//===- InstructionCombining.cpp - Combine multiple instructions -----------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
//
// InstructionCombining - Combine instructions to form fewer, simple
// instructions. This pass does not modify the CFG This pass is where algebraic
//
// This is a simple worklist driven algorithm.
//
-// This pass guarantees that the following cannonicalizations are performed on
+// This pass guarantees that the following canonicalizations are performed on
// the program:
// 1. If a binary operator has a constant operand, it is moved to the RHS
// 2. Bitwise operators with constant operands are always grouped so that
Instruction *visitInstruction(Instruction &I) { return 0; }
private:
+ Instruction *visitCallSite(CallSite CS);
bool transformConstExprCastCall(CallSite CS);
// InsertNewInstBefore - insert an instruction New before instruction Old
WorkList.push_back(New); // Add to worklist
}
+ public:
// ReplaceInstUsesWith - This method is to be used when an instruction is
// found to be dead, replacable with another preexisting expression. Here
// we add all uses of I to the worklist, replace all uses of I with the new
I.replaceAllUsesWith(V);
return &I;
}
-
+ private:
/// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
/// InsertBefore instruction. This is specialized a bit to avoid inserting
/// casts that are known to not do anything...
// SimplifyCommutative - This performs a few simplifications for commutative
// operators...
bool SimplifyCommutative(BinaryOperator &I);
+
+ Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
+ ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
};
RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
// isOnlyUse - Return true if this instruction will be deleted if we stop using
// it.
static bool isOnlyUse(Value *V) {
- return V->use_size() == 1 || isa<Constant>(V);
+ return V->hasOneUse() || isa<Constant>(V);
}
// SimplifyCommutative - This performs a few simplifications for commutative
// non-constant operand of the multiply.
//
static inline Value *dyn_castFoldableMul(Value *V) {
- if (V->use_size() == 1 && V->getType()->isInteger())
+ if (V->hasOneUse() && V->getType()->isInteger())
if (Instruction *I = dyn_cast<Instruction>(V))
if (I->getOpcode() == Instruction::Mul)
if (isa<Constant>(I->getOperand(1)))
// Otherwise, if the LHS is not of the same opcode as the root, return.
Instruction *LHSI = dyn_cast<Instruction>(LHS);
- while (LHSI && LHSI->getOpcode() == Opcode && LHSI->use_size() == 1) {
+ while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
// Should we apply this transform to the RHS?
bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
if (Constant *C2 = dyn_castMaskingAnd(RHS))
if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
+ if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
+ if (Instruction *ILHS = dyn_cast<Instruction>(LHS)) {
+ switch (ILHS->getOpcode()) {
+ case Instruction::Xor:
+ // ~X + C --> (C-1) - X
+ if (ConstantInt *XorRHS = dyn_cast<ConstantInt>(ILHS->getOperand(1)))
+ if (XorRHS->isAllOnesValue())
+ return BinaryOperator::create(Instruction::Sub,
+ *CRHS - *ConstantInt::get(I.getType(), 1),
+ ILHS->getOperand(0));
+ break;
+ default: break;
+ }
+ }
+ }
+
return Changed ? &I : 0;
}
return BinaryOperator::createNot(Op1);
if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1))
- if (Op1I->use_size() == 1) {
+ if (Op1I->hasOneUse()) {
// Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
// is not used by anyone else...
//
return BinaryOperator::create(Instruction::Mul, SI->getOperand(0),
*CI << *ShOp);
- const Type *Ty = CI->getType();
- int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
- switch (Val) {
- case -1: // X * -1 -> -X
+ if (CI->isNullValue())
+ return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
+ if (CI->equalsInt(1)) // X * 1 == X
+ return ReplaceInstUsesWith(I, Op0);
+ if (CI->isAllOnesValue()) // X * -1 == 0 - X
return BinaryOperator::createNeg(Op0, I.getName());
- case 0:
- return ReplaceInstUsesWith(I, Op1); // Eliminate 'mul double %X, 0'
- case 1:
- return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul int %X, 1'
- }
+ int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
if (uint64_t C = Log2(Val)) // Replace X*(2^C) with X << C
return new ShiftInst(Instruction::Shl, Op0,
ConstantUInt::get(Type::UByteTy, C));
return CS->getValue() == Val+1;
}
+/// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
+/// are carefully arranged to allow folding of expressions such as:
+///
+/// (A < B) | (A > B) --> (A != B)
+///
+/// Bit value '4' represents that the comparison is true if A > B, bit value '2'
+/// represents that the comparison is true if A == B, and bit value '1' is true
+/// if A < B.
