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Eliminate all of the SCEV Expansion code which is really part of the

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IndVars pass, not part of SCEV *analysis*.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13134 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-04-23 21:29:03 +00:00
parent 2cdf0a7a32
commit b06432c276
1 changed files with 9 additions and 213 deletions
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222
lib/Analysis/ScalarEvolution.cpp
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@ -33,10 +33,6 @@
// higher-level code, such as the code that recognizes PHI nodes of various // higher-level code, such as the code that recognizes PHI nodes of various
// types, computes the execution count of a loop, etc. // types, computes the execution count of a loop, etc.
// //
// Orthogonal to the analysis of code above, this file also implements the
// ScalarEvolutionRewriter class, which is used to emit code that represents the
// various recurrences present in a loop, in canonical forms.
//
// TODO: We should use these routines and value representations to implement // TODO: We should use these routines and value representations to implement
// dependence analysis! // dependence analysis!
// //
@ -160,13 +156,6 @@ bool SCEVCouldNotCompute::hasComputableLoopEvolution(const Loop *L) const {
return false; return false;
} }
Value *SCEVCouldNotCompute::expandCodeFor(ScalarEvolutionRewriter &SER,
Instruction *InsertPt) {
assert(0 && "Attempt to use a SCEVCouldNotCompute object!");
return 0;
}
void SCEVCouldNotCompute::print(std::ostream &OS) const { void SCEVCouldNotCompute::print(std::ostream &OS) const {
OS << "***COULDNOTCOMPUTE***"; OS << "***COULDNOTCOMPUTE***";
} }
@ -358,7 +347,7 @@ void SCEVUnknown::print(std::ostream &OS) const {
/// getIntegerSCEV - Given an integer or FP type, create a constant for the /// getIntegerSCEV - Given an integer or FP type, create a constant for the
/// specified signed integer value and return a SCEV for the constant. /// specified signed integer value and return a SCEV for the constant.
static SCEVHandle getIntegerSCEV(int Val, const Type *Ty) { SCEVHandle SCEVUnknown::getIntegerSCEV(int Val, const Type *Ty) {
Constant *C; Constant *C;
if (Val == 0) if (Val == 0)
C = Constant::getNullValue(Ty); C = Constant::getNullValue(Ty);
@ -393,7 +382,7 @@ static SCEVHandle getNegativeSCEV(const SCEVHandle &V) {
if (SCEVConstant *VC = dyn_cast<SCEVConstant>(V)) if (SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
return SCEVUnknown::get(ConstantExpr::getNeg(VC->getValue())); return SCEVUnknown::get(ConstantExpr::getNeg(VC->getValue()));
return SCEVMulExpr::get(V, getIntegerSCEV(-1, V->getType())); return SCEVMulExpr::get(V, SCEVUnknown::getIntegerSCEV(-1, V->getType()));
} }
/// getMinusSCEV - Return a SCEV corresponding to LHS - RHS. /// getMinusSCEV - Return a SCEV corresponding to LHS - RHS.
@ -438,11 +427,12 @@ static SCEVHandle PartialFact(SCEVHandle V, unsigned NumSteps) {
const Type *Ty = V->getType(); const Type *Ty = V->getType();
if (NumSteps == 0) if (NumSteps == 0)
return getIntegerSCEV(1, Ty); return SCEVUnknown::getIntegerSCEV(1, Ty);
SCEVHandle Result = V; SCEVHandle Result = V;
for (unsigned i = 1; i != NumSteps; ++i) for (unsigned i = 1; i != NumSteps; ++i)
Result = SCEVMulExpr::get(Result, getMinusSCEV(V, getIntegerSCEV(i, Ty))); Result = SCEVMulExpr::get(Result, getMinusSCEV(V,
SCEVUnknown::getIntegerSCEV(i, Ty)));
return Result; return Result;
} }
@ -465,7 +455,7 @@ SCEVHandle SCEVAddRecExpr::evaluateAtIteration(SCEVHandle It) const {
SCEVHandle BC = PartialFact(It, i); SCEVHandle BC = PartialFact(It, i);
Divisor *= i; Divisor *= i;
SCEVHandle Val = SCEVUDivExpr::get(SCEVMulExpr::get(BC, getOperand(i)), SCEVHandle Val = SCEVUDivExpr::get(SCEVMulExpr::get(BC, getOperand(i)),
getIntegerSCEV(Divisor, Ty)); SCEVUnknown::getIntegerSCEV(Divisor,Ty));
Result = SCEVAddExpr::get(Result, Val); Result = SCEVAddExpr::get(Result, Val);
} }
return Result; return Result;
@ -558,7 +548,7 @@ SCEVHandle SCEVAddExpr::get(std::vector<SCEVHandle> &Ops) {
if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2 if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
// Found a match, merge the two values into a multiply, and add any // Found a match, merge the two values into a multiply, and add any
// remaining values to the result. // remaining values to the result.
