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llvm/lib/Analysis/InstructionSimplify.cpp
Duncan Sands aceb03eb58 InstructionSimplify should be able to simplify A+B==B+A to 'true' 
but wasn't due to the same logic bug that caused PR14361.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168186 91177308-0d34-0410-b5e6-96231b3b80d8
2012-11-16 19:41:26 +00:00

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//===- InstructionSimplify.cpp - Fold instruction operands ----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements routines for folding instructions into simpler forms
// 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"). All operands are assumed to have already been
// simplified: This is usually true and assuming it simplifies the logic (if
// they have not been simplified then results are correct but maybe suboptimal).
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "instsimplify"
#include "llvm/GlobalAlias.h"
#include "llvm/Operator.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/PatternMatch.h"
#include "llvm/Support/ValueHandle.h"
#include "llvm/DataLayout.h"
using namespace llvm;
using namespace llvm::PatternMatch;
enum { RecursionLimit = 3 };
STATISTIC(NumExpand, "Number of expansions");
STATISTIC(NumFactor , "Number of factorizations");
STATISTIC(NumReassoc, "Number of reassociations");
struct Query {
const DataLayout *TD;
const TargetLibraryInfo *TLI;
const DominatorTree *DT;
Query(const DataLayout *td, const TargetLibraryInfo *tli,
const DominatorTree *dt) : TD(td), TLI(tli), DT(dt) {}
};
static Value *SimplifyAndInst(Value *, Value *, const Query &, unsigned);
static Value *SimplifyBinOp(unsigned, Value *, Value *, const Query &,
unsigned);
static Value *SimplifyCmpInst(unsigned, Value *, Value *, const Query &,
unsigned);
static Value *SimplifyOrInst(Value *, Value *, const Query &, unsigned);
static Value *SimplifyXorInst(Value *, Value *, const Query &, unsigned);
static Value *SimplifyTruncInst(Value *, Type *, const Query &, unsigned);
/// getFalse - For a boolean type, or a vector of boolean type, return false, or
/// a vector with every element false, as appropriate for the type.
static Constant *getFalse(Type *Ty) {
assert(Ty->getScalarType()->isIntegerTy(1) &&
"Expected i1 type or a vector of i1!");
return Constant::getNullValue(Ty);
}
/// getTrue - For a boolean type, or a vector of boolean type, return true, or
/// a vector with every element true, as appropriate for the type.
static Constant *getTrue(Type *Ty) {
assert(Ty->getScalarType()->isIntegerTy(1) &&
"Expected i1 type or a vector of i1!");
return Constant::getAllOnesValue(Ty);
}
/// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
Value *RHS) {
CmpInst *Cmp = dyn_cast<CmpInst>(V);
if (!Cmp)
return false;
CmpInst::Predicate CPred = Cmp->getPredicate();
Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
if (CPred == Pred && CLHS == LHS && CRHS == RHS)
return true;
return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
CRHS == LHS;
}
/// 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 are processing instructions (and/or basic blocks) that have not been
// fully added to a function, the parent nodes may still be null. Simply
// return the conservative answer in these cases.
if (!I->getParent() || !P->getParent() || !I->getParent()->getParent())
return false;
// If we have a DominatorTree then do a precise test.
if (DT) {
if (!DT->isReachableFromEntry(P->getParent()))
return true;
if (!DT->isReachableFromEntry(I->getParent()))
return false;
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;
}
/// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
/// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
/// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
/// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
/// Returns the simplified value, or null if no simplification was performed.
static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
unsigned OpcToExpand, const Query &Q,
unsigned MaxRecurse) {
Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
// Check whether the expression has the form "(A op' B) op C".
if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
if (Op0->getOpcode() == OpcodeToExpand) {
// It does! Try turning it into "(A op C) op' (B op C)".
Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
// Do "A op C" and "B op C" both simplify?
if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse))
if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
// They do! Return "L op' R" if it simplifies or is already available.
// If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
&& L == B && R == A)) {
++NumExpand;
return LHS;
}
// Otherwise return "L op' R" if it simplifies.
if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
++NumExpand;
return V;
}
}
}
// Check whether the expression has the form "A op (B op' C)".
if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
if (Op1->getOpcode() == OpcodeToExpand) {
// It does! Try turning it into "(A op B) op' (A op C)".
Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
// Do "A op B" and "A op C" both simplify?
if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse))
if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) {
// They do! Return "L op' R" if it simplifies or is already available.
// If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
&& L == C && R == B)) {
++NumExpand;
return RHS;
}
// Otherwise return "L op' R" if it simplifies.
if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
++NumExpand;
return V;
}
}
}
return 0;
}
/// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
/// using the operation OpCodeToExtract. For example, when Opcode is Add and
/// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
/// Returns the simplified value, or null if no simplification was performed.
static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
unsigned OpcToExtract, const Query &Q,
unsigned MaxRecurse) {
Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract;
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
if (!Op0 || Op0->getOpcode() != OpcodeToExtract ||
!Op1 || Op1->getOpcode() != OpcodeToExtract)
return 0;
// The expression has the form "(A op' B) op (C op' D)".
Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
// Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
// 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 || (Instruction::isCommutative(OpcodeToExtract) && A == D)) {
Value *DD = A == C ? D : C;
// Form "A op' (B op DD)" if it simplifies completely.
// Does "B op DD" simplify?
if (Value *V = SimplifyBinOp(Opcode, B, DD, Q, MaxRecurse)) {
// It does! Return "A op' V" if it simplifies or is already available.
// If V equals B then "A op' V" is just the LHS. If V equals DD then
// "A op' V" is just the RHS.
if (V == B || V == DD) {
++NumFactor;
return V == B ? LHS : RHS;
}
// Otherwise return "A op' V" if it simplifies.
if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, Q, MaxRecurse)) {
++NumFactor;
return W;
}
}
}
// Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
// 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 || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
Value *CC = B == D ? C : D;
// Form "(A op CC) op' B" if it simplifies completely..
// Does "A op CC" simplify?
if (Value *V = SimplifyBinOp(Opcode, A, CC, Q, MaxRecurse)) {
// It does! Return "V op' B" if it simplifies or is already available.
// If V equals A then "V op' B" is just the LHS. If V equals CC then
// "V op' B" is just the RHS.
if (V == A || V == CC) {
++NumFactor;
return V == A ? LHS : RHS;
}
// Otherwise return "V op' B" if it simplifies.
if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, Q, MaxRecurse)) {
++NumFactor;
return W;
}
}
}
return 0;
}
/// SimplifyAssociativeBinOp - Generic simplifications for associative binary
/// operations. Returns the simpler value, or null if none was found.
static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
const Query &Q, unsigned MaxRecurse) {
Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
// Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
if (Op0 && Op0->getOpcode() == Opcode) {
Value *A = Op0->getOperand(0);
Value *B = Op0->getOperand(1);
Value *C = RHS;
// Does "B op C" simplify?
if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
// It does! Return "A op V" if it simplifies or is already available.
// If V equals B then "A op V" is just the LHS.
if (V == B) return LHS;
// Otherwise return "A op V" if it simplifies.
if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
++NumReassoc;
return W;
}
}
}
// Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
if (Op1 && Op1->getOpcode() == Opcode) {
Value *A = LHS;
Value *B = Op1->getOperand(0);
Value *C = Op1->getOperand(1);
// Does "A op B" simplify?
if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
// It does! Return "V op C" if it simplifies or is already available.
