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Fix a bug where we could delete dead invoke instructions with uses.

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In functions where we fully constant prop the return value, replace all
ret instructions with 'ret undef'.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18786 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-12-11 02:53:57 +00:00
parent 1fce09125c
commit 0417feba29
1 changed files with 26 additions and 0 deletions
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26
lib/Transforms/Scalar/SCCP.cpp
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@ -172,6 +172,13 @@ public:
return ValueState;
}
/// getTrackedFunctionRetVals - Get the inferred return value map.
///
const hash_map<Function*, LatticeVal> &getTrackedFunctionRetVals() {
return TrackedFunctionRetVals;
}
private:
// markConstant - Make a value be marked as "constant". If the value
// is not already a constant, add it to the instruction work list so that
@ -1138,6 +1145,8 @@ bool IPSCCP::runOnModule(Module &M) {
if (Succ->begin() != Succ->end() && isa<PHINode>(Succ->begin()))
TI->getSuccessor(i)->removePredecessor(BB);
}
if (!TI->use_empty())
TI->replaceAllUsesWith(UndefValue::get(TI->getType()));
BB->getInstList().erase(TI);
} else {
@ -1183,5 +1192,22 @@ bool IPSCCP::runOnModule(Module &M) {
F->getBasicBlockList().erase(DeadBB);
}
}
// If we inferred constant or undef return values for a function, we replaced
// all call uses with the inferred value. This means we don't need to bother
// actually returning anything from the function. Replace all return
// instructions with return undef.
const hash_map<Function*, LatticeVal> &RV =Solver.getTrackedFunctionRetVals();
for (hash_map<Function*, LatticeVal>::const_iterator I = RV.begin(),
E = RV.end(); I != E; ++I)
if (!I->second.isOverdefined() &&
I->first->getReturnType() != Type::VoidTy) {
Function *F = I->first;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator()))
if (!isa<UndefValue>(RI->getOperand(0)))
RI->setOperand(0, UndefValue::get(F->getReturnType()));
}
return MadeChanges;
}