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Let simplify cfg simplify bb with only debug and lifetime intrinsics.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134057 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola
2011-06-29 05:25:47 +00:00
parent c4a84304a0
commit 0fb7dcd48f
5 changed files with 68 additions and 11 deletions
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lib/Transforms/Utils/Local.cpp
+12 -10
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@@ -536,9 +536,9 @@ static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
/// TryToSimplifyUncondBranchFromEmptyBlock - BB is known to contain an
/// unconditional branch, and contains no instructions other than PHI nodes,
/// potential debug intrinsics and the branch. If possible, eliminate BB by
/// rewriting all the predecessors to branch to the successor block and return
/// true. If we can't transform, return false.
/// potential side-effect free intrinsics and the branch. If possible,
/// eliminate BB by rewriting all the predecessors to branch to the successor
/// block and return true. If we can't transform, return false.
bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB) {
assert(BB != &BB->getParent()->getEntryBlock() &&
"TryToSimplifyUncondBranchFromEmptyBlock called on entry block!");
@@ -613,13 +613,15 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB) {
}
}
while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
if (Succ->getSinglePredecessor()) {
// BB is the only predecessor of Succ, so Succ will end up with exactly
// the same predecessors BB had.
Succ->getInstList().splice(Succ->begin(),
BB->getInstList(), BB->begin());
} else {
if (Succ->getSinglePredecessor()) {
// BB is the only predecessor of Succ, so Succ will end up with exactly
// the same predecessors BB had.
// Copy over any phi, debug or lifetime instruction.
BB->getTerminator()->eraseFromParent();
Succ->getInstList().splice(Succ->begin(), BB->getInstList());
} else {
while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
// We explicitly check for such uses in CanPropagatePredecessorsForPHIs.
assert(PN->use_empty() && "There shouldn't be any uses here!");
PN->eraseFromParent();