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Fix PR 3471, and some cleanups.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64177 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen
2009-02-09 22:14:15 +00:00
parent 65b52dffe0
commit 1de17d574c
2 changed files with 65 additions and 17 deletions
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lib/Transforms/Scalar/LoopStrengthReduce.cpp
+32 -17
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@@ -430,8 +430,8 @@ static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L,
if (!AddRec->isAffine()) return false;
// If Start contains an SCEVAddRecExpr from a different loop, other than an
// outer loop of the current loop, reject it. SCEV has no concept of operating
// on one loop at a time so don't confuse it with such expressions.
// outer loop of the current loop, reject it. SCEV has no concept of
// operating on one loop at a time so don't confuse it with such expressions.
if (containsAddRecFromDifferentLoop(Start, L))
return false;
@@ -774,14 +774,14 @@ void BasedUser::RewriteInstructionToUseNewBase(const SCEVHandle &NewBase,
// which need not be an immediate predecessor of this PHI. This way we
// need only one copy of it even if it is referenced multiple times in
// the PHI. We don't do this when the original expression is inside the
// loop because multiple copies sometimes do useful sinking of code in that
// case(?).
// loop because multiple copies sometimes do useful sinking of code in
// that case(?).
Instruction *OldLoc = dyn_cast<Instruction>(OperandValToReplace);
if (L->contains(OldLoc->getParent())) {
// If this is a critical edge, split the edge so that we do not insert the
// code on all predecessor/successor paths. We do this unless this is the
// canonical backedge for this loop, as this can make some inserted code
// be in an illegal position.
// If this is a critical edge, split the edge so that we do not insert
// the code on all predecessor/successor paths. We do this unless this
// is the canonical backedge for this loop, as this can make some
// inserted code be in an illegal position.
BasicBlock *PHIPred = PN->getIncomingBlock(i);
if (e != 1 && PHIPred->getTerminator()->getNumSuccessors() > 1 &&
(PN->getParent() != L->getHeader() || !L->contains(PHIPred))) {
@@ -1224,19 +1224,21 @@ bool LoopStrengthReduce::ValidStride(bool HasBaseReg,
return true;
}
/// RequiresTypeConversion - Returns true if converting Ty to NewTy is not
/// RequiresTypeConversion - Returns true if converting Ty1 to Ty2 is not
/// a nop.
bool LoopStrengthReduce::RequiresTypeConversion(const Type *Ty1,
const Type *Ty2) {
if (Ty1 == Ty2)
return false;
if (Ty1->canLosslesslyBitCastTo(Ty2))
return false;
if (TLI && TLI->isTruncateFree(Ty1, Ty2))
return false;
return (!Ty1->canLosslesslyBitCastTo(Ty2) &&
!(isa<PointerType>(Ty2) &&
Ty1->canLosslesslyBitCastTo(UIntPtrTy)) &&
!(isa<PointerType>(Ty1) &&
Ty2->canLosslesslyBitCastTo(UIntPtrTy)));
if (isa<PointerType>(Ty2) && Ty1->canLosslesslyBitCastTo(UIntPtrTy))
return false;
if (isa<PointerType>(Ty1) && Ty2->canLosslesslyBitCastTo(UIntPtrTy))
return false;
return true;
}
/// CheckForIVReuse - Returns the multiple if the stride is the multiple
@@ -1661,15 +1663,28 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(const SCEVHandle &Stride,
Rewriter.clear();
// If we are reusing the iv, then it must be multiplied by a constant
// factor take advantage of addressing mode scale component.
// factor to take advantage of the addressing mode scale component.
if (!isa<SCEVConstant>(RewriteFactor) ||
!cast<SCEVConstant>(RewriteFactor)->isZero()) {
// If we're reusing an IV with a nonzero base (currently this happens
// only when all reuses are outside the loop) subtract that base here.
// The base has been used to initialize the PHI node but we don't want
// it here.
if (!ReuseIV.Base->isZero())
RewriteExpr = SE->getMinusSCEV(RewriteExpr, ReuseIV.Base);
if (!ReuseIV.Base->isZero()) {
SCEVHandle typedBase = ReuseIV.Base;
if (RewriteExpr->getType()->getPrimitiveSizeInBits() !=
ReuseIV.Base->getType()->getPrimitiveSizeInBits()) {
// It's possible the original IV is a larger type than the new IV,
// in which case we have to truncate the Base. We checked in
// RequiresTypeConversion that this is valid.
assert (RewriteExpr->getType()->getPrimitiveSizeInBits() <
ReuseIV.Base->getType()->getPrimitiveSizeInBits() &&
"Unexpected lengthening conversion!");
typedBase = SE->getTruncateExpr(ReuseIV.Base,
RewriteExpr->getType());
}
RewriteExpr = SE->getMinusSCEV(RewriteExpr, typedBase);
}
// Multiply old variable, with base removed, by new scale factor.
RewriteExpr = SE->getMulExpr(RewriteFactor,