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;
});
}
TCA emitFunctionEnterHelper(CodeBlock& cb, UniqueStubs& us) {
alignJmpTarget(cb);
auto const start = vwrap(cb, [&] (Vout& v) {
auto const ar = v.makeReg();
v << copy{rvmfp(), ar};
// Fully set up the call frame for the stub. We can't skip this like we do
// in other stubs because we need the return IP for this frame in the %rbp
// chain, in order to find the proper fixup for the VMRegAnchor in the
// intercept handler.
v << stublogue{true};
v << copy{rsp(), rvmfp()};
// When we call the event hook, it might tell us to skip the callee
// (because of fb_intercept). If that happens, we need to return to the
// caller, but the handler will have already popped the callee's frame.
// So, we need to save these values for later.
v << pushm{ar[AROFF(m_savedRip)]};
v << pushm{ar[AROFF(m_sfp)]};
v << copy2{ar, v.cns(EventHook::NormalFunc), rarg(0), rarg(1)};
bool (*hook)(const ActRec*, int) = &EventHook::onFunctionCall;
v << call{TCA(hook)};
});
us.functionEnterHelperReturn = vwrap2(cb, [&] (Vout& v, Vout& vcold) {
auto const sf = v.makeReg();
v << testb{rret(), rret(), sf};
unlikelyIfThen(v, vcold, CC_Z, sf, [&] (Vout& v) {
auto const saved_rip = v.makeReg();
// The event hook has already cleaned up the stack and popped the
// callee's frame, so we're ready to continue from the original call
// site. We just need to grab the fp/rip of the original frame that we
// saved earlier, and sync rvmsp().
v << pop{rvmfp()};
v << pop{saved_rip};
// Drop our call frame; the stublogue{} instruction guarantees that this
// is exactly 16 bytes.
v << lea{rsp()[16], rsp()};
// Sync vmsp and return to the caller. This unbalances the return stack
// buffer, but if we're intercepting, we probably don't care.
v << load{rvmtl()[rds::kVmspOff], rvmsp()};
v << jmpr{saved_rip};
});
// Skip past the stuff we saved for the intercept case.
v << lea{rsp()[16], rsp()};
// Restore rvmfp() and return to the callee's func prologue.
v << stubret{RegSet(), true};
});
return start;
}
