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[X86][SSE] Add zero element and general 64-bit VZEXT_LOAD support to EltsFromConsecutiveLoads

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This patch adds support for trailing zero elements to VZEXT_LOAD loads (and checks that no zero elts occur within the consecutive load).

It also generalizes the 64-bit VZEXT_LOAD load matching to work for loads other than 2x32-bit loads.

After this patch it will also be easier to add support for other basic load patterns like 32-bit VZEXT_LOAD loads, PMOVZX and subvector load insertion.

Differential Revision: http://reviews.llvm.org/D16217

llvm-svn: 258798
This commit is contained in:
Simon Pilgrim 2016-01-26 09:30:08 +00:00
parent 6dd1abcce8
commit 0800d72a1a
2 changed files with 94 additions and 101 deletions
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143
lib/Target/X86/X86ISelLowering.cpp
View File

@ -5480,55 +5480,84 @@ LowerAsSplatVectorLoad(SDValue SrcOp, MVT VT, SDLoc dl, SelectionDAG &DAG) {
/// elements can be replaced by a single large load which has the same value as
/// a build_vector or insert_subvector whose loaded operands are 'Elts'.
///
/// Example: <load i32 *a, load i32 *a+4, undef, undef> -> zextload a
///
/// FIXME: we'd also like to handle the case where the last elements are zero
/// rather than undef via VZEXT_LOAD, but we do not detect that case today.
/// There's even a handy isZeroNode for that purpose.
/// Example: <load i32 *a, load i32 *a+4, zero, undef> -> zextload a
static SDValue EltsFromConsecutiveLoads(EVT VT, ArrayRef<SDValue> Elts,
SDLoc &DL, SelectionDAG &DAG,
bool isAfterLegalize) {
unsigned NumElems = Elts.size();
LoadSDNode *LDBase = nullptr;
unsigned LastLoadedElt = -1U;
int LastLoadedElt = -1;
SmallBitVector LoadMask(NumElems, false);
SmallBitVector ZeroMask(NumElems, false);
SmallBitVector UndefMask(NumElems, false);
// For each element in the initializer, see if we've found a load or an undef.
// If we don't find an initial load element, or later load elements are
// non-consecutive, bail out.
auto PeekThroughBitcast = [](SDValue V) {
while (V.getNode() && V.getOpcode() == ISD::BITCAST)
V = V.getOperand(0);
return V;
};
// For each element in the initializer, see if we've found a load, zero or an
// undef.
for (unsigned i = 0; i < NumElems; ++i) {
SDValue Elt = Elts[i];
// Look through a bitcast.
if (Elt.getNode() && Elt.getOpcode() == ISD::BITCAST)
Elt = Elt.getOperand(0);
if (!Elt.getNode() ||
(Elt.getOpcode() != ISD::UNDEF && !ISD::isNON_EXTLoad(Elt.getNode())))
SDValue Elt = PeekThroughBitcast(Elts[i]);
if (!Elt.getNode())
return SDValue();
if (!LDBase) {
if (Elt.getNode()->getOpcode() == ISD::UNDEF)
return SDValue();
LDBase = cast<LoadSDNode>(Elt.getNode());
LastLoadedElt = i;
continue;
}
if (Elt.getOpcode() == ISD::UNDEF)
continue;
LoadSDNode *LD = cast<LoadSDNode>(Elt);
EVT LdVT = Elt.getValueType();
// Each loaded element must be the correct fractional portion of the
