/// removeDeadFunctions - Remove dead functions that are not included in
/// DNR (Do Not Remove) list.
bool Inliner::removeDeadFunctions(CallGraph &CG, bool AlwaysInlineOnly) {
SmallVector<CallGraphNode*, 16> FunctionsToRemove;
// Scan for all of the functions, looking for ones that should now be removed
// from the program. Insert the dead ones in the FunctionsToRemove set.
for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) {
CallGraphNode *CGN = I->second;
Function *F = CGN->getFunction();
if (!F || F->isDeclaration())
continue;
// Handle the case when this function is called and we only want to care
// about always-inline functions. This is a bit of a hack to share code
// between here and the InlineAlways pass.
if (AlwaysInlineOnly &&
!F->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
Attribute::AlwaysInline))
continue;
// If the only remaining users of the function are dead constants, remove
// them.
F->removeDeadConstantUsers();
if (!F->isDefTriviallyDead())
continue;
// Remove any call graph edges from the function to its callees.
CGN->removeAllCalledFunctions();
// Remove any edges from the external node to the function's call graph
// node. These edges might have been made irrelegant due to
// optimization of the program.
CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN);
// Removing the node for callee from the call graph and delete it.
FunctionsToRemove.push_back(CGN);
}
if (FunctionsToRemove.empty())
return false;
// Now that we know which functions to delete, do so. We didn't want to do
// this inline, because that would invalidate our CallGraph::iterator
// objects. :(
//
// Note that it doesn't matter that we are iterating over a non-stable order
// here to do this, it doesn't matter which order the functions are deleted
// in.
array_pod_sort(FunctionsToRemove.begin(), FunctionsToRemove.end());
FunctionsToRemove.erase(std::unique(FunctionsToRemove.begin(),
FunctionsToRemove.end()),
FunctionsToRemove.end());
for (SmallVectorImpl<CallGraphNode *>::iterator I = FunctionsToRemove.begin(),
E = FunctionsToRemove.end();
I != E; ++I) {
delete CG.removeFunctionFromModule(*I);
++NumDeleted;
}
return true;
}
/// removeDeadFunctions - Remove dead functions that are not included in
/// DNR (Do Not Remove) list.
bool Inliner::removeDeadFunctions(CallGraph &CG,
SmallPtrSet<const Function *, 16> *DNR) {
SmallPtrSet<CallGraphNode*, 16> FunctionsToRemove;
// Scan for all of the functions, looking for ones that should now be removed
// from the program. Insert the dead ones in the FunctionsToRemove set.
for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) {
CallGraphNode *CGN = I->second;
if (CGN->getFunction() == 0)
continue;
Function *F = CGN->getFunction();
// If the only remaining users of the function are dead constants, remove
// them.
F->removeDeadConstantUsers();
if (DNR && DNR->count(F))
continue;
if (!F->hasLinkOnceLinkage() && !F->hasLocalLinkage() &&
!F->hasAvailableExternallyLinkage())
continue;
if (!F->use_empty())
continue;
// Remove any call graph edges from the function to its callees.
CGN->removeAllCalledFunctions();
// Remove any edges from the external node to the function's call graph
// node. These edges might have been made irrelegant due to
// optimization of the program.
CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN);
// Removing the node for callee from the call graph and delete it.
FunctionsToRemove.insert(CGN);
}
// Now that we know which functions to delete, do so. We didn't want to do
// this inline, because that would invalidate our CallGraph::iterator
// objects. :(
//
// Note that it doesn't matter that we are iterating over a non-stable set
// here to do this, it doesn't matter which order the functions are deleted
// in.
bool Changed = false;
for (SmallPtrSet<CallGraphNode*, 16>::iterator I = FunctionsToRemove.begin(),
E = FunctionsToRemove.end(); I != E; ++I) {
resetCachedCostInfo((*I)->getFunction());
delete CG.removeFunctionFromModule(*I);
++NumDeleted;
Changed = true;
}
return Changed;
}
// doFinalization - Remove now-dead linkonce functions at the end of
// processing to avoid breaking the SCC traversal.
bool Inliner::doFinalization(CallGraph &CG) {
std::set<CallGraphNode*> FunctionsToRemove;
// Scan for all of the functions, looking for ones that should now be removed
// from the program. Insert the dead ones in the FunctionsToRemove set.
for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) {
CallGraphNode *CGN = I->second;
if (Function *F = CGN ? CGN->getFunction() : 0) {
// If the only remaining users of the function are dead constants, remove
// them.
