[llvm] r211261 - Refactored and updated SimplifyUsingDistributiveLaws() to
Dinesh Dwivedi
dinesh.d at samsung.com
Thu Jun 19 01:29:18 PDT 2014
Author: dinesh
Date: Thu Jun 19 03:29:18 2014
New Revision: 211261
URL: http://llvm.org/viewvc/llvm-project?rev=211261&view=rev
Log:
Refactored and updated SimplifyUsingDistributiveLaws() to
* Find factorization opportunities using identity values.
* Find factorization opportunities by treating shl(X, C) as mul (X, shl(C))
* Keep NSW flag while simplifying instruction using factorization.
This fixes PR19263.
Differential Revision: http://reviews.llvm.org/D3799
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
llvm/trunk/test/Transforms/InstCombine/add2.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp?rev=211261&r1=211260&r2=211261&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp Thu Jun 19 03:29:18 2014
@@ -865,30 +865,6 @@ Value *FAddCombine::createAddendVal
return createFMul(OpndVal, Coeff.getValue(Instr->getType()));
}
-// dyn_castFoldableMul - If this value is a multiply that can be folded into
-// other computations (because it has a constant operand), return the
-// non-constant operand of the multiply, and set CST to point to the multiplier.
-// Otherwise, return null.
-//
-static inline Value *dyn_castFoldableMul(Value *V, Constant *&CST) {
- if (!V->hasOneUse() || !V->getType()->isIntOrIntVectorTy())
- return nullptr;
-
- Instruction *I = dyn_cast<Instruction>(V);
- if (!I) return nullptr;
-
- if (I->getOpcode() == Instruction::Mul)
- if ((CST = dyn_cast<Constant>(I->getOperand(1))))
- return I->getOperand(0);
- if (I->getOpcode() == Instruction::Shl)
- if ((CST = dyn_cast<Constant>(I->getOperand(1)))) {
- // The multiplier is really 1 << CST.
- CST = ConstantExpr::getShl(ConstantInt::get(V->getType(), 1), CST);
- return I->getOperand(0);
- }
- return nullptr;
-}
-
// If one of the operands only has one non-zero bit, and if the other
// operand has a known-zero bit in a more significant place than it (not
// including the sign bit) the ripple may go up to and fill the zero, but
@@ -1089,24 +1065,6 @@ Instruction *InstCombiner::visitAdd(Bina
if (Value *V = dyn_castNegVal(RHS))
return BinaryOperator::CreateSub(LHS, V);
-
- {
- Constant *C2;
- if (Value *X = dyn_castFoldableMul(LHS, C2)) {
- if (X == RHS) // X*C + X --> X * (C+1)
- return BinaryOperator::CreateMul(RHS, AddOne(C2));
-
- // X*C1 + X*C2 --> X * (C1+C2)
- Constant *C1;
- if (X == dyn_castFoldableMul(RHS, C1))
- return BinaryOperator::CreateMul(X, ConstantExpr::getAdd(C1, C2));
- }
-
- // X + X*C --> X * (C+1)
- if (dyn_castFoldableMul(RHS, C2) == LHS)
- return BinaryOperator::CreateMul(LHS, AddOne(C2));
- }
-
// A+B --> A|B iff A and B have no bits set in common.
if (IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
APInt LHSKnownOne(IT->getBitWidth(), 0);
@@ -1593,16 +1551,6 @@ Instruction *InstCombiner::visitSub(Bina
}
}
- Constant *C1;
- if (Value *X = dyn_castFoldableMul(Op0, C1)) {
- if (X == Op1) // X*C - X --> X * (C-1)
- return BinaryOperator::CreateMul(Op1, SubOne(C1));
-
- Constant *C2; // X*C1 - X*C2 -> X * (C1-C2)
- if (X == dyn_castFoldableMul(Op1, C2))
- return BinaryOperator::CreateMul(X, ConstantExpr::getSub(C1, C2));
- }
-
// Optimize pointer differences into the same array into a size. Consider:
// &A[10] - &A[0]: we should compile this to "10".
if (DL) {
Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=211261&r1=211260&r2=211261&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Thu Jun 19 03:29:18 2014
@@ -395,6 +395,127 @@ static bool RightDistributesOverLeft(Ins
return false;
}
+/// This function returns identity value for given opcode, which can be used to
+/// factor patterns like (X * 2) + X ==> (X * 2) + (X * 1) ==> X * (2 + 1).
