diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp --- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -1681,6 +1681,125 @@ return nullptr; } +static Instruction *simplifyIRemMulShl(BinaryOperator &I, + InstCombinerImpl &IC) { + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + // Variety of transform for (urem/srem (mul/shl X, Y), (mul/shl X, Z)) + Value *A, *B, *C, *D; + if (!(match(Op0, m_Mul(m_Value(A), m_Value(B))) || + match(Op0, m_Shl(m_Value(A), m_Value(B)))) || + !(match(Op1, m_Mul(m_Value(C), m_Value(D))) || + match(Op1, m_Shl(m_Value(C), m_Value(D))))) + return nullptr; + + Value *X, *Y, *Z; + X = nullptr; + // Do this by hand as opposed to using m_Specific because either A/B (or + // C/D) can be our X. + if (A == C || A == D) { + X = A; + Y = B; + Z = A == C ? D : C; + } else if (B == C || B == D) { + X = B; + Y = A; + Z = B == C ? D : C; + } + + if (!X) + return nullptr; + + // BO0 = X * Y + BinaryOperator *BO0 = dyn_cast(Op0); + // BO1 = X * Z + BinaryOperator *BO1 = dyn_cast(Op1); + + if (!BO0 || !BO1) + return nullptr; + + // If X is constant 1, then we avoid both in the mul and shl case. + Constant *CX = dyn_cast(X); + if (CX && CX->isOneValue()) + return nullptr; + + Type *Ty = I.getType(); + + ConstantInt *ConstY = dyn_cast(Y); + ConstantInt *ConstZ = dyn_cast(Z); + if (Ty->isVectorTy()) { + auto *VConstY = dyn_cast(Y); + auto *VConstZ = dyn_cast(Z); + if (VConstY && VConstZ) { + VConstY = VConstY->getSplatValue(); + VConstZ = VConstZ->getSplatValue(); + if (VConstY && VConstZ) { + ConstY = dyn_cast(VConstY); + ConstZ = dyn_cast(VConstZ); + } + } + } + bool IsSigned = I.getOpcode() == Instruction::SRem; + + bool NSW0 = BO0->hasNoSignedWrap(); + bool NSW1 = BO1->hasNoSignedWrap(); + bool NUW0 = BO0->hasNoUnsignedWrap(); + bool NUW1 = BO1->hasNoUnsignedWrap(); + + // Try to handle constant cases first. + if (!ConstY || !ConstZ) + return nullptr; + + APInt APIntY = ConstY->getValue(); + APInt APIntZ = ConstZ->getValue(); + + // Just treat the shifts as mul, we may end up returning a mul by power + // of 2 but that will be cleaned up later. + if (BO0->getOpcode() == Instruction::Shl) + APIntY = APInt(APIntY.getBitWidth(), 1) << APIntY; + if (BO1->getOpcode() == Instruction::Shl) + APIntZ = APInt(APIntZ.getBitWidth(), 1) << APIntZ; + + APInt RemYZ = IsSigned ? APIntY.srem(APIntZ) : APIntY.urem(APIntZ); + + // (rem (mul nuw/nsw X, Y), (mul X, Z)) + // if (rem Y, Z) == 0 + // -> 0 + if (RemYZ.isZero() && (IsSigned ? NSW0 : NUW0)) + return IC.replaceInstUsesWith(I, ConstantInt::getNullValue(Ty)); + + // (rem (mul X, Y), (mul nuw/nsw X, Z)) + // if (rem Y, Z) == Y + // -> (mul nuw/nsw X, Y) + if (RemYZ == APIntY && (IsSigned ? NSW1 : NUW1)) { + // We are returning Op0 essentially but we can also add no wrap flags. + BinaryOperator *BO = + BinaryOperator::CreateMul(X, ConstantInt::get(Ty, APIntY)); + // We