#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Support/ValueHandle.h"
#include "llvm/Instructions.h"
+#include "llvm/Support/PatternMatch.h"
using namespace llvm;
+using namespace llvm::PatternMatch;
+#define MaxRecursionDepth 3
+
+static Value *SimplifyBinOp(unsigned, Value *, Value *, const TargetData *,
+ unsigned);
+static Value *SimplifyCmpInst(unsigned, Value *, Value *, const TargetData *,
+ unsigned);
+
+/// 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) {
+ SelectInst *SI;
+ if (isa<SelectInst>(LHS)) {
+ SI = cast<SelectInst>(LHS);
+ } else {
+ assert(isa<SelectInst>(RHS) && "No select instruction operand!");
+ SI = cast<SelectInst>(RHS);
+ }
+
+ // Evaluate the BinOp on the true and false branches of the select.
+ Value *TV;
+ Value *FV;
+ if (SI == LHS) {
+ TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, TD, MaxRecurse);
+ FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, TD, MaxRecurse);
+ } else {
+ TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), TD, MaxRecurse);
+ FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), TD, MaxRecurse);
+ }
+
+ // If they simplified to the same value, then return the common value.
+ // If they both failed to simplify then return null.
+ if (TV == FV)
+ return TV;
+
+ // If one branch simplified to undef, return the other one.
+ if (TV && isa<UndefValue>(TV))
+ return FV;
+ if (FV && isa<UndefValue>(FV))
+ return TV;
+
+ // If applying the operation did not change the true and false select values,
+ // then the result of the binop is the select itself.
+ if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
+ return SI;
+
+ // If one branch simplified and the other did not, and the simplified
+ // value is equal to the unsimplified one, return the simplified value.
+ // For example, select (cond, X, X & Z) & Z -> X & Z.
+ if ((FV && !TV) || (TV && !FV)) {
+ // Check that the simplified value has the form "X op Y" where "op" is the
+ // same as the original operation.
+ Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
+ if (Simplified && Simplified->getOpcode() == Opcode) {
+ // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
+ // We already know that "op" is the same as for the simplified value. See
+ // if the operands match too. If so, return the simplified value.
+ Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
+ Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
+ Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
+ if (Simplified->getOperand(0) == UnsimplifiedLHS &&
+ Simplified->getOperand(1) == UnsimplifiedRHS)
+ return Simplified;
+ if (Simplified->isCommutative() &&
+ Simplified->getOperand(1) == UnsimplifiedLHS &&
+ Simplified->getOperand(0) == UnsimplifiedRHS)
+ return Simplified;
+ }
+ }
-/// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
-/// fold the result. If not, this returns null.
-Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
- const TargetData *TD) {
- if (Constant *CLHS = dyn_cast<Constant>(LHS))
- if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
- Constant *COps[] = {CLHS, CRHS};
- return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, 2, TD);
- }
return 0;
}
+/// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
+/// try to simplify the comparison by seeing whether both branches of the select
+/// result in the same value. Returns the common value if so, otherwise returns
+/// null.
+static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
+ Value *RHS, const TargetData *TD,
+ unsigned MaxRecurse) {
+ // Make sure the select is on the LHS.
+ if (!isa<SelectInst>(LHS)) {
+ std::swap(LHS, RHS);
+ Pred = CmpInst::getSwappedPredicate(Pred);
+ }
+ assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
+ SelectInst *SI = cast<SelectInst>(LHS);
-/// SimplifyCompare - Given operands for a CmpInst, see if we can
-/// fold the result.
-Value *llvm::SimplifyCompare(unsigned Predicate, Value *LHS, Value *RHS,
+ // 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,
+ MaxRecurse))
+ // It does! Does "cmp FV, RHS" simplify?
+ if (Value *FCmp = SimplifyCmpInst(Pred, SI->getFalseValue(), RHS, TD,
+ MaxRecurse))
+ // It does! If they simplified to the same value, then use it as the
+ // result of the original comparison.