+static Value *getIdentityValue(Instruction::BinaryOps OpCode, Value *V) {
+ if (isa<Constant>(V))
+ return nullptr;
+
+ if (OpCode == Instruction::Mul)
+ return ConstantInt::get(V->getType(), 1);
+
+ // TODO: We can handle other cases e.g. Instruction::And, Instruction::Or etc.
+
+ return nullptr;
+}
+
+/// This function factors binary ops which can be combined using distributive
+/// laws. This also factor SHL as MUL e.g. SHL(X, 2) ==> MUL(X, 4).
+Instruction::BinaryOps getBinOpsForFactorization(BinaryOperator *Op,
+ Value *&LHS, Value *&RHS) {
+ if (!Op)
+ return Instruction::BinaryOpsEnd;
+
+ if (Op->getOpcode() == Instruction::Shl) {
+ if (Constant *CST = dyn_cast<Constant>(Op->getOperand(1))) {
+ // The multiplier is really 1 << CST.
+ RHS = ConstantExpr::getShl(ConstantInt::get(Op->getType(), 1), CST);
+ LHS = Op->getOperand(0);
+ return Instruction::Mul;
+ }
+ }
+
+ // TODO: We can add other conversions e.g. shr => div etc.
+
+ LHS = Op->getOperand(0);
+ RHS = Op->getOperand(1);
+ return Op->getOpcode();
+}
+
+/// This tries to simplify binary operations by factorizing out common terms
+/// (e. g. "(A*B)+(A*C)" -> "A*(B+C)").
+static Value *tryFactorization(InstCombiner::BuilderTy *Builder,
+ const DataLayout *DL, BinaryOperator &I,
+ Instruction::BinaryOps InnerOpcode, Value *A,
+ Value *B, Value *C, Value *D) {
+
+ // If any of A, B, C, D are null, we can not factor I, return early.
+ // Checking A and C should be enough.
+ if (!A || !C || !B || !D)
+ return nullptr;
+
+ Value *SimplifiedInst = nullptr;
+ Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+ Instruction::BinaryOps TopLevelOpcode = I.getOpcode();
+
+ // Does "X op' Y" always equal "Y op' X"?
+ bool InnerCommutative = Instruction::isCommutative(InnerOpcode);
+
+ // Does "X op' (Y op Z)" always equal "(X op' Y) op (X op' Z)"?
+ if (LeftDistributesOverRight(InnerOpcode, TopLevelOpcode))
+ // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
+ // commutative case, "(A op' B) op (C op' A)"?
+ if (A == C || (InnerCommutative && A == D)) {
+ if (A != C)
+ std::swap(C, D);
+ // Consider forming "A op' (B op D)".
+ // If "B op D" simplifies then it can be formed with no cost.
+ Value *V = SimplifyBinOp(TopLevelOpcode, B, D, DL);
+ // If "B op D" doesn't simplify then only go on if both of the existing
+ // operations "A op' B" and "C op' D" will be zapped as no longer used.
+ if (!V && LHS->hasOneUse() && RHS->hasOneUse())
+ V = Builder->CreateBinOp(TopLevelOpcode, B, D, RHS->getName());
+ if (V) {
+ SimplifiedInst = Builder->CreateBinOp(InnerOpcode, A, V);
+ }
+ }
+
+ // Does "(X op Y) op' Z" always equal "(X op' Z) op (Y op' Z)"?
+ if (!SimplifiedInst && RightDistributesOverLeft(TopLevelOpcode, InnerOpcode))
+ // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
+ // commutative case, "(A op' B) op (B op' D)"?
+ if (B == D || (InnerCommutative && B == C)) {
+ if (B != D)
+ std::swap(C, D);
+ // Consider forming "(A op C) op' B".
+ // If "A op C" simplifies then it can be formed with no cost.
+ Value *V = SimplifyBinOp(TopLevelOpcode, A, C, DL);
+
+ // If "A op C" doesn't simplify then only go on if both of the existing
+ // operations "A op' B" and "C op' D" will be zapped as no longer used.
+ if (!V && LHS->hasOneUse() && RHS->hasOneUse())
+ V = Builder->CreateBinOp(TopLevelOpcode, A, C, LHS->getName());
+ if (V) {
+ SimplifiedInst = Builder->CreateBinOp(InnerOpcode, V, B);
+ }
+ }
+
+ if (SimplifiedInst) {
+ ++NumFactor;
+ SimplifiedInst->takeName(&I);
+
+ // Check if we can add NSW flag to SimplifiedInst. If so, set NSW flag.