// If V equals B then "V op C" is just the RHS.
if (V == B) return RHS;
// Otherwise return "V op C" if it simplifies.
if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
++NumReassoc;
return W;
}
}
}
// The remaining transforms require commutativity as well as associativity.
if (!Instruction::isCommutative(Opcode))
return 0;
// Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
if (Op0 && Op0->getOpcode() == Opcode) {
Value *A = Op0->getOperand(0);
Value *B = Op0->getOperand(1);
Value *C = RHS;
// Does "C op A" simplify?
if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
// It does! Return "V op B" if it simplifies or is already available.
// If V equals A then "V op B" is just the LHS.
if (V == A) return LHS;
// Otherwise return "V op B" if it simplifies.
if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
++NumReassoc;
return W;
}
}
}
// Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
if (Op1 && Op1->getOpcode() == Opcode) {
Value *A = LHS;
Value *B = Op1->getOperand(0);
Value *C = Op1->getOperand(1);
// Does "C op A" simplify?
if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
// It does! Return "B op V" if it simplifies or is already available.
// If V equals C then "B op V" is just the RHS.
if (V == C) return RHS;
// Otherwise return "B op V" if it simplifies.
if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
++NumReassoc;
return W;
}
}
}
return 0;
}
/// 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 Query &Q, unsigned MaxRecurse) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
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, Q, MaxRecurse);
FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
} else {
TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, 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;
}
}
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 Query &Q,
unsigned MaxRecurse) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
// 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);
Value *Cond = SI->getCondition();
Value *TV = SI->getTrueValue();
Value *FV = SI->getFalseValue();
// Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
// Does "cmp TV, RHS" simplify?
Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse);
if (TCmp == Cond) {
// It not only simplified, it simplified to the select condition. Replace
// it with 'true'.
TCmp = getTrue(Cond->getType());
} else if (!TCmp) {
// It didn't simplify. However if "cmp TV, RHS" is equal to the select
// condition then we can replace it with 'true'. Otherwise give up.
if (!isSameCompare(Cond, Pred, TV, RHS))
return 0;
TCmp = getTrue(Cond->getType());
}
// Does "cmp FV, RHS" simplify?
Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse);
if (FCmp == Cond) {
// It not only simplified, it simplified to the select condition. Replace
// it with 'false'.
FCmp = getFalse(Cond->getType());
} else if (!FCmp) {
// It didn't simplify. However if "cmp FV, RHS" is equal to the select
// condition then we can replace it with 'false'. Otherwise give up.
if (!isSameCompare(Cond, Pred, FV, RHS))
return 0;
FCmp = getFalse(Cond->getType());
}
// If both sides simplified to the same value, then use it as the result of
// the original comparison.
if (TCmp == FCmp)
return TCmp;
// The remaining cases only make sense if the select condition has the same
// type as the result of the comparison, so bail out if this is not so.
if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
return 0;
// If the false value simplified to false, then the result of the compare
// is equal to "Cond && TCmp". This also catches the case when the false
// value simplified to false and the true value to true, returning "Cond".
if (match(FCmp, m_Zero()))
if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse))
return V;
// If the true value simplified to true, then the result of the compare
// is equal to "Cond || FCmp".
if (match(TCmp, m_One()))
if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse))
return V;
// Finally, if the false value simplified to true and the true value to
// false, then the result of the compare is equal to "!Cond".
if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
if (Value *V =
SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
Q, MaxRecurse))
return V;
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 Query &Q, unsigned MaxRecurse) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
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, Q.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, Q.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, Incoming, RHS, Q, MaxRecurse) :
SimplifyBinOp(Opcode, LHS, Incoming, Q, 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 Query &Q, unsigned MaxRecurse) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
// 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);
// Bail out if RHS and the phi may be mutually interdependent due to a loop.
if (!ValueDominatesPHI(RHS, PI, Q.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 = SimplifyCmpInst(Pred, Incoming, RHS, Q, 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.
static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const Query &Q, unsigned MaxRecurse) {
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,
Q.TD, Q.TLI);
}
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// X + undef -> undef
if (match(Op1, m_Undef()))
return Op1;
// X + 0 -> X
if (match(Op1, m_Zero()))
return Op0;
// X + (Y - X) -> Y
// (Y - X) + X -> Y
// Eg: X + -X -> 0
Value *Y = 0;
if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
return Y;
// X + ~X -> -1 since ~X = -X-1
if (match(Op0, m_Not(m_Specific(Op1))) ||
match(Op1, m_Not(m_Specific(Op0))))
return Constant::getAllOnesValue(Op0->getType());
/// i1 add -> xor.
if (MaxRecurse && Op0->getType()->isIntegerTy(1))
if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
return V;
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q,
MaxRecurse))
return V;
// Mul distributes over Add. Try some generic simplifications based on this.
if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
Q, MaxRecurse))
return V;
// 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;
}
Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const DataLayout *TD, const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
RecursionLimit);
}
/// \brief Accumulate the constant integer offset a GEP represents.
///
/// Given a getelementptr instruction/constantexpr, accumulate the constant
/// offset from the base pointer into the provided APInt 'Offset'. Returns true
/// if the GEP has all-constant indices. Returns false if any non-constant
/// index is encountered leaving the 'Offset' in an undefined state. The
/// 'Offset' APInt must be the bitwidth of the target's pointer size.
static bool accumulateGEPOffset(const DataLayout &TD, GEPOperator *GEP,
APInt &Offset) {
unsigned IntPtrWidth = TD.getPointerSizeInBits();
assert(IntPtrWidth == Offset.getBitWidth());
gep_type_iterator GTI = gep_type_begin(GEP);
for (User::op_iterator I = GEP->op_begin() + 1, E = GEP->op_end(); I != E;
++I, ++GTI) {
ConstantInt *OpC = dyn_cast<ConstantInt>(*I);
if (!OpC) return false;
if (OpC->isZero()) continue;
// Handle a struct index, which adds its field offset to the pointer.
if (StructType *STy = dyn_cast<StructType>(*GTI)) {
unsigned ElementIdx = OpC->getZExtValue();
const StructLayout *SL = TD.getStructLayout(STy);
Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx));
continue;
}
APInt TypeSize(IntPtrWidth, TD.getTypeAllocSize(GTI.getIndexedType()));
Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
}
return true;
}
/// \brief Compute the base pointer and cumulative constant offsets for V.
///
/// This strips all constant offsets off of V, leaving it the base pointer, and
/// accumulates the total constant offset applied in the returned constant. It
/// returns 0 if V is not a pointer, and returns the constant '0' if there are
/// no constant offsets applied.
static Constant *stripAndComputeConstantOffsets(const DataLayout &TD,
Value *&V) {
if (!V->getType()->isPointerTy())
return 0;
unsigned IntPtrWidth = TD.getPointerSizeInBits();
APInt Offset = APInt::getNullValue(IntPtrWidth);
// Even though we don't look through PHI nodes, we could be called on an
// instruction in an unreachable block, which may be on a cycle.
SmallPtrSet<Value *, 4> Visited;
Visited.insert(V);
do {
if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
if (!GEP->isInBounds() || !accumulateGEPOffset(TD, GEP, Offset))
break;
V = GEP->getPointerOperand();
} else if (Operator::getOpcode(V) == Instruction::BitCast) {
V = cast<Operator>(V)->getOperand(0);
} else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
if (GA->mayBeOverridden())
break;
V = GA->getAliasee();
} else {
break;
}
assert(V->getType()->isPointerTy() && "Unexpected operand type!");
} while (Visited.insert(V));
Type *IntPtrTy = TD.getIntPtrType(V->getContext());
return ConstantInt::get(IntPtrTy, Offset);
}
/// \brief Compute the constant difference between two pointer values.
