bool checkCalleeStackOverflow(const ActRec* calleeAR) {
auto const func = calleeAR->func();
auto const limit = func->maxStackCells() + kStackCheckPadding;
const void* const needed_top =
reinterpret_cast<const TypedValue*>(calleeAR) - limit;
const void* const lower_limit =
static_cast<char*>(vmRegsUnsafe().stack.getStackLowAddress()) +
Stack::sSurprisePageSize;
return needed_top < lower_limit;
}
/*
* Compute the stack and local type postconditions for a
* single-entry/single-exit tracelet.
*/
std::vector<RegionDesc::TypePred> IRBuilder::getKnownTypes() {
// This function is only correct when given a single-exit region, as
// in TransProfile. Furthermore, its output is only used to guide
// formation of profile-driven regions.
assert(tx->mode() == TransProfile);
// We want the state for the last block on the "main trace". Figure
// out which that is.
Block* mainExit = nullptr;
for (auto* b : rpoSortCfg(m_unit)) {
if (isMainExit(b)) {
assert(mainExit == nullptr);
mainExit = b;
}
}
assert(mainExit != nullptr);
// Load state for mainExit. This feels hacky.
FTRACE(1, "mainExit: B{}\n", mainExit->id());
m_state.startBlock(mainExit);
// Now use the current state to get all the types.
std::vector<RegionDesc::TypePred> result;
auto const curFunc = m_state.func();
auto const sp = m_state.sp();
auto const spOffset = m_state.spOffset();
for (unsigned i = 0; i < curFunc->maxStackCells(); ++i) {
auto t = getStackValue(sp, i).knownType;
if (!t.equals(Type::StackElem)) {
result.push_back({ RegionDesc::Location::Stack{i, spOffset - i}, t });
}
}
for (unsigned i = 0; i < curFunc->numLocals(); ++i) {
auto t = m_state.localType(i);
if (!t.equals(Type::Gen)) {
FTRACE(1, "Local {}: {}\n", i, t.toString());
result.push_back({ RegionDesc::Location::Local{i}, t });
}
}
return result;
}
std::vector<RegionDesc::TypePred> IRBuilder::getKnownTypes() const {
std::vector<RegionDesc::TypePred> result;
auto const curFunc = m_state.func();
auto const sp = m_state.sp();
auto const spOffset = m_state.spOffset();
for (unsigned i = 0; i < curFunc->maxStackCells(); ++i) {
auto t = getStackValue(sp, i).knownType;
if (!t.equals(Type::StackElem)) {
result.push_back({ RegionDesc::Location::Stack{i, spOffset - i}, t });
}
}
for (unsigned i = 0; i < curFunc->numLocals(); ++i) {
auto t = m_state.localType(i);
if (!t.equals(Type::Gen)) {
result.push_back({ RegionDesc::Location::Local{i}, t });
}
}
return result;
}
void cgCheckSurpriseAndStack(IRLS& env, const IRInstruction* inst) {
auto const fp = srcLoc(env, inst, 0).reg();
auto const extra = inst->extra<CheckSurpriseAndStack>();
auto const func = extra->func;
auto const off = func->getEntryForNumArgs(extra->argc) - func->base();
auto const fixup = Fixup(off, func->numSlotsInFrame());
auto& v = vmain(env);
auto const sf = v.makeReg();
auto const needed_top = v.makeReg();
v << lea{fp[-cellsToBytes(func->maxStackCells())], needed_top};
v << cmpqm{needed_top, rvmtl()[rds::kSurpriseFlagsOff], sf};
unlikelyIfThen(v, vcold(env), CC_AE, sf, [&] (Vout& v) {
auto const stub = tc::ustubs().functionSurprisedOrStackOverflow;
auto const done = v.makeBlock();
v << vinvoke{CallSpec::stub(stub), v.makeVcallArgs({}), v.makeTuple({}),
{done, label(env, inst->taken())}, fixup };
v = done;
});
}
