//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "instcombine"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Instructions.h"
+#include "llvm/Intrinsics.h"
#include "llvm/Pass.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/InstIterator.h"
#include "llvm/Support/InstVisitor.h"
-#include "llvm/Support/CallSite.h"
+#include "Support/Debug.h"
#include "Support/Statistic.h"
#include <algorithm>
using namespace llvm;
std::vector<Instruction*> WorkList;
TargetData *TD;
- void AddUsesToWorkList(Instruction &I) {
- // The instruction was simplified, add all users of the instruction to
- // the work lists because they might get more simplified now...
- //
+ /// AddUsersToWorkList - When an instruction is simplified, add all users of
+ /// the instruction to the work lists because they might get more simplified
+ /// now.
+ ///
+ void AddUsersToWorkList(Instruction &I) {
for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
UI != UE; ++UI)
WorkList.push_back(cast<Instruction>(*UI));
}
+ /// AddUsesToWorkList - When an instruction is simplified, add operands to
+ /// the work lists because they might get more simplified now.
+ ///
+ void AddUsesToWorkList(Instruction &I) {
+ for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
+ if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
+ WorkList.push_back(Op);
+ }
+
// removeFromWorkList - remove all instances of I from the worklist.
void removeFromWorkList(Instruction *I);
public:
AU.setPreservesCFG();
}
+ TargetData &getTargetData() const { return *TD; }
+
// Visitation implementation - Implement instruction combining for different
// instruction types. The semantics are as follows:
// Return Value:
Instruction *visitSetCondInst(BinaryOperator &I);
Instruction *visitShiftInst(ShiftInst &I);
Instruction *visitCastInst(CastInst &CI);
+ Instruction *visitSelectInst(SelectInst &CI);
Instruction *visitCallInst(CallInst &CI);
Instruction *visitInvokeInst(InvokeInst &II);
Instruction *visitPHINode(PHINode &PN);
Instruction *visitCallSite(CallSite CS);
bool transformConstExprCastCall(CallSite CS);
+ public:
// InsertNewInstBefore - insert an instruction New before instruction Old
// in the program. Add the new instruction to the worklist.
//
return New;
}
- 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
// modified.
//
Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
- AddUsesToWorkList(I); // Add all modified instrs to worklist
- I.replaceAllUsesWith(V);
- return &I;
+ AddUsersToWorkList(I); // Add all modified instrs to worklist
+ if (&I != V) {
+ I.replaceAllUsesWith(V);
+ return &I;
+ } else {
+ // If we are replacing the instruction with itself, this must be in a
+ // segment of unreachable code, so just clobber the instruction.
+ I.replaceAllUsesWith(Constant::getNullValue(I.getType()));
+ return &I;
+ }
}
+
+ // EraseInstFromFunction - When dealing with an instruction that has side
+ // effects or produces a void value, we can't rely on DCE to delete the
+ // instruction. Instead, visit methods should return the value returned by
+ // this function.
+ Instruction *EraseInstFromFunction(Instruction &I) {
+ assert(I.use_empty() && "Cannot erase instruction that is used!");
+ AddUsesToWorkList(I);
+ removeFromWorkList(&I);
+ I.getParent()->getInstList().erase(&I);
+ return 0; // Don't do anything with FI
+ }
+
+
private:
/// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
/// InsertBefore instruction. This is specialized a bit to avoid inserting
}
}
+// getUnsignedIntegralType - Given an signed integral type, return the unsigned
+// version of it that has the same size.
+static const Type *getUnsignedIntegralType(const Type *Ty) {
+ switch (Ty->getPrimitiveID()) {
+ default: assert(0 && "Invalid signed integer type!"); abort();
+ case Type::SByteTyID: return Type::UByteTy;
+ case Type::ShortTyID: return Type::UShortTy;
+ case Type::IntTyID: return Type::UIntTy;
+ case Type::LongTyID: return Type::ULongTy;
+ }
+}
+
// getPromotedType - Return the specified type promoted as it would be to pass
// though a va_arg area...
static const Type *getPromotedType(const Type *Ty) {
// 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(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 (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;
}
}
return Ty == Type::BoolTy ? 1 : Ty->getPrimitiveSize()*8;
}
+/// RemoveNoopCast - Strip off nonconverting casts from the value.