// requested vector load.
if (LdVT.getSizeInBits() != VT.getSizeInBits() / NumElems)
if (Elt.isUndef())
UndefMask[i] = true;
else if (X86::isZeroNode(Elt) || ISD::isBuildVectorAllZeros(Elt.getNode()))
ZeroMask[i] = true;
else if (ISD::isNON_EXTLoad(Elt.getNode())) {
LoadMask[i] = true;
LastLoadedElt = i;
// Each loaded element must be the correct fractional portion of the
// requested vector load.
if ((NumElems * Elt.getValueSizeInBits()) != VT.getSizeInBits())
return SDValue();
} else
return SDValue();
if (!DAG.isConsecutiveLoad(LD, LDBase, LdVT.getSizeInBits() / 8, i))
return SDValue();
LastLoadedElt = i;
}
assert((ZeroMask | UndefMask | LoadMask).count() == NumElems &&
"Incomplete element masks");
// Handle Special Cases - all undef or undef/zero.
if (UndefMask.count() == NumElems)
return DAG.getUNDEF(VT);
// FIXME: Should we return this as a BUILD_VECTOR instead?
if ((ZeroMask | UndefMask).count() == NumElems)
return VT.isInteger() ? DAG.getConstant(0, DL, VT)
: DAG.getConstantFP(0.0, DL, VT);
int FirstLoadedElt = LoadMask.find_first();
SDValue EltBase = PeekThroughBitcast(Elts[FirstLoadedElt]);
LoadSDNode *LDBase = cast<LoadSDNode>(EltBase);
EVT LDBaseVT = EltBase.getValueType();
// Consecutive loads can contain UNDEFS but not ZERO elements.
bool IsConsecutiveLoad = true;
for (int i = FirstLoadedElt + 1; i <= LastLoadedElt; ++i) {
if (LoadMask[i]) {
SDValue Elt = PeekThroughBitcast(Elts[i]);
LoadSDNode *LD = cast<LoadSDNode>(Elt);
if (!DAG.isConsecutiveLoad(LD, LDBase,
Elt.getValueType().getStoreSizeInBits() / 8,
i - FirstLoadedElt)) {
IsConsecutiveLoad = false;
break;
}
} else if (ZeroMask[i]) {
IsConsecutiveLoad = false;
break;
}
}
// LOAD - all consecutive load/undefs (must start/end with a load).
// If we have found an entire vector of loads and undefs, then return a large
// load of the entire vector width starting at the base pointer. If we found
// consecutive loads for the low half, generate a vzext_load node.
if (LastLoadedElt == NumElems - 1) {
// load of the entire vector width starting at the base pointer.
if (IsConsecutiveLoad && FirstLoadedElt == 0 &&
LastLoadedElt == (int)(NumElems - 1) && ZeroMask.none()) {
assert(LDBase && "Did not find base load for merging consecutive loads");
EVT EltVT = LDBase->getValueType(0);
// Ensure that the input vector size for the merged loads matches the
@ -5548,9 +5577,9 @@ static SDValue EltsFromConsecutiveLoads(EVT VT, ArrayRef<SDValue> Elts,
LDBase->getAlignment());
if (LDBase->hasAnyUseOfValue(1)) {
SDValue NewChain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other,
SDValue(LDBase, 1),
SDValue(NewLd.getNode(), 1));
SDValue NewChain =
DAG.getNode(ISD::TokenFactor, DL, MVT::Other, SDValue(LDBase, 1),
SDValue(NewLd.getNode(), 1));
DAG.ReplaceAllUsesOfValueWith(SDValue(LDBase, 1), NewChain);
DAG.UpdateNodeOperands(NewChain.getNode(), SDValue(LDBase, 1),
SDValue(NewLd.getNode(), 1));
@ -5559,11 +5588,14 @@ static SDValue EltsFromConsecutiveLoads(EVT VT, ArrayRef<SDValue> Elts,
return NewLd;
}