/// If the difference is not a constant, returns zero.
static Constant *computePointerDifference(const DataLayout &TD,
Value *LHS, Value *RHS) {
Constant *LHSOffset = stripAndComputeConstantOffsets(TD, LHS);
if (!LHSOffset)
return 0;
Constant *RHSOffset = stripAndComputeConstantOffsets(TD, RHS);
if (!RHSOffset)
return 0;
// If LHS and RHS are not related via constant offsets to the same base
// value, there is nothing we can do here.
if (LHS != RHS)
return 0;
// Otherwise, the difference of LHS - RHS can be computed as:
// LHS - RHS
// = (LHSOffset + Base) - (RHSOffset + Base)
// = LHSOffset - RHSOffset
return ConstantExpr::getSub(LHSOffset, RHSOffset);
}
/// SimplifySubInst - Given operands for a Sub, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const Query &Q, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0))
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
Ops, Q.TD, Q.TLI);
}
// X - undef -> undef
// undef - X -> undef
if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
return UndefValue::get(Op0->getType());
// X - 0 -> X
if (match(Op1, m_Zero()))
return Op0;
// X - X -> 0
if (Op0 == Op1)
return Constant::getNullValue(Op0->getType());
// (X*2) - X -> X
// (X<<1) - X -> X
Value *X = 0;
if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) ||
match(Op0, m_Shl(m_Specific(Op1), m_One())))
return Op1;
// (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
// For example, (X + Y) - Y -> X; (Y + X) - Y -> X
Value *Y = 0, *Z = Op1;
if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
// See if "V === Y - Z" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1))
// It does! Now see if "X + V" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
// See if "V === X - Z" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
// It does! Now see if "Y + V" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
}
// X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
// For example, X - (X + 1) -> -1
X = Op0;
if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
// See if "V === X - Y" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
// It does! Now see if "V - Z" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
// See if "V === X - Z" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
// It does! Now see if "V - Y" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
}
// Z - (X - Y) -> (Z - X) + Y if everything simplifies.
// For example, X - (X - Y) -> Y.
Z = Op0;
if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
// See if "V === Z - X" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1))
// It does! Now see if "V + Y" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
// trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies.
if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) &&
match(Op1, m_Trunc(m_Value(Y))))
if (X->getType() == Y->getType())
// See if "V === X - Y" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
// It does! Now see if "trunc V" simplifies.
if (Value *W = SimplifyTruncInst(V, Op0->getType(), Q, MaxRecurse-1))
// It does, return the simplified "trunc V".
return W;
// Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
if (Q.TD && match(Op0, m_PtrToInt(m_Value(X))) &&
match(Op1, m_PtrToInt(m_Value(Y))))
if (Constant *Result = computePointerDifference(*Q.TD, X, Y))
return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
// Mul distributes over Sub. Try some generic simplifications based on this.
if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
Q, MaxRecurse))
return V;
// i1 sub -> xor.
if (MaxRecurse && Op0->getType()->isIntegerTy(1))
if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
return V;
// Threading Sub 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::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const DataLayout *TD, const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
RecursionLimit);
}
/// SimplifyMulInst - Given operands for a Mul, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyMulInst(Value *Op0, Value *Op1, const Query &Q,
unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
Ops, Q.TD, Q.TLI);
}
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// X * undef -> 0
if (match(Op1, m_Undef()))
return Constant::getNullValue(Op0->getType());
// X * 0 -> 0
if (match(Op1, m_Zero()))
return Op1;
// X * 1 -> X
if (match(Op1, m_One()))
return Op0;
// (X / Y) * Y -> X if the division is exact.
Value *X = 0;
if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
return X;
// i1 mul -> and.
if (MaxRecurse && Op0->getType()->isIntegerTy(1))
if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1))
return V;
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q,
MaxRecurse))
return V;
// Mul distributes over Add. Try some generic simplifications based on this.
if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
Q, MaxRecurse))
return V;
// 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 (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q,
MaxRecurse))
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 (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q,
MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyMulInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
}
/// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
const Query &Q, unsigned MaxRecurse) {
if (Constant *C0 = dyn_cast<Constant>(Op0)) {
if (Constant *C1 = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { C0, C1 };
return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
}
}
bool isSigned = Opcode == Instruction::SDiv;
// X / undef -> undef
if (match(Op1, m_Undef()))
return Op1;
// undef / X -> 0
if (match(Op0, m_Undef()))
return Constant::getNullValue(Op0->getType());
// 0 / X -> 0, we don't need to preserve faults!
if (match(Op0, m_Zero()))
return Op0;
// X / 1 -> X
if (match(Op1, m_One()))
return Op0;
if (Op0->getType()->isIntegerTy(1))
// It can't be division by zero, hence it must be division by one.
return Op0;
// X / X -> 1
if (Op0 == Op1)
return ConstantInt::get(Op0->getType(), 1);
// (X * Y) / Y -> X if the multiplication does not overflow.
Value *X = 0, *Y = 0;
if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0);
// If the Mul knows it does not overflow, then we are good to go.
if ((isSigned && Mul->hasNoSignedWrap()) ||
(!isSigned && Mul->hasNoUnsignedWrap()))
return X;
// If X has the form X = A / Y then X * Y cannot overflow.
if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
return X;
}
// (X rem Y) / Y -> 0
if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
(!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
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 (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
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 (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
return V;
return 0;
}
/// SimplifySDivInst - Given operands for an SDiv, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifySDivInst(Value *Op0, Value *Op1, const Query &Q,
unsigned MaxRecurse) {
if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifySDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
}
/// SimplifyUDivInst - Given operands for a UDiv, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const Query &Q,
unsigned MaxRecurse) {
if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyUDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
}
static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const Query &Q,
unsigned) {
// undef / X -> undef (the undef could be a snan).
if (match(Op0, m_Undef()))
return Op0;
// X / undef -> undef
if (match(Op1, m_Undef()))
return Op1;
return 0;
}
Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyFDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
}
/// SimplifyRem - Given operands for an SRem or URem, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
const Query &Q, unsigned MaxRecurse) {
if (Constant *C0 = dyn_cast<Constant>(Op0)) {
if (Constant *C1 = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { C0, C1 };
return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
}
}
// X % undef -> undef
if (match(Op1, m_Undef()))
return Op1;
// undef % X -> 0
if (match(Op0, m_Undef()))
return Constant::getNullValue(Op0->getType());
// 0 % X -> 0, we don't need to preserve faults!
if (match(Op0, m_Zero()))
return Op0;
// X % 0 -> undef, we don't need to preserve faults!
if (match(Op1, m_Zero()))
return UndefValue::get(Op0->getType());
// X % 1 -> 0
if (match(Op1, m_One()))
return Constant::getNullValue(Op0->getType());
if (Op0->getType()->isIntegerTy(1))
// It can't be remainder by zero, hence it must be remainder by one.
return Constant::getNullValue(Op0->getType());
// X % X -> 0
if (Op0 == Op1)
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 (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
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 (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
return V;
return 0;
}
/// SimplifySRemInst - Given operands for an SRem, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifySRemInst(Value *Op0, Value *Op1, const Query &Q,
unsigned MaxRecurse) {
if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifySRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
}
/// SimplifyURemInst - Given operands for a URem, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q,
unsigned MaxRecurse) {
if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyURemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
}
static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const Query &,
unsigned) {
// undef % X -> undef (the undef could be a snan).
if (match(Op0, m_Undef()))
return Op0;
// X % undef -> undef
if (match(Op1, m_Undef()))
return Op1;
return 0;
}
Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyFRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
}
/// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
const Query &Q, unsigned MaxRecurse) {
if (Constant *C0 = dyn_cast<Constant>(Op0)) {
if (Constant *C1 = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { C0, C1 };
return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
}
}
// 0 shift by X -> 0
if (match(Op0, m_Zero()))
return Op0;
// X shift by 0 -> X
if (match(Op1, m_Zero()))
return Op0;
// X shift by undef -> undef because it may shift by the bitwidth.
if (match(Op1, m_Undef()))
return Op1;
// Shifting by the bitwidth or more is undefined.