+///
+static Value *RemoveNoopCast(Value *V) {
+ if (CastInst *CI = dyn_cast<CastInst>(V)) {
+ const Type *CTy = CI->getType();
+ const Type *OpTy = CI->getOperand(0)->getType();
+ if (CTy->isInteger() && OpTy->isInteger()) {
+ if (CTy->getPrimitiveSize() == OpTy->getPrimitiveSize())
+ return RemoveNoopCast(CI->getOperand(0));
+ } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
+ return RemoveNoopCast(CI->getOperand(0));
+ }
+ return V;
+}
+
Instruction *InstCombiner::visitSub(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
BinaryOperator::getNotArgument(cast<BinaryOperator>(Op1)),
ConstantExpr::get(Instruction::Add, C,
ConstantInt::get(I.getType(), 1)));
+ // -((uint)X >> 31) -> ((int)X >> 31)
+ // -((int)X >> 31) -> ((uint)X >> 31)
+ if (C->isNullValue()) {
+ Value *NoopCastedRHS = RemoveNoopCast(Op1);
+ if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
+ if (SI->getOpcode() == Instruction::Shr)
+ if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
+ const Type *NewTy;
+ if (SI->getType()->isSigned())
+ NewTy = getUnsignedIntegralType(SI->getType());
+ else
+ NewTy = getSignedIntegralType(SI->getType());
+ // Check to see if we are shifting out everything but the sign bit.
+ if (CU->getValue() == SI->getType()->getPrimitiveSize()*8-1) {
+ // Ok, the transformation is safe. Insert a cast of the incoming
+ // value, then the new shift, then the new cast.
+ Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
+ SI->getOperand(0)->getName());
+ Value *InV = InsertNewInstBefore(FirstCast, I);
+ Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
+ CU, SI->getName());
+ if (NewShift->getType() == I.getType())
+ return NewShift;
+ else {
+ InV = InsertNewInstBefore(NewShift, I);
+ return new CastInst(NewShift, I.getType());
+ }
+ }
+ }
+ }
+
+ // 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 (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
if (RHS->equalsInt(1)) // X % 1 == 0
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ if (RHS->isAllOnesValue()) // X % -1 == 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
// Check to see if this is an unsigned remainder with an exact power of 2,
// if so, convert to a bitwise and.
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 (CastInst *CI = dyn_cast<CastInst>(Op0)) {
Value *CastOp0 = CI->getOperand(0);
if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
- !isa<Argument>(Op1) &&
+ (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
(I.getOpcode() == Instruction::SetEQ ||
I.getOpcode() == Instruction::SetNE)) {
// We keep moving the cast from the left operand over to the right
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();
+ Value *FalseVal = SI.getFalseValue();
+
+ // select true, X, Y -> X
+ // select false, X, Y -> Y
+ if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
+ if (C == ConstantBool::True)
+ return ReplaceInstUsesWith(SI, TrueVal);
+ else {
+ assert(C == ConstantBool::False);
+ return ReplaceInstUsesWith(SI, FalseVal);
+ }
+
+ // select C, X, X -> X
+ if (TrueVal == FalseVal)
+ return ReplaceInstUsesWith(SI, TrueVal);
+
+ 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);
+ }
+ } 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;
+}
+
+
// CallInst simplification
//
Instruction *InstCombiner::visitCallInst(CallInst &CI) {
+ // Intrinsics cannot occur in an invoke, so handle them here instead of in
+ // visitCallSite.
+ if (Function *F = CI.getCalledFunction())
+ switch (F->getIntrinsicID()) {
+ case Intrinsic::memmove:
+ case Intrinsic::memcpy:
+ case Intrinsic::memset:
+ // memmove/cpy/set of zero bytes is a noop.
+ if (Constant *NumBytes = dyn_cast<Constant>(CI.getOperand(3))) {
+ if (NumBytes->isNullValue())
+ return EraseInstFromFunction(CI);
+ }
+ break;
+ default:
+ break;
+ }
+
return visitCallSite(&CI);
}
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));
}
}
// Otherwise, it's a call, just insert cast right after the call instr
InsertNewInstBefore(NC, *Caller);
}
- AddUsesToWorkList(*Caller);
+ AddUsersToWorkList(*Caller);
} else {
NV = Constant::getNullValue(Caller->getType());
}
return 0;
}
+static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
+ Instruction *InsertPoint,
+ InstCombiner *IC) {
+ unsigned PS = IC->getTargetData().getPointerSize();
+ const Type *VTy = V->getType();
+ Instruction *Cast;
+ if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
+ // We must insert a cast to ensure we sign-extend.
+ V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
+ V->getName()), *InsertPoint);
+ return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
+ *InsertPoint);
+}
+
Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
// Is it 'getelementptr %P, long 0' or 'getelementptr %P'
if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
return ReplaceInstUsesWith(GEP, GEP.getOperand(0));
+ // Eliminate unneeded casts for indices.
