dwarf2reader: support NaCl Saigo CFA pseudo-register -2#19
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Saigo LLVM emits DWARF CFI using register number -2 as a pseudo-register when describing the canonical frame address. Breakpad currently interprets this value as register 4294967294, which can produce invalid CFI rules and cause failures while processing symbols. Normalize the NaCl CFA pseudo-register to Breakpad's existing kCFARegister representation when parsing CFI operands.
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This was referenced Jul 13, 2026
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Gamelogic crash tests from Daemon's LGTM |
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Saigo LLVM emits DWARF CFI using register number -2 as a pseudo-register when describing the canonical frame address.
Breakpad currently interprets this value as register 4294967294, which can produce invalid CFI rules and cause failures while processing symbols.
Normalize the NaCl CFA pseudo-register to Breakpad's existing kCFARegister representation when parsing CFI operands.
Disclaimer: Like for the PHDR NaCl thing (DaemonEngine/native_client#6), I experimented using ChatGPT as a debugger assistant, providing the bot some diagnostic information in a discussion:
gdbbacktrace, output fromreadelf,llvm-dwarfdump, etc. The bot suggested me some diagnostics in order to figure out where the unexpected value was emitted. And after extensive testing of the build pipeline it turns out the problem got pretty well cornered!After such investigation has been done, I decided to patch breakpad because modifying LLVM would probably be a nightmare, and this seems to be the least intrusive workaround.