Revert r80926. It causes loop unswitch assertion and slow down some JIT tests significantly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81101 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/BreakCriticalEdges.cpp b/lib/Transforms/Utils/BreakCriticalEdges.cpp
index f5a1366..632aa2b 100644
--- a/lib/Transforms/Utils/BreakCriticalEdges.cpp
+++ b/lib/Transforms/Utils/BreakCriticalEdges.cpp
@@ -122,9 +122,9 @@
/// 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 @@
// 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 @@
// 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 @@
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;
}