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
if (CI->getValue().getLimitedValue() >=
Op0->getType()->getScalarSizeInBits())
return UndefValue::get(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 (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
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 (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
return V;
return 0;
}
/// SimplifyShlInst - Given operands for an Shl, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const Query &Q, unsigned MaxRecurse) {
if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse))
return V;
// undef << X -> 0
if (match(Op0, m_Undef()))
return Constant::getNullValue(Op0->getType());
// (X >> A) << A -> X
Value *X;
if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
return X;
return 0;
}
Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const DataLayout *TD, const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
RecursionLimit);
}
/// SimplifyLShrInst - Given operands for an LShr, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
const Query &Q, unsigned MaxRecurse) {
if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, Q, MaxRecurse))
return V;
// undef >>l X -> 0
if (match(Op0, m_Undef()))
return Constant::getNullValue(Op0->getType());
// (X << A) >> A -> X
Value *X;
if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap())
return X;
return 0;
}
Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyLShrInst(Op0, Op1, isExact, Query (TD, TLI, DT),
RecursionLimit);
}
/// SimplifyAShrInst - Given operands for an AShr, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
const Query &Q, unsigned MaxRecurse) {
if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, Q, MaxRecurse))
return V;
// all ones >>a X -> all ones
if (match(Op0, m_AllOnes()))
return Op0;
// undef >>a X -> all ones
if (match(Op0, m_Undef()))
return Constant::getAllOnesValue(Op0->getType());
// (X << A) >> A -> X
Value *X;
if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap())
return X;
return 0;
}
Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyAShrInst(Op0, Op1, isExact, Query (TD, TLI, DT),
RecursionLimit);
}
/// 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 Query &Q,
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, Q.TD, Q.TLI);
}
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// X & undef -> 0
if (match(Op1, m_Undef()))
return Constant::getNullValue(Op0->getType());
// X & X = X
if (Op0 == Op1)
return Op0;
// X & 0 = 0
if (match(Op1, m_Zero()))
return Op1;
// X & -1 = X
if (match(Op1, m_AllOnes()))
return Op0;
// A & ~A = ~A & A = 0
if (match(Op0, m_Not(m_Specific(Op1))) ||
match(Op1, m_Not(m_Specific(Op0))))
return Constant::getNullValue(Op0->getType());
// (A | ?) & A = A
Value *A = 0, *B = 0;
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 & (-A) = A if A is a power of two or zero.
if (match(Op0, m_Neg(m_Specific(Op1))) ||
match(Op1, m_Neg(m_Specific(Op0)))) {
if (isPowerOfTwo(Op0, Q.TD, /*OrZero*/true))
return Op0;
if (isPowerOfTwo(Op1, Q.TD, /*OrZero*/true))
return Op1;
}
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
MaxRecurse))
return V;
// And distributes over Or. Try some generic simplifications based on this.
if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
Q, MaxRecurse))
return V;
// And distributes over Xor. Try some generic simplifications based on this.
if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
Q, MaxRecurse))
return V;
// Or distributes over And. Try some generic simplifications based on this.
if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
Q, MaxRecurse))
return V;
// 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 (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q,
MaxRecurse))
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 (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q,
MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyAndInst(Op0, Op1, Query (TD, TLI, 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 Query &Q,
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, Q.TD, Q.TLI);
}
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// X | undef -> -1
if (match(Op1, m_Undef()))
return Constant::getAllOnesValue(Op0->getType());
// X | X = X
if (Op0 == Op1)
return Op0;
// X | 0 = X
if (match(Op1, m_Zero()))
return Op0;
// X | -1 = -1
if (match(Op1, m_AllOnes()))
return Op1;
// A | ~A = ~A | A = -1
if (match(Op0, m_Not(m_Specific(Op1))) ||
match(Op1, m_Not(m_Specific(Op0))))
return Constant::getAllOnesValue(Op0->getType());
// (A & ?) | A = A
Value *A = 0, *B = 0;
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 & ?) | A = -1
if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
(A == Op1 || B == Op1))
return Constant::getAllOnesValue(Op1->getType());
// A | ~(A & ?) = -1
if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
(A == Op0 || B == Op0))
return Constant::getAllOnesValue(Op0->getType());
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
MaxRecurse))
return V;
// Or distributes over And. Try some generic simplifications based on this.
if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,
MaxRecurse))
return V;
// And distributes over Or. Try some generic simplifications based on this.
if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
Q, MaxRecurse))
return V;
// 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 (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
MaxRecurse))
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 (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyOrInst(Op0, Op1, Query (TD, TLI, 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 Query &Q,
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, Q.TD, Q.TLI);
}
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// A ^ undef -> undef
if (match(Op1, m_Undef()))
return Op1;
// 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
if (match(Op0, m_Not(m_Specific(Op1))) ||
match(Op1, m_Not(m_Specific(Op0))))
return Constant::getAllOnesValue(Op0->getType());
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q,
MaxRecurse))
return V;
// And distributes over Xor. Try some generic simplifications based on this.
if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
Q, MaxRecurse))
return V;
// 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 DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyXorInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
}
static Type *GetCompareTy(Value *Op) {
return CmpInst::makeCmpResultType(Op->getType());
}
/// ExtractEquivalentCondition - Rummage around inside V looking for something
/// equivalent to the comparison "LHS Pred RHS". Return such a value if found,
/// otherwise return null. Helper function for analyzing max/min idioms.
static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred,
Value *LHS, Value *RHS) {
SelectInst *SI = dyn_cast<SelectInst>(V);
if (!SI)
return 0;
CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
if (!Cmp)
return 0;
Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
return Cmp;
if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
LHS == CmpRHS && RHS == CmpLHS)
return Cmp;
return 0;
}
static Constant *computePointerICmp(const DataLayout &TD,
CmpInst::Predicate Pred,
Value *LHS, Value *RHS) {
// We can only fold certain predicates on pointer comparisons.
switch (Pred) {
default:
return 0;
// Equality comaprisons are easy to fold.
case CmpInst::ICMP_EQ:
case CmpInst::ICMP_NE:
break;
// We can only handle unsigned relational comparisons because 'inbounds' on
// a GEP only protects against unsigned wrapping.
case CmpInst::ICMP_UGT:
case CmpInst::ICMP_UGE:
case CmpInst::ICMP_ULT:
case CmpInst::ICMP_ULE:
// However, we have to switch them to their signed variants to handle
// negative indices from the base pointer.
Pred = ICmpInst::getSignedPredicate(Pred);
break;
}
Constant *LHSOffset = stripAndComputeConstantOffsets(TD, LHS);
if (!LHSOffset)
return 0;
Constant *RHSOffset = stripAndComputeConstantOffsets(TD, RHS);
if (!RHSOffset)
return 0;
// If LHS and RHS are not related via constant offsets to the same base
// value, there is nothing we can do here.
if (LHS != RHS)
return 0;
return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset);
}
/// 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 Query &Q, unsigned MaxRecurse) {
CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
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, Q.TD, Q.TLI);
// If we have a constant, make sure it is on the RHS.
std::swap(LHS, RHS);
Pred = CmpInst::getSwappedPredicate(Pred);
}
Type *ITy = GetCompareTy(LHS); // The return type.
