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Adapt the x86 build_vector dagcombine to the current state of the legalizer. 

build vectors with i64 elements will only appear on 32b x86 before legalize.
Since vector widening occurs during legalize, and produces i64 build_vector 
elements, the dag combiner is never run on these before legalize splits them
into 32b elements.

Teach the build_vector dag combine in x86 back end to recognize consecutive 
loads producing the low part of the vector.

Convert the two uses of TLI's consecutive load recognizer to pass LoadSDNodes
since that was required implicitly.

Add a testcase for the transform.

Old:
	subl	$28, %esp
	movl	32(%esp), %eax
	movl	4(%eax), %ecx
	movl	%ecx, 4(%esp)
	movl	(%eax), %eax
	movl	%eax, (%esp)
	movaps	(%esp), %xmm0
	pmovzxwd	%xmm0, %xmm0
	movl	36(%esp), %eax
	movaps	%xmm0, (%eax)
	addl	$28, %esp
	ret

New:
	movl	4(%esp), %eax
	pmovzxwd	(%eax), %xmm0
	movl	8(%esp), %eax
	movaps	%xmm0, (%eax)
	ret

llvm-svn: 72957
This commit is contained in:
Nate Begeman 2009-06-05 21:37:30 +00:00
parent 3158790e32
commit 624690c6b2
5 changed files with 113 additions and 58 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
llvm/include/llvm/Target/TargetLowering.h
View File

@ -825,11 +825,11 @@ public:
virtual bool
isGAPlusOffset(SDNode *N, GlobalValue* &GA, int64_t &Offset) const;
/// isConsecutiveLoad - Return true if LD (which must be a LoadSDNode) is
/// loading 'Bytes' bytes from a location that is 'Dist' units away from the
/// location that the 'Base' load is loading from.
bool isConsecutiveLoad(SDNode *LD, SDNode *Base, unsigned Bytes, int Dist,
const MachineFrameInfo *MFI) const;
/// isConsecutiveLoad - Return true if LD is loading 'Bytes' bytes from a
/// location that is 'Dist' units away from the location that the 'Base' load
/// is loading from.
bool isConsecutiveLoad(LoadSDNode *LD, LoadSDNode *Base, unsigned Bytes,
int Dist, const MachineFrameInfo *MFI) const;
/// PerformDAGCombine - This method will be invoked for all target nodes and
/// for any target-independent nodes that the target has registered with

19
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -3626,30 +3626,29 @@ static SDNode *getBuildPairElt(SDNode *N, unsigned i) {
SDValue DAGCombiner::CombineConsecutiveLoads(SDNode *N, MVT VT) {
assert(N->getOpcode() == ISD::BUILD_PAIR);
SDNode *LD1 = getBuildPairElt(N, 0);
if (!ISD::isNON_EXTLoad(LD1) || !LD1->hasOneUse())
LoadSDNode *LD1 = dyn_cast<LoadSDNode>(getBuildPairElt(N, 0));
LoadSDNode *LD2 = dyn_cast<LoadSDNode>(getBuildPairElt(N, 1));
if (!LD1 || !LD2 || !ISD::isNON_EXTLoad(LD1) || !LD1->hasOneUse())
return SDValue();
MVT LD1VT = LD1->getValueType(0);
SDNode *LD2 = getBuildPairElt(N, 1);
const MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
if (ISD::isNON_EXTLoad(LD2) &&
LD2->hasOneUse() &&
// If both are volatile this would reduce the number of volatile loads.
// If one is volatile it might be ok, but play conservative and bail out.
!cast<LoadSDNode>(LD1)->isVolatile() &&
!cast<LoadSDNode>(LD2)->isVolatile() &&
!LD1->isVolatile() &&
!LD2->isVolatile() &&
TLI.isConsecutiveLoad(LD2, LD1, LD1VT.getSizeInBits()/8, 1, MFI)) {
LoadSDNode *LD = cast<LoadSDNode>(LD1);
unsigned Align = LD->getAlignment();
unsigned Align = LD1->getAlignment();
unsigned NewAlign = TLI.getTargetData()->
getABITypeAlignment(VT.getTypeForMVT());
if (NewAlign <= Align &&
(!LegalOperations || TLI.isOperationLegal(ISD::LOAD, VT)))
return DAG.getLoad(VT, N->getDebugLoc(), LD->getChain(), LD->getBasePtr(),
LD->getSrcValue(), LD->getSrcValueOffset(),
false, Align);
return DAG.getLoad(VT, N->getDebugLoc(), LD1->getChain(),
LD1->getBasePtr(), LD1->getSrcValue(),
LD1->getSrcValueOffset(), false, Align);
}
return SDValue();

