// reassociate the expression from ((? op A) op B) to (? op (A op B))
if (ShouldApply) {
BasicBlock *BB = Root.getParent();
- // All of the instructions have a single use and have no side-effects,
- // because of this, we can pull them all into the current basic block.
- if (LHSI->getParent() != BB) {
- // Move all of the instructions from root to LHSI into the current
- // block.
- Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
- Instruction *LastUse = &Root;
- while (TmpLHSI->getParent() == BB) {
- LastUse = TmpLHSI;
- TmpLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
- }
-
- // Loop over all of the instructions in other blocks, moving them into
- // the current one.
- Value *TmpLHS = TmpLHSI;
- do {
- TmpLHSI = cast<Instruction>(TmpLHS);
- // Remove from current block...
- TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
- // Insert before the last instruction...
- BB->getInstList().insert(LastUse, TmpLHSI);
- TmpLHS = TmpLHSI->getOperand(0);
- } while (TmpLHSI != LHSI);
- }
// Now all of the instructions are in the current basic block, go ahead
// and perform the reassociation.
// Make what used to be the LHS of the root be the user of the root...
Value *ExtraOperand = TmpLHSI->getOperand(1);
- if (&Root != TmpLHSI)
- Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
- else {
+ if (&Root == TmpLHSI) {
Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
return 0;
}
+ Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
- BB->getInstList().remove(&Root); // Remove root from the BB
- BB->getInstList().insert(TmpLHSI, &Root); // Insert root before TmpLHSI
+ TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
+ BasicBlock::iterator ARI = &Root; ++ARI;
+ BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
+ ARI = Root;
// Now propagate the ExtraOperand down the chain of instructions until we
// get to LHSI.
while (TmpLHSI != LHSI) {
Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
+ // Move the instruction to immediately before the chain we are
+ // constructing to avoid breaking dominance properties.
+ NextLHSI->getParent()->getInstList().remove(NextLHSI);
+ BB->getInstList().insert(ARI, NextLHSI);
+ ARI = NextLHSI;
+
Value *NextOp = NextLHSI->getOperand(1);
NextLHSI->setOperand(1, ExtraOperand);
TmpLHSI = NextLHSI;
}
};
+static Value *FoldOperationIntoSelectOperand(Instruction &BI, Value *SO,
+ InstCombiner *IC) {
+ // Figure out if the constant is the left or the right argument.
+ bool ConstIsRHS = isa<Constant>(BI.getOperand(1));
+ Constant *ConstOperand = cast<Constant>(BI.getOperand(ConstIsRHS));
+ if (Constant *SOC = dyn_cast<Constant>(SO)) {
+ if (ConstIsRHS)
+ return ConstantExpr::get(BI.getOpcode(), SOC, ConstOperand);
+ return ConstantExpr::get(BI.getOpcode(), ConstOperand, SOC);
+ }
+
+ Value *Op0 = SO, *Op1 = ConstOperand;
+ if (!ConstIsRHS)
+ std::swap(Op0, Op1);
+ Instruction *New;
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&BI))
+ New = BinaryOperator::create(BO->getOpcode(), Op0, Op1);
+ else if (ShiftInst *SI = dyn_cast<ShiftInst>(&BI))
+ New = new ShiftInst(SI->getOpcode(), Op0, Op1);
+ else {
+ assert(0 && "Unknown binary instruction type!");
+ abort();
+ }
+ return IC->InsertNewInstBefore(New, BI);
+}
+
+// FoldBinOpIntoSelect - Given an instruction with a select as one operand and a
+// constant as the other operand, try to fold the binary operator into the
+// select arguments.