Type *OpTy = LHS->getType(); // The operand type.
// 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));
// Special case logic when the operands have i1 type.
if (OpTy->getScalarType()->isIntegerTy(1)) {
switch (Pred) {
default: break;
case ICmpInst::ICMP_EQ:
// X == 1 -> X
if (match(RHS, m_One()))
return LHS;
break;
case ICmpInst::ICMP_NE:
// X != 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_UGT:
// X >u 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_UGE:
// X >=u 1 -> X
if (match(RHS, m_One()))
return LHS;
break;
case ICmpInst::ICMP_SLT:
// X <s 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_SLE:
// X <=s -1 -> X
if (match(RHS, m_One()))
return LHS;
break;
}
}
// icmp <object*>, <object*/null> - Different identified objects have
// different addresses (unless null), and what's more the address of an
// identified local is never equal to another argument (again, barring null).
// Note that generalizing to the case where LHS is a global variable address
// or null is pointless, since if both LHS and RHS are constants then we
// already constant folded the compare, and if only one of them is then we
// moved it to RHS already.
Value *LHSPtr = LHS->stripPointerCasts();
Value *RHSPtr = RHS->stripPointerCasts();
if (LHSPtr == RHSPtr)
return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
// Be more aggressive about stripping pointer adjustments when checking a
// comparison of an alloca address to another object. We can rip off all
// inbounds GEP operations, even if they are variable.
LHSPtr = LHSPtr->stripInBoundsOffsets();
if (llvm::isIdentifiedObject(LHSPtr)) {
RHSPtr = RHSPtr->stripInBoundsOffsets();
if (llvm::isKnownNonNull(LHSPtr) || llvm::isKnownNonNull(RHSPtr)) {
// If both sides are different identified objects, they aren't equal
// unless they're null.
if (LHSPtr != RHSPtr && llvm::isIdentifiedObject(RHSPtr) &&
Pred == CmpInst::ICMP_EQ)
return ConstantInt::get(ITy, false);
// A local identified object (alloca or noalias call) can't equal any
// incoming argument, unless they're both null or they belong to
// different functions. The latter happens during inlining.
if (Instruction *LHSInst = dyn_cast<Instruction>(LHSPtr))
if (Argument *RHSArg = dyn_cast<Argument>(RHSPtr))
if (LHSInst->getParent()->getParent() == RHSArg->getParent() &&
Pred == CmpInst::ICMP_EQ)
return ConstantInt::get(ITy, false);
}
// Assume that the constant null is on the right.
if (llvm::isKnownNonNull(LHSPtr) && isa<ConstantPointerNull>(RHSPtr)) {
if (Pred == CmpInst::ICMP_EQ)
return ConstantInt::get(ITy, false);
else if (Pred == CmpInst::ICMP_NE)
return ConstantInt::get(ITy, true);
}
} else if (Argument *LHSArg = dyn_cast<Argument>(LHSPtr)) {
RHSPtr = RHSPtr->stripInBoundsOffsets();
// An alloca can't be equal to an argument unless they come from separate
// functions via inlining.
if (AllocaInst *RHSInst = dyn_cast<AllocaInst>(RHSPtr)) {
if (LHSArg->getParent() == RHSInst->getParent()->getParent()) {
if (Pred == CmpInst::ICMP_EQ)
return ConstantInt::get(ITy, false);
else if (Pred == CmpInst::ICMP_NE)
return ConstantInt::get(ITy, true);
}
}
}
// If we are comparing with zero then try hard since this is a common case.
if (match(RHS, m_Zero())) {
bool LHSKnownNonNegative, LHSKnownNegative;
switch (Pred) {
default: llvm_unreachable("Unknown ICmp predicate!");
case ICmpInst::ICMP_ULT:
return getFalse(ITy);
case ICmpInst::ICMP_UGE:
return getTrue(ITy);
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_ULE:
if (isKnownNonZero(LHS, Q.TD))
return getFalse(ITy);
break;
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_UGT:
if (isKnownNonZero(LHS, Q.TD))
return getTrue(ITy);
break;
case ICmpInst::ICMP_SLT:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
if (LHSKnownNegative)
return getTrue(ITy);
if (LHSKnownNonNegative)
return getFalse(ITy);
break;
case ICmpInst::ICMP_SLE:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
if (LHSKnownNegative)
return getTrue(ITy);
if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD))
return getFalse(ITy);
break;
case ICmpInst::ICMP_SGE:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
if (LHSKnownNegative)
return getFalse(ITy);
if (LHSKnownNonNegative)
return getTrue(ITy);
break;
case ICmpInst::ICMP_SGT:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
if (LHSKnownNegative)
return getFalse(ITy);
if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD))
return getTrue(ITy);
break;
}
}
// See if we are doing a comparison with a constant integer.
if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
// Rule out tautological comparisons (eg., ult 0 or uge 0).
ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue());
if (RHS_CR.isEmptySet())
return ConstantInt::getFalse(CI->getContext());
if (RHS_CR.isFullSet())
return ConstantInt::getTrue(CI->getContext());
// Many binary operators with constant RHS have easy to compute constant
// range. Use them to check whether the comparison is a tautology.
uint32_t Width = CI->getBitWidth();
APInt Lower = APInt(Width, 0);
APInt Upper = APInt(Width, 0);
ConstantInt *CI2;
if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) {
// 'urem x, CI2' produces [0, CI2).
Upper = CI2->getValue();
} else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) {
// 'srem x, CI2' produces (-|CI2|, |CI2|).
Upper = CI2->getValue().abs();
Lower = (-Upper) + 1;
} else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
// 'udiv CI2, x' produces [0, CI2].
Upper = CI2->getValue() + 1;
} else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
// 'udiv x, CI2' produces [0, UINT_MAX / CI2].
APInt NegOne = APInt::getAllOnesValue(Width);
if (!CI2->isZero())
Upper = NegOne.udiv(CI2->getValue()) + 1;
} else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
// 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2].
APInt IntMin = APInt::getSignedMinValue(Width);
APInt IntMax = APInt::getSignedMaxValue(Width);
APInt Val = CI2->getValue().abs();
if (!Val.isMinValue()) {
Lower = IntMin.sdiv(Val);
Upper = IntMax.sdiv(Val) + 1;
}
} else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
// 'lshr x, CI2' produces [0, UINT_MAX >> CI2].
APInt NegOne = APInt::getAllOnesValue(Width);
if (CI2->getValue().ult(Width))
Upper = NegOne.lshr(CI2->getValue()) + 1;
} else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) {
// 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2].
APInt IntMin = APInt::getSignedMinValue(Width);
APInt IntMax = APInt::getSignedMaxValue(Width);
if (CI2->getValue().ult(Width)) {
Lower = IntMin.ashr(CI2->getValue());
Upper = IntMax.ashr(CI2->getValue()) + 1;
}
} else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) {
// 'or x, CI2' produces [CI2, UINT_MAX].
Lower = CI2->getValue();
} else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) {
// 'and x, CI2' produces [0, CI2].