+ // TODO: Check for NUW.
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(SimplifiedInst)) {
+ if (isa<OverflowingBinaryOperator>(SimplifiedInst)) {
+ bool HasNSW = false;
+ if (isa<OverflowingBinaryOperator>(&I))
+ HasNSW = I.hasNoSignedWrap();
+
+ if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
+ if (isa<OverflowingBinaryOperator>(Op0))
+ HasNSW &= Op0->hasNoSignedWrap();
+
+ if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
+ if (isa<OverflowingBinaryOperator>(Op1))
+ HasNSW &= Op1->hasNoSignedWrap();
+ BO->setHasNoSignedWrap(HasNSW);
+ }
+ }
+ }
+ return SimplifiedInst;
+}
+
/// SimplifyUsingDistributiveLaws - This tries to simplify binary operations
/// which some other binary operation distributes over either by factorizing
/// out common terms (eg "(A*B)+(A*C)" -> "A*(B+C)") or expanding out if this
@@ -404,65 +525,33 @@ Value *InstCombiner::SimplifyUsingDistri
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
- Instruction::BinaryOps TopLevelOpcode = I.getOpcode(); // op
// Factorization.
- if (Op0 && Op1 && Op0->getOpcode() == Op1->getOpcode()) {
- // The instruction has the form "(A op' B) op (C op' D)". Try to factorize
- // a common term.
- Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
- Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
- Instruction::BinaryOps InnerOpcode = Op0->getOpcode(); // op'
-
- // Does "X op' Y" always equal "Y op' X"?
- bool InnerCommutative = Instruction::isCommutative(InnerOpcode);
-
- // Does "X op' (Y op Z)" always equal "(X op' Y) op (X op' Z)"?
- if (LeftDistributesOverRight(InnerOpcode, TopLevelOpcode))
- // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
- // commutative case, "(A op' B) op (C op' A)"?
- if (A == C || (InnerCommutative && A == D)) {
- if (A != C)
- std::swap(C, D);
- // Consider forming "A op' (B op D)".
- // If "B op D" simplifies then it can be formed with no cost.
- Value *V = SimplifyBinOp(TopLevelOpcode, B, D, DL);
- // If "B op D" doesn't simplify then only go on if both of the existing
- // operations "A op' B" and "C op' D" will be zapped as no longer used.
- if (!V && Op0->hasOneUse() && Op1->hasOneUse())
- V = Builder->CreateBinOp(TopLevelOpcode, B, D, Op1->getName());
- if (V) {
- ++NumFactor;
- V = Builder->CreateBinOp(InnerOpcode, A, V);
- V->takeName(&I);
- return V;
- }
- }
-
- // Does "(X op Y) op' Z" always equal "(X op' Z) op (Y op' Z)"?
- if (RightDistributesOverLeft(TopLevelOpcode, InnerOpcode))
- // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
- // commutative case, "(A op' B) op (B op' D)"?
- if (B == D || (InnerCommutative && B == C)) {
- if (B != D)
- std::swap(C, D);
- // Consider forming "(A op C) op' B".
- // If "A op C" simplifies then it can be formed with no cost.
- Value *V = SimplifyBinOp(TopLevelOpcode, A, C, DL);
- // If "A op C" doesn't simplify then only go on if both of the existing
- // operations "A op' B" and "C op' D" will be zapped as no longer used.
- if (!V && Op0->hasOneUse() && Op1->hasOneUse())
- V = Builder->CreateBinOp(TopLevelOpcode, A, C, Op0->getName());
- if (V) {
- ++NumFactor;
- V = Builder->CreateBinOp(InnerOpcode, V, B);
- V->takeName(&I);
- return V;
- }
- }
+ Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
+ Instruction::BinaryOps LHSOpcode = getBinOpsForFactorization(Op0, A, B);
+ Instruction::BinaryOps RHSOpcode = getBinOpsForFactorization(Op1, C, D);
+
+ // The instruction has the form "(A op' B) op (C op' D)". Try to factorize
+ // a common term.
+ if (LHSOpcode == RHSOpcode) {
+ if (Value *V = tryFactorization(Builder, DL, I, LHSOpcode, A, B, C, D))
+ return V;
}
+ // The instruction has the form "(A op' B) op (C)". Try to factorize common
+ // term.