+ if (TCmp == FCmp)
+ return TCmp;
+ return 0;
+}
+
+/// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
+/// is a PHI instruction, try to simplify the binop by seeing whether evaluating
+/// 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) {
+ PHINode *PI;
+ if (isa<PHINode>(LHS)) {
+ PI = cast<PHINode>(LHS);
+ } else {
+ assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
+ PI = cast<PHINode>(RHS);
+ }
+
+ // Evaluate the BinOp on the incoming phi values.
+ Value *CommonValue = 0;
+ for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
+ Value *V = PI == LHS ?
+ SimplifyBinOp(Opcode, PI->getIncomingValue(i), RHS, TD, MaxRecurse) :
+ SimplifyBinOp(Opcode, LHS, PI->getIncomingValue(i), TD, MaxRecurse);
+ // If the operation failed to simplify, or simplified to a different value
+ // to previously, then give up.
+ if (!V || (CommonValue && V != CommonValue))
+ return 0;
+ CommonValue = V;
+ }
+
+ return CommonValue;
+}
+
+/// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
+/// try to simplify the comparison by seeing whether comparing with all of the
+/// 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) {
+ // Make sure the phi is on the LHS.
+ if (!isa<PHINode>(LHS)) {
+ std::swap(LHS, RHS);
+ Pred = CmpInst::getSwappedPredicate(Pred);
+ }
+ assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
+ PHINode *PI = cast<PHINode>(LHS);
+
+ // 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);
+ // If the operation failed to simplify, or simplified to a different value
+ // to previously, then give up.
+ if (!V || (CommonValue && V != CommonValue))
+ return 0;
+ CommonValue = V;
+ }
+
+ return 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) {
+ if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
+ if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
+ Constant *Ops[] = { CLHS, CRHS };
+ return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(),
+ Ops, 2, TD);
+ }
+
+ // Canonicalize the constant to the RHS.
+ std::swap(Op0, Op1);
+ }
+
+ if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
+ // X + undef -> undef
+ if (isa<UndefValue>(Op1C))
+ return Op1C;
+
+ // X + 0 --> X
+ if (Op1C->isNullValue())
+ return Op0;
+ }
+
+ // FIXME: Could pull several more out of instcombine.
+ 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) {
+ if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
+ if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
+ Constant *Ops[] = { CLHS, CRHS };
+ return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
+ Ops, 2, TD);
+ }
+
+ // Canonicalize the constant to the RHS.
+ std::swap(Op0, Op1);
+ }
+
+ // X & undef -> 0
+ if (isa<UndefValue>(Op1))
+ return Constant::getNullValue(Op0->getType());
+
+ // X & X = X
+ if (Op0 == Op1)
+ return Op0;
+
+ // X & <0,0> = <0,0>
+ if (isa<ConstantAggregateZero>(Op1))
+ 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;
+ }
+
+ // A & ~A = ~A & A = 0
+ Value *A, *B;
+ if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
+ (match(Op1, m_Not(m_Value(A))) && A == Op0))
+ return Constant::getNullValue(Op0->getType());
+
+ // (A | ?) & A = A
+ if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
+ (A == Op1 || B == Op1))
+ return Op1;
+
+ // A & (A | ?) = A
+ if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
+ (A == Op0 || B == Op0))
+ return Op0;
+
+ // (A & B) & A -> A & B
+ if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
+ (A == Op1 || B == Op1))
+ return Op0;
+
+ // A & (A & B) -> A & B
+ if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
+ (A == Op0 || B == Op0))
+ return Op1;
+
+ // 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,
+ 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,
+ MaxRecurse-1))
+ return V;
+
+ return 0;
+}
+
+Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD) {
+ return ::SimplifyAndInst(Op0, Op1, TD, MaxRecursionDepth);
+}
+
+/// 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) {
+ if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
+ if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
+ Constant *Ops[] = { CLHS, CRHS };
+ return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
+ Ops, 2, TD);
+ }
+
+ // Canonicalize the constant to the RHS.
