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Generalize the ChangeCompareStride code, in preparation for 

handling non-constant strides. No functionality change.

llvm-svn: 65363
This commit is contained in:
Dan Gohman 2009-02-24 01:58:00 +00:00
parent 94ceb61574
commit 5d1f458f0f
1 changed files with 102 additions and 100 deletions
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24
llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -2133,15 +2133,12 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
return Cond;
const SCEVConstant *SC = dyn_cast<SCEVConstant>(*CondStride);
if (!SC) return Cond;
ConstantInt *C = dyn_cast<ConstantInt>(Cond->getOperand(1));
if (!C) return Cond;
ICmpInst::Predicate Predicate = Cond->getPredicate();
int64_t CmpSSInt = SC->getValue()->getSExtValue();
int64_t CmpVal = C->getValue().getSExtValue();
unsigned BitWidth = C->getValue().getBitWidth();
unsigned BitWidth = (*CondStride)->getBitWidth();
uint64_t SignBit = 1ULL << (BitWidth-1);
const Type *CmpTy = C->getType();
const Type *CmpTy = Cond->getOperand(0)->getType();
const Type *NewCmpTy = NULL;
unsigned TyBits = CmpTy->getPrimitiveSizeInBits();
unsigned NewTyBits = 0;
@ -2149,6 +2146,11 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
Value *NewCmpLHS = NULL;
Value *NewCmpRHS = NULL;
int64_t Scale = 1;
SCEVHandle NewOffset = SE->getIntegerSCEV(0, UIntPtrTy);
std::stable_sort(StrideOrder.begin(), StrideOrder.end(), StrideCompare());
if (ConstantInt *C = dyn_cast<ConstantInt>(Cond->getOperand(1))) {
int64_t CmpVal = C->getValue().getSExtValue();
// Check stride constant and the comparision constant signs to detect
// overflow.
@ -2156,7 +2158,6 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
return Cond;
// Look for a suitable stride / iv as replacement.
std::stable_sort(StrideOrder.begin(), StrideOrder.end(), StrideCompare());
for (unsigned i = 0, e = StrideOrder.size(); i != e; ++i) {
std::map<SCEVHandle, IVUsersOfOneStride>::iterator SI =
IVUsesByStride.find(StrideOrder[i]);
@ -2244,8 +2245,14 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
NewCmpRHS = SCEVExpander::InsertCastOfTo(Instruction::IntToPtr,
NewCmpRHS, NewCmpTy);
}
NewOffset = TyBits == NewTyBits
? SE->getMulExpr(CondUse->Offset,
SE->getConstant(ConstantInt::get(CmpTy, Scale)))
: SE->getConstant(ConstantInt::get(NewCmpTy,
cast<SCEVConstant>(CondUse->Offset)->getValue()->getSExtValue()*Scale));
break;
}
}
// Forgo this transformation if it the increment happens to be
// unfortunately positioned after the condition, and the condition
@ -2275,11 +2282,6 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
OldCond->eraseFromParent();
IVUsesByStride[*CondStride].Users.pop_back();
SCEVHandle NewOffset = TyBits == NewTyBits
? SE->getMulExpr(CondUse->Offset,
SE->getConstant(ConstantInt::get(CmpTy, Scale)))
: SE->getConstant(ConstantInt::get(NewCmpTy,
cast<SCEVConstant>(CondUse->Offset)->getValue()->getSExtValue()*Scale));
IVUsesByStride[*NewStride].addUser(NewOffset, Cond, NewCmpLHS);
CondUse = &IVUsesByStride[*NewStride].Users.back();
CondStride = NewStride;