Simplify this code. LoopDeletion doesn't need to explicit check that
the loop exiting block dominates the latch block; if ScalarEvolution
can prove that the trip-count is finite, that's sufficient.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85165 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/LoopDeletion.cpp b/lib/Transforms/Scalar/LoopDeletion.cpp
index 8133a06..3fb6c91 100644
--- a/lib/Transforms/Scalar/LoopDeletion.cpp
+++ b/lib/Transforms/Scalar/LoopDeletion.cpp
@@ -33,8 +33,6 @@
// Possibly eliminate loop L if it is dead.
bool runOnLoop(Loop* L, LPPassManager& LPM);
- bool SingleDominatingExit(Loop* L,
- SmallVector<BasicBlock*, 4>& exitingBlocks);
bool IsLoopDead(Loop* L, SmallVector<BasicBlock*, 4>& exitingBlocks,
SmallVector<BasicBlock*, 4>& exitBlocks,
bool &Changed, BasicBlock *Preheader);
@@ -63,25 +61,6 @@
return new LoopDeletion();
}
-/// SingleDominatingExit - Checks that there is only a single blocks that
-/// branches out of the loop, and that it also g the latch block. Loops
-/// with multiple or non-latch-dominating exiting blocks could be dead, but we'd
-/// have to do more extensive analysis to make sure, for instance, that the
-/// control flow logic involved was or could be made loop-invariant.
-bool LoopDeletion::SingleDominatingExit(Loop* L,
- SmallVector<BasicBlock*, 4>& exitingBlocks) {
-
- if (exitingBlocks.size() != 1)
- return false;
-
- BasicBlock* latch = L->getLoopLatch();
- if (!latch)
- return false;
-
- DominatorTree& DT = getAnalysis<DominatorTree>();
- return DT.dominates(exitingBlocks[0], latch);
-}
-
/// IsLoopDead - Determined if a loop is dead. This assumes that we've already
/// checked for unique exit and exiting blocks, and that the code is in LCSSA
/// form.
@@ -154,9 +133,8 @@
if (exitBlocks.size() != 1)
return false;
- // Loops with multiple exits or exits that don't dominate the latch
- // are too complicated to handle correctly.
- if (!SingleDominatingExit(L, exitingBlocks))
+ // Loops with multiple exits are too complicated to handle correctly.
+ if (exitingBlocks.size() != 1)
return false;
// Finally, we have to check that the loop really is dead.