Upper = CI2->getValue() + 1;
}
if (Lower != Upper) {
ConstantRange LHS_CR = ConstantRange(Lower, Upper);
if (RHS_CR.contains(LHS_CR))
return ConstantInt::getTrue(RHS->getContext());
if (RHS_CR.inverse().contains(LHS_CR))
return ConstantInt::getFalse(RHS->getContext());
}
}
// Compare of cast, for example (zext X) != 0 -> X != 0
if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
Instruction *LI = cast<CastInst>(LHS);
Value *SrcOp = LI->getOperand(0);
Type *SrcTy = SrcOp->getType();
Type *DstTy = LI->getType();
// Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
// if the integer type is the same size as the pointer type.
if (MaxRecurse && Q.TD && isa<PtrToIntInst>(LI) &&
Q.TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) {
if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
// Transfer the cast to the constant.
if (Value *V = SimplifyICmpInst(Pred, SrcOp,
ConstantExpr::getIntToPtr(RHSC, SrcTy),
Q, MaxRecurse-1))
return V;
} else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
if (RI->getOperand(0)->getType() == SrcTy)
// Compare without the cast.
if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
Q, MaxRecurse-1))
return V;
}
}
if (isa<ZExtInst>(LHS)) {
// Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
// same type.
if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
// Compare X and Y. Note that signed predicates become unsigned.
if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
SrcOp, RI->getOperand(0), Q,
MaxRecurse-1))
return V;
}
// Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
// too. If not, then try to deduce the result of the comparison.
else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
// Compute the constant that would happen if we truncated to SrcTy then
// reextended to DstTy.
Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
// If the re-extended constant didn't change then this is effectively
// also a case of comparing two zero-extended values.
if (RExt == CI && MaxRecurse)
if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
SrcOp, Trunc, Q, MaxRecurse-1))
return V;
// Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
// there. Use this to work out the result of the comparison.
if (RExt != CI) {
switch (Pred) {
default: llvm_unreachable("Unknown ICmp predicate!");
// LHS <u RHS.
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
return ConstantInt::getFalse(CI->getContext());
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
return ConstantInt::getTrue(CI->getContext());
// LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
// is non-negative then LHS <s RHS.
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
return CI->getValue().isNegative() ?
ConstantInt::getTrue(CI->getContext()) :
ConstantInt::getFalse(CI->getContext());
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE:
return CI->getValue().isNegative() ?
ConstantInt::getFalse(CI->getContext()) :
ConstantInt::getTrue(CI->getContext());
}
}
}
}
if (isa<SExtInst>(LHS)) {
// Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
// same type.
if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
// Compare X and Y. Note that the predicate does not change.
if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
Q, MaxRecurse-1))
return V;
}
// Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
// too. If not, then try to deduce the result of the comparison.
else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
// Compute the constant that would happen if we truncated to SrcTy then
// reextended to DstTy.
Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
// If the re-extended constant didn't change then this is effectively
// also a case of comparing two sign-extended values.
if (RExt == CI && MaxRecurse)
if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1))
return V;
// Otherwise the upper bits of LHS are all equal, while RHS has varying
// bits there. Use this to work out the result of the comparison.
if (RExt != CI) {
switch (Pred) {
default: llvm_unreachable("Unknown ICmp predicate!");
case ICmpInst::ICMP_EQ:
return ConstantInt::getFalse(CI->getContext());
case ICmpInst::ICMP_NE:
return ConstantInt::getTrue(CI->getContext());
// If RHS is non-negative then LHS <s RHS. If RHS is negative then
// LHS >s RHS.
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
return CI->getValue().isNegative() ?
ConstantInt::getTrue(CI->getContext()) :
ConstantInt::getFalse(CI->getContext());
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE:
return CI->getValue().isNegative() ?
ConstantInt::getFalse(CI->getContext()) :
ConstantInt::getTrue(CI->getContext());
// If LHS is non-negative then LHS <u RHS. If LHS is negative then
// LHS >u RHS.
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
// Comparison is true iff the LHS <s 0.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
Constant::getNullValue(SrcTy),
Q, MaxRecurse-1))
return V;
break;
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
// Comparison is true iff the LHS >=s 0.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
Constant::getNullValue(SrcTy),
Q, MaxRecurse-1))
return V;
break;
}
}
}
}
}
// Special logic for binary operators.
BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
if (MaxRecurse && (LBO || RBO)) {
// Analyze the case when either LHS or RHS is an add instruction.
Value *A = 0, *B = 0, *C = 0, *D = 0;
// LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
if (LBO && LBO->getOpcode() == Instruction::Add) {
A = LBO->getOperand(0); B = LBO->getOperand(1);
NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
(CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
(CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
}
if (RBO && RBO->getOpcode() == Instruction::Add) {
C = RBO->getOperand(0); D = RBO->getOperand(1);
NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
(CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
(CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
}
// icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
if ((A == RHS || B == RHS) && NoLHSWrapProblem)
if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
Constant::getNullValue(RHS->getType()),
Q, MaxRecurse-1))
return V;
// icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
if ((C == LHS || D == LHS) && NoRHSWrapProblem)
if (Value *V = SimplifyICmpInst(Pred,
Constant::getNullValue(LHS->getType()),
C == LHS ? D : C, Q, MaxRecurse-1))
return V;
// icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
if (A && C && (A == C || A == D || B == C || B == D) &&
NoLHSWrapProblem && NoRHSWrapProblem) {
// Determine Y and Z in the form icmp (X+Y), (X+Z).
Value *Y, *Z;
if (A == C) {
Y = B;
Z = D;
} else if (A == D) {
Y = B;
Z = C;
} else if (B == C) {
Y = A;
Z = D;
} else if (B == D) {
Y = A;
Z = C;
}
if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse-1))
return V;
}
}
if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
bool KnownNonNegative, KnownNegative;
switch (Pred) {
default:
break;
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
if (!KnownNonNegative)
break;
// fall-through
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
return getFalse(ITy);
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE:
ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
if (!KnownNonNegative)
break;
// fall-through
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
return getTrue(ITy);
}
}
if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
bool KnownNonNegative, KnownNegative;
switch (Pred) {
default:
break;
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
if (!KnownNonNegative)
break;
// fall-through
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
return getTrue(ITy);
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE:
ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
if (!KnownNonNegative)
break;
// fall-through
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
return getFalse(ITy);
}
}
// x udiv y <=u x.
if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
// icmp pred (X /u Y), X
if (Pred == ICmpInst::ICMP_UGT)
return getFalse(ITy);
if (Pred == ICmpInst::ICMP_ULE)
return getTrue(ITy);
}
if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
LBO->getOperand(1) == RBO->getOperand(1)) {
switch (LBO->getOpcode()) {
default: break;
case Instruction::UDiv:
case Instruction::LShr:
if (ICmpInst::isSigned(Pred))
break;
// fall-through
case Instruction::SDiv:
case Instruction::AShr:
if (!LBO->isExact() || !RBO->isExact())
break;
if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
RBO->getOperand(0), Q, MaxRecurse-1))
return V;
break;
case Instruction::Shl: {
bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
if (!NUW && !NSW)
break;
if (!NSW && ICmpInst::isSigned(Pred))
break;
if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
RBO->getOperand(0), Q, MaxRecurse-1))
return V;
break;
}
}
}
// Simplify comparisons involving max/min.
Value *A, *B;
CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
// Signed variants on "max(a,b)>=a -> true".
if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
if (A != RHS) std::swap(A, B); // smax(A, B) pred A.
EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
// We analyze this as smax(A, B) pred A.
P = Pred;
} else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
(A == LHS || B == LHS)) {
if (A != LHS) std::swap(A, B); // A pred smax(A, B).
EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
// We analyze this as smax(A, B) swapped-pred A.
P = CmpInst::getSwappedPredicate(Pred);
} else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
(A == RHS || B == RHS)) {
if (A != RHS) std::swap(A, B); // smin(A, B) pred A.
EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
// We analyze this as smax(-A, -B) swapped-pred -A.
// Note that we do not need to actually form -A or -B thanks to EqP.
