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Revert r80926. It causes loop unswitch assertion and slow down some JIT tests significantly.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81101 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2009-09-06 02:26:10 +00:00
parent 92a97a9166
commit 8f78a58e14
11 changed files with 195 additions and 287 deletions
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65
lib/Transforms/Utils/BreakCriticalEdges.cpp
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@@ -122,9 +122,9 @@ bool llvm::isCriticalEdge(const TerminatorInst *TI, unsigned SuccNum,
/// false otherwise. This ensures that all edges to that dest go to one block
/// instead of each going to a different block.
//
BasicBlock *llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum,
Pass *P, bool MergeIdenticalEdges) {
if (!isCriticalEdge(TI, SuccNum, MergeIdenticalEdges)) return 0;
bool llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P,
bool MergeIdenticalEdges) {
if (!isCriticalEdge(TI, SuccNum, MergeIdenticalEdges)) return false;
BasicBlock *TIBB = TI->getParent();
BasicBlock *DestBB = TI->getSuccessor(SuccNum);
@@ -172,7 +172,7 @@ BasicBlock *llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum,
// If we don't have a pass object, we can't update anything...
if (P == 0) return NewBB;
if (P == 0) return true;
// Now update analysis information. Since the only predecessor of NewBB is
// the TIBB, TIBB clearly dominates NewBB. TIBB usually doesn't dominate
@@ -254,9 +254,9 @@ BasicBlock *llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum,
// Update LoopInfo if it is around.
if (LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>()) {
if (Loop *TIL = LI->getLoopFor(TIBB)) {
// If one or the other blocks were not in a loop, the new block is not
// either, and thus LI doesn't need to be updated.
// If one or the other blocks were not in a loop, the new block is not
// either, and thus LI doesn't need to be updated.
if (Loop *TIL = LI->getLoopFor(TIBB))
if (Loop *DestLoop = LI->getLoopFor(DestBB)) {
if (TIL == DestLoop) {
// Both in the same loop, the NewBB joins loop.
@@ -278,55 +278,6 @@ BasicBlock *llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum,
P->addBasicBlockToLoop(NewBB, LI->getBase());
}
}
// If TIBB is in a loop and DestBB is outside of that loop, split the
// other exit blocks of the loop that also have predecessors outside
// the loop, to maintain a LoopSimplify guarantee.
if (!TIL->contains(DestBB) &&
P->mustPreserveAnalysisID(LoopSimplifyID)) {
// For each unique exit block...
SmallVector<BasicBlock *, 4> ExitBlocks;
TIL->getExitBlocks(ExitBlocks);
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
// Collect all the preds that are inside the loop, and note
// whether there are any preds outside the loop.
SmallVector<BasicBlock *, 4> Preds;
bool AllPredsInLoop = false;
BasicBlock *Exit = ExitBlocks[i];
for (pred_iterator I = pred_begin(Exit), E = pred_end(Exit);
I != E; ++I)
if (TIL->contains(*I))
Preds.push_back(*I);
else
AllPredsInLoop = true;
// If there are any preds not in the loop, we'll need to split
// the edges. The Preds.empty() check is needed because a block
// may appear multiple times in the list. We can't use
// getUniqueExitBlocks above because that depends on LoopSimplify
// form, which we're in the process of restoring!
if (Preds.empty() || !AllPredsInLoop) continue;
BasicBlock *NewBB = SplitBlockPredecessors(Exit,
Preds.data(), Preds.size(),
"split", P);
// Update LCSSA form. This is fairly simple in LoopSimplify form:
// just move the existing LCSSA-mandated PHI nodes from the old exit
// block to the new one.
if (P->mustPreserveAnalysisID(LCSSAID))
for (BasicBlock::iterator I = Exit->begin();
PHINode *PN = dyn_cast<PHINode>(I); ++I)
PN->moveBefore(NewBB->getTerminator());
}
}
// LCSSA form was updated above for the case where LoopSimplify is
// available, which means that all predecessors of loop exit blocks
// are within the loop. Without LoopSimplify form, it would be
// necessary to insert a new phi.
assert((!P->mustPreserveAnalysisID(LCSSAID) ||
P->mustPreserveAnalysisID(LoopSimplifyID)) &&
"SplitCriticalEdge doesn't know how to update LCCSA form "
"without LoopSimplify!");
}
}
return NewBB;
return true;
}