diff --git a/include/llvm/Target/TargetLowering.h b/include/llvm/Target/TargetLowering.h index 6f9692ece15..80826cb6c3e 100644 --- a/include/llvm/Target/TargetLowering.h +++ b/include/llvm/Target/TargetLowering.h @@ -2718,8 +2718,6 @@ public: //===--------------------------------------------------------------------===// // Div utility functions // - SDValue BuildExactSDIV(SDValue Op1, SDValue Op2, SDLoc dl, - SelectionDAG &DAG) const; SDValue BuildSDIV(SDNode *N, const APInt &Divisor, SelectionDAG &DAG, bool IsAfterLegalization, std::vector<SDNode *> *Created) const; diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 2c4ab8b9f8f..29f9df6425e 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -2178,7 +2178,11 @@ SDValue DAGCombiner::visitSDIV(SDNode *N) { } // fold (sdiv X, pow2) -> simple ops after legalize + // FIXME: We check for the exact bit here because the generic lowering gives + // better results in that case. The target-specific lowering should learn how + // to handle exact sdivs efficiently. if (N1C && !N1C->isNullValue() && !N1C->isOpaque() && + !cast<BinaryWithFlagsSDNode>(N)->Flags.hasExact() && (N1C->getAPIntValue().isPowerOf2() || (-N1C->getAPIntValue()).isPowerOf2())) { // If dividing by powers of two is cheap, then don't perform the following diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp index 329c1706171..85b2d5f62ff 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -2238,17 +2238,11 @@ void SelectionDAGBuilder::visitSDiv(const User &I) { SDValue Op1 = getValue(I.getOperand(0)); SDValue Op2 = getValue(I.getOperand(1)); - // Turn exact SDivs into multiplications. - // FIXME: This should be in DAGCombiner, but it doesn't have access to the - // exact bit. - if (isa<BinaryOperator>(&I) && cast<BinaryOperator>(&I)->isExact() && - !isa<ConstantSDNode>(Op1) && - isa<ConstantSDNode>(Op2) && !cast<ConstantSDNode>(Op2)->isNullValue()) - setValue(&I, DAG.getTargetLoweringInfo() - .BuildExactSDIV(Op1, Op2, getCurSDLoc(), DAG)); - else - setValue(&I, DAG.getNode(ISD::SDIV, getCurSDLoc(), Op1.getValueType(), - Op1, Op2)); + SDNodeFlags Flags; + Flags.setExact(isa<PossiblyExactOperator>(&I) && + cast<PossiblyExactOperator>(&I)->isExact()); + setValue(&I, DAG.getNode(ISD::SDIV, getCurSDLoc(), Op1.getValueType(), Op1, + Op2, &Flags)); } void SelectionDAGBuilder::visitICmp(const User &I) { diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp index fc746588e69..e7722b392a8 100644 --- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp +++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp @@ -2674,10 +2674,9 @@ void TargetLowering::ComputeConstraintToUse(AsmOperandInfo &OpInfo, /// \brief Given an exact SDIV by a constant, create a multiplication /// with the multiplicative inverse of the constant. -SDValue TargetLowering::BuildExactSDIV(SDValue Op1, SDValue Op2, SDLoc dl, - SelectionDAG &DAG) const { - ConstantSDNode *C = cast<ConstantSDNode>(Op2); - APInt d = C->getAPIntValue(); +static SDValue BuildExactSDIV(const TargetLowering &TLI, SDValue Op1, APInt d, + SDLoc dl, SelectionDAG &DAG, + std::vector<SDNode *> &Created) { assert(d != 0 && "Division by zero!"); // Shift the value upfront if it is even, so the LSB is one. @@ -2685,10 +2684,11 @@ SDValue TargetLowering::BuildExactSDIV(SDValue Op1, SDValue Op2, SDLoc dl, if (ShAmt) { // TODO: For UDIV use SRL instead of SRA. SDValue Amt = - DAG.getConstant(ShAmt, dl, getShiftAmountTy(Op1.getValueType())); + DAG.getConstant(ShAmt, dl, TLI.getShiftAmountTy(Op1.getValueType())); SDNodeFlags Flags; Flags.setExact(true); Op1 = DAG.getNode(ISD::SRA, dl, Op1.getValueType(), Op1, Amt, &Flags); + Created.push_back(Op1.getNode()); d = d.ashr(ShAmt); } @@ -2697,8 +2697,10 @@ SDValue TargetLowering::BuildExactSDIV(SDValue Op1, SDValue Op2, SDLoc dl, while ((t = d*xn) != 1) xn *= APInt(d.getBitWidth(), 2) - t; - Op2 = DAG.getConstant(xn, dl, Op1.getValueType()); - return DAG.getNode(ISD::MUL, dl, Op1.getValueType(), Op1, Op2); + SDValue Op2 = DAG.getConstant(xn, dl, Op1.getValueType()); + SDValue Mul = DAG.getNode(ISD::MUL, dl, Op1.getValueType(), Op1, Op2); + Created.push_back(Mul.getNode()); + return Mul; } /// \brief Given an ISD::SDIV node expressing a divide by constant, @@ -2718,6 +2720,10 @@ SDValue TargetLowering::BuildSDIV(SDNode *N, const APInt &Divisor, if (!isTypeLegal(VT)) return SDValue(); + // If the sdiv has an 'exact' bit we can use a simpler lowering. + if (cast<BinaryWithFlagsSDNode>(N)->Flags.hasExact()) + return BuildExactSDIV(*this, N->getOperand(0), Divisor, dl, DAG, *Created); + APInt::ms magics = Divisor.magic(); // Multiply the numerator (operand 0) by the magic value diff --git a/test/CodeGen/X86/sdiv-exact.ll b/test/CodeGen/X86/sdiv-exact.ll index 4f8d3f05351..a6ace5bc31c 100644 --- a/test/CodeGen/X86/sdiv-exact.ll +++ b/test/CodeGen/X86/sdiv-exact.ll @@ -1,4 +1,4 @@ -; RUN: llc -march=x86 < %s | FileCheck %s +; RUN: llc -march=x86 -mattr=+sse2 < %s | FileCheck %s define i32 @test1(i32 %x) { %div = sdiv exact i32 %x, 25 @@ -16,3 +16,14 @@ define i32 @test2(i32 %x) { ; CHECK-NEXT: imull $-1431655765 ; CHECK-NEXT: ret } + +define <4 x i32> @test3(<4 x i32> %x) { + %div = sdiv exact <4 x i32> %x, <i32 24, i32 24, i32 24, i32 24> + ret <4 x i32> %div +; CHECK-LABEL: test3: +; CHECK: psrad $3, +; CHECK: pmuludq +; CHECK: pmuludq +; CHECK-NOT: psrad +; CHECK: ret +}