+ std::swap(Op0, Op1);
+ }
+
+ // X | undef -> -1
+ if (isa<UndefValue>(Op1))
+ return Constant::getAllOnesValue(Op0->getType());
+
+ // X | X = X
+ if (Op0 == Op1)
+ return Op0;
+
+ // X | <0,0> = X
+ if (isa<ConstantAggregateZero>(Op1))
+ 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;
+ }
+
+ // A | ~A = ~A | A = -1
+ Value *A, *B;
+ 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 & ?) | A = A
+ if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
+ (A == Op1 || B == Op1))
+ return Op1;
+
+ // A | (A & ?) = A
+ if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
+ (A == Op0 || B == Op0))
+ return Op0;
+
+ // (A | B) | A -> A | B
+ if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
+ (A == Op1 || B == Op1))
+ return Op0;
+
+ // A | (A | B) -> A | B
+ if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
+ (A == Op0 || B == Op0))
+ return Op1;
+
+ // 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,
+ 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,
+ MaxRecurse-1))
+ return V;
+
+ return 0;
+}
+
+Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD) {
+ return ::SimplifyOrInst(Op0, Op1, TD, MaxRecursionDepth);
+}
+
+static const Type *GetCompareTy(Value *Op) {
+ return CmpInst::makeCmpResultType(Op->getType());
+}
+
+/// 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) {
CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
-
- if (Constant *CLHS = dyn_cast<Constant>(LHS))
- if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
- Constant *COps[] = {CLHS, CRHS};
- return ConstantFoldCompareInstOperands(Pred, COps, 2, TD);
+ assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
+
+ if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
+ if (Constant *CRHS = dyn_cast<Constant>(RHS))
+ return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
+
+ // If we have a constant, make sure it is on the RHS.
+ std::swap(LHS, RHS);
+ Pred = CmpInst::getSwappedPredicate(Pred);
+ }
+
+ // ITy - This is the return type of the compare we're considering.
+ const Type *ITy = GetCompareTy(LHS);
+
+ // icmp X, X -> true/false
+ // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
+ // because X could be 0.
+ if (LHS == RHS || isa<UndefValue>(RHS))
+ return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
+
+ // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
+ // addresses never equal each other! We already know that Op0 != Op1.
+ if ((isa<GlobalValue>(LHS) || isa<AllocaInst>(LHS) ||
+ isa<ConstantPointerNull>(LHS)) &&
+ (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
+ isa<ConstantPointerNull>(RHS)))
+ return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
+
+ // See if we are doing a comparison with a constant.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
+ // If we have an icmp le or icmp ge instruction, turn it into the
+ // appropriate icmp lt or icmp gt instruction. This allows us to rely on
+ // them being folded in the code below.
+ switch (Pred) {
+ default: break;
+ case ICmpInst::ICMP_ULE:
+ if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
+ return ConstantInt::getTrue(CI->getContext());
+ break;
+ case ICmpInst::ICMP_SLE:
+ if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
+ return ConstantInt::getTrue(CI->getContext());
+ break;
+ case ICmpInst::ICMP_UGE:
+ if (CI->isMinValue(false)) // A >=u MIN -> TRUE
+ return ConstantInt::getTrue(CI->getContext());
+ break;
+ case ICmpInst::ICMP_SGE:
+ if (CI->isMinValue(true)) // A >=s MIN -> TRUE
+ return ConstantInt::getTrue(CI->getContext());
+ break;
}
-
- // If this is an integer compare and the LHS and RHS are the same, fold it.
- if (LHS == RHS)
- if (isa<IntegerType>(LHS->getType()) || isa<PointerType>(LHS->getType())) {
- if (ICmpInst::isTrueWhenEqual(Pred))
- return ConstantInt::getTrue(LHS->getContext());
- else
- return ConstantInt::getFalse(LHS->getContext());
+ }
+
+ // 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))
+ 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))
+ return V;
+
+ return 0;
+}
+
+Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
+ const TargetData *TD) {
+ return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, MaxRecursionDepth);
+}
+
+/// 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) {
+ CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
+ assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
+
+ if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
+ if (Constant *CRHS = dyn_cast<Constant>(RHS))
+ return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
+
+ // If we have a constant, make sure it is on the RHS.
