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Refactor rewriting for PHI nodes into a separate function.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96382 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-02-16 20:25:07 +00:00
parent 0a145f3d90
commit 3a02cbcd03
1 changed files with 70 additions and 49 deletions
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119
lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -1188,6 +1188,13 @@ public:
SCEVExpander &Rewriter,
SmallVectorImpl<WeakVH> &DeadInsts,
ScalarEvolution &SE, DominatorTree &DT) const;
void RewriteForPHI(PHINode *PN, const LSRFixup &LF,
const Formula &F,
Loop *L, Instruction *IVIncInsertPos,
SCEVExpander &Rewriter,
SmallVectorImpl<WeakVH> &DeadInsts,
ScalarEvolution &SE, DominatorTree &DT,
Pass *P) const;
void Rewrite(const LSRFixup &LF,
const Formula &F,
Loop *L, Instruction *IVIncInsertPos,
@ -2921,6 +2928,67 @@ Value *LSRInstance::Expand(const LSRFixup &LF,
return FullV;
}
/// RewriteForPHI - Helper for Rewrite. PHI nodes are special because the use
/// of their operands effectively happens in their predecessor blocks, so the
/// expression may need to be expanded in multiple places.
void LSRInstance::RewriteForPHI(PHINode *PN,
const LSRFixup &LF,
const Formula &F,
Loop *L, Instruction *IVIncInsertPos,
SCEVExpander &Rewriter,
SmallVectorImpl<WeakVH> &DeadInsts,
ScalarEvolution &SE, DominatorTree &DT,
Pass *P) const {
DenseMap<BasicBlock *, Value *> Inserted;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (PN->getIncomingValue(i) == LF.OperandValToReplace) {
BasicBlock *BB = PN->getIncomingBlock(i);
// 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, which complicates post-inc
// users.
if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 &&
!isa<IndirectBrInst>(BB->getTerminator()) &&
(PN->getParent() != L->getHeader() || !L->contains(BB))) {
// Split the critical edge.
BasicBlock *NewBB = SplitCriticalEdge(BB, PN->getParent(), P);
// If PN is outside of the loop and BB is in the loop, we want to
// move the block to be immediately before the PHI block, not
// immediately after BB.
if (L->contains(BB) && !L->contains(PN))
NewBB->moveBefore(PN->getParent());
// Splitting the edge can reduce the number of PHI entries we have.
e = PN->getNumIncomingValues();
BB = NewBB;
i = PN->getBasicBlockIndex(BB);
}
std::pair<DenseMap<BasicBlock *, Value *>::iterator, bool> Pair =
Inserted.insert(std::make_pair(BB, static_cast<Value *>(0)));
if (!Pair.second)
PN->setIncomingValue(i, Pair.first->second);
else {
Value *FullV = Expand(LF, F, BB->getTerminator(), L, IVIncInsertPos,
Rewriter, DeadInsts, SE, DT);
// If this is reuse-by-noop-cast, insert the noop cast.
const Type *OpTy = LF.OperandValToReplace->getType();
if (FullV->getType() != OpTy)
FullV =
CastInst::Create(CastInst::getCastOpcode(FullV, false,
OpTy, false),
FullV, LF.OperandValToReplace->getType(),
"tmp", BB->getTerminator());
PN->setIncomingValue(i, FullV);
Pair.first->second = FullV;
}
}
}
/// Rewrite - Emit instructions for the leading candidate expression for this
/// LSRUse (this is called "expanding"), and update the UserInst to reference
/// the newly expanded value.
@ -2931,63 +2999,16 @@ void LSRInstance::Rewrite(const LSRFixup &LF,
SmallVectorImpl<WeakVH> &DeadInsts,
ScalarEvolution &SE, DominatorTree &DT,
Pass *P) const {
const Type *OpTy = LF.OperandValToReplace->getType();
// First, find an insertion point that dominates UserInst. For PHI nodes,
// find the nearest block which dominates all the relevant uses.
if (PHINode *PN = dyn_cast<PHINode>(LF.UserInst)) {
DenseMap<BasicBlock *, Value *> Inserted;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (PN->getIncomingValue(i) == LF.OperandValToReplace) {
BasicBlock *BB = PN->getIncomingBlock(i);
// 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, which complicates post-inc
// users.
if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 &&
!isa<IndirectBrInst>(BB->getTerminator()) &&
(PN->getParent() != L->getHeader() || !L->contains(BB))) {
// Split the critical edge.
BasicBlock *NewBB = SplitCriticalEdge(BB, PN->getParent(), P);
// If PN is outside of the loop and BB is in the loop, we want to
// move the block to be immediately before the PHI block, not
// immediately after BB.
if (L->contains(BB) && !L->contains(PN))
NewBB->moveBefore(PN->getParent());
// Splitting the edge can reduce the number of PHI entries we have.
e = PN->getNumIncomingValues();
BB = NewBB;
i = PN->getBasicBlockIndex(BB);
}
std::pair<DenseMap<BasicBlock *, Value *>::iterator, bool> Pair =
Inserted.insert(std::make_pair(BB, static_cast<Value *>(0)));
if (!Pair.second)
PN->setIncomingValue(i, Pair.first->second);
else {
Value *FullV = Expand(LF, F, BB->getTerminator(), L, IVIncInsertPos,
Rewriter, DeadInsts, SE, DT);
// If this is reuse-by-noop-cast, insert the noop cast.
if (FullV->getType() != OpTy)
FullV =
CastInst::Create(CastInst::getCastOpcode(FullV, false,
OpTy, false),
FullV, LF.OperandValToReplace->getType(),
"tmp", BB->getTerminator());
PN->setIncomingValue(i, FullV);
Pair.first->second = FullV;
}
}
RewriteForPHI(PN, LF, F, L, IVIncInsertPos, Rewriter, DeadInsts, SE, DT, P);
} else {
Value *FullV = Expand(LF, F, LF.UserInst, L, IVIncInsertPos,
Rewriter, DeadInsts, SE, DT);
// If this is reuse-by-noop-cast, insert the noop cast.
const Type *OpTy = LF.OperandValToReplace->getType();
if (FullV->getType() != OpTy) {
Instruction *Cast =
CastInst::Create(CastInst::getCastOpcode(FullV, false, OpTy, false),