bool install_catch_trace(_Unwind_Context* ctx, _Unwind_Exception* exn,
bool do_side_exit, TypedValue unwinder_tv) {
auto const rip = (TCA)_Unwind_GetIP(ctx);
auto catchTraceOpt = mcg->getCatchTrace(rip);
FTRACE(1, "No catch trace entry for ip {}; bailing\n", rip);
if (!catchTraceOpt) return false;
auto catchTrace = *catchTraceOpt;
if (!catchTrace) {
// A few of our optimization passes must be aware of every path out of the
// trace, so throwing through jitted code without a catch block is very
// bad. This is indicated with a present but nullptr entry in the catch
// trace map.
const size_t kCallSize = 5;
const uint8_t kCallOpcode = 0xe8;
auto callAddr = rip - kCallSize;
TCA helperAddr = nullptr;
std::string helperName;
if (*callAddr == kCallOpcode) {
helperAddr = rip + *reinterpret_cast<int32_t*>(callAddr + 1);
}
always_assert_flog(false,
"Translated call to {} threw '{}' without "
"catch block, return address: {}\n",
getNativeFunctionName(helperAddr),
exceptionFromUnwindException(exn)->what(),
rip);
return false;
}
FTRACE(1, "installing catch trace {} for call {} with tv {}, "
"returning _URC_INSTALL_CONTEXT\n",
catchTrace, rip, unwinder_tv.pretty());
// In theory the unwind api will let us set registers in the frame
// before executing our landing pad. In practice, trying to use
// their recommended scratch registers results in a SEGV inside
// _Unwind_SetGR, so we pass things to the handler using the
// RDS. This also simplifies the handler code because it doesn't
// have to worry about saving its arguments somewhere while
// executing the exit trace.
unwindRdsInfo->unwinderScratch = (int64_t)exn;
unwindRdsInfo->doSideExit = do_side_exit;
if (do_side_exit) {
unwindRdsInfo->unwinderTv = unwinder_tv;
}
_Unwind_SetIP(ctx, (uint64_t)catchTrace);
tl_regState = VMRegState::DIRTY;
return true;
}
bool install_catch_trace(_Unwind_Context* ctx, _Unwind_Exception* exn,
bool do_side_exit, TypedValue unwinder_tv) {
auto const rip = (TCA)_Unwind_GetIP(ctx);
auto catchTrace = lookup_catch_trace(rip, exn);
if (!catchTrace) {
FTRACE(1, "No catch trace entry for ip {}; bailing\n", rip);
return false;
}
FTRACE(1, "installing catch trace {} for call {} with tv {}, "
"returning _URC_INSTALL_CONTEXT\n",
catchTrace, rip, unwinder_tv.pretty());
// If the catch trace isn't going to finish by calling _Unwind_Resume, we
// consume the exception here. Otherwise, we leave a pointer to it in RDS so
// endCatchHelper can pass it to _Unwind_Resume when it's done.
if (do_side_exit) {
unwindRdsInfo->exn = nullptr;
#ifndef _MSC_VER
__cxxabiv1::__cxa_begin_catch(exn);
__cxxabiv1::__cxa_end_catch();
#endif
} else {
unwindRdsInfo->exn = exn;
}
// In theory the unwind api will let us set registers in the frame before
// executing our landing pad. In practice, trying to use their recommended
// scratch registers results in a SEGV inside _Unwind_SetGR, so we pass
// things to the handler using the RDS. This also simplifies the handler code
// because it doesn't have to worry about saving its arguments somewhere
// while executing the exit trace.
unwindRdsInfo->doSideExit = do_side_exit;
if (do_side_exit) unwindRdsInfo->unwinderTv = unwinder_tv;
_Unwind_SetIP(ctx, (uint64_t)catchTrace);
tl_regState = VMRegState::DIRTY;
return true;
}