+static Instruction *FoldBinOpIntoSelect(Instruction &BI, SelectInst *SI,
+ InstCombiner *IC) {
+ // Don't modify shared select instructions
+ if (!SI->hasOneUse()) return 0;
+ Value *TV = SI->getOperand(1);
+ Value *FV = SI->getOperand(2);
+
+ if (isa<Constant>(TV) || isa<Constant>(FV)) {
+ Value *SelectTrueVal = FoldOperationIntoSelectOperand(BI, TV, IC);
+ Value *SelectFalseVal = FoldOperationIntoSelectOperand(BI, FV, IC);
+
+ return new SelectInst(SI->getCondition(), SelectTrueVal,
+ SelectFalseVal);
+ }
+ return 0;
+}
Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
bool Changed = SimplifyCommutative(I);
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
- // X + 0 --> X
- if (!I.getType()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop
- RHS == Constant::getNullValue(I.getType()))
- return ReplaceInstUsesWith(I, LHS);
+ if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
+ // X + 0 --> X
+ if (!I.getType()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop
+ RHSC->isNullValue())
+ return ReplaceInstUsesWith(I, LHS);
+
+ // X + (signbit) --> X ^ signbit
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
+ unsigned NumBits = CI->getType()->getPrimitiveSize()*8;
+ uint64_t Val = CI->getRawValue() & (1ULL << NumBits)-1;
+ if (Val == (1ULL << NumBits-1))
+ return BinaryOperator::create(Instruction::Xor, LHS, RHS);
+ }
+ }
// X + X --> X << 1
if (I.getType()->isInteger())
CRHS, ConstantInt::get(I.getType(), 1)),
ILHS->getOperand(0));
break;
+ case Instruction::Select:
+ // Try to fold constant add into select arguments.
+ if (Instruction *R = FoldBinOpIntoSelect(I,cast<SelectInst>(ILHS),this))
+ return R;
+
default: break;
}
}
}
}
}
+
+ // Try to fold constant sub into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
+ if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
+ return R;
}
if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1))
if (Op1F->getValue() == 1.0)
return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
}
+
+ // Try to fold constant mul into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
+ return R;
}
if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
}
Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
- // div X, 1 == X
if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
+ // div X, 1 == X
if (RHS->equalsInt(1))
return ReplaceInstUsesWith(I, I.getOperand(0));
+ // div X, -1 == -X
+ if (RHS->isAllOnesValue())
+ return BinaryOperator::createNeg(I.getOperand(0));
+
// Check to see if this is an unsigned division with an exact power of 2,
// if so, convert to a right shift.
if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
if (Instruction *Res = OptAndOp(Op0I, Op0CI, RHS, I))
return Res;
}
+
+ // Try to fold constant and into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
+ return R;
}
Value *Op0NotVal = dyn_castNotVal(Op0);
NotConstant(RHS)));
}
}
+
+ // Try to fold constant and into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
+ return R;
}
// (A & C1)|(A & C2) == A & (C1|C2)
default: break;
}
}
+
+ // Try to fold constant and into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
+ return R;
}
if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
if (CSI->isAllOnesValue())
return ReplaceInstUsesWith(I, CSI);
+ // Try to fold constant and into select arguments.
+ if (isa<Constant>(Op0))
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
+ if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
+ return R;
+
if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
// shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
// of a signed value.
return BinaryOperator::create(Instruction::Mul, BO->getOperand(0),
ConstantExpr::get(Instruction::Shl, BOOp, CUI));
+ // Try to fold constant and into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
+ return R;
// 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.
return 0;
}
+/// GetSelectFoldableOperands - We want to turn code that looks like this:
+/// %C = or %A, %B
+/// %D = select %cond, %C, %A
+/// into:
+/// %C = select %cond, %B, 0
+/// %D = or %A, %C
+///
+/// Assuming that the specified instruction is an operand to the select, return
+/// a bitmask indicating which operands of this instruction are foldable if they
+/// equal the other incoming value of the select.
+///
+static unsigned GetSelectFoldableOperands(Instruction *I) {
+ switch (I->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::Mul:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ return 3; // Can fold through either operand.
+ case Instruction::Sub: // Can only fold on the amount subtracted.
+ case Instruction::Shl: // Can only fold on the shift amount.
+ case Instruction::Shr:
+ return 1;
+ default:
+ return 0; // Cannot fold
+ }
+}
+
+/// GetSelectFoldableConstant - For the same transformation as the previous
+/// function, return the identity constant that goes into the select.
