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 @@ -1698,6 +1698,63 @@ return nullptr; } +// Variety of transform for (urem/srem (mul/shl X, Y), (mul/shl X, Z)) +static Instruction *simplifyIRemMulShl(BinaryOperator &I, + InstCombinerImpl &IC) { + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1), *X; + const APInt *Y, *Z; + if (!(match(Op0, m_Mul(m_Value(X), m_APInt(Y))) && + match(Op1, m_c_Mul(m_Specific(X), m_APInt(Z)))) && + !(match(Op0, m_Mul(m_APInt(Y), m_Value(X))) && + match(Op1, m_c_Mul(m_Specific(X), m_APInt(Z))))) + return nullptr; + + bool IsSRem = I.getOpcode() == Instruction::SRem; + + OverflowingBinaryOperator *BO0 = cast(Op0); + // TODO: We may be able to deduce more about nsw/nuw of BO0/BO1 based on Y >= + // Z or Z >= Y. + bool BO0HasNSW = BO0->hasNoSignedWrap(); + bool BO0HasNUW = BO0->hasNoUnsignedWrap(); + bool BO0NoWrap = IsSRem ? BO0HasNSW : BO0HasNUW; + + APInt RemYZ = IsSRem ? Y->srem(*Z) : Y->urem(*Z); + // (rem (mul nuw/nsw X, Y), (mul X, Z)) + // if (rem Y, Z) == 0 + // -> 0 + if (RemYZ.isZero() && BO0NoWrap) + return IC.replaceInstUsesWith(I, ConstantInt::getNullValue(I.getType())); + + OverflowingBinaryOperator *BO1 = cast(Op1); + bool BO1HasNSW = BO1->hasNoSignedWrap(); + bool BO1HasNUW = BO1->hasNoUnsignedWrap(); + bool BO1NoWrap = IsSRem ? BO1HasNSW : BO1HasNUW; + // (rem (mul X, Y), (mul nuw/nsw X, Z)) + // if (rem Y, Z) == Y + // -> (mul nuw/nsw X, Y) + if (RemYZ == *Y && BO1NoWrap) { + BinaryOperator *BO = + BinaryOperator::CreateMul(X, ConstantInt::get(I.getType(), *Y)); + // Copy any overflow flags from Op0. + BO->setHasNoSignedWrap(IsSRem || BO0HasNSW); + BO->setHasNoUnsignedWrap(!IsSRem || BO0HasNUW); + return BO; + } + + // (rem (mul nuw/nsw X, Y), (mul {nsw} X, Z)) + // if Y >= Z + // -> (mul {nuw} nsw X, (rem Y, Z)) + if (Y->uge(*Z) && (IsSRem ? (BO0HasNSW && BO1HasNSW) : BO0HasNUW)) { + BinaryOperator *BO = + BinaryOperator::CreateMul(X, ConstantInt::get(I.getType(), RemYZ)); + BO->setHasNoSignedWrap(); + BO->setHasNoUnsignedWrap(BO0HasNUW); + 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. @@ -1750,6 +1807,9 @@ } } + if (Instruction *R = simplifyIRemMulShl(I, *this)) + return R; + return nullptr; } diff --git a/llvm/test/Transforms/InstCombine/rem-mul-shl.ll b/llvm/test/Transforms/InstCombine/rem-mul-shl.ll --- a/llvm/test/Transforms/InstCombine/rem-mul-shl.ll +++ b/llvm/test/Transforms/InstCombine/rem-mul-shl.ll @@ -31,10 +31,7 @@ define @urem_XY_XZ_with_CY_rem_CZ_eq_0_scalable( %X) { ; CHECK-LABEL: @urem_XY_XZ_with_CY_rem_CZ_eq_0_scalable( -; CHECK-NEXT: [[BO0:%.*]] = mul nuw [[X:%.*]], shufflevector ( insertelement ( poison, i8 15, i64 0), poison, zeroinitializer) -; CHECK-NEXT: [[BO1:%.*]] = mul [[X]], shufflevector ( insertelement ( poison, i8 5, i64 0), poison, zeroinitializer) -; CHECK-NEXT: [[R:%.*]] = urem [[BO0]], [[BO1]] -; CHECK-NEXT: ret [[R]] +; CHECK-NEXT: ret zeroinitializer ; %BO0 = mul nuw %X, shufflevector( insertelement( poison, i8 15, i64 0) , poison, zeroinitializer) %BO1 = mul %X, shufflevector( insertelement( poison, i8 5, i64 0) , poison, zeroinitializer) @@ -44,10 +41,7 @@ define i8 @urem_XY_XZ_with_CY_rem_CZ_eq_0(i8 %X) { ; CHECK-LABEL: @urem_XY_XZ_with_CY_rem_CZ_eq_0( -; 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 @@ -70,9 +64,7 @@ define i8 @urem_XY_XZ_with_CY_lt_CZ(i8 %X) { ; CHECK-LABEL: @urem_XY_XZ_with_CY_lt_CZ( -; 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 @@ -122,9 +114,7 @@ define i8 @urem_XY_XZ_with_CY_gt_CZ(i8 %X) { ; CHECK-LABEL: @urem_XY_XZ_with_CY_gt_CZ( -; 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 @@ -242,10 +232,7 @@ ;; Signed Verions define @srem_XY_XZ_with_CY_rem_CZ_eq_0_scalable( %X) { ; CHECK-LABEL: @srem_XY_XZ_with_CY_rem_CZ_eq_0_scalable( -; CHECK-NEXT: [[BO0:%.*]] = mul nsw [[X:%.*]], shufflevector ( insertelement ( poison, i8 15, i64 0), poison, zeroinitializer) -; CHECK-NEXT: [[BO1:%.*]] = mul [[X]], shufflevector ( insertelement ( poison, i8 5, i64 0), poison, zeroinitializer) -; CHECK-NEXT: [[R:%.*]] = srem [[BO0]], [[BO1]] -; CHECK-NEXT: ret [[R]] +; CHECK-NEXT: ret zeroinitializer ; %BO0 = mul nsw %X, shufflevector( insertelement( poison, i8 15, i64 0) , poison, zeroinitializer) %BO1 = mul %X, shufflevector( insertelement( poison, i8 5, i64 0) , poison, zeroinitializer) @@ -255,10 +242,7 @@ define i8 @srem_XY_XZ_with_CY_rem_CZ_eq_0(i8 %X) { ; CHECK-LABEL: @srem_XY_XZ_with_CY_rem_CZ_eq_0( -; 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 @@ -294,9 +278,7 @@ define i8 @srem_XY_XZ_with_CY_lt_CZ_with_nuw_out(i8 %X) { ; CHECK-LABEL: @srem_XY_XZ_with_CY_lt_CZ_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 @@ -346,9 +328,7 @@ define i8 @srem_XY_XZ_with_CY_gt_CZ_with_nuw_out(i8 %X) { ; CHECK-LABEL: @srem_XY_XZ_with_CY_gt_CZ_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