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Fixed a bug where we did not handle constant 

expressions correctly.  These produced a result
variable with an initializer but no store
instruction, and the store instruction was as
a result never rewritten to become a store to a
persistent variable.

Now if the result variable has an initializer
but is never used, we generate a (redundant)
store instruction for it, which is then later
rewritten into a (useful) store to the persistent
result variable.

llvm-svn: 113300
This commit is contained in:
Sean Callanan 2010-09-07 22:43:19 +00:00
parent 4d19d2651d
commit 1e87fffb41
1 changed files with 34 additions and 3 deletions
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37
lldb/source/Expression/IRForTarget.cpp
View File

@ -172,11 +172,42 @@ IRForTarget::createResultVariable(llvm::Module &M,
named_metadata->addOperand(persistent_global_md);
if (log)
log->Printf("Replacing %s with %s",
PrintValue(result_global).c_str(),
log->Printf("Replacing %s with %s",
PrintValue(result_global).c_str(),
PrintValue(new_result_global).c_str());
if (result_global->hasNUses(0))
{
// We need to synthesize a store for this variable, because otherwise
// there's nothing to put into its equivalent persistent variable.
BasicBlock &entry_block(F.getEntryBlock());
Instruction *first_entry_instruction(entry_block.getFirstNonPHIOrDbg());
if (!first_entry_instruction)
return false;
if (!result_global->hasInitializer())
{
if (log)
log->Printf("Couldn't find initializer for unused variable");
return false;
}
Constant *initializer = result_global->getInitializer();
StoreInst *synthesized_store = new StoreInst::StoreInst(initializer,
new_result_global,
first_entry_instruction);
if (log)
log->Printf("Synthesized result store %s\n", PrintValue(synthesized_store).c_str());
}
else
{
result_global->replaceAllUsesWith(new_result_global);
}
result_global->replaceAllUsesWith(new_result_global);
result_global->eraseFromParent();
return true;