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Fix loops where the header has an exit, fixing a loop-unswitch crash on crafty

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26258 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-02-17 06:39:56 +00:00
parent 8ec18177da
commit 0017d480cc
1 changed files with 15 additions and 13 deletions
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20
lib/Transforms/Scalar/LoopUnswitch.cpp
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@ -136,20 +136,22 @@ static bool LoopValuesUsedOutsideLoop(Loop *L) {
static bool isTrivialLoopExitBlockHelper(Loop *L, BasicBlock *BB, static bool isTrivialLoopExitBlockHelper(Loop *L, BasicBlock *BB,
BasicBlock *&ExitBB, BasicBlock *&ExitBB,
std::set<BasicBlock*> &Visited) { std::set<BasicBlock*> &Visited) {
BasicBlock *Header = L->getHeader(); if (!Visited.insert(BB).second) {
for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI) {
if (!Visited.insert(*SI).second) {
// Already visited and Ok, end of recursion. // Already visited and Ok, end of recursion.
} else if (L->contains(*SI)) { return true;
// Check to see if the successor is a trivial loop exit. } else if (!L->contains(BB)) {
if (!isTrivialLoopExitBlockHelper(L, *SI, ExitBB, Visited))
return false;
} else {
// Otherwise, this is a loop exit, this is fine so long as this is the // Otherwise, this is a loop exit, this is fine so long as this is the
// first exit. // first exit.
if (ExitBB != 0) return false; if (ExitBB != 0) return false;
ExitBB = *SI; ExitBB = BB;
return true;
} }
// Otherwise, this is an unvisited intra-loop node. Check all successors.
for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI) {
// Check to see if the successor is a trivial loop exit.
if (!isTrivialLoopExitBlockHelper(L, *SI, ExitBB, Visited))
return false;
} }
// Okay, everything after this looks good, check to make sure that this block // Okay, everything after this looks good, check to make sure that this block