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* Pull range optimization code out into new InsertRangeTest function.

Browse Source 
* SubOne/AddOne functions always return ConstantInt, declare them as such
* Pull code for handling setcc X, cst, where cst is at the end of the range,
  or cc is LE or GE up earlier in visitSetCondInst.  This reduces #iterations
  in some cases.
* Fold: (div X, C1) op C2 -> range check, implementing div.ll:test6 - test9.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16588 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-09-29 17:40:11 +00:00
parent a2393502be
commit a96879a26d
1 changed files with 219 additions and 80 deletions
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299
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -209,6 +209,9 @@ namespace {
Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
bool Inside, Instruction &IB);
};
RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
@ -341,11 +344,13 @@ static unsigned Log2(uint64_t Val) {
}
// AddOne, SubOne - Add or subtract a constant one from an integer constant...
static Constant *AddOne(ConstantInt *C) {
return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));
static ConstantInt *AddOne(ConstantInt *C) {
return cast<ConstantInt>(ConstantExpr::getAdd(C,
ConstantInt::get(C->getType(), 1)));
}
static Constant *SubOne(ConstantInt *C) {
return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1));
static ConstantInt *SubOne(ConstantInt *C) {
return cast<ConstantInt>(ConstantExpr::getSub(C,
ConstantInt::get(C->getType(), 1)));
}
// isTrueWhenEqual - Return true if the specified setcondinst instruction is
@ -1241,6 +1246,51 @@ Instruction *InstCombiner::OptAndOp(Instruction *Op,
}
/// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
/// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
/// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
/// insert new instructions.
Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
bool Inside, Instruction &IB) {
assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
"Lo is not <= Hi in range emission code!");
if (Inside) {
if (Lo == Hi) // Trivially false.
return new SetCondInst(Instruction::SetNE, V, V);
if (cast<ConstantIntegral>(Lo)->isMinValue())
return new SetCondInst(Instruction::SetLT, V, Hi);
Constant *AddCST = ConstantExpr::getNeg(Lo);
Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
InsertNewInstBefore(Add, IB);
// Convert to unsigned for the comparison.
const Type *UnsType = Add->getType()->getUnsignedVersion();
Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
AddCST = ConstantExpr::getAdd(AddCST, Hi);
AddCST = ConstantExpr::getCast(AddCST, UnsType);
return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
}
if (Lo == Hi) // Trivially true.
return new SetCondInst(Instruction::SetEQ, V, V);
Hi = SubOne(cast<ConstantInt>(Hi));
if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
return new SetCondInst(Instruction::SetGT, V, Hi);
// Emit X-Lo > Hi-Lo-1
Constant *AddCST = ConstantExpr::getNeg(Lo);
Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
InsertNewInstBefore(Add, IB);
// Convert to unsigned for the comparison.
const Type *UnsType = Add->getType()->getUnsignedVersion();
Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
AddCST = ConstantExpr::getAdd(AddCST, Hi);
AddCST = ConstantExpr::getCast(AddCST, UnsType);
return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
}
Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
bool Changed = SimplifyCommutative(I);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
@ -1375,19 +1425,8 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
break; // (X > 13 & X != 15) -> no change
case Instruction::SetLT: { // (X > 13 & X < 15) -> (X-14) <u 1
Constant *AddCST = ConstantExpr::getNeg(AddOne(LHSCst));
Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
LHSVal->getName()+".off");
InsertNewInstBefore(Add, I);
// Convert to unsigned for the comparison.
const Type *UnsType = Add->getType()->getUnsignedVersion();
Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
AddCST = ConstantExpr::getAdd(AddCST, RHSCst);
AddCST = ConstantExpr::getCast(AddCST, UnsType);
return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
}
break;
case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
}
}
}
@ -1396,8 +1435,6 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
return Changed ? &I : 0;
}
Instruction *InstCombiner::visitOr(BinaryOperator &I) {
bool Changed = SimplifyCommutative(I);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
@ -1541,18 +1578,8 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
default: assert(0 && "Unknown integer condition code!");
case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
break;
case Instruction::SetGT: {// (X < 13 | X > 15) -> (X-13) > 2
Constant *AddCST = ConstantExpr::getNeg(LHSCst);
Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
LHSVal->getName()+".off");
InsertNewInstBefore(Add, I);
// Convert to unsigned for the comparison.