P = CmpInst::getSwappedPredicate(Pred);
} else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
(A == LHS || B == LHS)) {
if (A != LHS) std::swap(A, B); // A pred smin(A, B).
EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
// We analyze this as smax(-A, -B) pred -A.
// Note that we do not need to actually form -A or -B thanks to EqP.
P = Pred;
}
if (P != CmpInst::BAD_ICMP_PREDICATE) {
// Cases correspond to "max(A, B) p A".
switch (P) {
default:
break;
case CmpInst::ICMP_EQ:
case CmpInst::ICMP_SLE:
// Equivalent to "A EqP B". This may be the same as the condition tested
// in the max/min; if so, we can just return that.
if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
return V;
if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
return V;
// Otherwise, see if "A EqP B" simplifies.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
return V;
break;
case CmpInst::ICMP_NE:
case CmpInst::ICMP_SGT: {
CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
// Equivalent to "A InvEqP B". This may be the same as the condition
// tested in the max/min; if so, we can just return that.
if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
return V;
if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
return V;
// Otherwise, see if "A InvEqP B" simplifies.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
return V;
break;
}
case CmpInst::ICMP_SGE:
// Always true.
return getTrue(ITy);
case CmpInst::ICMP_SLT:
// Always false.
return getFalse(ITy);
}
}
// Unsigned variants on "max(a,b)>=a -> true".
P = CmpInst::BAD_ICMP_PREDICATE;
if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
if (A != RHS) std::swap(A, B); // umax(A, B) pred A.
EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
// We analyze this as umax(A, B) pred A.
P = Pred;
} else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
(A == LHS || B == LHS)) {
if (A != LHS) std::swap(A, B); // A pred umax(A, B).
EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
// We analyze this as umax(A, B) swapped-pred A.
P = CmpInst::getSwappedPredicate(Pred);
} else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
(A == RHS || B == RHS)) {
if (A != RHS) std::swap(A, B); // umin(A, B) pred A.
EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
// We analyze this as umax(-A, -B) swapped-pred -A.
// Note that we do not need to actually form -A or -B thanks to EqP.
P = CmpInst::getSwappedPredicate(Pred);
} else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
(A == LHS || B == LHS)) {
if (A != LHS) std::swap(A, B); // A pred umin(A, B).
EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
// We analyze this as umax(-A, -B) pred -A.
// Note that we do not need to actually form -A or -B thanks to EqP.
P = Pred;
}
if (P != CmpInst::BAD_ICMP_PREDICATE) {
// Cases correspond to "max(A, B) p A".
switch (P) {
default:
break;
case CmpInst::ICMP_EQ:
case CmpInst::ICMP_ULE:
// Equivalent to "A EqP B". This may be the same as the condition tested
// in the max/min; if so, we can just return that.
if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
return V;
if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
return V;
// Otherwise, see if "A EqP B" simplifies.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
return V;
break;
case CmpInst::ICMP_NE:
case CmpInst::ICMP_UGT: {
CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
// Equivalent to "A InvEqP B". This may be the same as the condition
// tested in the max/min; if so, we can just return that.
if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
return V;
if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
return V;
// Otherwise, see if "A InvEqP B" simplifies.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
return V;
break;
}
case CmpInst::ICMP_UGE:
// Always true.
return getTrue(ITy);
case CmpInst::ICMP_ULT:
// Always false.
return getFalse(ITy);
}
}
// Variants on "max(x,y) >= min(x,z)".
Value *C, *D;
if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
(A == C || A == D || B == C || B == D)) {
// max(x, ?) pred min(x, ?).
if (Pred == CmpInst::ICMP_SGE)
// Always true.
return getTrue(ITy);
if (Pred == CmpInst::ICMP_SLT)
// Always false.
return getFalse(ITy);
} else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
(A == C || A == D || B == C || B == D)) {
// min(x, ?) pred max(x, ?).
if (Pred == CmpInst::ICMP_SLE)
// Always true.
return getTrue(ITy);
if (Pred == CmpInst::ICMP_SGT)
// Always false.
return getFalse(ITy);
} else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
(A == C || A == D || B == C || B == D)) {
// max(x, ?) pred min(x, ?).
if (Pred == CmpInst::ICMP_UGE)
// Always true.
return getTrue(ITy);
if (Pred == CmpInst::ICMP_ULT)
// Always false.
return getFalse(ITy);
} else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
(A == C || A == D || B == C || B == D)) {
// min(x, ?) pred max(x, ?).
if (Pred == CmpInst::ICMP_ULE)
// Always true.
return getTrue(ITy);
if (Pred == CmpInst::ICMP_UGT)
// Always false.
return getFalse(ITy);
}
// Simplify comparisons of related pointers using a powerful, recursive
// GEP-walk when we have target data available..
if (Q.TD && LHS->getType()->isPointerTy() && RHS->getType()->isPointerTy())
if (Constant *C = computePointerICmp(*Q.TD, Pred, LHS, RHS))
return C;
if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
(ICmpInst::isEquality(Pred) ||
(GLHS->isInBounds() && GRHS->isInBounds() &&
Pred == ICmpInst::getSignedPredicate(Pred)))) {
// The bases are equal and the indices are constant. Build a constant
// expression GEP with the same indices and a null base pointer to see
// what constant folding can make out of it.
Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
Constant *NewLHS = ConstantExpr::getGetElementPtr(Null, IndicesLHS);
SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
Constant *NewRHS = ConstantExpr::getGetElementPtr(Null, IndicesRHS);
return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
}
}
}
// 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 (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
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 (isa<PHINode>(LHS) || isa<PHINode>(RHS))
if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyICmpInst(Predicate, LHS, RHS, Query (TD, TLI, 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 Query &Q, 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, Q.TD, Q.TLI);
// 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 (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
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 (isa<PHINode>(LHS) || isa<PHINode>(RHS))
if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyFCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
RecursionLimit);
}
/// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
/// the result. If not, this returns null.
static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal,
Value *FalseVal, const Query &Q,
unsigned MaxRecurse) {
// 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>(CondVal)) { // select undef, X, Y -> X or Y
if (isa<Constant>(TrueVal))
return TrueVal;
return FalseVal;
}
if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
return FalseVal;
if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
return TrueVal;
return 0;
}
Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Query (TD, TLI, DT),
RecursionLimit);
}
/// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyGEPInst(ArrayRef<Value *> Ops, const Query &Q, unsigned) {
// The type of the GEP pointer operand.
PointerType *PtrTy = dyn_cast<PointerType>(Ops[0]->getType());
// The GEP pointer operand is not a pointer, it's a vector of pointers.
if (!PtrTy)
return 0;
// getelementptr P -> P.
if (Ops.size() == 1)
return Ops[0];
if (isa<UndefValue>(Ops[0])) {
// Compute the (pointer) type returned by the GEP instruction.
Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, Ops.slice(1));
Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
return UndefValue::get(GEPTy);
}
if (Ops.size() == 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 (Q.TD) {
Type *Ty = PtrTy->getElementType();
if (Ty->isSized() && Q.TD->getTypeAllocSize(Ty) == 0)
return Ops[0];
}
}
// Check to see if this is constant foldable.