+///
+static unsigned getSetCondCode(const SetCondInst *SCI) {
+ switch (SCI->getOpcode()) {
+ // False -> 0
+ case Instruction::SetGT: return 1;
+ case Instruction::SetEQ: return 2;
+ case Instruction::SetGE: return 3;
+ case Instruction::SetLT: return 4;
+ case Instruction::SetNE: return 5;
+ case Instruction::SetLE: return 6;
+ // True -> 7
+ default:
+ assert(0 && "Invalid SetCC opcode!");
+ return 0;
+ }
+}
+
+/// getSetCCValue - This is the complement of getSetCondCode, which turns an
+/// opcode and two operands into either a constant true or false, or a brand new
+/// SetCC instruction.
+static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
+ switch (Opcode) {
+ case 0: return ConstantBool::False;
+ case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
+ case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
+ case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
+ case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
+ case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
+ case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
+ case 7: return ConstantBool::True;
+ default: assert(0 && "Illegal SetCCCode!"); return 0;
+ }
+}
+
+// FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
+struct FoldSetCCLogical {
+ InstCombiner &IC;
+ Value *LHS, *RHS;
+ FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
+ : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
+ bool shouldApply(Value *V) const {
+ if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
+ return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
+ SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
+ return false;
+ }
+ Instruction *apply(BinaryOperator &Log) const {
+ SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
+ if (SCI->getOperand(0) != LHS) {
+ assert(SCI->getOperand(1) == LHS);
+ SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
+ }
+
+ unsigned LHSCode = getSetCondCode(SCI);
+ unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
+ unsigned Code;
+ switch (Log.getOpcode()) {
+ case Instruction::And: Code = LHSCode & RHSCode; break;
+ case Instruction::Or: Code = LHSCode | RHSCode; break;
+ case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
+ default: assert(0 && "Illegal logical opcode!"); return 0;
+ }
+
+ Value *RV = getSetCCValue(Code, LHS, RHS);
+ if (Instruction *I = dyn_cast<Instruction>(RV))
+ return I;
+ // Otherwise, it's a constant boolean value...
+ return IC.ReplaceInstUsesWith(Log, RV);
+ }
+};
+
+
+// OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
+// the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
+// guaranteed to be either a shift instruction or a binary operator.
+Instruction *InstCombiner::OptAndOp(Instruction *Op,
+ ConstantIntegral *OpRHS,
+ ConstantIntegral *AndRHS,
+ BinaryOperator &TheAnd) {
+ Value *X = Op->getOperand(0);
+ switch (Op->getOpcode()) {
+ case Instruction::Xor:
+ if ((*AndRHS & *OpRHS)->isNullValue()) {
+ // (X ^ C1) & C2 --> (X & C2) iff (C1&C2) == 0
+ return BinaryOperator::create(Instruction::And, X, AndRHS);
+ } else if (Op->hasOneUse()) {
+ // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
+ std::string OpName = Op->getName(); Op->setName("");
+ Instruction *And = BinaryOperator::create(Instruction::And,
+ X, AndRHS, OpName);
+ InsertNewInstBefore(And, TheAnd);
+ return BinaryOperator::create(Instruction::Xor, And, *AndRHS & *OpRHS);
+ }
+ break;
+ case Instruction::Or:
+ // (X | C1) & C2 --> X & C2 iff C1 & C1 == 0
+ if ((*AndRHS & *OpRHS)->isNullValue())
+ return BinaryOperator::create(Instruction::And, X, AndRHS);
+ else {
+ Constant *Together = *AndRHS & *OpRHS;
+ if (Together == AndRHS) // (X | C) & C --> C
+ return ReplaceInstUsesWith(TheAnd, AndRHS);
+
+ if (Op->hasOneUse() && Together != OpRHS) {
+ // (X | C1) & C2 --> (X | (C1&C2)) & C2
+ std::string Op0Name = Op->getName(); Op->setName("");
+ Instruction *Or = BinaryOperator::create(Instruction::Or, X,
+ Together, Op0Name);
+ InsertNewInstBefore(Or, TheAnd);
+ return BinaryOperator::create(Instruction::And, Or, AndRHS);
+ }
+ }
+ break;
+ case Instruction::Add:
+ if (Op->hasOneUse()) {
+ // Adding a one to a single bit bit-field should be turned into an XOR
+ // of the bit. First thing to check is to see if this AND is with a
+ // single bit constant.
+ unsigned long long AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
+
+ // Clear bits that are not part of the constant.
+ AndRHSV &= (1ULL << AndRHS->getType()->getPrimitiveSize()*8)-1;
+
+ // If there is only one bit set...
+ if ((AndRHSV & (AndRHSV-1)) == 0) {
+ // Ok, at this point, we know that we are masking the result of the
+ // ADD down to exactly one bit. If the constant we are adding has
+ // no bits set below this bit, then we can eliminate the ADD.
+ unsigned long long AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
+
+ // Check to see if any bits below the one bit set in AndRHSV are set.