15
llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
View File

@ -2070,13 +2070,13 @@ bool TargetLowering::isGAPlusOffset(SDNode *N, GlobalValue* &GA,
}
/// isConsecutiveLoad - Return true if LD (which must be a LoadSDNode) is
/// loading 'Bytes' bytes from a location that is 'Dist' units away from the
/// location that the 'Base' load is loading from.
bool TargetLowering::isConsecutiveLoad(SDNode *LD, SDNode *Base,
/// isConsecutiveLoad - Return true if LD is loading 'Bytes' bytes from a
/// location that is 'Dist' units away from the location that the 'Base' load
/// is loading from.
bool TargetLowering::isConsecutiveLoad(LoadSDNode *LD, LoadSDNode *Base,
unsigned Bytes, int Dist,
const MachineFrameInfo *MFI) const {
if (LD->getOperand(0).getNode() != Base->getOperand(0).getNode())
if (LD->getChain() != Base->getChain())
return false;
MVT VT = LD->getValueType(0);
if (VT.getSizeInBits() / 8 != Bytes)
@ -2094,6 +2094,11 @@ bool TargetLowering::isConsecutiveLoad(SDNode *LD, SDNode *Base,
if (FS != BFS || FS != (int)Bytes) return false;
return MFI->getObjectOffset(FI) == (MFI->getObjectOffset(BFI) + Dist*Bytes);
}
if (Loc.getOpcode() == ISD::ADD && Loc.getOperand(0) == BaseLoc) {
ConstantSDNode *V = dyn_cast<ConstantSDNode>(Loc.getOperand(1));
if (V && (V->getSExtValue() == Dist*Bytes))
return true;
}
GlobalValue *GV1 = NULL;
GlobalValue *GV2 = NULL;