+ bool MadeChange = false;
+ gep_type_iterator GTI = gep_type_begin(GEP);
+ for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
+ if (isa<SequentialType>(*GTI)) {
+ if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
+ Value *Src = CI->getOperand(0);
+ const Type *SrcTy = Src->getType();
+ const Type *DestTy = CI->getType();
+ if (Src->getType()->isInteger()) {
+ if (SrcTy->getPrimitiveSize() == DestTy->getPrimitiveSize()) {
+ // We can always eliminate a cast from ulong or long to the other.
+ // We can always eliminate a cast from uint to int or the other on
+ // 32-bit pointer platforms.
+ if (DestTy->getPrimitiveSize() >= TD->getPointerSize()) {
+ MadeChange = true;
+ GEP.setOperand(i, Src);
+ }
+ } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
+ SrcTy->getPrimitiveSize() == 4) {
+ // We can always eliminate a cast from int to [u]long. We can
+ // eliminate a cast from uint to [u]long iff the target is a 32-bit
+ // pointer target.
+ if (SrcTy->isSigned() ||
+ SrcTy->getPrimitiveSize() >= TD->getPointerSize()) {
+ MadeChange = true;
+ GEP.setOperand(i, Src);
+ }
+ }
+ }
+ }
+ // If we are using a wider index than needed for this platform, shrink it
+ // to what we need. If the incoming value needs a cast instruction,
+ // insert it. This explicit cast can make subsequent optimizations more
+ // obvious.
+ Value *Op = GEP.getOperand(i);
+ if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
+ 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);
+ MadeChange = true;
+ }
+ }
+ if (MadeChange) return &GEP;
+
// Combine Indices - If the source pointer to this getelementptr instruction
// is a getelementptr instruction, combine the indices of the two
// getelementptr instructions into a single instruction.
//
+ std::vector<Value*> SrcGEPOperands;
if (GetElementPtrInst *Src = dyn_cast<GetElementPtrInst>(GEP.getOperand(0))) {
+ SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GEP.getOperand(0))) {
+ if (CE->getOpcode() == Instruction::GetElementPtr)
+ SrcGEPOperands.assign(CE->op_begin(), CE->op_end());
+ }
+
+ if (!SrcGEPOperands.empty()) {
std::vector<Value *> Indices;
// Can we combine the two pointer arithmetics offsets?
- if (Src->getNumOperands() == 2 && isa<Constant>(Src->getOperand(1)) &&
+ if (SrcGEPOperands.size() == 2 && isa<Constant>(SrcGEPOperands[1]) &&
isa<Constant>(GEP.getOperand(1))) {
+ Constant *SGC = cast<Constant>(SrcGEPOperands[1]);
+ Constant *GC = cast<Constant>(GEP.getOperand(1));
+ if (SGC->getType() != GC->getType()) {
+ SGC = ConstantExpr::getSignExtend(SGC, Type::LongTy);
+ GC = ConstantExpr::getSignExtend(GC, Type::LongTy);
+ }
+
// Replace: gep (gep %P, long C1), long C2, ...
// With: gep %P, long (C1+C2), ...
- Value *Sum = ConstantExpr::get(Instruction::Add,
- cast<Constant>(Src->getOperand(1)),
- cast<Constant>(GEP.getOperand(1)));
- assert(Sum && "Constant folding of longs failed!?");
- GEP.setOperand(0, Src->getOperand(0));
- GEP.setOperand(1, Sum);
- AddUsesToWorkList(*Src); // Reduce use count of Src
+ GEP.setOperand(0, SrcGEPOperands[0]);
+ GEP.setOperand(1, ConstantExpr::getAdd(SGC, GC));
+ if (Instruction *I = dyn_cast<Instruction>(GEP.getOperand(0)))
+ AddUsersToWorkList(*I); // Reduce use count of Src
return &GEP;
- } else if (Src->getNumOperands() == 2) {
+ } else if (SrcGEPOperands.size() == 2) {
// Replace: gep (gep %P, long B), long A, ...
// With: T = long A+B; gep %P, T, ...
//
// chain to be resolved before we perform this transformation. This
// avoids us creating a TON of code in some cases.
//
- if (isa<GetElementPtrInst>(Src->getOperand(0)) &&
- cast<Instruction>(Src->getOperand(0))->getNumOperands() == 2)
+ if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
+ cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
return 0; // Wait until our source is folded to completion.
