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Avoid inserting an entry block unless we need it

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llvm-svn: 3336
This commit is contained in:
Chris Lattner 2002-08-14 21:35:02 +00:00
parent 2f101c0f0e
commit 80b897953e
1 changed files with 9 additions and 5 deletions
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14
lib/Transforms/Scalar/ADCE.cpp
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@ -235,11 +235,15 @@ bool ADCE::doADCE() {
dropReferencesOfDeadInstructionsInLiveBlock(I);
} else { // If there are some blocks dead...
// Insert a new entry node to eliminate the entry node as a special case.
BasicBlock *NewEntry = new BasicBlock();
NewEntry->getInstList().push_back(new BranchInst(&Func->front()));
Func->getBasicBlockList().push_front(NewEntry);
AliveBlocks.insert(NewEntry); // This block is always alive!
// If the entry node is dead, insert a new entry node to eliminate the entry
// node as a special case.
//
if (!AliveBlocks.count(&Func->front())) {
BasicBlock *NewEntry = new BasicBlock();
NewEntry->getInstList().push_back(new BranchInst(&Func->front()));
Func->getBasicBlockList().push_front(NewEntry);
AliveBlocks.insert(NewEntry); // This block is always alive!
}
// Loop over all of the alive blocks in the function. If any successor
// blocks are not alive, we adjust the outgoing branches to branch to the