/*
* Attempts to begin inlining, and returns whether or not it successed.
*
* When doing gen-time inlining, we set up a series of IR instructions
* that looks like this:
*
* fp0 = DefFP
* sp = DefSP<offset>
*
* // ... normal stuff happens ...
*
* // FPI region:
* SpillFrame sp, ...
* // ... probably some StStks due to argument expressions
* fp2 = DefInlineFP<func,retBC,retSP,off> sp
*
* // ... callee body ...
*
* InlineReturn fp2
*
* In DCE we attempt to remove the InlineReturn and DefInlineFP instructions if
* they aren't needed.
*/
bool beginInlining(IRGS& env,
unsigned numParams,
const Func* target,
Offset returnBcOffset) {
auto const& fpiStack = env.irb->fpiStack();
assertx(!fpiStack.empty() &&
"Inlining does not support calls with the FPush* in a different Tracelet");
assertx(returnBcOffset >= 0 && "returnBcOffset before beginning of caller");
assertx(curFunc(env)->base() + returnBcOffset < curFunc(env)->past() &&
"returnBcOffset past end of caller");
FTRACE(1, "[[[ begin inlining: {}\n", target->fullName()->data());
SSATmp** params = (SSATmp**)alloca(sizeof(SSATmp*) * numParams);
for (unsigned i = 0; i < numParams; ++i) {
params[numParams - i - 1] = popF(env);
}
auto const prevSP = fpiStack.front().returnSP;
auto const prevSPOff = fpiStack.front().returnSPOff;
spillStack(env);
auto const calleeSP = sp(env);
always_assert_flog(
prevSP == calleeSP,
"FPI stack pointer and callee stack pointer didn't match in beginInlining"
);
auto const& info = fpiStack.front();
always_assert(!isFPushCuf(info.fpushOpc) && !info.interp);
auto ctx = [&] {
if (info.ctx || isFPushFunc(info.fpushOpc)) {
return info.ctx;
}
constexpr int32_t adjust = offsetof(ActRec, m_r) - offsetof(ActRec, m_this);
IRSPOffset ctxOff{invSPOff(env) - info.returnSPOff - adjust};
return gen(env, LdStk, TCtx, IRSPOffsetData{ctxOff}, sp(env));
}();
DefInlineFPData data;
data.target = target;
data.retBCOff = returnBcOffset;
data.fromFPushCtor = isFPushCtor(info.fpushOpc);
data.ctx = ctx;
data.retSPOff = prevSPOff;
data.spOffset = offsetFromIRSP(env, BCSPOffset{0});
// Push state and update the marker before emitting any instructions so
// they're all given markers in the callee.
auto const key = SrcKey {
target,
target->getEntryForNumArgs(numParams),
false
};
env.bcStateStack.emplace_back(key);
env.inlineLevel++;
updateMarker(env);
auto const calleeFP = gen(env, DefInlineFP, data, calleeSP, fp(env));
for (unsigned i = 0; i < numParams; ++i) {
stLocRaw(env, i, calleeFP, params[i]);
}
const bool hasVariadicArg = target->hasVariadicCaptureParam();
for (unsigned i = numParams; i < target->numLocals() - hasVariadicArg; ++i) {
/*
* Here we need to be generating hopefully-dead stores to initialize
* non-parameter locals to KindOfUninit in case we have to leave the trace.
*/
stLocRaw(env, i, calleeFP, cns(env, TUninit));
}
if (hasVariadicArg) {
auto argNum = target->numLocals() - 1;
always_assert(numParams <= argNum);
stLocRaw(env, argNum, calleeFP, cns(env, staticEmptyArray()));
}
return true;
}
/**
* Discard the current frame, assuming that a PHP exception given in
* phpException argument, or C++ exception (phpException == nullptr)
* is being thrown. Returns an exception to propagate, or nulltpr
* if the VM execution should be resumed.
