//===----------------------------------------------------------------------===//
//
// This file implements routines for folding instructions into simpler forms
-// that do not require creating new instructions. For example, this does
-// constant folding, and can handle identities like (X&0)->0.
+// that do not require creating new instructions. This does constant folding
+// ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
+// returning a constant ("and i32 %x, 0" -> "0") or an already existing value
+// ("and i32 %x, %x" -> "%x").
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/ConstantFolding.h"
-#include "llvm/Support/ValueHandle.h"
-#include "llvm/Instructions.h"
+#include "llvm/Analysis/Dominators.h"
#include "llvm/Support/PatternMatch.h"
+#include "llvm/Support/ValueHandle.h"
+#include "llvm/Target/TargetData.h"
using namespace llvm;
using namespace llvm::PatternMatch;
-#define MaxRecursionDepth 3
+#define RecursionLimit 3
static Value *SimplifyBinOp(unsigned, Value *, Value *, const TargetData *,
- unsigned);
+ const DominatorTree *, unsigned);
static Value *SimplifyCmpInst(unsigned, Value *, Value *, const TargetData *,
- unsigned);
+ const DominatorTree *, unsigned);
+
+/// ValueDominatesPHI - Does the given value dominate the specified phi node?
+static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I)
+ // Arguments and constants dominate all instructions.
+ return true;
+
+ // If we have a DominatorTree then do a precise test.
+ if (DT)
+ return DT->dominates(I, P);
+
+ // Otherwise, if the instruction is in the entry block, and is not an invoke,
+ // then it obviously dominates all phi nodes.
+ if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
+ !isa<InvokeInst>(I))
+ return true;
+
+ return false;
+}
/// ThreadBinOpOverSelect - In the case of a binary operation with a select
/// instruction as an operand, try to simplify the binop by seeing whether
/// evaluating it on both branches of the select results in the same value.
/// Returns the common value if so, otherwise returns null.
static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
- const TargetData *TD, unsigned MaxRecurse) {
+ const TargetData *TD,
+ const DominatorTree *DT,
+ unsigned MaxRecurse) {
SelectInst *SI;
if (isa<SelectInst>(LHS)) {
SI = cast<SelectInst>(LHS);
Value *TV;
Value *FV;
if (SI == LHS) {
- TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, TD, MaxRecurse);
- FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, TD, MaxRecurse);
+ TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, TD, DT, MaxRecurse);
+ FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, TD, DT, MaxRecurse);
} else {
- TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), TD, MaxRecurse);
- FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), TD, MaxRecurse);
+ TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), TD, DT, MaxRecurse);
+ FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), TD, DT, MaxRecurse);
}
// If they simplified to the same value, then return the common value.
/// null.
static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, const TargetData *TD,
+ const DominatorTree *DT,
unsigned MaxRecurse) {
// Make sure the select is on the LHS.
if (!isa<SelectInst>(LHS)) {
// Now that we have "cmp select(cond, TV, FV), RHS", analyse it.
// Does "cmp TV, RHS" simplify?
- if (Value *TCmp = SimplifyCmpInst(Pred, SI->getTrueValue(), RHS, TD,
+ if (Value *TCmp = SimplifyCmpInst(Pred, SI->getTrueValue(), RHS, TD, DT,
MaxRecurse))
// It does! Does "cmp FV, RHS" simplify?
- if (Value *FCmp = SimplifyCmpInst(Pred, SI->getFalseValue(), RHS, TD,
+ if (Value *FCmp = SimplifyCmpInst(Pred, SI->getFalseValue(), RHS, TD, DT,
MaxRecurse))
// It does! If they simplified to the same value, then use it as the
// result of the original comparison.
/// it on the incoming phi values yields the same result for every value. If so
/// returns the common value, otherwise returns null.
static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
- const TargetData *TD, unsigned MaxRecurse) {
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
PHINode *PI;
if (isa<PHINode>(LHS)) {
PI = cast<PHINode>(LHS);
+ // Bail out if RHS and the phi may be mutually interdependent due to a loop.