const Type *UnsType = Add->getType()->getUnsignedVersion();
Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
AddCST = ConstantExpr::getAdd(AddCST, RHSCst);
AddCST = ConstantExpr::getCast(AddCST, UnsType);
return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
}
case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
return ReplaceInstUsesWith(I, RHS);
@ -1721,6 +1748,36 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
return Changed ? &I : 0;
}
/// MulWithOverflow - Compute Result = In1*In2, returning true if the result
/// overflowed for this type.
static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
ConstantInt *In2) {
Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
}
static bool isPositive(ConstantInt *C) {
return cast<ConstantSInt>(C)->getValue() >= 0;
}
/// AddWithOverflow - Compute Result = In1+In2, returning true if the result
/// overflowed for this type.
static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
ConstantInt *In2) {
Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
if (In1->getType()->isUnsigned())
return cast<ConstantUInt>(Result)->getValue() <
cast<ConstantUInt>(In1)->getValue();
if (isPositive(In1) != isPositive(In2))
return false;
if (isPositive(In1))
return cast<ConstantSInt>(Result)->getValue() <
cast<ConstantSInt>(In1)->getValue();
return cast<ConstantSInt>(Result)->getValue() >
cast<ConstantSInt>(In1)->getValue();
}
Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
bool Changed = SimplifyCommutative(I);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
@ -1770,6 +1827,50 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
// See if we are doing a comparison between a constant and an instruction that
// can be folded into the comparison.
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
// Check to see if we are comparing against the minimum or maximum value...
if (CI->isMinValue()) {
if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
return ReplaceInstUsesWith(I, ConstantBool::False);
if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
return ReplaceInstUsesWith(I, ConstantBool::True);
if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
return BinaryOperator::createSetEQ(Op0, Op1);
if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
return BinaryOperator::createSetNE(Op0, Op1);
} else if (CI->isMaxValue()) {
if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
return ReplaceInstUsesWith(I, ConstantBool::False);
if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
return ReplaceInstUsesWith(I, ConstantBool::True);
if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
return BinaryOperator::createSetEQ(Op0, Op1);
if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
return BinaryOperator::createSetNE(Op0, Op1);
// Comparing against a value really close to min or max?
} else if (isMinValuePlusOne(CI)) {
if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
return BinaryOperator::createSetEQ(Op0, SubOne(CI));
if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
return BinaryOperator::createSetNE(Op0, SubOne(CI));
} else if (isMaxValueMinusOne(CI)) {
if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
return BinaryOperator::createSetEQ(Op0, AddOne(CI));
if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
return BinaryOperator::createSetNE(Op0, AddOne(CI));
}
// If we still have a setle or setge instruction, turn it into the
// appropriate setlt or setgt instruction. Since the border cases have
// already been handled above, this requires little checking.
//
if (I.getOpcode() == Instruction::SetLE)
return BinaryOperator::createSetLT(Op0, AddOne(CI));
if (I.getOpcode() == Instruction::SetGE)
return BinaryOperator::createSetGT(Op0, SubOne(CI));
if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
switch (LHSI->getOpcode()) {
case Instruction::PHI:
@ -1864,12 +1965,8 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
return ReplaceInstUsesWith(I, ConstantBool::True);
case Instruction::SetLT:
return ReplaceInstUsesWith(I, ConstantExpr::getSetLT(Max, CI));
case Instruction::SetLE:
return ReplaceInstUsesWith(I, ConstantExpr::getSetLE(Max, CI));
case Instruction::SetGT:
return ReplaceInstUsesWith(I, ConstantExpr::getSetGT(Min, CI));
case Instruction::SetGE:
return ReplaceInstUsesWith(I, ConstantExpr::getSetGE(Min, CI));
}
}
@ -1968,6 +2065,92 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
}
break;
case Instruction::Div:
// Fold: (div X, C1) op C2 -> range check
if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
// Fold this div into the comparison, producing a range check.
// Determine, based on the divide type, what the range is being
// checked. If there is an overflow on the low or high side, remember
// it, otherwise compute the range [low, hi) bounding the new value.
bool LoOverflow = false, HiOverflow = 0;
ConstantInt *LoBound = 0, *HiBound = 0;
ConstantInt *Prod;
bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
} else if (LHSI->getType()->isUnsigned()) { // udiv
LoBound = Prod;
LoOverflow = ProdOV;
HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
} else if (isPositive(DivRHS)) { // Divisor is > 0.
if (CI->isNullValue()) { // (X / pos) op 0
// Can't overflow.
LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
HiBound = DivRHS;
} else if (isPositive(CI)) { // (X / pos) op pos
LoBound = Prod;
LoOverflow = ProdOV;
HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
} else { // (X / pos) op neg
Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
LoOverflow = AddWithOverflow(LoBound, Prod,
cast<ConstantInt>(DivRHSH));
HiBound = Prod;
HiOverflow = ProdOV;
}
} else { // Divisor is < 0.
if (CI->isNullValue()) { // (X / neg) op 0
LoBound = AddOne(DivRHS);
HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
} else if (isPositive(CI)) { // (X / neg) op pos
HiOverflow = LoOverflow = ProdOV;
if (!LoOverflow)
LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
HiBound = AddOne(Prod);
} else { // (X / neg) op neg
LoBound = Prod;
LoOverflow = HiOverflow = ProdOV;
HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
}
}
if (LoBound) {
Value *X = LHSI->getOperand(0);
std::cerr << "DIV FOLD: " << *LHSI;
std::cerr << "DIV FOLD: " << I << "\n";
switch (I.getOpcode()) {
default: assert(0 && "Unhandled setcc opcode!");
case Instruction::SetEQ:
if (LoOverflow && HiOverflow)
return ReplaceInstUsesWith(I, ConstantBool::False);
else if (HiOverflow)
return new SetCondInst(Instruction::SetGE, X, LoBound);
else if (LoOverflow)
return new SetCondInst(Instruction::SetLT, X, HiBound);
else
return InsertRangeTest(X, LoBound, HiBound, true, I);
case Instruction::SetNE:
if (LoOverflow && HiOverflow)
return ReplaceInstUsesWith(I, ConstantBool::True);
else if (HiOverflow)
return new SetCondInst(Instruction::SetLT, X, LoBound);
else if (LoOverflow)
return new SetCondInst(Instruction::SetGE, X, HiBound);
else
return InsertRangeTest(X, LoBound, HiBound, false, I);
case Instruction::SetLT:
if (LoOverflow)
return ReplaceInstUsesWith(I, ConstantBool::False);
return new SetCondInst(Instruction::SetLT, X, LoBound);
case Instruction::SetGT:
if (HiOverflow)
return ReplaceInstUsesWith(I, ConstantBool::False);
return new SetCondInst(Instruction::SetGE, X, HiBound);
}
}
}
break;
case Instruction::Select:
// If either operand of the select is a constant, we can fold the
// comparison into the select arms, which will cause one to be
@ -2157,50 +2340,6 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
}
}
}
// Check to see if we are comparing against the minimum or maximum value...
if (CI->isMinValue()) {
if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
return ReplaceInstUsesWith(I, ConstantBool::False);
if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
return ReplaceInstUsesWith(I, ConstantBool::True);
if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
return BinaryOperator::createSetEQ(Op0, Op1);
if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
return BinaryOperator::createSetNE(Op0, Op1);
} else if (CI->isMaxValue()) {
if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
return ReplaceInstUsesWith(I, ConstantBool::False);
if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
return ReplaceInstUsesWith(I, ConstantBool::True);
if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
return BinaryOperator::createSetEQ(Op0, Op1);
if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
return BinaryOperator::createSetNE(Op0, Op1);
// Comparing against a value really close to min or max?
} else if (isMinValuePlusOne(CI)) {
if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
return BinaryOperator::createSetEQ(Op0, SubOne(CI));
if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
return BinaryOperator::createSetNE(Op0, SubOne(CI));
} else if (isMaxValueMinusOne(CI)) {
if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
return BinaryOperator::createSetEQ(Op0, AddOne(CI));
if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
return BinaryOperator::createSetNE(Op0, AddOne(CI));
}
// If we still have a setle or setge instruction, turn it into the
// appropriate setlt or setgt instruction. Since the border cases have
// already been handled above, this requires little checking.
//
if (I.getOpcode() == Instruction::SetLE)
return BinaryOperator::createSetLT(Op0, AddOne(CI));
if (I.getOpcode() == Instruction::SetGE)
return BinaryOperator::createSetGT(Op0, SubOne(CI));
}
// Test to see if the operands of the setcc are casted versions of other
@ -2875,7 +3014,7 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
}
}
}
if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
!isa<Constant>(TrueVal))