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Fix a bug in the unreachable block elim pass. Dropping all references on a

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basic block clear()'s all of the operands lists, including phis.  This
caused removePredecessor to get confused later.  Because of this, we just
nuke (without prejudice) PHI nodes in unreachable blocks.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@14635 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-07-06 06:36:11 +00:00
parent ba466362c4
commit 7f0566c123
1 changed files with 11 additions and 4 deletions
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15
lib/CodeGen/UnreachableBlockElim.cpp
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@ -21,6 +21,8 @@
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/Passes.h"
#include "llvm/iPHINode.h"
#include "llvm/Constant.h"
#include "llvm/Function.h"
#include "llvm/Pass.h"
#include "llvm/Support/CFG.h"
@ -52,10 +54,15 @@ bool UnreachableBlockElim::runOnFunction(Function &F) {
std::vector<BasicBlock*> DeadBlocks;
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
if (!Reachable.count(I)) {
DeadBlocks.push_back(I);
for (succ_iterator SI = succ_begin(&*I), E = succ_end(&*I); SI != E; ++SI)
(*SI)->removePredecessor(I);
I->dropAllReferences();
BasicBlock *BB = I;
DeadBlocks.push_back(BB);
while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) {
PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
BB->getInstList().pop_front();
}
for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
(*SI)->removePredecessor(BB);
BB->dropAllReferences();
}
if (DeadBlocks.empty()) return false;