+ if (!ValueDominatesPHI(RHS, PI, DT))
+ return 0;
} else {
assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
PI = cast<PHINode>(RHS);
+ // Bail out if LHS and the phi may be mutually interdependent due to a loop.
+ if (!ValueDominatesPHI(LHS, PI, DT))
+ return 0;
}
// Evaluate the BinOp on the incoming phi values.
Value *CommonValue = 0;
for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
+ Value *Incoming = PI->getIncomingValue(i);
+ // If the incoming value is the phi node itself, it can safely be skipped.
+ if (Incoming == PI) continue;
Value *V = PI == LHS ?
- SimplifyBinOp(Opcode, PI->getIncomingValue(i), RHS, TD, MaxRecurse) :
- SimplifyBinOp(Opcode, LHS, PI->getIncomingValue(i), TD, MaxRecurse);
+ SimplifyBinOp(Opcode, Incoming, RHS, TD, DT, MaxRecurse) :
+ SimplifyBinOp(Opcode, LHS, Incoming, TD, DT, MaxRecurse);
// If the operation failed to simplify, or simplified to a different value
// to previously, then give up.
if (!V || (CommonValue && V != CommonValue))
/// incoming phi values yields the same result every time. If so returns the
/// common result, otherwise returns null.
static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
- const TargetData *TD, unsigned MaxRecurse) {
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
// Make sure the phi is on the LHS.
if (!isa<PHINode>(LHS)) {
std::swap(LHS, RHS);
assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
PHINode *PI = cast<PHINode>(LHS);
+ // Bail out if RHS and the phi may be mutually interdependent due to a loop.
+ if (!ValueDominatesPHI(RHS, PI, DT))
+ return 0;
+
// Evaluate the BinOp on the incoming phi values.
Value *CommonValue = 0;
for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
- Value *V = SimplifyCmpInst(Pred, PI->getIncomingValue(i), RHS, TD,
- MaxRecurse);
+ Value *Incoming = PI->getIncomingValue(i);
+ // If the incoming value is the phi node itself, it can safely be skipped.
+ if (Incoming == PI) continue;
+ Value *V = SimplifyCmpInst(Pred, Incoming, RHS, TD, DT, MaxRecurse);
// If the operation failed to simplify, or simplified to a different value
// to previously, then give up.
if (!V || (CommonValue && V != CommonValue))
/// SimplifyAddInst - Given operands for an Add, see if we can
/// fold the result. If not, this returns null.
Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
- const TargetData *TD) {
+ const TargetData *TD, const DominatorTree *) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
}
// FIXME: Could pull several more out of instcombine.
+
+ // Threading Add over selects and phi nodes is pointless, so don't bother.
+ // Threading over the select in "A + select(cond, B, C)" means evaluating
+ // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
+ // only if B and C are equal. If B and C are equal then (since we assume
+ // that operands have already been simplified) "select(cond, B, C)" should
+ // have been simplified to the common value of B and C already. Analysing
+ // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
+ // for threading over phi nodes.