SCEVHandle Two = getIntegerSCEV(2, Ty); SCEVHandle Two = SCEVUnknown::getIntegerSCEV(2, Ty);
SCEVHandle Mul = SCEVMulExpr::get(Ops[i], Two); SCEVHandle Mul = SCEVMulExpr::get(Ops[i], Two);
if (Ops.size() == 2) if (Ops.size() == 2)
return Mul; return Mul;
@ -609,7 +599,7 @@ SCEVHandle SCEVAddExpr::get(std::vector<SCEVHandle> &Ops) {
MulOps.erase(MulOps.begin()+MulOp); MulOps.erase(MulOps.begin()+MulOp);
InnerMul = SCEVMulExpr::get(MulOps); InnerMul = SCEVMulExpr::get(MulOps);
} }
SCEVHandle One = getIntegerSCEV(1, Ty); SCEVHandle One = SCEVUnknown::getIntegerSCEV(1, Ty);
SCEVHandle AddOne = SCEVAddExpr::get(InnerMul, One); SCEVHandle AddOne = SCEVAddExpr::get(InnerMul, One);
SCEVHandle OuterMul = SCEVMulExpr::get(AddOne, Ops[AddOp]); SCEVHandle OuterMul = SCEVMulExpr::get(AddOne, Ops[AddOp]);
if (Ops.size() == 2) return OuterMul; if (Ops.size() == 2) return OuterMul;
@ -976,137 +966,6 @@ SCEVHandle SCEVUnknown::get(Value *V) {
} }
//===----------------------------------------------------------------------===//
// Non-trivial closed-form SCEV Expanders
//===----------------------------------------------------------------------===//
Value *SCEVTruncateExpr::expandCodeFor(ScalarEvolutionRewriter &SER,
Instruction *InsertPt) {
Value *V = SER.ExpandCodeFor(getOperand(), InsertPt);
return new CastInst(V, getType(), "tmp.", InsertPt);
}
Value *SCEVZeroExtendExpr::expandCodeFor(ScalarEvolutionRewriter &SER,
Instruction *InsertPt) {
Value *V = SER.ExpandCodeFor(getOperand(), InsertPt,
getOperand()->getType()->getUnsignedVersion());
return new CastInst(V, getType(), "tmp.", InsertPt);
}
Value *SCEVAddExpr::expandCodeFor(ScalarEvolutionRewriter &SER,
Instruction *InsertPt) {
const Type *Ty = getType();
Value *V = SER.ExpandCodeFor(getOperand(getNumOperands()-1), InsertPt, Ty);
// Emit a bunch of add instructions
for (int i = getNumOperands()-2; i >= 0; --i)
V = BinaryOperator::create(Instruction::Add, V,
SER.ExpandCodeFor(getOperand(i), InsertPt, Ty),
"tmp.", InsertPt);
return V;
}
Value *SCEVMulExpr::expandCodeFor(ScalarEvolutionRewriter &SER,
Instruction *InsertPt) {
const Type *Ty = getType();
int FirstOp = 0; // Set if we should emit a subtract.