F->removeDeadConstantUsers();
if ((F->hasLinkOnceLinkage() || F->hasInternalLinkage()) &&
F->use_empty()) {
// Remove any call graph edges from the function to its callees.
while (!CGN->empty())
CGN->removeCallEdgeTo((CGN->end()-1)->second);
// Remove any edges from the external node to the function's call graph
// node. These edges might have been made irrelegant due to
// optimization of the program.
CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN);
// Removing the node for callee from the call graph and delete it.
FunctionsToRemove.insert(CGN);
}
}
}
// Now that we know which functions to delete, do so. We didn't want to do
// this inline, because that would invalidate our CallGraph::iterator
// objects. :(
bool Changed = false;
for (std::set<CallGraphNode*>::iterator I = FunctionsToRemove.begin(),
E = FunctionsToRemove.end(); I != E; ++I) {
delete CG.removeFunctionFromModule(*I);
++NumDeleted;
Changed = true;
}
return Changed;
}
/// Remove dead functions that are not included in DNR (Do Not Remove) list.
bool Inliner::removeDeadFunctions(CallGraph &CG, bool AlwaysInlineOnly) {
SmallVector<CallGraphNode*, 16> FunctionsToRemove;
SmallVector<CallGraphNode *, 16> DeadFunctionsInComdats;
SmallDenseMap<const Comdat *, int, 16> ComdatEntriesAlive;
auto RemoveCGN = [&](CallGraphNode *CGN) {
// Remove any call graph edges from the function to its callees.
CGN->removeAllCalledFunctions();
// Remove any edges from the external node to the function's call graph
// node. These edges might have been made irrelegant due to
// optimization of the program.
CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN);
// Removing the node for callee from the call graph and delete it.
FunctionsToRemove.push_back(CGN);
};
// Scan for all of the functions, looking for ones that should now be removed
// from the program. Insert the dead ones in the FunctionsToRemove set.
for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) {
CallGraphNode *CGN = I->second;
Function *F = CGN->getFunction();
if (!F || F->isDeclaration())
continue;
// Handle the case when this function is called and we only want to care
// about always-inline functions. This is a bit of a hack to share code
// between here and the InlineAlways pass.
if (AlwaysInlineOnly && !F->hasFnAttribute(Attribute::AlwaysInline))
continue;
// If the only remaining users of the function are dead constants, remove
// them.
F->removeDeadConstantUsers();
if (!F->isDefTriviallyDead())
continue;
// It is unsafe to drop a function with discardable linkage from a COMDAT
// without also dropping the other members of the COMDAT.
// The inliner doesn't visit non-function entities which are in COMDAT
// groups so it is unsafe to do so *unless* the linkage is local.
if (!F->hasLocalLinkage()) {
if (const Comdat *C = F->getComdat()) {
--ComdatEntriesAlive[C];
DeadFunctionsInComdats.push_back(CGN);
continue;
}
}
RemoveCGN(CGN);
}
if (!DeadFunctionsInComdats.empty()) {
// Count up all the entities in COMDAT groups
auto ComdatGroupReferenced = [&](const Comdat *C) {
auto I = ComdatEntriesAlive.find(C);
if (I != ComdatEntriesAlive.end())
++(I->getSecond());
};
for (const Function &F : CG.getModule())
if (const Comdat *C = F.getComdat())
ComdatGroupReferenced(C);
for (const GlobalVariable &GV : CG.getModule().globals())
if (const Comdat *C = GV.getComdat())
ComdatGroupReferenced(C);
for (const GlobalAlias &GA : CG.getModule().aliases())
if (const Comdat *C = GA.getComdat())
ComdatGroupReferenced(C);
for (CallGraphNode *CGN : DeadFunctionsInComdats) {
Function *F = CGN->getFunction();
const Comdat *C = F->getComdat();
int NumAlive = ComdatEntriesAlive[C];
// We can remove functions in a COMDAT group if the entire group is dead.
assert(NumAlive >= 0);
if (NumAlive > 0)
continue;
RemoveCGN(CGN);
}
}
if (FunctionsToRemove.empty())
return false;
// Now that we know which functions to delete, do so. We didn't want to do
// this inline, because that would invalidate our CallGraph::iterator
// objects. :(
//
// Note that it doesn't matter that we are iterating over a non-stable order
// here to do this, it doesn't matter which order the functions are deleted
// in.
array_pod_sort(FunctionsToRemove.begin(), FunctionsToRemove.end());
FunctionsToRemove.erase(std::unique(FunctionsToRemove.begin(),
FunctionsToRemove.end()),
FunctionsToRemove.end());
for (SmallVectorImpl<CallGraphNode *>::iterator I = FunctionsToRemove.begin(),
E = FunctionsToRemove.end();
I != E; ++I) {
delete CG.removeFunctionFromModule(*I);
++NumDeleted;
}
return true;
}