can add nsw/nuw if remainder op is signed/unsigned, also we + // can copy any overflow flags from Op0. + if (IsSigned || NSW0) + BO->setHasNoSignedWrap(); + if (!IsSigned || NUW0) + BO->setHasNoUnsignedWrap(); + return BO; + } + + // (rem (mul nuw/nsw X, Y), (mul {nsw} X, Z)) + // if Y >= Z + // -> (mul {nuw} nsw X, (rem Y, Z)) + // NB: (rem Y, Z) is a constant. + if (APIntY.uge(APIntZ) && (IsSigned ? (NSW0 && NSW1) : NUW0)) { + BinaryOperator *BO = + BinaryOperator::CreateMul(X, ConstantInt::get(Ty, RemYZ)); + BO->setHasNoSignedWrap(); + if (!IsSigned || NUW0) + BO->setHasNoUnsignedWrap(); + return BO; + } + + return nullptr; +} + /// This function implements the transforms common to both integer remainder /// instructions (urem and srem). It is called by the visitors to those integer /// remainder instructions. @@ -1733,6 +1852,9 @@ } } + if (Instruction *R = simplifyIRemMulShl(I, *this)) + return R; + return nullptr; } diff --git a/llvm/test/Transforms/InstCombine/urem-mul.ll b/llvm/test/Transforms/InstCombine/urem-mul.ll --- a/llvm/test/Transforms/InstCombine/urem-mul.ll +++ b/llvm/test/Transforms/InstCombine/urem-mul.ll @@ -31,10 +31,7 @@ define i8 @urem_CY_CZ_is_zero(i8 %X) { ; CHECK-LABEL: @urem_CY_CZ_is_zero( -; CHECK-NEXT: [[BO0:%.*]] = mul nuw i8 [[X:%.*]], 15 -; CHECK-NEXT: [[BO1:%.*]] = mul i8 [[X]], 5 -; CHECK-NEXT: [[R:%.*]] = urem i8 [[BO0]], [[BO1]] -; CHECK-NEXT: ret i8 [[R]] +; CHECK-NEXT: ret i8 0 ; %BO0 = mul nuw i8 %X, 15 %BO1 = mul i8 %X, 5 @@ -57,9 +54,7 @@ define i8 @urem_CY_CZ_is_BO0(i8 %X) { ; CHECK-LABEL: @urem_CY_CZ_is_BO0( -; CHECK-NEXT: [[BO0:%.*]] = mul i8 [[X:%.*]], 3 -; CHECK-NEXT: [[BO1:%.*]] = mul nuw i8 [[X]], 12 -; CHECK-NEXT: [[R:%.*]] = urem i8 [[BO0]], [[BO1]] +; CHECK-NEXT: [[R:%.*]] = mul nuw i8 [[X:%.*]], 3 ; CHECK-NEXT: ret i8 [[R]] ; %BO0 = mul i8 %X, 3 @@ -70,9 +65,7 @@ define <2 x i8> @urem_CY_CZ_is_BO0_with_nsw_out(<2 x i8> %X) { ; CHECK-LABEL: @urem_CY_CZ_is_BO0_with_nsw_out( -; CHECK-NEXT: [[BO0:%.*]] = shl nsw <2 x i8> [[X:%.*]], -; CHECK-NEXT: [[BO1:%.*]] = mul nuw <2 x i8> [[X]], -; CHECK-NEXT: [[R:%.*]] = urem <2 x i8> [[BO0]], [[BO1]] +; CHECK-NEXT: [[R:%.*]] = shl nuw nsw <2 x i8> [[X:%.*]], ; CHECK-NEXT: ret <2 x i8> [[R]] ; %BO0 = shl nsw <2 x i8> %X, @@ -83,9 +76,7 @@ define i8 @urem_CY_CZ_is_BO0_no_nsw_out(i8 %X) { ; CHECK-LABEL: @urem_CY_CZ_is_BO0_no_nsw_out( -; CHECK-NEXT: [[BO0:%.*]] = mul nuw i8 [[X:%.*]], 3 -; CHECK-NEXT: [[BO1:%.*]] = shl nuw nsw i8 [[X]], 3 -; CHECK-NEXT: [[R:%.*]] = urem i8 [[BO0]], [[BO1]] +; CHECK-NEXT: [[R:%.*]] = mul nuw i8 [[X:%.*]], 3 ; CHECK-NEXT: ret i8 [[R]] ; %BO0 = mul nuw i8 %X, 3 @@ -109,9 +100,7 @@ define i8 @urem_CY_CZ_is_mul_X_RemYZ(i8 %X) { ; CHECK-LABEL: @urem_CY_CZ_is_mul_X_RemYZ( -; CHECK-NEXT: [[BO0:%.*]] = mul nuw i8 [[X:%.*]], 21 -; CHECK-NEXT: [[BO1:%.*]] = mul i8 [[X]], 6 -; CHECK-NEXT: [[R:%.