[llvm-commits] [llvm] r96382 - /llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
Dan Gohman
gohman at apple.com
Tue Feb 16 12:25:20 PST 2010
Author: djg
Date: Tue Feb 16 14:25:07 2010
New Revision: 96382
URL: http://llvm.org/viewvc/llvm-project?rev=96382&view=rev
Log:
Refactor rewriting for PHI nodes into a separate function.
Modified:
llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=96382&r1=96381&r2=96382&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Tue Feb 16 14:25:07 2010
@@ -1188,6 +1188,13 @@
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 @@
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 @@
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),
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