// FIXME: This code is stolen from CallGraph::addToCallGraph(Function *F), which
// happens to be private. It is better for this functionality exposed by the
// CallGraph.
static void buildCGN(CallGraph &CG, CallGraphNode *Node) {
Function *F = Node->getFunction();
// Look for calls by this function.
for (Instruction &I : instructions(F))
if (CallSite CS = CallSite(cast<Value>(&I))) {
const Function *Callee = CS.getCalledFunction();
if (!Callee || !Intrinsic::isLeaf(Callee->getIntrinsicID()))
// Indirect calls of intrinsics are not allowed so no need to check.
// We can be more precise here by using TargetArg returned by
// Intrinsic::isLeaf.
Node->addCalledFunction(CS, CG.getCallsExternalNode());
else if (!Callee->isIntrinsic())
Node->addCalledFunction(CS, CG.getOrInsertFunction(Callee));
}
}
// When we see the coroutine the first time, we insert an indirect call to a
// devirt trigger function and mark the coroutine that it is now ready for
// split.
static void prepareForSplit(Function &F, CallGraph &CG) {
Module &M = *F.getParent();
#ifndef NDEBUG
Function *DevirtFn = M.getFunction(CORO_DEVIRT_TRIGGER_FN);
assert(DevirtFn && "coro.devirt.trigger function not found");
#endif
F.addFnAttr(CORO_PRESPLIT_ATTR, PREPARED_FOR_SPLIT);
// Insert an indirect call sequence that will be devirtualized by CoroElide
// pass:
// %0 = call i8* @llvm.coro.subfn.addr(i8* null, i8 -1)
// %1 = bitcast i8* %0 to void(i8*)*
// call void %1(i8* null)
coro::LowererBase Lowerer(M);
Instruction *InsertPt = F.getEntryBlock().getTerminator();
auto *Null = ConstantPointerNull::get(Type::getInt8PtrTy(F.getContext()));
auto *DevirtFnAddr =
Lowerer.makeSubFnCall(Null, CoroSubFnInst::RestartTrigger, InsertPt);
auto *IndirectCall = CallInst::Create(DevirtFnAddr, Null, "", InsertPt);
// Update CG graph with an indirect call we just added.
CG[&F]->addCalledFunction(IndirectCall, CG.getCallsExternalNode());
}