+ std::swap(LHS, RHS);
+ Pred = CmpInst::getSwappedPredicate(Pred);
+ }
+
+ // Fold trivial predicates.
+ if (Pred == FCmpInst::FCMP_FALSE)
+ return ConstantInt::get(GetCompareTy(LHS), 0);
+ if (Pred == FCmpInst::FCMP_TRUE)
+ return ConstantInt::get(GetCompareTy(LHS), 1);
+
+ if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
+ return UndefValue::get(GetCompareTy(LHS));
+
+ // fcmp x,x -> true/false. Not all compares are foldable.
+ if (LHS == RHS) {
+ if (CmpInst::isTrueWhenEqual(Pred))
+ return ConstantInt::get(GetCompareTy(LHS), 1);
+ if (CmpInst::isFalseWhenEqual(Pred))
+ return ConstantInt::get(GetCompareTy(LHS), 0);
+ }
+
+ // Handle fcmp with constant RHS
+ if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
+ // If the constant is a nan, see if we can fold the comparison based on it.
+ if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
+ if (CFP->getValueAPF().isNaN()) {
+ if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
+ return ConstantInt::getFalse(CFP->getContext());
+ assert(FCmpInst::isUnordered(Pred) &&
+ "Comparison must be either ordered or unordered!");
+ // True if unordered.
+ return ConstantInt::getTrue(CFP->getContext());
+ }
+ // Check whether the constant is an infinity.
+ if (CFP->getValueAPF().isInfinity()) {
+ if (CFP->getValueAPF().isNegative()) {
+ switch (Pred) {
+ case FCmpInst::FCMP_OLT:
+ // No value is ordered and less than negative infinity.
+ return ConstantInt::getFalse(CFP->getContext());
+ case FCmpInst::FCMP_UGE:
+ // All values are unordered with or at least negative infinity.
+ return ConstantInt::getTrue(CFP->getContext());
+ default:
+ break;
+ }
+ } else {
+ switch (Pred) {
+ case FCmpInst::FCMP_OGT:
+ // No value is ordered and greater than infinity.
+ return ConstantInt::getFalse(CFP->getContext());
+ case FCmpInst::FCMP_ULE:
+ // All values are unordered with and at most infinity.
+ return ConstantInt::getTrue(CFP->getContext());
+ default:
+ break;
+ }
+ }
+ }
}
+ }
+
+ // 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))
+ 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))
+ return V;
+
return 0;
}
+Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
+ const TargetData *TD) {
+ return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, MaxRecursionDepth);
+}
+
+/// 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) {
+ // select true, X, Y -> X
+ // select false, X, Y -> Y
+ if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
+ return CB->getZExtValue() ? TrueVal : FalseVal;
+
+ // select C, X, X -> X
+ if (TrueVal == FalseVal)
+ return TrueVal;
+
+ if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
+ return FalseVal;
+ if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
+ return TrueVal;
+ if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
+ if (isa<Constant>(TrueVal))
+ return TrueVal;
+ return FalseVal;
+ }
+
+ 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) {
+ // getelementptr P -> P.
+ if (NumOps == 1)
+ return Ops[0];
+
+ // TODO.
+ //if (isa<UndefValue>(Ops[0]))
+ // return UndefValue::get(GEP.getType());
+
+ // getelementptr P, 0 -> P.
+ if (NumOps == 2)
+ if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
+ if (C->isZero())
+ return Ops[0];
+
+ // Check to see if this is constant foldable.