+ if ((AddRHS & (AndRHSV-1)) == 0) {
+ // If not, the only thing that can effect the output of the AND is
+ // the bit specified by AndRHSV. If that bit is set, the effect of
+ // the XOR is to toggle the bit. If it is clear, then the ADD has
+ // no effect.
+ if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
+ TheAnd.setOperand(0, X);
+ return &TheAnd;
+ } else {
+ std::string Name = Op->getName(); Op->setName("");
+ // Pull the XOR out of the AND.
+ Instruction *NewAnd =
+ BinaryOperator::create(Instruction::And, X, AndRHS, Name);
+ InsertNewInstBefore(NewAnd, TheAnd);
+ return BinaryOperator::create(Instruction::Xor, NewAnd, AndRHS);
+ }
+ }
+ }
+ }
+ break;
+
+ case Instruction::Shl: {
+ // We know that the AND will not produce any of the bits shifted in, so if
+ // the anded constant includes them, clear them now!
+ //
+ Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
+ Constant *CI = *AndRHS & *(*AllOne << *OpRHS);
+ if (CI != AndRHS) {
+ TheAnd.setOperand(1, CI);
+ return &TheAnd;
+ }
+ break;
+ }
+ case Instruction::Shr:
+ // We know that the AND will not produce any of the bits shifted in, so if
+ // the anded constant includes them, clear them now! This only applies to
+ // unsigned shifts, because a signed shr may bring in set bits!
+ //
+ if (AndRHS->getType()->isUnsigned()) {
+ Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
+ Constant *CI = *AndRHS & *(*AllOne >> *OpRHS);
+ if (CI != AndRHS) {
+ TheAnd.setOperand(1, CI);
+ return &TheAnd;
+ }
+ }
+ break;
+ }
+ return 0;
+}
+
Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
bool Changed = SimplifyCommutative(I);
if (RHS->isAllOnesValue())
return ReplaceInstUsesWith(I, Op0);
- if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
+ // Optimize a variety of ((val OP C1) & C2) combinations...
+ if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
+ Instruction *Op0I = cast<Instruction>(Op0);
Value *X = Op0I->getOperand(0);
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
- if (Op0I->getOpcode() == Instruction::Xor) {
- if ((*RHS & *Op0CI)->isNullValue()) {
- // (X ^ C1) & C2 --> (X & C2) iff (C1&C2) == 0
- return BinaryOperator::create(Instruction::And, X, RHS);
- } else if (isOnlyUse(Op0)) {
- // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
- std::string Op0Name = Op0I->getName(); Op0I->setName("");
- Instruction *And = BinaryOperator::create(Instruction::And,
- X, RHS, Op0Name);
- InsertNewInstBefore(And, I);
- return BinaryOperator::create(Instruction::Xor, And, *RHS & *Op0CI);
- }
- } else if (Op0I->getOpcode() == Instruction::Or) {
- // (X | C1) & C2 --> X & C2 iff C1 & C1 == 0
- if ((*RHS & *Op0CI)->isNullValue())
- return BinaryOperator::create(Instruction::And, X, RHS);
-
- Constant *Together = *RHS & *Op0CI;
- if (Together == RHS) // (X | C) & C --> C
- return ReplaceInstUsesWith(I, RHS);
-
- if (isOnlyUse(Op0)) {
- if (Together != Op0CI) {
- // (X | C1) & C2 --> (X | (C1&C2)) & C2
- std::string Op0Name = Op0I->getName(); Op0I->setName("");
- Instruction *Or = BinaryOperator::create(Instruction::Or, X,
- Together, Op0Name);
- InsertNewInstBefore(Or, I);
- return BinaryOperator::create(Instruction::And, Or, RHS);
- }
- }
- }
+ if (Instruction *Res = OptAndOp(Op0I, Op0CI, RHS, I))
+ return Res;
}
}
if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
+ if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
+ if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
+ return R;
+
return Changed ? &I : 0;
}
return BinaryOperator::createNot(And);
}
+ // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
+ if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
+ if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
+ return R;
+
return Changed ? &I : 0;
}
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
// xor (setcc A, B), true = not (setcc A, B) = setncc A, B
if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
- if (RHS == ConstantBool::True && SCI->use_size() == 1)
+ if (RHS == ConstantBool::True && SCI->hasOneUse())
return new SetCondInst(SCI->getInverseCondition(),
SCI->getOperand(0), SCI->getOperand(1));
}
if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
- if (Op0I->getOpcode() == Instruction::Or && Op0I->use_size() == 1) {
+ if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
cast<BinaryOperator>(Op0I)->swapOperands();
if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
if (ConstantExpr::get(Instruction::And, C1, C2)->isNullValue())
return BinaryOperator::create(Instruction::Or, Op0, Op1);
+ // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
+ if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
+ if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
+ return R;
+
return Changed ? &I : 0;
}
return new SetCondInst(I.getOpcode(), BOp0, NegVal);
else if (Value *NegVal = dyn_castNegVal(BOp0))
return new SetCondInst(I.getOpcode(), NegVal, BOp1);
- else if (BO->use_size() == 1) {
+ else if (BO->hasOneUse()) {
Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
BO->setName("");
InsertNewInstBefore(Neg, I);
// If the operand is an bitwise operator with a constant RHS, and the
// shift is the only use, we can pull it out of the shift.