if (SCEVConstant *SC = dyn_cast<SCEVConstant>(getOperand(0)))
if (SC->getValue()->isAllOnesValue())
FirstOp = 1;
int i = getNumOperands()-2;
Value *V = SER.ExpandCodeFor(getOperand(i+1), InsertPt, Ty);
// Emit a bunch of multiply instructions
for (; i >= FirstOp; --i)
V = BinaryOperator::create(Instruction::Mul, V,
SER.ExpandCodeFor(getOperand(i), InsertPt, Ty),
"tmp.", InsertPt);
// -1 * ... ---> 0 - ...
if (FirstOp == 1)
V = BinaryOperator::create(Instruction::Sub, Constant::getNullValue(Ty), V,
"tmp.", InsertPt);
return V;
}
Value *SCEVUDivExpr::expandCodeFor(ScalarEvolutionRewriter &SER,
Instruction *InsertPt) {
const Type *Ty = getType();
Value *LHS = SER.ExpandCodeFor(getLHS(), InsertPt, Ty);
Value *RHS = SER.ExpandCodeFor(getRHS(), InsertPt, Ty);
return BinaryOperator::create(Instruction::Div, LHS, RHS, "tmp.", InsertPt);
}
Value *SCEVAddRecExpr::expandCodeFor(ScalarEvolutionRewriter &SER,
Instruction *InsertPt) {
const Type *Ty = getType();
// We cannot yet do fp recurrences, e.g. the xform of {X,+,F} --> X+{0,+,F}
assert(Ty->isIntegral() && "Cannot expand fp recurrences yet!");
// {X,+,F} --> X + {0,+,F}
if (!isa<SCEVConstant>(getStart()) ||
!cast<SCEVConstant>(getStart())->getValue()->isNullValue()) {
Value *Start = SER.ExpandCodeFor(getStart(), InsertPt, Ty);
std::vector<SCEVHandle> NewOps(op_begin(), op_end());
NewOps[0] = getIntegerSCEV(0, getType());
Value *Rest = SER.ExpandCodeFor(SCEVAddRecExpr::get(NewOps, getLoop()),
InsertPt, getType());
// FIXME: look for an existing add to use.
return BinaryOperator::create(Instruction::Add, Rest, Start, "tmp.",
InsertPt);
}
// {0,+,1} --> Insert a canonical induction variable into the loop!
if (getNumOperands() == 2 && getOperand(1) == getIntegerSCEV(1, getType())) {
// Create and insert the PHI node for the induction variable in the
// specified loop.
BasicBlock *Header = getLoop()->getHeader();
PHINode *PN = new PHINode(Ty, "indvar", Header->begin());
PN->addIncoming(Constant::getNullValue(Ty), L->getLoopPreheader());
pred_iterator HPI = pred_begin(Header);
assert(HPI != pred_end(Header) && "Loop with zero preds???");
if (!getLoop()->contains(*HPI)) ++HPI;
assert(HPI != pred_end(Header) && getLoop()->contains(*HPI) &&
"No backedge in loop?");
// Insert a unit add instruction right before the terminator corresponding
// to the back-edge.
Constant *One = Ty->isFloatingPoint() ? (Constant*)ConstantFP::get(Ty, 1.0)
: (Constant*)ConstantInt::get(Ty, 1);
Instruction *Add = BinaryOperator::create(Instruction::Add, PN, One,
"indvar.next",
(*HPI)->getTerminator());
pred_iterator PI = pred_begin(Header);
if (*PI == L->getLoopPreheader())
++PI;
PN->addIncoming(Add, *PI);
return PN;
}
// Get the canonical induction variable I for this loop.
Value *I = SER.GetOrInsertCanonicalInductionVariable(getLoop(), Ty);
if (getNumOperands() == 2) { // {0,+,F} --> i*F
Value *F = SER.ExpandCodeFor(getOperand(1), InsertPt, Ty);
return BinaryOperator::create(Instruction::Mul, I, F, "tmp.", InsertPt);
}
// If this is a chain of recurrences, turn it into a closed form, using the
// folders, then expandCodeFor the closed form. This allows the folders to
// simplify the expression without having to build a bunch of special code
// into this folder.
