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If an alias is dead and so is its aliasee, then globaldce would

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crash because the alias would still be using the aliasee when the
aliasee was deleted.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64844 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands 2009-02-17 23:05:26 +00:00
parent 0d90e5d08b
commit cdf5ffb7fb
2 changed files with 20 additions and 8 deletions
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24
lib/Transforms/IPO/GlobalDCE.cpp
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@ -82,7 +82,7 @@ bool GlobalDCE::runOnModule(Module &M) {
I != E; ++I) { I != E; ++I) {
Changed |= RemoveUnusedGlobalValue(*I); Changed |= RemoveUnusedGlobalValue(*I);
// Externally visible aliases are needed. // Externally visible aliases are needed.
if (!I->hasInternalLinkage() && !I->hasLinkOnceLinkage()) if (!I->hasLocalLinkage() && !I->hasLinkOnceLinkage())
GlobalIsNeeded(I); GlobalIsNeeded(I);
} }
@ -107,6 +107,15 @@ bool GlobalDCE::runOnModule(Module &M) {
I->deleteBody(); I->deleteBody();
} }
// The third pass drops targets of aliases which are dead...
std::vector<GlobalAlias*> DeadAliases;
for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end(); I != E;
++I)
if (!AliveGlobals.count(I)) {
DeadAliases.push_back(I);
I->setAliasee(0);
}
if (!DeadFunctions.empty()) { if (!DeadFunctions.empty()) {
// Now that all interferences have been dropped, delete the actual objects // Now that all interferences have been dropped, delete the actual objects
// themselves. // themselves.
@ -128,14 +137,13 @@ bool GlobalDCE::runOnModule(Module &M) {
} }
// Now delete any dead aliases. // Now delete any dead aliases.
for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end(); I != E;) { if (!DeadAliases.empty()) {
Module::alias_iterator J = I++; for (unsigned i = 0, e = DeadAliases.size(); i != e; ++i) {
if (!AliveGlobals.count(J)) { RemoveUnusedGlobalValue(*DeadAliases[i]);
RemoveUnusedGlobalValue(*J); M.getAliasList().erase(DeadAliases[i]);
M.getAliasList().erase(J);
++NumAliases;
Changed = true;
} }
NumAliases += DeadAliases.size();
Changed = true;
} }
// Make sure that all memory is released // Make sure that all memory is released

4
test/Transforms/GlobalDCE/2009-02-17-AliasUsesAliasee.ll Normal file
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@ -0,0 +1,4 @@
; RUN: llvm-as < %s | opt -globaldce
@A = alias internal void ()* @F
define internal void @F() { ret void }