- if (Op0->use_size() == 1)
+ if (Op0->hasOneUse())
if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0))
if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
bool isValid = true; // Valid only for And, Or, Xor
// propagate the cast into the instruction. Also, only handle integral types
// for now.
if (Instruction *SrcI = dyn_cast<Instruction>(Src))
- if (SrcI->use_size() == 1 && Src->getType()->isIntegral() &&
+ if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
CI.getType()->isInteger()) { // Don't mess with casts to bool here
const Type *DestTy = CI.getType();
unsigned SrcBitSize = getTypeSizeInBits(Src->getType());
// CallInst simplification
//
Instruction *InstCombiner::visitCallInst(CallInst &CI) {
- if (transformConstExprCastCall(&CI)) return 0;
- return 0;
+ return visitCallSite(&CI);
}
// InvokeInst simplification
//
Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
- if (transformConstExprCastCall(&II)) return 0;
- return 0;
+ return visitCallSite(&II);
}
// getPromotedType - Return the specified type promoted as it would be to pass
}
}
+// visitCallSite - Improvements for call and invoke instructions.
+//
+Instruction *InstCombiner::visitCallSite(CallSite CS) {
+ bool Changed = false;
+
+ // If the callee is a constexpr cast of a function, attempt to move the cast
+ // to the arguments of the call/invoke.
+ if (transformConstExprCastCall(CS)) return 0;
+
+ Value *Callee = CS.getCalledValue();
+ const PointerType *PTy = cast<PointerType>(Callee->getType());
+ const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
+ if (FTy->isVarArg()) {
+ // See if we can optimize any arguments passed through the varargs area of
+ // the call.
+ for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
+ E = CS.arg_end(); I != E; ++I)
+ if (CastInst *CI = dyn_cast<CastInst>(*I)) {
+ // If this cast does not effect the value passed through the varargs
+ // area, we can eliminate the use of the cast.
+ Value *Op = CI->getOperand(0);
+ if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
+ *I = Op;
+ Changed = true;
+ }
+ }
+ }
+
+ return Changed ? CS.getInstruction() : 0;
+}
+
// transformConstExprCastCall - If the callee is a constexpr cast of a function,
// attempt to move the cast to the arguments of the call/invoke.
//
// Check to see if we can DIE the instruction...
if (isInstructionTriviallyDead(I)) {
// Add operands to the worklist...
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
- if (Instruction *Op = dyn_cast<Instruction>(I->getOperand(i)))
- WorkList.push_back(Op);
-
+ if (I->getNumOperands() < 4)
+ for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
+ if (Instruction *Op = dyn_cast<Instruction>(I->getOperand(i)))
+ WorkList.push_back(Op);
++NumDeadInst;
- BasicBlock::iterator BBI = I;
- if (dceInstruction(BBI)) {
- removeFromWorkList(I);
- continue;
- }
- }
+
+ I->getParent()->getInstList().erase(I);
+ removeFromWorkList(I);
+ continue;
+ }
// Instruction isn't dead, see if we can constant propagate it...
if (Constant *C = ConstantFoldInstruction(I)) {
ReplaceInstUsesWith(*I, C);
++NumConstProp;
- BasicBlock::iterator BBI = I;
- if (dceInstruction(BBI)) {
- removeFromWorkList(I);
- continue;
- }
+ I->getParent()->getInstList().erase(I);
+ removeFromWorkList(I);
+ continue;
}
-
+
// Now that we have an instruction, try combining it to simplify it...
if (Instruction *Result = visit(*I)) {
++NumCombined;
// Instructions can end up on the worklist more than once. Make sure
// we do not process an instruction that has been deleted.
removeFromWorkList(I);
- ReplaceInstWithInst(I, Result);
+
+ // Move the name to the new instruction first...
+ std::string OldName = I->getName(); I->setName("");
+ Result->setName(OldName);
+
+ // Insert the new instruction into the basic block...
+ BasicBlock *InstParent = I->getParent();
+ InstParent->getInstList().insert(I, Result);
+
+ // Everything uses the new instruction now...
+ I->replaceAllUsesWith(Result);
+
+ // Erase the old instruction.
+ InstParent->getInstList().erase(I);
} else {
BasicBlock::iterator II = I;
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