+
return 0;
}
/// SimplifyAndInst - Given operands for an And, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
- unsigned MaxRecurse) {
+ const DominatorTree *DT, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
if (Op0 == Op1)
return Op0;
- // X & <0,0> = <0,0>
- if (isa<ConstantAggregateZero>(Op1))
+ // X & 0 = 0
+ if (match(Op1, m_Zero()))
return Op1;
- // X & <-1,-1> = X
- if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1))
- if (CP->isAllOnesValue())
- return Op0;
-
- if (ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1)) {
- // X & 0 = 0
- if (Op1CI->isZero())
- return Op1CI;
- // X & -1 = X
- if (Op1CI->isAllOnesValue())
- return Op0;
- }
+ // X & -1 = X
+ if (match(Op1, m_AllOnes()))
+ return Op0;
// A & ~A = ~A & A = 0
- Value *A, *B;
+ Value *A = 0, *B = 0;
if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
(match(Op1, m_Not(m_Value(A))) && A == Op0))
return Constant::getNullValue(Op0->getType());
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (MaxRecurse && (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)))
- if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD,
+ if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD, DT,
MaxRecurse-1))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (MaxRecurse && (isa<PHINode>(Op0) || isa<PHINode>(Op1)))
- if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD,
+ if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD, DT,
MaxRecurse-1))
return V;
return 0;
}
-Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD) {
- return ::SimplifyAndInst(Op0, Op1, TD, MaxRecursionDepth);
+Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT) {
+ return ::SimplifyAndInst(Op0, Op1, TD, DT, RecursionLimit);
}
/// SimplifyOrInst - Given operands for an Or, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
- unsigned MaxRecurse) {
+ const DominatorTree *DT, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
if (Op0 == Op1)
return Op0;
- // X | <0,0> = X
- if (isa<ConstantAggregateZero>(Op1))
+ // X | 0 = X
+ if (match(Op1, m_Zero()))
return Op0;
- // X | <-1,-1> = <-1,-1>
- if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1))
- if (CP->isAllOnesValue())
- return Op1;
-
- if (ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1)) {
- // X | 0 = X
- if (Op1CI->isZero())
- return Op0;
- // X | -1 = -1
- if (Op1CI->isAllOnesValue())
- return Op1CI;
- }
+ // X | -1 = -1
+ if (match(Op1, m_AllOnes()))
+ return Op1;
// A | ~A = ~A | A = -1
- Value *A, *B;
+ Value *A = 0, *B = 0;
if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
(match(Op1, m_Not(m_Value(A))) && A == Op0))
return Constant::getAllOnesValue(Op0->getType());
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (MaxRecurse && (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)))
- if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD,
+ if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD, DT,
MaxRecurse-1))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (MaxRecurse && (isa<PHINode>(Op0) || isa<PHINode>(Op1)))
- if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD,
+ if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD, DT,
MaxRecurse-1))
return V;
return 0;
}
-Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD) {
- return ::SimplifyOrInst(Op0, Op1, TD, MaxRecursionDepth);
+Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT) {
+ return ::SimplifyOrInst(Op0, Op1, TD, DT, RecursionLimit);
+}
+
+/// SimplifyXorInst - Given operands for a Xor, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT, unsigned MaxRecurse) {
+ if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
+ if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
+ Constant *Ops[] = { CLHS, CRHS };
+ return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
+ Ops, 2, TD);
+ }
+
+ // Canonicalize the constant to the RHS.
+ std::swap(Op0, Op1);
+ }
+
+ // A ^ undef -> undef
+ if (isa<UndefValue>(Op1))
+ return UndefValue::get(Op0->getType());
+
+ // A ^ 0 = A
+ if (match(Op1, m_Zero()))
+ return Op0;
+
+ // A ^ A = 0
+ if (Op0 == Op1)
+ return Constant::getNullValue(Op0->getType());
+
+ // A ^ ~A = ~A ^ A = -1
+ Value *A = 0, *B = 0;
+ if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
+ (match(Op1, m_Not(m_Value(A))) && A == Op0))
+ return Constant::getAllOnesValue(Op0->getType());
+
+ // (A ^ B) ^ A = B
+ if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
+ (A == Op1 || B == Op1))
+ return A == Op1 ? B : A;
+
+ // A ^ (A ^ B) = B
+ if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
+ (A == Op0 || B == Op0))
+ return A == Op0 ? B : A;
+
+ // Threading Xor over selects and phi nodes is pointless, so don't bother.
+ // Threading over the select in "A ^ select(cond, B, C)" means evaluating
+ // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
+ // only if B and C are equal. If B and C are equal then (since we assume
+ // that operands have already been simplified) "select(cond, B, C)" should
+ // have been simplified to the common value of B and C already. Analysing
+ // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
+ // for threading over phi nodes.
