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[X86] XFormVExtractWithShuffleIntoLoad - handle shuffle mask scaling 

If the target shuffle mask is from a wider type, attempt to scale the mask so that the extraction can attempt to peek through.

Fixes the regression mentioned in rL368662

Reapplying this as rL368308 had to be reverted as part of rL368660 to revert rL368276

llvm-svn: 368663
This commit is contained in:
Simon Pilgrim 2019-08-13 11:11:42 +00:00
parent 1a8d790cf5
commit e7b350a5d1
2 changed files with 29 additions and 16 deletions
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40
llvm/lib/Target/X86/X86ISelLowering.cpp
View File

@ -34307,8 +34307,9 @@ SDValue X86TargetLowering::SimplifyMultipleUseDemandedBitsForTargetNode(
/// folded into a single element load.
/// Similar handling for VECTOR_SHUFFLE is performed by DAGCombiner, but
/// shuffles have been custom lowered so we need to handle those here.
static SDValue XFormVExtractWithShuffleIntoLoad(SDNode *N, SelectionDAG &DAG,
TargetLowering::DAGCombinerInfo &DCI) {
static SDValue
XFormVExtractWithShuffleIntoLoad(SDNode *N, SelectionDAG &DAG,
TargetLowering::DAGCombinerInfo &DCI) {
if (DCI.isBeforeLegalizeOps())
return SDValue();
@ -34320,13 +34321,17 @@ static SDValue XFormVExtractWithShuffleIntoLoad(SDNode *N, SelectionDAG &DAG,
return SDValue();
EVT OriginalVT = InVec.getValueType();
unsigned NumOriginalElts = OriginalVT.getVectorNumElements();
// Peek through bitcasts, don't duplicate a load with other uses.
InVec = peekThroughOneUseBitcasts(InVec);
EVT CurrentVT = InVec.getValueType();
if (!CurrentVT.isVector() ||
CurrentVT.getVectorNumElements() != OriginalVT.getVectorNumElements())
if (!CurrentVT.isVector())
return SDValue();
unsigned NumCurrentElts = CurrentVT.getVectorNumElements();
if ((NumOriginalElts % NumCurrentElts) != 0)
return SDValue();
if (!isTargetShuffle(InVec.getOpcode()))
@ -34343,10 +34348,17 @@ static SDValue XFormVExtractWithShuffleIntoLoad(SDNode *N, SelectionDAG &DAG,
ShuffleOps, ShuffleMask, UnaryShuffle))
return SDValue();
unsigned Scale = NumOriginalElts / NumCurrentElts;
if (Scale > 1) {
SmallVector<int, 16> ScaledMask;
scaleShuffleMask<int>(Scale, ShuffleMask, ScaledMask);
ShuffleMask = std::move(ScaledMask);
}
assert(ShuffleMask.size() == NumOriginalElts && "Shuffle mask size mismatch");
// Select the input vector, guarding against out of range extract vector.
unsigned NumElems = CurrentVT.getVectorNumElements();
int Elt = cast<ConstantSDNode>(EltNo)->getZExtValue();
int Idx = (Elt > (int)NumElems) ? SM_SentinelUndef : ShuffleMask[Elt];
int Idx = (Elt > (int)NumOriginalElts) ? SM_SentinelUndef : ShuffleMask[Elt];
if (Idx == SM_SentinelZero)
return EltVT.isInteger() ? DAG.getConstant(0, SDLoc(N), EltVT)
@ -34359,8 +34371,9 @@ static SDValue XFormVExtractWithShuffleIntoLoad(SDNode *N, SelectionDAG &DAG,
if (llvm::any_of(ShuffleMask, [](int M) { return M == SM_SentinelZero; }))
return SDValue();
assert(0 <= Idx && Idx < (int)(2 * NumElems) && "Shuffle index out of range");
SDValue LdNode = (Idx < (int)NumElems) ? ShuffleOps[0] : ShuffleOps[1];
assert(0 <= Idx && Idx < (int)(2 * NumOriginalElts) &&
"Shuffle index out of range");
SDValue LdNode = (Idx < (int)NumOriginalElts) ? ShuffleOps[0] : ShuffleOps[1];
// If inputs to shuffle are the same for both ops, then allow 2 uses
unsigned AllowedUses =
@ -34380,7 +34393,7 @@ static SDValue XFormVExtractWithShuffleIntoLoad(SDNode *N, SelectionDAG &DAG,
LoadSDNode *LN0 = cast<LoadSDNode>(LdNode);
if (!LN0 ||!LN0->hasNUsesOfValue(AllowedUses, 0) || LN0->isVolatile())
if (!LN0 || !LN0->hasNUsesOfValue(AllowedUses, 0) || LN0->isVolatile())
return SDValue();
// If there's a bitcast before the shuffle, check if the load type and
@ -34398,10 +34411,11 @@ static SDValue XFormVExtractWithShuffleIntoLoad(SDNode *N, SelectionDAG &DAG,
SDLoc dl(N);
// Create shuffle node taking into account the case that its a unary shuffle
SDValue Shuffle = (UnaryShuffle) ? DAG.getUNDEF(CurrentVT) : ShuffleOps[1];
Shuffle = DAG.getVectorShuffle(CurrentVT, dl, ShuffleOps[0], Shuffle,
ShuffleMask);
Shuffle = DAG.getBitcast(OriginalVT, Shuffle);
SDValue Shuffle = UnaryShuffle ? DAG.getUNDEF(OriginalVT)
: DAG.getBitcast(OriginalVT, ShuffleOps[1]);
Shuffle = DAG.getVectorShuffle(OriginalVT, dl,
DAG.getBitcast(OriginalVT, ShuffleOps[0]),
Shuffle, ShuffleMask);
return DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, N->getValueType(0), Shuffle,
EltNo);
}

5
llvm/test/CodeGen/X86/insertps-combine.ll
View File

@ -285,13 +285,12 @@ define float @extract_lane_insertps_5123(<4 x float> %a0, <4 x float> *%p1) {
define float @extract_lane_insertps_6123(<4 x float> %a0, <4 x float> *%p1) {
; SSE-LABEL: extract_lane_insertps_6123:
; SSE: # %bb.0:
; SSE-NEXT: movaps (%rdi), %xmm0
; SSE-NEXT: movhlps {{.*#+}} xmm0 = xmm0[1,1]
; SSE-NEXT: movss {{.*#+}} xmm0 = mem[0],zero,zero,zero
; SSE-NEXT: retq
;
; AVX-LABEL: extract_lane_insertps_6123:
; AVX: # %bb.0:
; AVX-NEXT: vpermilpd {{.*#+}} xmm0 = mem[1,0]
; AVX-NEXT: vmovss {{.*#+}} xmm0 = mem[0],zero,zero,zero
; AVX-NEXT: retq
%a1 = load <4 x float>, <4 x float> *%p1
%res = call <4 x float> @llvm.x86.sse41.insertps(<4 x float> %a0, <4 x float> %a1, i8 128)