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- Fixed a bogus if condition.

Browse Source 
- Added more debugging info.
- Allow reuse of IV of negative stride. e.g. -4 stride == 2 * iv of -2 stride.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26841 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2006-03-18 08:03:12 +00:00
parent c7029805ef
commit 21495775e7
1 changed files with 25 additions and 19 deletions
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44
lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -77,15 +77,20 @@ namespace {
};
/// IVInfo - This structure keeps track of one IV expression inserted during
/// StrengthReduceStridedIVUsers. It contains the base value, as well as the
/// PHI node and increment value created for rewrite.
/// StrengthReduceStridedIVUsers. It contains the stride, the common base, as
/// well as the PHI node and increment value created for rewrite.
struct IVExpr {
SCEVHandle Stride;
SCEVHandle Base;
PHINode *PHI;
Value *IncV;
IVExpr(const SCEVHandle &base, PHINode *phi, Value *incv)
: Base(base), PHI(phi), IncV(incv) {}
IVExpr()
: Stride(SCEVUnknown::getIntegerSCEV(0, Type::UIntTy)),
Base (SCEVUnknown::getIntegerSCEV(0, Type::UIntTy)) {}
IVExpr(const SCEVHandle &stride, const SCEVHandle &base, PHINode *phi,
Value *incv)
: Stride(stride), Base(base), PHI(phi), IncV(incv) {}
};
/// IVsOfOneStride - This structure keeps track of all IV expression inserted
@ -93,8 +98,9 @@ namespace {
struct IVsOfOneStride {
std::vector<IVExpr> IVs;
void addIV(const SCEVHandle &Base, PHINode *PHI, Value *IncV) {
IVs.push_back(IVExpr(Base, PHI, IncV));
void addIV(const SCEVHandle &Stride, const SCEVHandle &Base, PHINode *PHI,
Value *IncV) {
IVs.push_back(IVExpr(Stride, Base, PHI, IncV));
}
};
@ -863,22 +869,20 @@ static bool isZero(SCEVHandle &V) {
/// CheckForIVReuse - Returns the multiple if the stride is the multiple
/// of a previous stride and it is a legal value for the target addressing
/// mode scale component. This allows the users of this stride to be rewritten
/// as prev iv * factor. It returns 1 if no reuse is possible.
/// as prev iv * factor. It returns 0 if no reuse is possible.
unsigned LoopStrengthReduce::CheckForIVReuse(const SCEVHandle &Stride,
IVExpr &IV) {
if (!TLI)
return 1;
if (!TLI) return 0;
if (SCEVConstant *SC = dyn_cast<SCEVConstant>(Stride)) {
unsigned SInt = SC->getValue()->getRawValue();
if (SInt == 1)
return 1;
int64_t SInt = SC->getValue()->getSExtValue();
if (SInt == 1) return 0;
for (TargetLowering::legal_am_scale_iterator
I = TLI->legal_am_scale_begin(), E = TLI->legal_am_scale_end();
I != E; ++I) {
unsigned Scale = *I;
if (SInt >= Scale && (SInt % Scale) != 0)
if (abs(SInt) < Scale || (SInt % Scale) != 0)
continue;
std::map<SCEVHandle, IVsOfOneStride>::iterator SI =
IVsByStride.find(SCEVUnknown::getIntegerSCEV(SInt/Scale, Type::UIntTy));
@ -894,7 +898,7 @@ unsigned LoopStrengthReduce::CheckForIVReuse(const SCEVHandle &Stride,
}
}
return 1;
return 0;
}
@ -929,9 +933,11 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(const SCEVHandle &Stride,
// field of the target addressing mode.
PHINode *NewPHI = NULL;
Value *IncV = NULL;
IVExpr ReuseIV(Stride, NULL, NULL);
IVExpr ReuseIV;
unsigned RewriteFactor = CheckForIVReuse(Stride, ReuseIV);
if (RewriteFactor > 1) {
if (RewriteFactor != 0) {
DEBUG(std::cerr << "BASED ON IV of STRIDE " << *ReuseIV.Stride
<< " and BASE " << *ReuseIV.Base << " :\n");
NewPHI = ReuseIV.PHI;
IncV = ReuseIV.IncV;
}
@ -994,7 +1000,7 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(const SCEVHandle &Stride,
= PreheaderRewriter.expandCodeFor(CommonExprs, PreInsertPt,
ReplacedTy);
if (RewriteFactor == 1) {
if (RewriteFactor == 0) {
// Create a new Phi for this base, and stick it in the loop header.
NewPHI = new PHINode(ReplacedTy, "iv.", PhiInsertBefore);
++NumInserted;
@ -1018,7 +1024,7 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(const SCEVHandle &Stride,
NewPHI->addIncoming(IncV, LatchBlock);
// Remember this in case a later stride is multiple of this.
IVsByStride[Stride].addIV(CommonExprs, NewPHI, IncV);
IVsByStride[Stride].addIV(Stride, CommonExprs, NewPHI, IncV);
} else {
Constant *C = dyn_cast<Constant>(CommonBaseV);
if (!C ||
@ -1076,7 +1082,7 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(const SCEVHandle &Stride,
// If we are reusing the iv, then it must be multiplied by a constant
// factor take advantage of addressing mode scale component.
if (RewriteFactor != 1) {
if (RewriteFactor != 0) {
RewriteExpr =
SCEVMulExpr::get(SCEVUnknown::getIntegerSCEV(RewriteFactor,
RewriteExpr->getType()),