SCEVHandle IH = SCEVUnknown::get(I); // Get I as a "symbolic" SCEV.
SCEVHandle V = evaluateAtIteration(IH);
//std::cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
return SER.ExpandCodeFor(V, InsertPt, Ty);
}
//===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===//
// ScalarEvolutionsImpl Definition and Implementation // ScalarEvolutionsImpl Definition and Implementation
//===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===//
@ -2099,7 +1958,7 @@ SCEVHandle SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range) const {
if (SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart())) if (SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart()))
if (!SC->getValue()->isNullValue()) { if (!SC->getValue()->isNullValue()) {
std::vector<SCEVHandle> Operands(op_begin(), op_end()); std::vector<SCEVHandle> Operands(op_begin(), op_end());
Operands[0] = getIntegerSCEV(0, SC->getType()); Operands[0] = SCEVUnknown::getIntegerSCEV(0, SC->getType());
SCEVHandle Shifted = SCEVAddRecExpr::get(Operands, getLoop()); SCEVHandle Shifted = SCEVAddRecExpr::get(Operands, getLoop());
if (SCEVAddRecExpr *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted)) if (SCEVAddRecExpr *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted))
return ShiftedAddRec->getNumIterationsInRange( return ShiftedAddRec->getNumIterationsInRange(
@ -2348,66 +2207,3 @@ void ScalarEvolution::print(std::ostream &OS) const {
PrintLoopInfo(OS, this, *I); PrintLoopInfo(OS, this, *I);
} }
//===----------------------------------------------------------------------===//
// ScalarEvolutionRewriter Class Implementation
//===----------------------------------------------------------------------===//
Value *ScalarEvolutionRewriter::
GetOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty) {
assert((Ty->isInteger() || Ty->isFloatingPoint()) &&
"Can only insert integer or floating point induction variables!");
// Check to see if we already inserted one.
SCEVHandle H = SCEVAddRecExpr::get(getIntegerSCEV(0, Ty),
getIntegerSCEV(1, Ty), L);
return ExpandCodeFor(H, 0, Ty);
}
/// ExpandCodeFor - Insert code to directly compute the specified SCEV
/// expression into the program. The inserted code is inserted into the
/// specified block.
Value *ScalarEvolutionRewriter::ExpandCodeFor(SCEVHandle SH,
Instruction *InsertPt,
const Type *Ty) {
std::map<SCEVHandle, Value*>::iterator ExistVal =InsertedExpressions.find(SH);
Value *V;
if (ExistVal != InsertedExpressions.end()) {
V = ExistVal->second;
} else {
// Ask the recurrence object to expand the code for itself.
V = SH->expandCodeFor(*this, InsertPt);
// Cache the generated result.
InsertedExpressions.insert(std::make_pair(SH, V));
}
if (Ty == 0 || V->getType() == Ty)
return V;
if (Constant *C = dyn_cast<Constant>(V))
return ConstantExpr::getCast(C, Ty);
else if (Instruction *I = dyn_cast<Instruction>(V)) {
// Check to see if there is already a cast. If there is, use it.
for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
UI != E; ++UI) {
if ((*UI)->getType() == Ty)
if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI))) {
BasicBlock::iterator It = I; ++It;
while (isa<PHINode>(It)) ++It;
if (It != BasicBlock::iterator(CI)) {
// Splice the cast immediately after the operand in question.
I->getParent()->getInstList().splice(It,
CI->getParent()->getInstList(),
CI);
}
return CI;
}
}
BasicBlock::iterator IP = I; ++IP;
if (InvokeInst *II = dyn_cast<InvokeInst>(I))
IP = II->getNormalDest()->begin();
while (isa<PHINode>(IP)) ++IP;
return new CastInst(V, Ty, V->getName(), IP);
} else {
// FIXME: check to see if there is already a cast!
return new CastInst(V, Ty, V->getName(), InsertPt);
}
}