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late-gc-lowering: Prevent infinite recursion #42445

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Merged
merged 1 commit into from
Oct 2, 2021
Merged

late-gc-lowering: Prevent infinite recursion #42445

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3 changes: 2 additions & 1 deletion src/llvm-final-gc-lowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -218,10 +218,11 @@ bool FinalLowerGC::doInitialization(Module &M) {

bool FinalLowerGC::doFinalization(Module &M)
{
GlobalValue *functionList[] = {queueRootFunc, poolAllocFunc, bigAllocFunc};
queueRootFunc = poolAllocFunc = bigAllocFunc = nullptr;
auto used = M.getGlobalVariable("llvm.compiler.used");
if (!used)
return false;
GlobalValue *functionList[] = {queueRootFunc, poolAllocFunc, bigAllocFunc};
SmallPtrSet<Constant*, 16> InitAsSet(
functionList,
functionList + sizeof(functionList) / sizeof(void*));
Expand Down
25 changes: 17 additions & 8 deletions src/llvm-late-gc-lowering.cpp
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Expand Up @@ -1153,12 +1153,14 @@ static bool isConstGV(GlobalVariable *gv)
return gv->isConstant() || gv->getMetadata("julia.constgv");
}

static bool isLoadFromConstGV(LoadInst *LI, bool &task_local);
static bool isLoadFromConstGV(Value *v, bool &task_local)
typedef llvm::SmallPtrSet<PHINode*, 1> PhiSet;

static bool isLoadFromConstGV(LoadInst *LI, bool &task_local, PhiSet *seen = nullptr);
static bool isLoadFromConstGV(Value *v, bool &task_local, PhiSet *seen = nullptr)
{
v = v->stripInBoundsOffsets();
if (auto LI = dyn_cast<LoadInst>(v))
return isLoadFromConstGV(LI, task_local);
return isLoadFromConstGV(LI, task_local, seen);
if (auto gv = dyn_cast<GlobalVariable>(v))
return isConstGV(gv);
// null pointer
Expand All @@ -1169,12 +1171,19 @@ static bool isLoadFromConstGV(Value *v, bool &task_local)
return (CE->getOpcode() == Instruction::IntToPtr &&
isa<ConstantData>(CE->getOperand(0)));
if (auto SL = dyn_cast<SelectInst>(v))
return (isLoadFromConstGV(SL->getTrueValue(), task_local) &&
isLoadFromConstGV(SL->getFalseValue(), task_local));
return (isLoadFromConstGV(SL->getTrueValue(), task_local, seen) &&
isLoadFromConstGV(SL->getFalseValue(), task_local, seen));
if (auto Phi = dyn_cast<PHINode>(v)) {
PhiSet ThisSet(&Phi, &Phi);
if (!seen)
seen = &ThisSet;
else if (seen->count(Phi))
return true;
else
seen->insert(Phi);
auto n = Phi->getNumIncomingValues();
for (unsigned i = 0; i < n; ++i) {
if (!isLoadFromConstGV(Phi->getIncomingValue(i), task_local)) {
if (!isLoadFromConstGV(Phi->getIncomingValue(i), task_local, seen)) {
return false;
}
}
Expand Down Expand Up @@ -1206,7 +1215,7 @@ static bool isLoadFromConstGV(Value *v, bool &task_local)
//
// The white list implemented here and above in `isLoadFromConstGV(Value*)` should
// cover all the cases we and LLVM generates.
static bool isLoadFromConstGV(LoadInst *LI, bool &task_local)
static bool isLoadFromConstGV(LoadInst *LI, bool &task_local, PhiSet *seen)
{
// We only emit single slot GV in codegen
// but LLVM global merging can change the pointer operands to GEPs/bitcasts
Expand All @@ -1216,7 +1225,7 @@ static bool isLoadFromConstGV(LoadInst *LI, bool &task_local)
{"jtbaa_immut", "jtbaa_const", "jtbaa_datatype"})) {
if (gv)
return true;
return isLoadFromConstGV(load_base, task_local);
return isLoadFromConstGV(load_base, task_local, seen);
}
if (gv)
return isConstGV(gv);
Expand Down