*]] = urem i8 [[BO0]], [[BO1]] +; CHECK-NEXT: [[R:%.*]] = mul nuw nsw i8 [[X:%.*]], 3 ; CHECK-NEXT: ret i8 [[R]] ; %BO0 = mul nuw i8 %X, 21 @@ -229,10 +218,7 @@ ;; Signed Verions define i8 @srem_CY_CZ_is_zero(i8 %X) { ; CHECK-LABEL: @srem_CY_CZ_is_zero( -; CHECK-NEXT: [[BO0:%.*]] = mul nsw i8 [[X:%.*]], 9 -; CHECK-NEXT: [[BO1:%.*]] = mul i8 [[X]], 3 -; CHECK-NEXT: [[R:%.*]] = srem i8 [[BO0]], [[BO1]] -; CHECK-NEXT: ret i8 [[R]] +; CHECK-NEXT: ret i8 0 ; %BO0 = mul nsw i8 %X, 9 %BO1 = mul i8 %X, 3 @@ -255,9 +241,7 @@ define <2 x i8> @srem_CY_CZ_is_BO0(<2 x i8> %X) { ; CHECK-LABEL: @srem_CY_CZ_is_BO0( -; CHECK-NEXT: [[BO0:%.*]] = shl <2 x i8> [[X:%.*]], -; CHECK-NEXT: [[BO1:%.*]] = mul nsw <2 x i8> [[X]], -; CHECK-NEXT: [[R:%.*]] = srem <2 x i8> [[BO0]], [[BO1]] +; CHECK-NEXT: [[R:%.*]] = shl nsw <2 x i8> [[X:%.*]], ; CHECK-NEXT: ret <2 x i8> [[R]] ; %BO0 = shl <2 x i8> %X, @@ -268,9 +252,7 @@ define i8 @srem_CY_CZ_is_BO0_with_nuw_out(i8 %X) { ; CHECK-LABEL: @srem_CY_CZ_is_BO0_with_nuw_out( -; CHECK-NEXT: [[BO0:%.*]] = mul nuw i8 [[X:%.*]], 5 -; CHECK-NEXT: [[BO1:%.*]] = mul nsw i8 [[X]], 15 -; CHECK-NEXT: [[R:%.*]] = srem i8 [[BO0]], [[BO1]] +; CHECK-NEXT: [[R:%.*]] = mul nuw nsw i8 [[X:%.*]], 5 ; CHECK-NEXT: ret i8 [[R]] ; %BO0 = mul nuw i8 %X, 5 @@ -281,9 +263,7 @@ define i8 @srem_CY_CZ_is_BO0_no_nsw_out(i8 %X) { ; CHECK-LABEL: @srem_CY_CZ_is_BO0_no_nsw_out( -; CHECK-NEXT: [[BO0:%.*]] = mul nsw i8 [[X:%.*]], 5 -; CHECK-NEXT: [[BO1:%.*]] = shl nuw nsw i8 [[X]], 4 -; CHECK-NEXT: [[R:%.*]] = srem i8 [[BO0]], [[BO1]] +; CHECK-NEXT: [[R:%.*]] = mul nsw i8 [[X:%.*]], 5 ; CHECK-NEXT: ret i8 [[R]] ; %BO0 = mul nsw i8 %X, 5 @@ -307,9 +287,7 @@ define i8 @srem_CY_CZ_is_mul_X_RemYZ(i8 %X) { ; CHECK-LABEL: @srem_CY_CZ_is_mul_X_RemYZ( -; CHECK-NEXT: [[BO0:%.*]] = shl nsw i8 [[X:%.*]], 3 -; CHECK-NEXT: [[BO1:%.*]] = mul nsw i8 [[X]], 6 -; CHECK-NEXT: [[R:%.*]] = srem i8 [[BO0]], [[BO1]] +; CHECK-NEXT: [[R:%.*]] = shl nsw i8 [[X:%.*]], 1 ; CHECK-NEXT: ret i8 [[R]] ; %BO0 = shl nsw i8 %X, 3 @@ -320,9 +298,7 @@ define i8 @srem_CY_CZ_is_mul_X_RemYZ_with_nuw_out(i8 %X) { ; CHECK-LABEL: @srem_CY_CZ_is_mul_X_RemYZ_with_nuw_out( -; CHECK-NEXT: [[BO0:%.*]] = mul nuw nsw i8 [[X:%.*]], 10 -; CHECK-NEXT: [[BO1:%.*]] = mul nsw i8 [[X]], 6 -; CHECK-NEXT: [[R:%.*]] = srem i8 [[BO0]], [[BO1]] +; CHECK-NEXT: [[R:%.*]] = shl nuw nsw i8 [[X:%.*]], 2 ; CHECK-NEXT: ret i8 [[R]] ; %BO0 = mul nsw nuw i8 %X, 10 @@ -333,9 +309,7 @@ define <2 x i8> @srem_CY_CZ_is_mul_X_RemYZ_no_nuw_out(<2 x i8> %X) { ; CHECK-LABEL: @srem_CY_CZ_is_mul_X_RemYZ_no_nuw_out( -; CHECK-NEXT: [[BO0:%.*]] = mul nsw <2 x i8> [[X:%.*]], -; CHECK-NEXT: [[BO1:%.*]] = shl nuw nsw <2 x i8> [[X]], -; CHECK-NEXT: [[R:%.*]] = srem <2 x i8> [[BO0]], [[BO1]] +; CHECK-NEXT: [[R:%.*]] = shl nsw <2 x i8> [[X:%.*]], ; CHECK-NEXT: ret <2 x i8> [[R]] ; %BO0 = mul nsw <2 x i8> %X,