+ for (unsigned i = 0; i != NumOps; ++i)
+ if (!isa<Constant>(Ops[i]))
+ return 0;
+
+ return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]),
+ (Constant *const*)Ops+1, NumOps-1);
+}
+
+
+//=== 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) {
+ switch (Opcode) {
+ case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, MaxRecurse);
+ case Instruction::Or: return SimplifyOrInst(LHS, RHS, TD, MaxRecurse);
+ default:
+ if (Constant *CLHS = dyn_cast<Constant>(LHS))
+ if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
+ Constant *COps[] = {CLHS, CRHS};
+ return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, 2, TD);
+ }
+
+ // 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))
+ 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))
+ return V;
+
+ return 0;
+ }
+}
+
+Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
+ const TargetData *TD) {
+ return ::SimplifyBinOp(Opcode, LHS, RHS, TD, MaxRecursionDepth);
+}
+
+/// 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) {
+ if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
+ return SimplifyICmpInst(Predicate, LHS, RHS, TD, MaxRecurse);
+ return SimplifyFCmpInst(Predicate, LHS, RHS, TD, MaxRecurse);
+}
+
+Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
+ const TargetData *TD) {
+ return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, MaxRecursionDepth);
+}
+
+/// 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) {
+ switch (I->getOpcode()) {
+ default:
+ return ConstantFoldInstruction(I, TD);
+ case Instruction::Add:
+ return SimplifyAddInst(I->getOperand(0), I->getOperand(1),
+ cast<BinaryOperator>(I)->hasNoSignedWrap(),
+ cast<BinaryOperator>(I)->hasNoUnsignedWrap(), TD);
+ case Instruction::And:
+ return SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD);
+ case Instruction::Or:
+ return SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD);
+ case Instruction::ICmp:
+ return SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
+ I->getOperand(0), I->getOperand(1), TD);
+ case Instruction::FCmp:
+ return SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
+ I->getOperand(0), I->getOperand(1), TD);
+ case Instruction::Select:
+ return SimplifySelectInst(I->getOperand(0), I->getOperand(1),
+ I->getOperand(2), TD);
+ case Instruction::GetElementPtr: {
+ SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
+ return SimplifyGEPInst(&Ops[0], Ops.size(), TD);
+ }
+ case Instruction::PHI:
+ return cast<PHINode>(I)->hasConstantValue();
+ }
+}
+
+/// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
+/// delete the From instruction. In addition to a basic RAUW, this does a
+/// recursive simplification of the newly formed instructions. This catches
+/// things where one simplification exposes other opportunities. This only
+/// simplifies and deletes scalar operations, it does not change the CFG.
+///
+void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
+ const TargetData *TD) {
+ assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
+
+ // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
+ // we can know if it gets deleted out from under us or replaced in a
+ // recursive simplification.
+ WeakVH FromHandle(From);
+ WeakVH ToHandle(To);
+
+ while (!From->use_empty()) {
+ // Update the instruction to use the new value.
+ Use &TheUse = From->use_begin().getUse();
+ Instruction *User = cast<Instruction>(TheUse.getUser());
+ TheUse = To;
+
+ // Check to see if the instruction can be folded due to the operand
+ // replacement. For example changing (or X, Y) into (or X, -1) can replace
+ // the 'or' with -1.
+ Value *SimplifiedVal;
+ {
+ // Sanity check to make sure 'User' doesn't dangle across
+ // SimplifyInstruction.
+ AssertingVH<> UserHandle(User);
+
+ SimplifiedVal = SimplifyInstruction(User, TD);
+ if (SimplifiedVal == 0) continue;
+ }
+
+ // Recursively simplify this user to the new value.
+ ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD);
+ From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
+ To = ToHandle;
+
+ assert(ToHandle && "To value deleted by recursive simplification?");
+
+ // If the recursive simplification ended up revisiting and deleting
+ // 'From' then we're done.
+ if (From == 0)
+ return;
+ }
+
+ // If 'From' has value handles referring to it, do a real RAUW to update them.
+ From->replaceAllUsesWith(To);
+
+ From->eraseFromParent();
+}
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