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
if (!isa<Constant>(Ops[i]))
return 0;
return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), Ops.slice(1));
}
Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyGEPInst(Ops, Query (TD, TLI, DT), RecursionLimit);
}
/// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we
/// can fold the result. If not, this returns null.
static Value *SimplifyInsertValueInst(Value *Agg, Value *Val,
ArrayRef<unsigned> Idxs, const Query &Q,
unsigned) {
if (Constant *CAgg = dyn_cast<Constant>(Agg))
if (Constant *CVal = dyn_cast<Constant>(Val))
return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
// insertvalue x, undef, n -> x
if (match(Val, m_Undef()))
return Agg;
// insertvalue x, (extractvalue y, n), n
if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
if (EV->getAggregateOperand()->getType() == Agg->getType() &&
EV->getIndices() == Idxs) {
// insertvalue undef, (extractvalue y, n), n -> y
if (match(Agg, m_Undef()))
return EV->getAggregateOperand();
// insertvalue y, (extractvalue y, n), n -> y
if (Agg == EV->getAggregateOperand())
return Agg;
}
return 0;
}
Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val,
ArrayRef<unsigned> Idxs,
const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyInsertValueInst(Agg, Val, Idxs, Query (TD, TLI, DT),
RecursionLimit);
}
/// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
static Value *SimplifyPHINode(PHINode *PN, const Query &Q) {
// 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, Q.DT) ? CommonValue : 0;
return CommonValue;
}
static Value *SimplifyTruncInst(Value *Op, Type *Ty, const Query &Q, unsigned) {
if (Constant *C = dyn_cast<Constant>(Op))
return ConstantFoldInstOperands(Instruction::Trunc, Ty, C, Q.TD, Q.TLI);
return 0;
}
Value *llvm::SimplifyTruncInst(Value *Op, Type *Ty, const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyTruncInst(Op, Ty, Query (TD, TLI, DT), RecursionLimit);
}
//=== 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 Query &Q, unsigned MaxRecurse) {
switch (Opcode) {
case Instruction::Add:
return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
Q, MaxRecurse);
case Instruction::Sub:
return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
Q, MaxRecurse);
case Instruction::Mul: return SimplifyMulInst (LHS, RHS, Q, MaxRecurse);
case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, Q, MaxRecurse);
case Instruction::SRem: return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
case Instruction::URem: return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, Q, MaxRecurse);
case Instruction::Shl:
return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
Q, MaxRecurse);
case Instruction::LShr:
return SimplifyLShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
case Instruction::AShr:
return SimplifyAShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
case Instruction::And: return SimplifyAndInst(LHS, RHS, Q, MaxRecurse);
case Instruction::Or: return SimplifyOrInst (LHS, RHS, Q, MaxRecurse);
case Instruction::Xor: return SimplifyXorInst(LHS, RHS, Q, 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, Q.TD,
Q.TLI);
}
// If the operation is associative, try some generic simplifications.
if (Instruction::isAssociative(Opcode))
if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, Q, MaxRecurse))
return V;
// 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 (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, Q, MaxRecurse))
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 (isa<PHINode>(LHS) || isa<PHINode>(RHS))
if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, Q, MaxRecurse))
return V;
return 0;
}
}
Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
const DataLayout *TD, const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyBinOp(Opcode, LHS, RHS, Query (TD, TLI, 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 Query &Q, unsigned MaxRecurse) {
if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
return SimplifyFCmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
}
Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const DataLayout *TD, const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
RecursionLimit);
}
static Value *SimplifyCallInst(CallInst *CI, const Query &) {
// call undef -> undef
if (isa<UndefValue>(CI->getCalledValue()))
return UndefValue::get(CI->getType());
return 0;
}
/// SimplifyInstruction - See if we can compute a simplified version of this
/// instruction. If not, this returns null.
Value *llvm::SimplifyInstruction(Instruction *I, const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
Value *Result;
switch (I->getOpcode()) {
default:
Result = ConstantFoldInstruction(I, TD, TLI);
break;
case Instruction::Add:
Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->hasNoSignedWrap(),
cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
TD, TLI, DT);
break;
case Instruction::Sub:
Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->hasNoSignedWrap(),
cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
TD, TLI, DT);
break;
case Instruction::Mul:
Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
break;
case Instruction::SDiv:
Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
break;
case Instruction::UDiv:
Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
break;
case Instruction::FDiv:
Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
break;
case Instruction::SRem:
Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
break;
case Instruction::URem:
Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
break;
case Instruction::FRem:
Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
break;
case Instruction::Shl:
Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->hasNoSignedWrap(),
cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
TD, TLI, DT);
break;
case Instruction::LShr:
Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->isExact(),
TD, TLI, DT);
break;
case Instruction::AShr:
Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->isExact(),
TD, TLI, DT);
break;
case Instruction::And:
Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
break;
case Instruction::Or:
Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
break;
case Instruction::Xor:
Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
break;
case Instruction::ICmp:
Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
I->getOperand(0), I->getOperand(1), TD, TLI, DT);
break;
case Instruction::FCmp:
Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
I->getOperand(0), I->getOperand(1), TD, TLI, DT);
break;
case Instruction::Select:
Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
I->getOperand(2), TD, TLI, DT);
break;
case Instruction::GetElementPtr: {
SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
Result = SimplifyGEPInst(Ops, TD, TLI, DT);
break;
}
case Instruction::InsertValue: {
InsertValueInst *IV = cast<InsertValueInst>(I);
Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
IV->getInsertedValueOperand(),
IV->getIndices(), TD, TLI, DT);
break;
}
case Instruction::PHI:
Result = SimplifyPHINode(cast<PHINode>(I), Query (TD, TLI, DT));
break;
case Instruction::Call:
Result = SimplifyCallInst(cast<CallInst>(I), Query (TD, TLI, DT));
break;
case Instruction::Trunc:
Result = SimplifyTruncInst(I->getOperand(0), I->getType(), TD, TLI, 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 a safe value instead.
return Result == I ? UndefValue::get(I->getType()) : Result;
}
/// \brief Implementation of recursive simplification through an instructions
/// uses.
///
/// This is the common implementation of the recursive simplification routines.
/// If we have a pre-simplified value in 'SimpleV', that is forcibly used to
/// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of
/// instructions to process and attempt to simplify it using
/// InstructionSimplify.
///
/// This routine returns 'true' only when *it* simplifies something. The passed
/// in simplified value does not count toward this.
static bool replaceAndRecursivelySimplifyImpl(Instruction *I, Value *SimpleV,
const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
bool Simplified = false;
SmallSetVector<Instruction *, 8> Worklist;
// If we have an explicit value to collapse to, do that round of the
// simplification loop by hand initially.
if (SimpleV) {
for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE;
++UI)
if (*UI != I)
Worklist.insert(cast<Instruction>(*UI));
// Replace the instruction with its simplified value.
I->replaceAllUsesWith(SimpleV);
// Gracefully handle edge cases where the instruction is not wired into any
// parent block.
if (I->getParent())
I->eraseFromParent();
} else {
Worklist.insert(I);
}
// Note that we must test the size on each iteration, the worklist can grow.
for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
I = Worklist[Idx];
// See if this instruction simplifies.
SimpleV = SimplifyInstruction(I, TD, TLI, DT);
if (!SimpleV)
continue;
Simplified = true;
// Stash away all the uses of the old instruction so we can check them for
// recursive simplifications after a RAUW. This is cheaper than checking all
// uses of To on the recursive step in most cases.
for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE;
++UI)
Worklist.insert(cast<Instruction>(*UI));
// Replace the instruction with its simplified value.
I->replaceAllUsesWith(SimpleV);
// Gracefully handle edge cases where the instruction is not wired into any
// parent block.
if (I->getParent())
I->eraseFromParent();
}
return Simplified;
}
bool llvm::recursivelySimplifyInstruction(Instruction *I,
const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return replaceAndRecursivelySimplifyImpl(I, 0, TD, TLI, DT);
}
bool llvm::replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV,
const DataLayout *TD,
const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!");
assert(SimpleV && "Must provide a simplified value.");
return replaceAndRecursivelySimplifyImpl(I, SimpleV, TD, TLI, DT);
}
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