#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Support/ValueHandle.h"
#include "llvm/Instructions.h"
#include "llvm/Support/PatternMatch.h"
using namespace llvm;
using namespace llvm::PatternMatch;
-/// SimplifyAndInst - Given operands for an And, see if we can
+/// SimplifyAddInst - Given operands for an Add, see if we can
/// fold the result. If not, this returns null.
-Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1,
+Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const TargetData *TD) {
+ if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
+ if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
+ Constant *Ops[] = { CLHS, CRHS };
+ return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(),
+ Ops, 2, TD);
+ }
+
+ // Canonicalize the constant to the RHS.
+ std::swap(Op0, Op1);
+ }
+
+ if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
+ // X + undef -> undef
+ if (isa<UndefValue>(Op1C))
+ return Op1C;
+
+ // X + 0 --> X
+ if (Op1C->isNullValue())
+ return Op0;
+ }
+
+ // FIXME: Could pull several more out of instcombine.
+ return 0;
+}
+
+/// SimplifyAndInst - Given operands for an And, see if we can
+/// fold the result. If not, this returns null.
+Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
// A & ~A = ~A & A = 0
Value *A, *B;
- if (match(Op0, m_Not(m_Value(A)) && A == Op1) ||
- match(Op1, m_Not(m_Value(A)) && A == Op0))
+ if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
+ (match(Op1, m_Not(m_Value(A))) && A == Op0))
return Constant::getNullValue(Op0->getType());
// (A | ?) & A = A
(A == Op0 || B == Op0))
return Op0;
+ // (A & B) & A -> A & B
+ if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
+ (A == Op1 || B == Op1))
+ return Op0;
+
+ // A & (A & B) -> A & B
+ if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
+ (A == Op0 || B == Op0))
+ return Op1;
+
return 0;
}
/// SimplifyOrInst - Given operands for an Or, see if we can
/// fold the result. If not, this returns null.
-Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1,
- const TargetData *TD) {
+Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
// A | ~A = ~A | A = -1
Value *A, *B;
- if (match(Op0, m_Not(m_Value(A)) && A == Op1) ||
- match(Op1, m_Not(m_Value(A)) && A == Op0))
+ if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
+ (match(Op1, m_Not(m_Value(A))) && A == Op0))
return Constant::getAllOnesValue(Op0->getType());
// (A & ?) | A = A
(A == Op0 || B == Op0))
return Op0;
- return 0;
-}
+ // (A | B) | A -> A | B
+ if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
+ (A == Op1 || B == Op1))
+ return Op0;
+ // A | (A | B) -> A | B
+ if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
+ (A == Op0 || B == Op0))
+ return Op1;
+ return 0;
+}
static const Type *GetCompareTy(Value *Op) {
const Type *ITy = GetCompareTy(LHS);
// icmp X, X -> true/false
- if (LHS == RHS)
+ // 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));
-
- if (isa<UndefValue>(RHS)) // X icmp undef -> undef
- return UndefValue::get(ITy);
// icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
// addresses never equal each other! We already know that Op0 != Op1.
// 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;
+ }
+ }
+ }
}
}
return 0;
}
+/// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
+/// the result. If not, this returns null.
+Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal,
+ const TargetData *TD) {
+ // select true, X, Y -> X
+ // select false, X, Y -> Y
+ if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
+ return CB->getZExtValue() ? TrueVal : FalseVal;
+
+ // select C, X, X -> X
+ if (TrueVal == FalseVal)
+ return TrueVal;
+
+ if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
+ return FalseVal;
+ if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
+ return TrueVal;
+ if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
+ if (isa<Constant>(TrueVal))
+ return TrueVal;
+ return FalseVal;
+ }
+
+
+
+ return 0;
+}
+
+
+/// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
+/// fold the result. If not, this returns null.
+Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps,
+ const TargetData *TD) {
+ // getelementptr P -> P.
+ if (NumOps == 1)
+ return Ops[0];
+
+ // TODO.
+ //if (isa<UndefValue>(Ops[0]))
+ // return UndefValue::get(GEP.getType());
+
+ // getelementptr P, 0 -> P.
+ if (NumOps == 2)
+ if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
+ if (C->isZero())
+ return Ops[0];
+
+ // Check to see if this is constant foldable.
+ for (unsigned i = 0; i != NumOps; ++i)
+ if (!isa<Constant>(Ops[i]))
+ return 0;
+
+ return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]),
+ (Constant *const*)Ops+1, NumOps-1);
+}
+
+
//=== Helper functions for higher up the class hierarchy.
/// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
switch (I->getOpcode()) {
default:
return ConstantFoldInstruction(I, TD);
+ case Instruction::Add:
+ return SimplifyAddInst(I->getOperand(0), I->getOperand(1),
+ cast<BinaryOperator>(I)->hasNoSignedWrap(),
+ cast<BinaryOperator>(I)->hasNoUnsignedWrap(), TD);
case Instruction::And:
return SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD);
case Instruction::Or:
case Instruction::FCmp:
return SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
I->getOperand(0), I->getOperand(1), TD);
+ case Instruction::Select:
+ return SimplifySelectInst(I->getOperand(0), I->getOperand(1),
+ I->getOperand(2), TD);
+ case Instruction::GetElementPtr: {
+ SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
+ return SimplifyGEPInst(&Ops[0], Ops.size(), TD);
}
+ }
+}
+
+/// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
+/// delete the From instruction. In addition to a basic RAUW, this does a
+/// recursive simplification of the newly formed instructions. This catches
+/// things where one simplification exposes other opportunities. This only
+/// simplifies and deletes scalar operations, it does not change the CFG.
+///
+void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
+ const TargetData *TD) {
+ assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
+
+ // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
+ // we can know if it gets deleted out from under us or replaced in a
+ // recursive simplification.
+ WeakVH FromHandle(From);
+ WeakVH ToHandle(To);
+
+ while (!From->use_empty()) {
+ // Update the instruction to use the new value.
+ Use &TheUse = From->use_begin().getUse();
+ Instruction *User = cast<Instruction>(TheUse.getUser());
+ TheUse = To;
+
+ // Check to see if the instruction can be folded due to the operand
+ // replacement. For example changing (or X, Y) into (or X, -1) can replace
+ // the 'or' with -1.
+ Value *SimplifiedVal;
+ {
+ // Sanity check to make sure 'User' doesn't dangle across
+ // SimplifyInstruction.
+ AssertingVH<> UserHandle(User);
+
+ SimplifiedVal = SimplifyInstruction(User, TD);
+ if (SimplifiedVal == 0) continue;
+ }
+
+ // Recursively simplify this user to the new value.
+ ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD);
+ From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
+ To = ToHandle;
+
+ assert(ToHandle && "To value deleted by recursive simplification?");
+
+ // If the recursive simplification ended up revisiting and deleting
+ // 'From' then we're done.
+ if (From == 0)
+ return;
+ }
+
+ // If 'From' has value handles referring to it, do a real RAUW to update them.
+ From->replaceAllUsesWith(To);
+
+ From->eraseFromParent();
}
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