From 5d79bb5d32be680858f8ffa6a820eb2276950c0c Mon Sep 17 00:00:00 2001 From: Chandler Carruth Date: Fri, 4 Jul 2014 08:11:49 +0000 Subject: [PATCH] [x86] Generalize BuildVectorSDNode::getConstantSplatValue to work for any constant, constant FP, or undef splat and to tolerate any undef lanes in a splat, then replace all uses of isSplatVector in X86's lowering with it. This fixes issues where undef lanes in an otherwise splat vector would prevent the splat logic from firing. It is a touch more awkward to use this interface, but it is much more accurate. Suggestions for better interface structuring welcome. With this fix, the code generated with the widening legalization strategy for widen_cast-4.ll is *dramatically* improved as the special lowering strategies for a v16i8 SRA kick in even though the high lanes are undef. We also get a slightly different choice for broadcasting an aligned memory location, and use vpshufd instead of vbroadcastss. This looks like a minor win for pipelining and domain crossing, but a minor loss for the number of micro-ops. I suspect its a wash, but folks can easily tweak the lowering if they want. llvm-svn: 212324 --- llvm/include/llvm/CodeGen/SelectionDAGNodes.h | 8 +- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 13 +- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 28 +++-- llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp | 34 ++--- llvm/lib/Target/X86/X86ISelLowering.cpp | 151 ++++++++++++----------- llvm/test/CodeGen/X86/vector-gep.ll | 2 +- llvm/test/CodeGen/X86/widen_cast-4.ll | 25 +++- 7 files changed, 148 insertions(+), 113 deletions(-) diff --git a/llvm/include/llvm/CodeGen/SelectionDAGNodes.h b/llvm/include/llvm/CodeGen/SelectionDAGNodes.h index 5df4067..0943fa1 100644 --- a/llvm/include/llvm/CodeGen/SelectionDAGNodes.h +++ b/llvm/include/llvm/CodeGen/SelectionDAGNodes.h @@ -1584,10 +1584,10 @@ public: bool isBigEndian = false) const; /// getConstantSplatValue - Check if this is a constant splat, and if so, - /// return the splat value only if it is a ConstantSDNode. Otherwise - /// return nullptr. This is a simpler form of isConstantSplat. - /// Get the constant splat only if you care about the splat value. - ConstantSDNode *getConstantSplatValue() const; + /// return the splatted value. Otherwise return a null SDValue. This is + /// a simpler form of isConstantSplat. Get the constant splat only if you + /// care about the splat value. + SDValue getConstantSplatValue() const; bool isConstant() const; diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 7198203..9a91dcc 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -654,13 +654,12 @@ static ConstantSDNode *isConstOrConstSplat(SDValue N) { if (ConstantSDNode *CN = dyn_cast(N)) return CN; - if (BuildVectorSDNode *BV = dyn_cast(N)) { - ConstantSDNode *CN = BV->getConstantSplatValue(); - - // BuildVectors can truncate their operands. Ignore that case here. - if (CN && CN->getValueType(0) == N.getValueType().getScalarType()) - return CN; - } + if (BuildVectorSDNode *BV = dyn_cast(N)) + if (SDValue Splat = BV->getConstantSplatValue()) + if (auto *CN = dyn_cast(Splat)) + // BuildVectors can truncate their operands. Ignore that case here. + if (CN->getValueType(0) == N.getValueType().getScalarType()) + return CN; return nullptr; } diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index 3a8a5f9..fb7d1b1 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -6603,16 +6603,28 @@ bool BuildVectorSDNode::isConstantSplat(APInt &SplatValue, return true; } -ConstantSDNode *BuildVectorSDNode::getConstantSplatValue() const { - SDValue Op0 = getOperand(0); - if (Op0.getOpcode() != ISD::Constant) - return nullptr; +SDValue BuildVectorSDNode::getConstantSplatValue() const { + SDValue Splatted; + for (unsigned i = 0, e = getNumOperands(); i != e; ++i) { + SDValue Op = getOperand(i); + if (Op.getOpcode() == ISD::UNDEF) + continue; + if (Op.getOpcode() != ISD::Constant && Op.getOpcode() != ISD::ConstantFP) + return SDValue(); - for (unsigned i = 1, e = getNumOperands(); i != e; ++i) - if (getOperand(i) != Op0) - return nullptr; + if (!Splatted) + Splatted = Op; + else if (Splatted != Op) + return SDValue(); + } + + if (!Splatted) { + assert(getOperand(0).getOpcode() == ISD::UNDEF && + "Can only have a splat without a constant for all undefs."); + return getOperand(0); + } - return cast(Op0); + return Splatted; } bool BuildVectorSDNode::isConstant() const { diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp index ad91d4a..1b3e428 100644 --- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp @@ -1152,14 +1152,15 @@ bool TargetLowering::isConstTrueVal(const SDNode *N) const { bool IsVec = false; const ConstantSDNode *CN = dyn_cast(N); - if (!CN) { - const BuildVectorSDNode *BV = dyn_cast(N); - if (!BV) - return false; - - IsVec = true; - CN = BV->getConstantSplatValue(); - } + if (!CN) + if (auto *BV = dyn_cast(N)) + if (SDValue Splat = BV->getConstantSplatValue()) + if (auto *SplatCN = dyn_cast(Splat)) { + IsVec = true; + CN = SplatCN; + } + if (!CN) + return false; switch (getBooleanContents(IsVec)) { case UndefinedBooleanContent: @@ -1179,14 +1180,15 @@ bool TargetLowering::isConstFalseVal(const SDNode *N) const { bool IsVec = false; const ConstantSDNode *CN = dyn_cast(N); - if (!CN) { - const BuildVectorSDNode *BV = dyn_cast(N); - if (!BV) - return false; - - IsVec = true; - CN = BV->getConstantSplatValue(); - } + if (!CN) + if (auto *BV = dyn_cast(N)) + if (SDValue Splat = BV->getConstantSplatValue()) + if (auto *SplatCN = dyn_cast(Splat)) { + IsVec = true; + CN = SplatCN; + } + if (!CN) + return false; if (getBooleanContents(IsVec) == UndefinedBooleanContent) return !CN->getAPIntValue()[0]; diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp index 7488cec..b372950 100644 --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -4858,19 +4858,6 @@ static bool ShouldXformToMOVLP(SDNode *V1, SDNode *V2, return true; } -/// isSplatVector - Returns true if N is a BUILD_VECTOR node whose elements are -/// all the same. -static bool isSplatVector(SDNode *N) { - if (N->getOpcode() != ISD::BUILD_VECTOR) - return false; - - SDValue SplatValue = N->getOperand(0); - for (unsigned i = 1, e = N->getNumOperands(); i != e; ++i) - if (N->getOperand(i) != SplatValue) - return false; - return true; -} - /// isZeroShuffle - Returns true if N is a VECTOR_SHUFFLE that can be resolved /// to an zero vector. /// FIXME: move to dag combiner / method on ShuffleVectorSDNode @@ -5779,17 +5766,20 @@ static SDValue LowerVectorBroadcast(SDValue Op, const X86Subtarget* Subtarget, return SDValue(); case ISD::BUILD_VECTOR: { + auto *BVOp = cast(Op.getNode()); // The BUILD_VECTOR node must be a splat. - if (!isSplatVector(Op.getNode())) + SDValue Splat = BVOp->getConstantSplatValue(); + if (!Splat) return SDValue(); - Ld = Op.getOperand(0); + Ld = Splat; ConstSplatVal = (Ld.getOpcode() == ISD::Constant || Ld.getOpcode() == ISD::ConstantFP); // The suspected load node has several users. Make sure that all // of its users are from the BUILD_VECTOR node. // Constants may have multiple users. + // FIXME: This doesn't make sense if the build vector contains undefs. if (!ConstSplatVal && !Ld->hasNUsesOfValue(VT.getVectorNumElements(), 0)) return SDValue(); break; @@ -9375,8 +9365,12 @@ X86TargetLowering::LowerVECTOR_SHUFFLE(SDValue Op, SelectionDAG &DAG) const { bool Commuted = false; // FIXME: This should also accept a bitcast of a splat? Be careful, not // 1,1,1,1 -> v8i16 though. - V1IsSplat = isSplatVector(V1.getNode()); - V2IsSplat = isSplatVector(V2.getNode()); + if (auto *BVOp = dyn_cast(V1.getNode())) + if (BVOp->getConstantSplatValue()) + V1IsSplat = true; + if (auto *BVOp = dyn_cast(V2.getNode())) + if (BVOp->getConstantSplatValue()) + V2IsSplat = true; // Canonicalize the splat or undef, if present, to be on the RHS. if (!V2IsUndef && V1IsSplat && !V2IsSplat) { @@ -15171,10 +15165,11 @@ static SDValue LowerScalarImmediateShift(SDValue Op, SelectionDAG &DAG, SDValue Amt = Op.getOperand(1); // Optimize shl/srl/sra with constant shift amount. - if (isSplatVector(Amt.getNode())) { - SDValue SclrAmt = Amt->getOperand(0); - if (ConstantSDNode *C = dyn_cast(SclrAmt)) { - uint64_t ShiftAmt = C->getZExtValue(); + if (auto *BVAmt = dyn_cast(Amt)) { + if (SDValue Splat = BVAmt->getConstantSplatValue()) { + uint64_t ShiftAmt = Splat.getOpcode() == ISD::UNDEF + ? 0 + : cast(Splat)->getZExtValue(); if (VT == MVT::v2i64 || VT == MVT::v4i32 || VT == MVT::v8i16 || (Subtarget->hasInt256() && @@ -19423,27 +19418,35 @@ static SDValue PerformSELECTCombine(SDNode *N, SelectionDAG &DAG, Other->getOpcode() == ISD::SUB && DAG.isEqualTo(OpRHS, CondRHS)) return DAG.getNode(X86ISD::SUBUS, DL, VT, OpLHS, OpRHS); - // If the RHS is a constant we have to reverse the const canonicalization. - // x > C-1 ? x+-C : 0 --> subus x, C - if (CC == ISD::SETUGT && Other->getOpcode() == ISD::ADD && - isSplatVector(CondRHS.getNode()) && isSplatVector(OpRHS.getNode())) { - APInt A = cast(OpRHS.getOperand(0))->getAPIntValue(); - if (CondRHS.getConstantOperandVal(0) == -A-1) - return DAG.getNode(X86ISD::SUBUS, DL, VT, OpLHS, - DAG.getConstant(-A, VT)); - } + if (auto *OpRHSBV = dyn_cast(OpRHS)) { + SDValue OpRHSSplat = OpRHSBV->getConstantSplatValue(); + auto *OpRHSSplatConst = dyn_cast(OpRHSSplat); + if (auto *CondRHSBV = dyn_cast(CondRHS)) { + // If the RHS is a constant we have to reverse the const + // canonicalization. + // x > C-1 ? x+-C : 0 --> subus x, C + SDValue CondRHSSplat = CondRHSBV->getConstantSplatValue(); + auto *CondRHSSplatConst = dyn_cast(CondRHSSplat); + if (CC == ISD::SETUGT && Other->getOpcode() == ISD::ADD && + CondRHSSplatConst && OpRHSSplatConst) { + APInt A = OpRHSSplatConst->getAPIntValue(); + if (CondRHSSplatConst->getAPIntValue() == -A - 1) + return DAG.getNode(X86ISD::SUBUS, DL, VT, OpLHS, + DAG.getConstant(-A, VT)); + } + } - // Another special case: If C was a sign bit, the sub has been - // canonicalized into a xor. - // FIXME: Would it be better to use computeKnownBits to determine whether - // it's safe to decanonicalize the xor? - // x s< 0 ? x^C : 0 --> subus x, C - if (CC == ISD::SETLT && Other->getOpcode() == ISD::XOR && - ISD::isBuildVectorAllZeros(CondRHS.getNode()) && - isSplatVector(OpRHS.getNode())) { - APInt