Changes in directory llvm/lib/Transforms/Scalar:
LoopStrengthReduce.cpp updated: 1.85 -> 1.86
---
Log message:
Only reuse a previous IV if it would not require a type conversion.
---
Diffs of the changes: (+17 -14)
LoopStrengthReduce.cpp | 31 +++++++++++++++++--------------
1 files changed, 17 insertions(+), 14 deletions(-)
Index: llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
diff -u llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:1.85
llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:1.86
--- llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:1.85 Wed Jun 28
18:17:24 2006
+++ llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp Tue Jul 18 14:07:58 2006
@@ -187,7 +187,7 @@
void OptimizeIndvars(Loop *L);
- unsigned CheckForIVReuse(const SCEVHandle &Stride, IVExpr &IV);
+ unsigned CheckForIVReuse(const SCEVHandle&, IVExpr&, const Type*);
void StrengthReduceStridedIVUsers(const SCEVHandle &Stride,
IVUsersOfOneStride &Uses,
@@ -872,7 +872,7 @@
/// mode scale component. This allows the users of this stride to be rewritten
/// as prev iv * factor. It returns 0 if no reuse is possible.
unsigned LoopStrengthReduce::CheckForIVReuse(const SCEVHandle &Stride,
- IVExpr &IV) {
+ IVExpr &IV, const Type *Ty) {
if (!TLI) return 0;
if (SCEVConstant *SC = dyn_cast<SCEVConstant>(Stride)) {
@@ -892,7 +892,9 @@
for (std::vector<IVExpr>::iterator II = SI->second.IVs.begin(),
IE = SI->second.IVs.end(); II != IE; ++II)
// FIXME: Only handle base == 0 for now.
- if (isZero(II->Base)) {
+ // Only reuse previous IV if it would not require a type conversion.
+ if (isZero(II->Base) &&
+ II->Base->getType()->isLosslesslyConvertibleTo(Ty)) {
IV = *II;
return Scale;
}
@@ -929,13 +931,24 @@
"Base value is not loop invariant!");
}
+ // We now have a whole bunch of uses of like-strided induction variables, but
+ // they might all have different bases. We want to emit one PHI node for
this
+ // stride which we fold as many common expressions (between the IVs) into as
+ // possible. Start by identifying the common expressions in the base values
+ // for the strides (e.g. if we have "A+C+B" and "A+B+D" as our bases, find
+ // "A+B"), emit it to the preheader, then remove the expression from the
+ // UsersToProcess base values.
+ SCEVHandle CommonExprs =
+ RemoveCommonExpressionsFromUseBases(UsersToProcess);
+
// Check if it is possible to reuse a IV with stride that is factor of this
// stride. And the multiple is a number that can be encoded in the scale
// field of the target addressing mode.
PHINode *NewPHI = NULL;
Value *IncV = NULL;
IVExpr ReuseIV;
- unsigned RewriteFactor = CheckForIVReuse(Stride, ReuseIV);
+ unsigned RewriteFactor = CheckForIVReuse(Stride, ReuseIV,
+ CommonExprs->getType());
if (RewriteFactor != 0) {
DEBUG(std::cerr << "BASED ON IV of STRIDE " << *ReuseIV.Stride
<< " and BASE " << *ReuseIV.Base << " :\n");
@@ -943,16 +956,6 @@
IncV = ReuseIV.IncV;
}
- // We now have a whole bunch of uses of like-strided induction variables, but
- // they might all have different bases. We want to emit one PHI node for
this
- // stride which we fold as many common expressions (between the IVs) into as
- // possible. Start by identifying the common expressions in the base values
- // for the strides (e.g. if we have "A+C+B" and "A+B+D" as our bases, find
- // "A+B"), emit it to the preheader, then remove the expression from the
- // UsersToProcess base values.
- SCEVHandle CommonExprs =
- RemoveCommonExpressionsFromUseBases(UsersToProcess);
-
// Next, figure out what we can represent in the immediate fields of
// instructions. If we can represent anything there, move it to the imm
// fields of the BasedUsers. We do this so that it increases the commonality
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