- Value *Sum = BinaryOperator::create(Instruction::Add, Src->getOperand(1),
- GEP.getOperand(1),
- Src->getName()+".sum", &GEP);
- GEP.setOperand(0, Src->getOperand(0));
+ Value *Sum, *SO1 = SrcGEPOperands[1], *GO1 = GEP.getOperand(1);
+ if (SO1 == Constant::getNullValue(SO1->getType())) {
+ Sum = GO1;
+ } else if (GO1 == Constant::getNullValue(GO1->getType())) {
+ Sum = SO1;
+ } else {
+ // If they aren't the same type, convert both to an integer of the
+ // target's pointer size.
+ if (SO1->getType() != GO1->getType()) {
+ if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
+ SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
+ } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
+ GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
+ } else {
+ unsigned PS = TD->getPointerSize();
+ Instruction *Cast;
+ if (SO1->getType()->getPrimitiveSize() == PS) {
+ // Convert GO1 to SO1's type.
+ GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
+
+ } else if (GO1->getType()->getPrimitiveSize() == PS) {
+ // Convert SO1 to GO1's type.
+ SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
+ } else {
+ const Type *PT = TD->getIntPtrType();
+ SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
+ GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
+ }
+ }
+ }
+ Sum = BinaryOperator::create(Instruction::Add, SO1, GO1,
+ GEP.getOperand(0)->getName()+".sum", &GEP);
+ WorkList.push_back(cast<Instruction>(Sum));
+ }
+ GEP.setOperand(0, SrcGEPOperands[0]);
GEP.setOperand(1, Sum);
- WorkList.push_back(cast<Instruction>(Sum));
return &GEP;
- } else if (*GEP.idx_begin() == Constant::getNullValue(Type::LongTy) &&
- Src->getNumOperands() != 1) {
+ } else if (isa<Constant>(*GEP.idx_begin()) &&
+ cast<Constant>(*GEP.idx_begin())->isNullValue() &&
+ SrcGEPOperands.size() != 1) {
// Otherwise we can do the fold if the first index of the GEP is a zero
- Indices.insert(Indices.end(), Src->idx_begin(), Src->idx_end());
+ Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
+ SrcGEPOperands.end());
Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
- } else if (Src->getOperand(Src->getNumOperands()-1) ==
- Constant::getNullValue(Type::LongTy)) {
- // If the src gep ends with a constant array index, merge this get into
- // it, even if we have a non-zero array index.
- Indices.insert(Indices.end(), Src->idx_begin(), Src->idx_end()-1);
- Indices.insert(Indices.end(), GEP.idx_begin(), GEP.idx_end());
+ } else if (SrcGEPOperands.back() ==
+ Constant::getNullValue(SrcGEPOperands.back()->getType())) {
+ // We have to check to make sure this really is an ARRAY index we are
+ // ending up with, not a struct index.
+ generic_gep_type_iterator<std::vector<Value*>::iterator>
+ GTI = gep_type_begin(SrcGEPOperands[0]->getType(),
+ SrcGEPOperands.begin()+1, SrcGEPOperands.end());
+ std::advance(GTI, SrcGEPOperands.size()-2);
+ if (isa<SequentialType>(*GTI)) {
+ // If the src gep ends with a constant array index, merge this get into
+ // it, even if we have a non-zero array index.
+ Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
+ SrcGEPOperands.end()-1);
+ Indices.insert(Indices.end(), GEP.idx_begin(), GEP.idx_end());
+ }
}
if (!Indices.empty())
- return new GetElementPtrInst(Src->getOperand(0), Indices, GEP.getName());
+ return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(GEP.getOperand(0))) {
// GEP of global variable. If all of the indices for this GEP are
// Create and insert the replacement instruction...
if (isa<MallocInst>(AI))
- New = new MallocInst(NewTy, 0, AI.getName(), &AI);
+ New = new MallocInst(NewTy, 0, AI.getName());
else {
assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
- New = new AllocaInst(NewTy, 0, AI.getName(), &AI);
+ New = new AllocaInst(NewTy, 0, AI.getName());
}
+
+ InsertNewInstBefore(New, AI);
// Scan to the end of the allocation instructions, to skip over a block of
// allocas if possible...
// Now that I is pointing to the first non-allocation-inst in the block,
// insert our getelementptr instruction...
//
- std::vector<Value*> Idx(2, Constant::getNullValue(Type::LongTy));
+ std::vector<Value*> Idx(2, Constant::getNullValue(Type::IntTy));
Value *V = new GetElementPtrInst(New, Idx, New->getName()+".sub", It);
// Now make everything use the getelementptr instead of the original
// allocation.