//TODO: The code below fires only for for loading the low v2i32 / v2f32
//of a v4i32 / v4f32. It's probably worth generalizing.
EVT EltVT = VT.getVectorElementType();
if (NumElems == 4 && LastLoadedElt == 1 && (EltVT.getSizeInBits() == 32) &&
DAG.getTargetLoweringInfo().isTypeLegal(MVT::v2i64)) {
int LoadSize =
(1 + LastLoadedElt - FirstLoadedElt) * LDBaseVT.getStoreSizeInBits();
// VZEXT_LOAD - consecutive load/undefs followed by zeros/undefs.
// TODO: The code below fires only for for loading the low 64-bits of a
// of a 128-bit vector. It's probably worth generalizing more.
if (IsConsecutiveLoad && FirstLoadedElt == 0 && VT.is128BitVector() &&
(LoadSize == 64 && DAG.getTargetLoweringInfo().isTypeLegal(MVT::v2i64))) {
SDVTList Tys = DAG.getVTList(MVT::v2i64, MVT::Other);
SDValue Ops[] = { LDBase->getChain(), LDBase->getBasePtr() };
SDValue ResNode =
@ -5577,8 +5609,9 @@ static SDValue EltsFromConsecutiveLoads(EVT VT, ArrayRef<SDValue> Elts,
// terms of dependency. We create a TokenFactor for LDBase and ResNode, and
// update uses of LDBase's output chain to use the TokenFactor.
if (LDBase->hasAnyUseOfValue(1)) {
SDValue NewChain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other,
SDValue(LDBase, 1), SDValue(ResNode.getNode(), 1));
SDValue NewChain =
DAG.getNode(ISD::TokenFactor, DL, MVT::Other, SDValue(LDBase, 1),
SDValue(ResNode.getNode(), 1));
DAG.ReplaceAllUsesOfValueWith(SDValue(LDBase, 1), NewChain);
DAG.UpdateNodeOperands(NewChain.getNode(), SDValue(LDBase, 1),
SDValue(ResNode.getNode(), 1));
@ -6551,16 +6584,18 @@ X86TargetLowering::LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG) const {
if (IsAllConstants)
return SDValue();
// For AVX-length vectors, see if we can use a vector load to get all of the
// elements, otherwise build the individual 128-bit pieces and use
// See if we can use a vector load to get all of the elements.
if (VT.is128BitVector() || VT.is256BitVector() || VT.is512BitVector()) {
SmallVector<SDValue, 64> V(Op->op_begin(), Op->op_begin() + NumElems);
if (SDValue LD = EltsFromConsecutiveLoads(VT, V, dl, DAG, false))
return LD;
}
// For AVX-length vectors, build the individual 128-bit pieces and use
// shuffles to put them in place.
if (VT.is256BitVector() || VT.is512BitVector()) {
SmallVector<SDValue, 64> V(Op->op_begin(), Op->op_begin() + NumElems);
// Check for a build vector of consecutive loads.
if (SDValue LD = EltsFromConsecutiveLoads(VT, V, dl, DAG, false))
return LD;
EVT HVT = EVT::getVectorVT(*DAG.getContext(), ExtVT, NumElems/2);
// Build both the lower and upper subvector.
@ -6648,10 +6683,6 @@ X86TargetLowering::LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG) const {
for (unsigned i = 0; i < NumElems; ++i)
V[i] = Op.getOperand(i);
// Check for elements which are consecutive loads.
if (SDValue LD = EltsFromConsecutiveLoads(VT, V, dl, DAG, false))
return LD;
// Check for a build vector from mostly shuffle plus few inserting.
if (SDValue Sh = buildFromShuffleMostly(Op, DAG))
return Sh;