*/
ObjectData* tearDownFrame(ActRec*& fp, Stack& stack, PC& pc,
ObjectData* phpException) {
auto const func = fp->func();
auto const curOp = peek_op(pc);
auto const prevFp = fp->sfp();
auto const soff = fp->m_soff;
ITRACE(1, "tearDownFrame: {} ({})\n",
func->fullName()->data(),
func->unit()->filepath()->data());
ITRACE(1, " fp {} prevFp {}\n",
implicit_cast<void*>(fp),
implicit_cast<void*>(prevFp));
// When throwing from a constructor, we normally want to avoid running the
// destructor on an object that hasn't been fully constructed yet. But if
// we're unwinding through the constructor's RetC, the constructor has
// logically finished and we're unwinding for some internal reason (timeout
// or user profiler, most likely). More importantly, fp->m_this may have
// already been destructed and/or overwritten due to sharing space with
// fp->m_r.
if (curOp != OpRetC &&
fp->hasThis() &&
fp->getThis()->getVMClass()->getCtor() == func &&
fp->getThis()->getVMClass()->getDtor()) {
/*
* Looks like an FPushCtor call, but it could still have been called
* directly. Check the fpi region to be sure.
*/
Offset prevPc;
auto outer = g_context->getPrevVMState(fp, &prevPc);
if (outer) {
auto fe = outer->func()->findPrecedingFPI(prevPc);
if (fe && isFPushCtor(outer->func()->unit()->getOp(fe->m_fpushOff))) {
fp->getThis()->setNoDestruct();
}
}
}
auto const decRefLocals = [&] {
/*
* It is possible that locals have already been decref'd.
*
* Here's why:
*
* - If a destructor for any of these things throws a php
* exception, it's swallowed at the dtor boundary and we keep
* running php.
*
* - If the destructor for any of these things throws a fatal,
* it's swallowed, and we set surprise flags to throw a fatal
* from now on.
*
* - If the second case happened and we have to run another
* destructor, its enter hook will throw, but it will be
* swallowed again.
*
* - Finally, the exit hook for the returning function can
* throw, but this happens last so everything is destructed.
*
* - When that happens, exit hook sets localsDecRefd flag.
*/
if (!fp->localsDecRefd()) {
try {
// Note that we must convert locals and the $this to
// uninit/zero during unwind. This is because a backtrace
// from another destructing object during this unwind may try
// to read them.
frame_free_locals_unwind(fp, func->numLocals(), phpException);
} catch (...) {}
}
};
if (LIKELY(!fp->resumed())) {
decRefLocals();
if (UNLIKELY(func->isAsyncFunction()) &&
phpException &&
!fp->isFCallAwait()) {
// If in an eagerly executed async function, wrap the user exception
// into a failed StaticWaitHandle and return it to the caller.
auto const waitHandle = c_StaticWaitHandle::CreateFailed(phpException);
phpException = nullptr;
stack.ndiscard(func->numSlotsInFrame());
stack.ret();
assert(stack.topTV() == &fp->m_r);
cellCopy(make_tv<KindOfObject>(waitHandle), fp->m_r);
} else {
// Free ActRec.
stack.ndiscard(func->numSlotsInFrame());
stack.discardAR();
}
} else if (func->isAsyncFunction()) {
auto const waitHandle = frame_afwh(fp);
if (phpException) {
// Handle exception thrown by async function.
decRefLocals();
waitHandle->fail(phpException);
phpException = nullptr;
} else if (waitHandle->isRunning()) {
// Let the C++ exception propagate. If the current frame represents async
// function that is running, mark it as abruptly interrupted. Some opcodes
// like Await may change state of the async function just before exit hook
// decides to throw C++ exception.
decRefLocals();
waitHandle->failCpp();
}
} else if (func->isAsyncGenerator()) {
auto const gen = frame_async_generator(fp);
if (phpException) {
// Handle exception thrown by async generator.
decRefLocals();
auto eagerResult = gen->fail(phpException);
phpException = nullptr;
if (eagerResult) {
stack.pushObjectNoRc(eagerResult);
}
} else if (gen->isEagerlyExecuted() || gen->getWaitHandle()->isRunning()) {
// Fail the async generator and let the C++ exception propagate.
decRefLocals();
gen->failCpp();
}
} else if (func->isNonAsyncGenerator()) {
// Mark the generator as finished.
decRefLocals();
frame_generator(fp)->fail();
} else {
not_reached();
}
/*
* At the final ActRec in this nesting level.
*/
if (UNLIKELY(!prevFp)) {
pc = nullptr;
fp = nullptr;
return phpException;
}
assert(stack.isValidAddress(reinterpret_cast<uintptr_t>(prevFp)) ||
prevFp->resumed());
auto const prevOff = soff + prevFp->func()->base();
pc = prevFp->func()->unit()->at(prevOff);
fp = prevFp;
return phpException;
}