- ReplaceInstUsesWith(AI, V);
- return &AI;
+ return ReplaceInstUsesWith(AI, V);
}
+
+ // If alloca'ing a zero byte object, replace the alloca with a null pointer.
+ // Note that we only do this for alloca's, because malloc should allocate and
+ // return a unique pointer, even for a zero byte allocation.
+ if (isa<AllocaInst>(AI) && TD->getTypeSize(AI.getAllocatedType()) == 0)
+ return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
+
return 0;
}
return &FI;
}
+ // If we have 'free null' delete the instruction. This can happen in stl code
+ // when lots of inlining happens.
+ if (isa<ConstantPointerNull>(Op))
+ return EraseInstFromFunction(FI);
+
return 0;
}
/// expression, or null if something is funny.
///
static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
- if (CE->getOperand(1) != Constant::getNullValue(Type::LongTy))
+ if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
return 0; // Do not allow stepping over the value!
// Loop over all of the operands, tracking down which value we are
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;
}
Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
// Change br (not X), label True, label False to: br X, label False, True
- if (BI.isConditional() && !isa<Constant>(BI.getCondition()))
+ if (BI.isConditional() && !isa<Constant>(BI.getCondition())) {
if (Value *V = dyn_castNotVal(BI.getCondition())) {
BasicBlock *TrueDest = BI.getSuccessor(0);
BasicBlock *FalseDest = BI.getSuccessor(1);
BI.setSuccessor(0, FalseDest);
BI.setSuccessor(1, TrueDest);
return &BI;
+ } else if (SetCondInst *I = dyn_cast<SetCondInst>(BI.getCondition())) {
+ // Cannonicalize setne -> seteq
+ if ((I->getOpcode() == Instruction::SetNE ||
+ I->getOpcode() == Instruction::SetLE ||
+ I->getOpcode() == Instruction::SetGE) && I->hasOneUse()) {
+ std::string Name = I->getName(); I->setName("");
+ Instruction::BinaryOps NewOpcode =
+ SetCondInst::getInverseCondition(I->getOpcode());
+ Value *NewSCC = BinaryOperator::create(NewOpcode, I->getOperand(0),
+ I->getOperand(1), Name, I);
+ BasicBlock *TrueDest = BI.getSuccessor(0);
+ BasicBlock *FalseDest = BI.getSuccessor(1);
+ // Swap Destinations and condition...
+ BI.setCondition(NewSCC);
+ BI.setSuccessor(0, FalseDest);
+ BI.setSuccessor(1, TrueDest);
+ removeFromWorkList(I);
+ I->getParent()->getInstList().erase(I);
+ WorkList.push_back(cast<Instruction>(NewSCC));
+ return &BI;
+ }
}
+ }
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
if (isInstructionTriviallyDead(I)) {
// Add operands to the worklist...
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);
+ AddUsesToWorkList(*I);
++NumDeadInst;
I->getParent()->getInstList().erase(I);
// Instruction isn't dead, see if we can constant propagate it...
if (Constant *C = ConstantFoldInstruction(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);
+ AddUsesToWorkList(*I);
ReplaceInstUsesWith(*I, C);
++NumConstProp;
continue;
}
+ // Check to see if any of the operands of this instruction are a
+ // ConstantPointerRef. Since they sneak in all over the place and inhibit
+ // optimization, we want to strip them out unconditionally!
+ for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
+ if (ConstantPointerRef *CPR =
+ dyn_cast<ConstantPointerRef>(I->getOperand(i))) {
+ I->setOperand(i, CPR->getValue());
+ Changed = true;
+ }
+
// Now that we have an instruction, try combining it to simplify it...
if (Instruction *Result = visit(*I)) {
++NumCombined;
// Should we replace the old instruction with a new one?
if (Result != I) {
+ DEBUG(std::cerr << "IC: Old = " << *I
+ << " New = " << *Result);
+
// Instructions can end up on the worklist more than once. Make sure
// we do not process an instruction that has been deleted.
removeFromWorkList(I);
// Erase the old instruction.
InstParent->getInstList().erase(I);
} else {
+ DEBUG(std::cerr << "IC: MOD = " << *I);
+
BasicBlock::iterator II = I;
// If the instruction was modified, it's possible that it is now dead.
if (Result) {
WorkList.push_back(Result);
- AddUsesToWorkList(*Result);
+ AddUsersToWorkList(*Result);
}
Changed = true;
}
projects / oota-llvm.git / blobdiff