//
//===----------------------------------------------------------------------===//
-#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
+#include "llvm/Analysis/LoopInfo.h"
using namespace llvm;
+/// InsertCastOfTo - Insert a cast of V to the specified type, doing what
+/// we can to share the casts.
+Value *SCEVExpander::InsertCastOfTo(Instruction::CastOps opcode, Value *V,
+ const Type *Ty) {
+ // FIXME: keep track of the cast instruction.
+ if (Constant *C = dyn_cast<Constant>(V))
+ return ConstantExpr::getCast(opcode, C, Ty);
+
+ if (Argument *A = dyn_cast<Argument>(V)) {
+ // Check to see if there is already a cast!
+ for (Value::use_iterator UI = A->use_begin(), E = A->use_end();
+ UI != E; ++UI) {
+ if ((*UI)->getType() == Ty)
+ if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI))) {
+ // If the cast isn't the first instruction of the function, move it.
+ if (BasicBlock::iterator(CI) !=
+ A->getParent()->getEntryBlock().begin()) {
+ CI->moveBefore(A->getParent()->getEntryBlock().begin());
+ }
+ return CI;
+ }
+ }
+ return CastInst::create(opcode, V, Ty, V->getName(),
+ A->getParent()->getEntryBlock().begin());
+ }
+
+ Instruction *I = 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;
+ if (isa<InvokeInst>(I))
+ It = cast<InvokeInst>(I)->getNormalDest()->begin();
+ while (isa<PHINode>(It)) ++It;
+ if (It != BasicBlock::iterator(CI)) {
+ // Splice the cast immediately after the operand in question.
+ CI->moveBefore(It);
+ }
+ return CI;
+ }
+ }
+ BasicBlock::iterator IP = I; ++IP;
+ if (InvokeInst *II = dyn_cast<InvokeInst>(I))
+ IP = II->getNormalDest()->begin();
+ while (isa<PHINode>(IP)) ++IP;
+ return CastInst::create(opcode, V, Ty, V->getName(), IP);
+}
+
+/// InsertBinop - Insert the specified binary operator, doing a small amount
+/// of work to avoid inserting an obviously redundant operation.
+Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, Value *LHS,
+ Value *RHS, Instruction *&InsertPt) {
+ // Fold a binop with constant operands.
+ if (Constant *CLHS = dyn_cast<Constant>(LHS))
+ if (Constant *CRHS = dyn_cast<Constant>(RHS))
+ return ConstantExpr::get(Opcode, CLHS, CRHS);
+
+ // Do a quick scan to see if we have this binop nearby. If so, reuse it.
+ unsigned ScanLimit = 6;
+ for (BasicBlock::iterator IP = InsertPt, E = InsertPt->getParent()->begin();
+ ScanLimit; --IP, --ScanLimit) {
+ if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(IP))
+ if (BinOp->getOpcode() == Opcode && BinOp->getOperand(0) == LHS &&
+ BinOp->getOperand(1) == RHS) {
+ // If we found the instruction *at* the insert point, insert later
+ // instructions after it.
+ if (BinOp == InsertPt)
+ InsertPt = ++IP;
+ return BinOp;
+ }
+ if (IP == E) break;
+ }
+
+ // If we don't have
+ return BinaryOperator::create(Opcode, LHS, RHS, "tmp", InsertPt);
+}
+
Value *SCEVExpander::visitMulExpr(SCEVMulExpr *S) {
- const Type *Ty = S->getType();
int FirstOp = 0; // Set if we should emit a subtract.
if (SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getOperand(0)))
if (SC->getValue()->isAllOnesValue())
FirstOp = 1;
int i = S->getNumOperands()-2;
- Value *V = expandInTy(S->getOperand(i+1), Ty);
+ Value *V = expand(S->getOperand(i+1));
// Emit a bunch of multiply instructions
for (; i >= FirstOp; --i)
- V = BinaryOperator::createMul(V, expandInTy(S->getOperand(i), Ty),
- "tmp.", InsertPt);
+ V = InsertBinop(Instruction::Mul, V, expand(S->getOperand(i)),
+ InsertPt);
// -1 * ... ---> 0 - ...
if (FirstOp == 1)
- V = BinaryOperator::createNeg(V, "tmp.", InsertPt);
+ V = InsertBinop(Instruction::Sub, Constant::getNullValue(V->getType()), V,
+ InsertPt);
return V;
}
const Type *Ty = S->getType();
const Loop *L = S->getLoop();
// We cannot yet do fp recurrences, e.g. the xform of {X,+,F} --> X+{0,+,F}
- assert(Ty->isIntegral() && "Cannot expand fp recurrences yet!");
+ assert(Ty->isInteger() && "Cannot expand fp recurrences yet!");
// {X,+,F} --> X + {0,+,F}
if (!isa<SCEVConstant>(S->getStart()) ||
- !cast<SCEVConstant>(S->getStart())->getValue()->isNullValue()) {
- Value *Start = expandInTy(S->getStart(), Ty);
+ !cast<SCEVConstant>(S->getStart())->getValue()->isZero()) {
+ Value *Start = expand(S->getStart());
std::vector<SCEVHandle> NewOps(S->op_begin(), S->op_end());
NewOps[0] = SCEVUnknown::getIntegerSCEV(0, Ty);
- Value *Rest = expandInTy(SCEVAddRecExpr::get(NewOps, L), Ty);
+ Value *Rest = expand(SCEVAddRecExpr::get(NewOps, L));
// FIXME: look for an existing add to use.
- return BinaryOperator::createAdd(Rest, Start, "tmp.", InsertPt);
+ return InsertBinop(Instruction::Add, Rest, Start, InsertPt);
}
// {0,+,1} --> Insert a canonical induction variable into the 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)
- : ConstantInt::get(Ty, 1);
+ Constant *One = ConstantInt::get(Ty, 1);
Instruction *Add = BinaryOperator::createAdd(PN, One, "indvar.next",
(*HPI)->getTerminator());
// If this is a simple linear addrec, emit it now as a special case.
if (S->getNumOperands() == 2) { // {0,+,F} --> i*F
- Value *F = expandInTy(S->getOperand(1), Ty);
+ Value *F = expand(S->getOperand(1));
// IF the step is by one, just return the inserted IV.
- if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(F))
- if (CI->getRawValue() == 1)
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(F))
+ if (CI->getValue() == 1)
return I;
// If the insert point is directly inside of the loop, emit the multiply at
}
}
- return BinaryOperator::createMul(I, F, "tmp.", MulInsertPt);
+ return InsertBinop(Instruction::Mul, I, F, MulInsertPt);
}
// If this is a chain of recurrences, turn it into a closed form, using the
SCEVHandle IH = SCEVUnknown::get(I); // Get I as a "symbolic" SCEV.
SCEVHandle V = S->evaluateAtIteration(IH);
- //std::cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
+ //cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
- return expandInTy(V, Ty);
+ return expand(V);
}
+
+Value *SCEVExpander::expand(SCEV *S) {
+ // Check to see if we already expanded this.
+ std::map<SCEVHandle, Value*>::iterator I = InsertedExpressions.find(S);
+ if (I != InsertedExpressions.end())
+ return I->second;
+
+ Value *V = visit(S);
+ InsertedExpressions[S] = V;
+ return V;
+}
+
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