49
llvm/lib/Target/X86/X86ISelLowering.cpp
View File

@ -7675,8 +7675,9 @@ static bool EltsFromConsecutiveLoads(ShuffleVectorSDNode *N, unsigned NumElems,
if (Elt.getOpcode() == ISD::UNDEF)
continue;
if (!TLI.isConsecutiveLoad(Elt.getNode(), Base,
EVT.getSizeInBits()/8, i, MFI))
LoadSDNode *LD = cast<LoadSDNode>(Elt);
LoadSDNode *LDBase = cast<LoadSDNode>(Base);
if (!TLI.isConsecutiveLoad(LD, LDBase, EVT.getSizeInBits()/8, i, MFI))
return false;
}
return true;
@ -7751,11 +7752,15 @@ static SDValue PerformBuildVectorCombine(SDNode *N, SelectionDAG &DAG,
MVT VT = N->getValueType(0);
MVT EVT = VT.getVectorElementType();
// Before or during type legalization, we want to try and convert a
// build_vector of an i64 load and a zero value into vzext_movl before the
// legalizer can break it up.
// FIXME: does the case below remove the need to do this?
if (DCI.isBeforeLegalize() || DCI.isCalledByLegalizer()) {
if ((EVT != MVT::i64 && EVT != MVT::f64) || Subtarget->is64Bit())
// We are looking for load i64 and zero extend. We want to transform
// it before legalizer has a chance to expand it. Also look for i64
// BUILD_PAIR bit casted to f64.
return SDValue();
// This must be an insertion into a zero vector.
SDValue HighElt = N->getOperand(1);
if (!isZeroNode(HighElt))
@ -7791,6 +7796,40 @@ static SDValue PerformBuildVectorCombine(SDNode *N, SelectionDAG &DAG,
return ResNode;
}
// The type legalizer will have broken apart v2i64 build_vector created during
// widening before the code which handles that case is run. Look for build
// vector (load, load + 4, 0/undef, 0/undef)
if (VT == MVT::v4i32 || VT == MVT::v4f32) {
LoadSDNode *LD0 = dyn_cast<LoadSDNode>(N->getOperand(0));
LoadSDNode *LD1 = dyn_cast<LoadSDNode>(N->getOperand(1));
if (!LD0 || !LD1)
return SDValue();
if (LD0->getExtensionType() != ISD::NON_EXTLOAD ||
LD1->getExtensionType() != ISD::NON_EXTLOAD)
return SDValue();
// Make sure the second elt is a consecutive load.
if (!TLI.isConsecutiveLoad(LD1, LD0, EVT.getSizeInBits()/8, 1,
DAG.getMachineFunction().getFrameInfo()))
return SDValue();
SDValue N2 = N->getOperand(2);
SDValue N3 = N->getOperand(3);
if (!isZeroNode(N2) && N2.getOpcode() != ISD::UNDEF)
return SDValue();
if (!isZeroNode(N3) && N3.getOpcode() != ISD::UNDEF)
return SDValue();
SDVTList Tys = DAG.getVTList(MVT::v2i64, MVT::Other);
SDValue Ops[] = { LD0->getChain(), LD0->getBasePtr() };
SDValue ResNode = DAG.getNode(X86ISD::VZEXT_LOAD, dl, Tys, Ops, 2);
TargetLowering::TargetLoweringOpt TLO(DAG);
TLO.CombineTo(SDValue(LD0, 1), ResNode.getValue(1));
DCI.CommitTargetLoweringOpt(TLO);
return DAG.getNode(ISD::BIT_CONVERT, dl, VT, ResNode);
}
return SDValue();
}
/// PerformSELECTCombine - Do target-specific dag combines on SELECT nodes.
static SDValue PerformSELECTCombine(SDNode *N, SelectionDAG &DAG,
const X86Subtarget *Subtarget) {

16
llvm/test/CodeGen/X86/dagcombine-buildvector.ll
View File

@ -1,13 +1,25 @@
; RUN: llvm-as < %s | llc -march=x86 -mattr=+sse2 -o %t -f
; RUN: llvm-as < %s | llc -march=x86 -mcpu=penryn -disable-mmx -o %t -f
; RUN: grep unpcklpd %t | count 1
; RUN: grep movapd %t | count 1
; RUN: grep movaps %t | count 1
; Shows a dag combine bug that will generate an illegal build vector
; with v2i64 build_vector i32, i32.
define void @test(<2 x double>* %dst, <4 x double> %src) {
define void @test(<2 x double>* %dst, <4 x double> %src) nounwind {
entry:
%tmp7.i = shufflevector <4 x double> %src, <4 x double> undef, <2 x i32> < i32 0, i32 2 >
store <2 x double> %tmp7.i, <2 x double>* %dst
ret void
}
define void @test2(<4 x i16>* %src, <4 x i32>* %dest) nounwind {
entry:
%tmp1 = load <4 x i16>* %src
%tmp3 = shufflevector <4 x i16> %tmp1, <4 x i16> undef, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 undef, i32 undef, i32 undef, i32 undef>
%0 = tail call <4 x i32> @llvm.x86.sse41.pmovzxwd(<8 x i16> %tmp3)
store <4 x i32> %0, <4 x i32>* %dest
ret void
}
declare <4 x i32> @llvm.x86.sse41.pmovzxwd(<8 x i16>) nounwind readnone