    vpaddd {{\.?LCPI[0-9]+_[0-9]+}}, %ymm0, %ymm1
+; KNL_32-NEXT:    movw $255, %ax
+; KNL_32-NEXT:    kmovw %eax, %k1
+; KNL_32-NEXT:    vpgatherdd (,%zmm1), %zmm0 {%k1}
+; KNL_32-NEXT:    # kill: def $ymm0 killed $ymm0 killed $zmm0
+; KNL_32-NEXT:    retl
+;
+; SKX_SMALL-LABEL: test_const_fold:
+; SKX_SMALL:       # %bb.0: # %entry
+; SKX_SMALL-NEXT:    vpsllq $3, %zmm0, %zmm0
+; SKX_SMALL-NEXT:    vpbroadcastq %rdi, %zmm1
+; SKX_SMALL-NEXT:    vpaddq %zmm1, %zmm0, %zmm0
+; SKX_SMALL-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %zmm0, %zmm1
+; SKX_SMALL-NEXT:    kxnorw %k0, %k0, %k1
+; SKX_SMALL-NEXT:    vpgatherqd (,%zmm1), %ymm0 {%k1}
+; SKX_SMALL-NEXT:    retq
+;
+; SKX_LARGE-LABEL: test_const_fold:
+; SKX_LARGE:       # %bb.0: # %entry
+; SKX_LARGE-NEXT:    vpsllq $3, %zmm0, %zmm0
+; SKX_LARGE-NEXT:    vpbroadcastq %rdi, %zmm1
+; SKX_LARGE-NEXT:    vpaddq %zmm1, %zmm0, %zmm0
+; SKX_LARGE-NEXT:    movabsq ${{\.?LCPI[0-9]+_[0-9]+}}, %rax
+; SKX_LARGE-NEXT:    vpaddq (%rax), %zmm0, %zmm1
+; SKX_LARGE-NEXT:    kxnorw %k0, %k0, %k1
+; SKX_LARGE-NEXT:    vpgatherqd (,%zmm1), %ymm0 {%k1}
+; SKX_LARGE-NEXT:    retq
+;
+; SKX_32-LABEL: test_const_fold:
+; SKX_32:       # %bb.0: # %entry
+; SKX_32-NEXT:    vpmovqd %zmm0, %ymm0
+; SKX_32-NEXT:    vpslld $3, %ymm0, %ymm0
+; SKX_32-NEXT:    vpaddd {{[0-9]+}}(%esp){1to8}, %ymm0, %ymm0
+; SKX_32-NEXT:    kxnorw %k0, %k0, %k1
+; SKX_32-NEXT:    vpaddd {{\.?LCPI[0-9]+_[0-9]+}}, %ymm0, %ymm1
+; SKX_32-NEXT:    vpgatherdd (,%ymm1), %ymm0 {%k1}
+; SKX_32-NEXT:    retl
+entry:
+  %add = add <8 x i64> %i1, <i64 0, i64 1, i64 2, i64 3, i64 4, i64 5, i64 6, i64 7>
+  %arrayidx = getelementptr  %struct.ST2, %struct.ST2* %base, <8 x i64> %add, i32 1
+  %res = call <8 x i32> @llvm.masked.gather.v8i32.v8p0i32(<8 x i32*> %arrayidx, i32 4, <8 x i1> <i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true>, <8 x i32> undef)
+  ret <8 x i32> %res
+}