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Don't create a swift async unwind plan when in a function prologue #2645

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merged 2 commits into from
Mar 10, 2021
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Don't create a swift async unwind plan when in a function prologue #2645

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24aee51
Don't create a swift async unwind plan when in a function prologue
jasonmolenda Mar 10, 2021
be1dbf1
If Function found for $pc, don't also look at Symbol
jasonmolenda Mar 10, 2021
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32 changes: 31 additions & 1 deletion lldb/source/Target/SwiftLanguageRuntime.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2299,7 +2299,8 @@ SwiftLanguageRuntime::GetRuntimeUnwindPlan(ProcessSP process_sp,
RegisterContext *regctx,
bool &behaves_like_zeroth_frame) {

ArchSpec arch = process_sp->GetTarget().GetArchitecture();
Target &target(process_sp->GetTarget());
ArchSpec arch = target.GetArchitecture();
uint32_t async_context_regnum;
uint32_t fp_regnum;
uint32_t pc_regnum;
Expand Down Expand Up @@ -2335,6 +2336,35 @@ SwiftLanguageRuntime::GetRuntimeUnwindPlan(ProcessSP process_sp,
return UnwindPlanSP();
}

// If we're in the prologue of a function, don't provide a Swift async
// unwind plan. We can be tricked by unmodified caller-registers that
// make this look like an async frame when this is a standard ABI function
// call, and the parent is the async frame.
// This assumes that the frame pointer register will be modified in the
// prologue.
Address pc;
pc.SetLoadAddress(regctx->GetPC(), &target);
SymbolContext sc;
if (pc.IsValid()) {
pc.CalculateSymbolContext(&sc,
eSymbolContextFunction | eSymbolContextSymbol);
if (sc.function) {
Address func_start_addr = sc.function->GetAddressRange().GetBaseAddress();
AddressRange prologue_range(func_start_addr,
sc.function->GetPrologueByteSize());
if (prologue_range.ContainsLoadAddress(pc, &target)) {
return UnwindPlanSP();
}
} else if (sc.symbol) {
Address func_start_addr = sc.symbol->GetAddress();
AddressRange prologue_range(func_start_addr,
sc.symbol->GetPrologueByteSize());
if (prologue_range.ContainsLoadAddress(pc, &target)) {
return UnwindPlanSP();
}
}
}

addr_t saved_fp = LLDB_INVALID_ADDRESS;
Status error;
if (!process_sp->ReadMemory(fp, &saved_fp, 8, error))
Expand Down