+ if (Value *V = tryFactorization(Builder, DL, I, LHSOpcode, A, B, RHS,
+ getIdentityValue(LHSOpcode, RHS)))
+ return V;
+
+ // The instruction has the form "(B) op (C op' D)". Try to factorize common
+ // term.
+ if (Value *V = tryFactorization(Builder, DL, I, RHSOpcode, LHS,
+ getIdentityValue(RHSOpcode, LHS), C, D))
+ return V;
+
// Expansion.
+ Instruction::BinaryOps TopLevelOpcode = I.getOpcode();
if (Op0 && RightDistributesOverLeft(Op0->getOpcode(), TopLevelOpcode)) {
// The instruction has the form "(A op' B) op C". See if expanding it out
// to "(A op C) op' (B op C)" results in simplifications.
Modified: llvm/trunk/test/Transforms/InstCombine/add2.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/add2.ll?rev=211261&r1=211260&r2=211261&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/add2.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/add2.ll Thu Jun 19 03:29:18 2014
@@ -86,3 +86,71 @@ define i16 @test9(i16 %a) {
; CHECK-NEXT: %d = mul i16 %a, -32767
; CHECK-NEXT: ret i16 %d
}
+
+define i16 @add_nsw_mul_nsw(i16 %x) {
+ %add1 = add nsw i16 %x, %x
+ %add2 = add nsw i16 %add1, %x
+ ret i16 %add2
+; CHECK-LABEL: @add_nsw_mul_nsw(
+; CHECK-NEXT: %add2 = mul nsw i16 %x, 3
+; CHECK-NEXT: ret i16 %add2
+}
+
+define i16 @mul_add_to_mul_1(i16 %x) {
+ %mul1 = mul nsw i16 %x, 8
+ %add2 = add nsw i16 %x, %mul1
+ ret i16 %add2
+; CHECK-LABEL: @mul_add_to_mul_1(
+; CHECK-NEXT: %add2 = mul nsw i16 %x, 9
+; CHECK-NEXT: ret i16 %add2
+}
+
+define i16 @mul_add_to_mul_2(i16 %x) {
+ %mul1 = mul nsw i16 %x, 8
+ %add2 = add nsw i16 %mul1, %x
+ ret i16 %add2
+; CHECK-LABEL: @mul_add_to_mul_2(
+; CHECK-NEXT: %add2 = mul nsw i16 %x, 9
+; CHECK-NEXT: ret i16 %add2
+}
+
+define i16 @mul_add_to_mul_3(i16 %a) {
+ %mul1 = mul i16 %a, 2
+ %mul2 = mul i16 %a, 3
+ %add = add nsw i16 %mul1, %mul2
+ ret i16 %add
+; CHECK-LABEL: @mul_add_to_mul_3(
+; CHECK-NEXT: %add = mul i16 %a, 5
+; CHECK-NEXT: ret i16 %add
+}
+
+define i16 @mul_add_to_mul_4(i16 %a) {
+ %mul1 = mul nsw i16 %a, 2
+ %mul2 = mul nsw i16 %a, 7
+ %add = add nsw i16 %mul1, %mul2
+ ret i16 %add
+; CHECK-LABEL: @mul_add_to_mul_4(
+; CHECK-NEXT: %add = mul nsw i16 %a, 9
+; CHECK-NEXT: ret i16 %add
+}
+
+define i16 @mul_add_to_mul_5(i16 %a) {
+ %mul1 = mul nsw i16 %a, 3
+ %mul2 = mul nsw i16 %a, 7
+ %add = add nsw i16 %mul1, %mul2
+ ret i16 %add
+; CHECK-LABEL: @mul_add_to_mul_5(
+; CHECK-NEXT: %add = mul nsw i16 %a, 10
+; CHECK-NEXT: ret i16 %add
+}
+
+define i32 @mul_add_to_mul_6(i32 %x, i32 %y) {
+ %mul1 = mul nsw i32 %x, %y
+ %mul2 = mul nsw i32 %mul1, 5
+ %add = add nsw i32 %mul1, %mul2
+ ret i32 %add
+; CHECK-LABEL: @mul_add_to_mul_6(
+; CHECK-NEXT: %mul1 = mul nsw i32 %x, %y
+; CHECK-NEXT: %add = mul nsw i32 %mul1, 6
+; CHECK-NEXT: ret i32 %add
+}
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