A = cast(OpRHS.getOperand(0))->getAPIntValue(); - if (A.isSignBit()) - return DAG.getNode(X86ISD::SUBUS, DL, VT, OpLHS, OpRHS); + // Another special case: If C was a sign bit, the sub has been + // canonicalized into a xor. + // FIXME: Would it be better to use computeKnownBits to determine + // whether it's safe to decanonicalize the xor? + // x s< 0 ? x^C : 0 --> subus x, C + if (CC == ISD::SETLT && Other->getOpcode() == ISD::XOR && + ISD::isBuildVectorAllZeros(CondRHS.getNode()) && OpRHSSplatConst) { + APInt A = OpRHSSplatConst->getAPIntValue(); + if (A.isSignBit()) + return DAG.getNode(X86ISD::SUBUS, DL, VT, OpLHS, OpRHS); + } } } } @@ -20152,16 +20155,16 @@ static SDValue PerformSHLCombine(SDNode *N, SelectionDAG &DAG) { // vector operations in many cases. Also, on sandybridge ADD is faster than // shl. // (shl V, 1) -> add V,V - if (isSplatVector(N1.getNode())) { - assert(N0.getValueType().isVector() && "Invalid vector shift type"); - ConstantSDNode *N1C = dyn_cast(N1->getOperand(0)); - // We shift all of the values by one. In many cases we do not have - // hardware support for this operation. This is better expressed as an ADD - // of two values. - if (N1C && (1 == N1C->getZExtValue())) { - return DAG.getNode(ISD::ADD, SDLoc(N), VT, N0, N0); + if (auto *N1BV = dyn_cast(N1)) + if (SDValue N1Splat = N1BV->getConstantSplatValue()) { + assert(N0.getValueType().isVector() && "Invalid vector shift type"); + // We shift all of the values by one. In many cases we do not have + // hardware support for this operation. This is better expressed as an ADD + // of two values. + if (N1Splat.getOpcode() == ISD::Constant && + cast(N1Splat)->getZExtValue() == 1) + return DAG.getNode(ISD::ADD, SDLoc(N), VT, N0, N0); } - } return SDValue(); } @@ -20180,20 +20183,19 @@ static SDValue performShiftToAllZeros(SDNode *N, SelectionDAG &DAG, SDValue Amt = N->getOperand(1); SDLoc DL(N); - if (isSplatVector(Amt.getNode())) { - SDValue SclrAmt = Amt->getOperand(0); - if (ConstantSDNode *C = dyn_cast(SclrAmt)) { - APInt ShiftAmt = C->getAPIntValue(); - unsigned MaxAmount = VT.getVectorElementType().getSizeInBits(); - - // SSE2/AVX2 logical shifts always return a vector of 0s - // if the shift amount is bigger than or equal to - // the element size. The constant shift amount will be - // encoded as a 8-bit immediate. - if (ShiftAmt.trunc(8).uge(MaxAmount)) - return getZeroVector(VT, Subtarget, DAG, DL); - } - } + if (auto *AmtBV = dyn_cast(Amt)) + if (SDValue AmtSplat = AmtBV->getConstantSplatValue()) + if (auto *AmtConst = dyn_cast(AmtSplat)) { + APInt ShiftAmt = AmtConst->getAPIntValue(); + unsigned MaxAmount = VT.getVectorElementType().getSizeInBits(); + + // SSE2/AVX2 logical shifts always return a vector of 0s + // if the shift amount is bigger than or equal to + // the element size. The constant shift amount will be + // encoded as a 8-bit immediate. + if (ShiftAmt.trunc(8).uge(MaxAmount)) + return getZeroVector(VT, Subtarget, DAG, DL); + } return SDValue(); } @@ -20387,9 +20389,10 @@ static SDValue WidenMaskArithmetic(SDNode *N, SelectionDAG &DAG, // The right side has to be a 'trunc' or a constant vector. bool RHSTrunc = N1.getOpcode() == ISD::TRUNCATE; - bool RHSConst = (isSplatVector(N1.getNode()) && - isa(N1->getOperand(0))); - if (!RHSTrunc && !RHSConst) + SDValue RHSConstSplat; + if (auto *RHSBV = dyn_cast(N1)) + RHSConstSplat = RHSBV->getConstantSplatValue(); + if (!RHSTrunc && !RHSConstSplat) return SDValue(); const TargetLowering &TLI = DAG.getTargetLoweringInfo(); @@ -20399,9 +20402,9 @@ static SDValue WidenMaskArithmetic(SDNode *N, SelectionDAG &DAG, // Set N0 and N1 to hold the inputs to the new wide operation. N0 = N0->getOperand(0); - if (RHSConst) { + if (RHSConstSplat) { N1 = DAG.getNode(ISD::ZERO_EXTEND, DL, WideVT.getScalarType(), - N1->getOperand(0)); + RHSConstSplat); SmallVector C(WideVT.getVectorNumElements(), N1); N1 = DAG.getNode(ISD::BUILD_VECTOR, DL, WideVT, C); } else if (RHSTrunc) { @@ -20547,12 +20550,10 @@ static SDValue PerformOrCombine(SDNode *N, SelectionDAG &DAG, unsigned EltBits = MaskVT.getVectorElementType().getSizeInBits(); unsigned SraAmt = ~0; if (Mask.getOpcode() == ISD::SRA) { - SDValue Amt = Mask.getOperand(1); - if (isSplatVector(Amt.getNode())) { - SDValue SclrAmt = Amt->getOperand(0); - if (ConstantSDNode *C = dyn_cast(SclrAmt)) - SraAmt = C->getZExtValue(); - } + if (auto *AmtBV = dyn_cast(Mask.getOperand(1))) + if (SDValue AmtSplat = AmtBV->getConstantSplatValue()) + if (auto *AmtConst = dyn_cast(AmtSplat)) + SraAmt = AmtConst->getZExtValue(); } else if (Mask.getOpcode() == X86ISD::VSRAI) { SDValue SraC = Mask.getOperand(1); SraAmt = cast(SraC)->getZExtValue(); diff --git a/llvm/test/CodeGen/X86/vector-gep.ll b/llvm/test/CodeGen/X86/vector-gep.ll index 9c68f44..61edb1e 100644 --- a/llvm/test/CodeGen/X86/vector-gep.ll +++ b/llvm/test/CodeGen/X86/vector-gep.ll @@ -5,7 +5,7 @@ define <4 x i32*> @AGEP0(i32* %ptr) nounwind { entry: ;CHECK-LABEL: AGEP0 -;CHECK: vbroadcast +;CHECK: vpshufd {{.*}} # xmm0 = mem[0,0,0,0] ;CHECK-NEXT: vpaddd ;CHECK-NEXT: ret %vecinit.i = insertelement <4 x i32*> undef, i32* %ptr, i32 0 diff --git a/llvm/test/CodeGen/X86/widen_cast-4.ll b/llvm/test/CodeGen/X86/widen_cast-4.ll index 1bc06a7..03dffc4 100644 --- a/llvm/test/CodeGen/X86/widen_cast-4.ll +++ b/llvm/test/CodeGen/X86/widen_cast-4.ll @@ -1,8 +1,9 @@ ; RUN: llc < %s -march=x86 -mattr=+sse4.2 | FileCheck %s -; CHECK: psraw -; CHECK: psraw +; RUN: llc < %s -march=x86 -mattr=+sse4.2 -x86-experimental-vector-widening-legalization | FileCheck %s --check-prefix=CHECK-WIDE define void @update(i64* %dst_i, i64* %src_i, i32 %n) nounwind { +; CHECK-LABEL: update: +; CHECK-WIDE-LABEL: update: entry: %dst_i.addr = alloca i64* ; [#uses=2] %src_i.addr = alloca i64* ; [#uses=2] @@ -23,6 +24,8 @@ forcond: ; preds = %forinc, %entry br i1 %cmp, label %forbody, label %afterfor forbody: ; preds = %forcond +; CHECK: %forbody +; CHECK-WIDE: %forbody %tmp2 = load i32* %i ; [#uses=1] %tmp3 = load i64** %dst_i.addr ; [#uses=1] %arrayidx = getelementptr i64* %tmp3, i32 %tmp2 ; [#uses=1] @@ -44,6 +47,24 @@ forbody: ; preds = %forcond %shr = ashr <8 x i8> %add, < i8 2, i8 2, i8 2, i8 2, i8 2, i8 2, i8 2, i8 2 > ; <<8 x i8>> [#uses=1] store <8 x i8> %shr, <8 x i8>* %arrayidx10 br label %forinc +; CHECK: pmovzxbw +; CHECK-NEXT: paddw +; CHECK-NEXT: psllw $8 +; CHECK-NEXT: psraw $8 +; CHECK-NEXT: psraw $2 +; CHECK-NEXT: pshufb +; CHECK-NEXT: movlpd +; +; FIXME: We shouldn't require both a movd and an insert. +; CHECK-WIDE: movd +; CHECK-WIDE-NEXT: pinsrd +; CHECK-WIDE-NEXT: paddb +; CHECK-WIDE-NEXT: psrlw $2 +; CHECK-WIDE-NEXT: pand +; CHECK-WIDE-NEXT: pxor +; CHECK-WIDE-NEXT: psubb +; CHECK-WIDE-NEXT: pextrd +; CHECK-WIDE-NEXT: movd forinc: ; preds = %forbody %tmp15 = load i32* %i ; [#uses=1] -- 2.7.4