+
+ return 0;
+}
+
+Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT) {
+ return ::SimplifyXorInst(Op0, Op1, TD, DT, RecursionLimit);
}
static const Type *GetCompareTy(Value *Op) {
/// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
- const TargetData *TD, unsigned MaxRecurse) {
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
// If the comparison is with the result of a select instruction, check whether
// comparing with either branch of the select always yields the same value.
if (MaxRecurse && (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)))
- if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, MaxRecurse-1))
+ if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse-1))
return V;
// If the comparison is with the result of a phi instruction, check whether
// doing the compare with each incoming phi value yields a common result.
if (MaxRecurse && (isa<PHINode>(LHS) || isa<PHINode>(RHS)))
- if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, MaxRecurse-1))
+ if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse-1))
return V;
return 0;
}
Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
- const TargetData *TD) {
- return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, MaxRecursionDepth);
+ const TargetData *TD, const DominatorTree *DT) {
+ return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
}
/// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
- const TargetData *TD, unsigned MaxRecurse) {
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
// If the comparison is with the result of a select instruction, check whether
// comparing with either branch of the select always yields the same value.
if (MaxRecurse && (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)))
- if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, MaxRecurse-1))
+ if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse-1))
return V;
// If the comparison is with the result of a phi instruction, check whether
// doing the compare with each incoming phi value yields a common result.
if (MaxRecurse && (isa<PHINode>(LHS) || isa<PHINode>(RHS)))
- if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, MaxRecurse-1))
+ if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse-1))
return V;
return 0;
}
Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
- const TargetData *TD) {
- return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, MaxRecursionDepth);
+ const TargetData *TD, const DominatorTree *DT) {
+ return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
}
/// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
/// the result. If not, this returns null.
Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal,
- const TargetData *TD) {
+ const TargetData *TD, const DominatorTree *) {
// select true, X, Y -> X
// select false, X, Y -> Y
if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
return 0;
}
-
/// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
/// fold the result. If not, this returns null.
Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps,
- const TargetData *TD) {
+ const TargetData *TD, const DominatorTree *) {
+ // The type of the GEP pointer operand.
+ const PointerType *PtrTy = cast<PointerType>(Ops[0]->getType());
+
// getelementptr P -> P.
if (NumOps == 1)
return Ops[0];
- // TODO.
- //if (isa<UndefValue>(Ops[0]))
- // return UndefValue::get(GEP.getType());
+ if (isa<UndefValue>(Ops[0])) {
+ // Compute the (pointer) type returned by the GEP instruction.
+ const Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, &Ops[1],
+ NumOps-1);
+ const Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
+ return UndefValue::get(GEPTy);
+ }
- // getelementptr P, 0 -> P.
- if (NumOps == 2)
+ if (NumOps == 2) {
+ // getelementptr P, 0 -> P.
if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
if (C->isZero())
return Ops[0];
+ // getelementptr P, N -> P if P points to a type of zero size.
+ if (TD) {
+ const Type *Ty = PtrTy->getElementType();
+ if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0)
+ return Ops[0];
+ }
+ }
// Check to see if this is constant foldable.
for (unsigned i = 0; i != NumOps; ++i)
(Constant *const*)Ops+1, NumOps-1);
}
+/// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
+static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) {
+ // If all of the PHI's incoming values are the same then replace the PHI node
+ // with the common value.
+ Value *CommonValue = 0;
+ bool HasUndefInput = false;
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ Value *Incoming = PN->getIncomingValue(i);
+ // If the incoming value is the phi node itself, it can safely be skipped.
+ if (Incoming == PN) continue;
+ if (isa<UndefValue>(Incoming)) {
+ // Remember that we saw an undef value, but otherwise ignore them.
+ HasUndefInput = true;
+ continue;
+ }
+ if (CommonValue && Incoming != CommonValue)
+ return 0; // Not the same, bail out.
+ CommonValue = Incoming;
+ }
+
+ // If CommonValue is null then all of the incoming values were either undef or
+ // equal to the phi node itself.
+ if (!CommonValue)
+ return UndefValue::get(PN->getType());
+
+ // If we have a PHI node like phi(X, undef, X), where X is defined by some
+ // instruction, we cannot return X as the result of the PHI node unless it
+ // dominates the PHI block.