52
test/CodeGen/X86/merge-consecutive-loads-128.ll
View File

@ -347,18 +347,12 @@ define <8 x i16> @merge_8i16_i16_34uuuuuu(i16* %ptr) nounwind uwtable noinline s
define <8 x i16> @merge_8i16_i16_45u7zzzz(i16* %ptr) nounwind uwtable noinline ssp {
; SSE-LABEL: merge_8i16_i16_45u7zzzz:
; SSE: # BB#0:
; SSE-NEXT: pxor %xmm0, %xmm0
; SSE-NEXT: pinsrw $0, 8(%rdi), %xmm0
; SSE-NEXT: pinsrw $1, 10(%rdi), %xmm0
; SSE-NEXT: pinsrw $3, 14(%rdi), %xmm0
; SSE-NEXT: movq {{.*#+}} xmm0 = mem[0],zero
; SSE-NEXT: retq
;
; AVX-LABEL: merge_8i16_i16_45u7zzzz:
; AVX: # BB#0:
; AVX-NEXT: vpxor %xmm0, %xmm0, %xmm0
; AVX-NEXT: vpinsrw $0, 8(%rdi), %xmm0, %xmm0
; AVX-NEXT: vpinsrw $1, 10(%rdi), %xmm0, %xmm0
; AVX-NEXT: vpinsrw $3, 14(%rdi), %xmm0, %xmm0
; AVX-NEXT: vmovq {{.*#+}} xmm0 = mem[0],zero
; AVX-NEXT: retq
%ptr0 = getelementptr inbounds i16, i16* %ptr, i64 4
%ptr1 = getelementptr inbounds i16, i16* %ptr, i64 5
@ -478,46 +472,14 @@ define <16 x i8> @merge_16i8_i8_01u3uuzzuuuuuzzz(i8* %ptr) nounwind uwtable noin
}
define <16 x i8> @merge_16i8_i8_0123uu67uuuuuzzz(i8* %ptr) nounwind uwtable noinline ssp {
; SSE2-LABEL: merge_16i8_i8_0123uu67uuuuuzzz:
; SSE2: # BB#0:
; SSE2-NEXT: movzbl 2(%rdi), %eax
; SSE2-NEXT: movzbl 3(%rdi), %ecx
; SSE2-NEXT: shll $8, %ecx
; SSE2-NEXT: orl %eax, %ecx
; SSE2-NEXT: movzbl (%rdi), %eax
; SSE2-NEXT: movzbl 1(%rdi), %edx
; SSE2-NEXT: shll $8, %edx
; SSE2-NEXT: orl %eax, %edx
; SSE2-NEXT: pxor %xmm0, %xmm0
; SSE2-NEXT: pinsrw $0, %edx, %xmm0
; SSE2-NEXT: pinsrw $1, %ecx, %xmm0
; SSE2-NEXT: movzbl 6(%rdi), %eax
; SSE2-NEXT: movzbl 7(%rdi), %ecx
; SSE2-NEXT: shll $8, %ecx
; SSE2-NEXT: orl %eax, %ecx
; SSE2-NEXT: pinsrw $3, %ecx, %xmm0
; SSE2-NEXT: retq
;
; SSE41-LABEL: merge_16i8_i8_0123uu67uuuuuzzz:
; SSE41: # BB#0:
; SSE41-NEXT: pxor %xmm0, %xmm0
; SSE41-NEXT: pinsrb $0, (%rdi), %xmm0
; SSE41-NEXT: pinsrb $1, 1(%rdi), %xmm0
; SSE41-NEXT: pinsrb $2, 2(%rdi), %xmm0
; SSE41-NEXT: pinsrb $3, 3(%rdi), %xmm0
; SSE41-NEXT: pinsrb $6, 6(%rdi), %xmm0
; SSE41-NEXT: pinsrb $7, 7(%rdi), %xmm0
; SSE41-NEXT: retq
; SSE-LABEL: merge_16i8_i8_0123uu67uuuuuzzz:
; SSE: # BB#0:
; SSE-NEXT: movq {{.*#+}} xmm0 = mem[0],zero
; SSE-NEXT: retq
;
; AVX-LABEL: merge_16i8_i8_0123uu67uuuuuzzz:
; AVX: # BB#0:
; AVX-NEXT: vpxor %xmm0, %xmm0, %xmm0
; AVX-NEXT: vpinsrb $0, (%rdi), %xmm0, %xmm0
; AVX-NEXT: vpinsrb $1, 1(%rdi), %xmm0, %xmm0
; AVX-NEXT: vpinsrb $2, 2(%rdi), %xmm0, %xmm0
; AVX-NEXT: vpinsrb $3, 3(%rdi), %xmm0, %xmm0
; AVX-NEXT: vpinsrb $6, 6(%rdi), %xmm0, %xmm0
; AVX-NEXT: vpinsrb $7, 7(%rdi), %xmm0, %xmm0
; AVX-NEXT: vmovq {{.*#+}} xmm0 = mem[0],zero
; AVX-NEXT: retq
%ptr0 = getelementptr inbounds i8, i8* %ptr, i64 0
%ptr1 = getelementptr inbounds i8, i8* %ptr, i64 1