+static Constant *GetSelectFoldableConstant(Instruction *I) {
+ switch (I->getOpcode()) {
+ default: assert(0 && "This cannot happen!"); abort();
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Or:
+ case Instruction::Xor:
+ return Constant::getNullValue(I->getType());
+ case Instruction::Shl:
+ case Instruction::Shr:
+ return Constant::getNullValue(Type::UByteTy);
+ case Instruction::And:
+ return ConstantInt::getAllOnesValue(I->getType());
+ case Instruction::Mul:
+ return ConstantInt::get(I->getType(), 1);
+ }
+}
+
Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
Value *CondVal = SI.getCondition();
Value *TrueVal = SI.getTrueValue();
if (TrueVal == FalseVal)
return ReplaceInstUsesWith(SI, TrueVal);
- // Selecting between two constants?
- if (Constant *TrueValC = dyn_cast<Constant>(TrueVal))
- if (Constant *FalseValC = dyn_cast<Constant>(FalseVal)) {
- if (SI.getType() == Type::BoolTy &&
- isa<ConstantBool>(TrueValC) && isa<ConstantBool>(FalseValC)) {
- // select C, true, false -> C
- if (TrueValC == ConstantBool::True)
- return ReplaceInstUsesWith(SI, CondVal);
- // select C, false, true -> !C
- return BinaryOperator::createNot(CondVal);
+ if (SI.getType() == Type::BoolTy)
+ if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
+ if (C == ConstantBool::True) {
+ // Change: A = select B, true, C --> A = or B, C
+ return BinaryOperator::create(Instruction::Or, CondVal, FalseVal);
+ } else {
+ // Change: A = select B, false, C --> A = and !B, C
+ Value *NotCond =
+ InsertNewInstBefore(BinaryOperator::createNot(CondVal,
+ "not."+CondVal->getName()), SI);
+ return BinaryOperator::create(Instruction::And, NotCond, FalseVal);
}
-
- // If the true constant is a 1 and the false is a zero, turn this into a
- // cast from bool.
- if (FalseValC->isNullValue() && isa<ConstantInt>(TrueValC) &&
- cast<ConstantInt>(TrueValC)->getRawValue() == 1)
+ } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
+ if (C == ConstantBool::False) {
+ // Change: A = select B, C, false --> A = and B, C
+ return BinaryOperator::create(Instruction::And, CondVal, TrueVal);
+ } else {
+ // Change: A = select B, C, true --> A = or !B, C
+ Value *NotCond =
+ InsertNewInstBefore(BinaryOperator::createNot(CondVal,
+ "not."+CondVal->getName()), SI);
+ return BinaryOperator::create(Instruction::Or, NotCond, TrueVal);
+ }
+ }
+
+ // Selecting between two integer constants?
+ if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
+ if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
+ // select C, 1, 0 -> cast C to int
+ if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
return new CastInst(CondVal, SI.getType());
+ } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
+ // select C, 0, 1 -> cast !C to int
+ Value *NotCond =
+ InsertNewInstBefore(BinaryOperator::createNot(CondVal,
+ "not."+CondVal->getName()), SI);
+ return new CastInst(NotCond, SI.getType());
+ }
+ }
+
+ // See if we are selecting two values based on a comparison of the two values.
+ if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
+ if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
+ // Transform (X == Y) ? X : Y -> Y
+ if (SCI->getOpcode() == Instruction::SetEQ)
+ return ReplaceInstUsesWith(SI, FalseVal);
+ // Transform (X != Y) ? X : Y -> X
+ if (SCI->getOpcode() == Instruction::SetNE)
+ return ReplaceInstUsesWith(SI, TrueVal);
+ // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
+
+ } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
+ // Transform (X == Y) ? Y : X -> X
+ if (SCI->getOpcode() == Instruction::SetEQ)
+ return ReplaceInstUsesWith(SI, FalseVal);
+ // Transform (X != Y) ? Y : X -> Y
+ if (SCI->getOpcode() == Instruction::SetNE)
+ return ReplaceInstUsesWith(SI, TrueVal);
+ // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
}
+ }
+
+ // See if we can fold the select into one of our operands.