+ if (HasUndefInput)
+ return ValueDominatesPHI(CommonValue, PN, DT) ? CommonValue : 0;
+
+ return CommonValue;
+}
+
//=== Helper functions for higher up the class hierarchy.
/// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
- const TargetData *TD, unsigned MaxRecurse) {
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
switch (Opcode) {
- case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, MaxRecurse);
- case Instruction::Or: return SimplifyOrInst(LHS, RHS, TD, MaxRecurse);
+ case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, DT, MaxRecurse);
+ case Instruction::Or: return SimplifyOrInst(LHS, RHS, TD, DT, MaxRecurse);
default:
if (Constant *CLHS = dyn_cast<Constant>(LHS))
if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (MaxRecurse && (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)))
- if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, MaxRecurse-1))
+ if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, DT,
+ MaxRecurse-1))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (MaxRecurse && (isa<PHINode>(LHS) || isa<PHINode>(RHS)))
- if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, MaxRecurse-1))
+ if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, DT, MaxRecurse-1))
return V;
return 0;
}
Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
- const TargetData *TD) {
- return ::SimplifyBinOp(Opcode, LHS, RHS, TD, MaxRecursionDepth);
+ const TargetData *TD, const DominatorTree *DT) {
+ return ::SimplifyBinOp(Opcode, LHS, RHS, TD, DT, RecursionLimit);
}
/// SimplifyCmpInst - Given operands for a CmpInst, see if we can
/// fold the result.
static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
- const TargetData *TD, unsigned MaxRecurse) {
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
- return SimplifyICmpInst(Predicate, LHS, RHS, TD, MaxRecurse);
- return SimplifyFCmpInst(Predicate, LHS, RHS, TD, MaxRecurse);
+ return SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
+ return SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
}
Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
- const TargetData *TD) {
- return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, MaxRecursionDepth);
+ const TargetData *TD, const DominatorTree *DT) {
+ return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
}
/// SimplifyInstruction - See if we can compute a simplified version of this
/// instruction. If not, this returns null.
Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
const DominatorTree *DT) {
+ Value *Result;
+
switch (I->getOpcode()) {
default:
- return ConstantFoldInstruction(I, TD);
+ Result = ConstantFoldInstruction(I, TD);
+ break;
case Instruction::Add:
- return SimplifyAddInst(I->getOperand(0), I->getOperand(1),
- cast<BinaryOperator>(I)->hasNoSignedWrap(),
- cast<BinaryOperator>(I)->hasNoUnsignedWrap(), TD);
+ Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
+ cast<BinaryOperator>(I)->hasNoSignedWrap(),
+ cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
+ TD, DT);
+ break;
case Instruction::And:
- return SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD);
+ Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
case Instruction::Or:
- return SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD);
+ Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
+ case Instruction::Xor:
+ Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
case Instruction::ICmp:
- return SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
- I->getOperand(0), I->getOperand(1), TD);
+ Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
+ I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
case Instruction::FCmp:
- return SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
- I->getOperand(0), I->getOperand(1), TD);
+ Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
+ I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
case Instruction::Select:
- return SimplifySelectInst(I->getOperand(0), I->getOperand(1),
- I->getOperand(2), TD);
+ Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
+ I->getOperand(2), TD, DT);
+ break;
case Instruction::GetElementPtr: {
SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
- return SimplifyGEPInst(&Ops[0], Ops.size(), TD);
+ Result = SimplifyGEPInst(&Ops[0], Ops.size(), TD, DT);
+ break;
}
case Instruction::PHI:
- return cast<PHINode>(I)->hasConstantValue(DT);
+ Result = SimplifyPHINode(cast<PHINode>(I), DT);
+ break;
}
+
+ /// If called on unreachable code, the above logic may report that the
+ /// instruction simplified to itself. Make life easier for users by
+ /// detecting that case here, returning null if it occurs.
+ return Result == I ? 0 : Result;
}
/// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
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