+ if (SI.getType()->isInteger()) {
+ // See the comment above GetSelectFoldableOperands for a description of the
+ // transformation we are doing here.
+ if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
+ if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
+ !isa<Constant>(FalseVal))
+ if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
+ unsigned OpToFold = 0;
+ if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
+ OpToFold = 1;
+ } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
+ OpToFold = 2;
+ }
+
+ if (OpToFold) {
+ Constant *C = GetSelectFoldableConstant(TVI);
+ std::string Name = TVI->getName(); TVI->setName("");
+ Instruction *NewSel =
+ new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
+ Name);
+ InsertNewInstBefore(NewSel, SI);
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
+ return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
+ else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
+ return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
+ else {
+ assert(0 && "Unknown instruction!!");
+ }
+ }
+ }
+
+ if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
+ if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
+ !isa<Constant>(TrueVal))
+ if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
+ unsigned OpToFold = 0;
+ if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
+ OpToFold = 1;
+ } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
+ OpToFold = 2;
+ }
+ if (OpToFold) {
+ Constant *C = GetSelectFoldableConstant(FVI);
+ std::string Name = FVI->getName(); FVI->setName("");
+ Instruction *NewSel =
+ new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
+ Name);
+ InsertNewInstBefore(NewSel, SI);
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
+ return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
+ else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
+ return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
+ else {
+ assert(0 && "Unknown instruction!!");
+ }
+ }
+ }
+ }
return 0;
}
if ((*AI)->getType() == ParamTy) {
Args.push_back(*AI);
} else {
- Instruction *Cast = new CastInst(*AI, ParamTy, "tmp");
- InsertNewInstBefore(Cast, *Caller);
- Args.push_back(Cast);
+ Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
+ *Caller));
}
}
// obvious.
Value *Op = GEP.getOperand(i);
if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
- if (!isa<Constant>(Op)) {
+ if (Constant *C = dyn_cast<Constant>(Op)) {
+ GEP.setOperand(i, ConstantExpr::getCast(C, TD->getIntPtrType()));
+ MadeChange = true;
+ } else {
Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
Op->getName()), GEP);
GEP.setOperand(i, Op);
Value *Op = LI.getOperand(0);
if (LI.isVolatile()) return 0;
- if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(Op))
- Op = CPR->getValue();
+ if (Constant *C = dyn_cast<Constant>(Op))
+ if (C->isNullValue()) // load null -> 0
+ return ReplaceInstUsesWith(LI, Constant::getNullValue(LI.getType()));
+ else if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(C))
+ Op = CPR->getValue();
// Instcombine load (constant global) into the value loaded...
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
if (GV->isConstant() && !GV->isExternal())
if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
return ReplaceInstUsesWith(LI, V);
+
+ // load (cast X) --> cast (load X) iff safe
+ if (CastInst *CI = dyn_cast<CastInst>(Op)) {
+ const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
+ if (const PointerType *SrcTy =
+ dyn_cast<PointerType>(CI->getOperand(0)->getType())) {
+ const Type *SrcPTy = SrcTy->getElementType();
+ if (TD->getTypeSize(SrcPTy) == TD->getTypeSize(DestPTy) &&
+ (SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
+ (DestPTy->isInteger() || isa<PointerType>(DestPTy))) {
+ // Okay, we are casting from one integer or pointer type to another of
+ // the same size. Instead of casting the pointer before the load, cast
+ // the result of the loaded value.
+ Value *NewLoad = InsertNewInstBefore(new LoadInst(CI->getOperand(0),
+ CI->getName()), LI);
+ // Now cast the result of the load.
+ return new CastInst(NewLoad, LI.getType());
+ }
+ }
+ }
+
return 0;
}
bool Changed = false;
TD = &getAnalysis<TargetData>();
- WorkList.insert(WorkList.end(), inst_begin(F), inst_end(F));
+ for (inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i) {
+ WorkList.push_back(&*i);
+ }
+
while (!WorkList.empty()) {
Instruction *I = WorkList.back(); // Get an instruction from the worklist
projects / oota-llvm.git / blobdiff