| name | check-parity |
| description | Check that aarch64 JIT interpreter functions match generic CPU behavior |
| allowed-tools | Bash, Read, Grep |
| argument-hint | ["opcode-name"] |
Check Interpreter Parity
Run the interpreter parity check and analyze results. If an opcode name is given, show a side-by-side diff for that specific opcode.
Steps
-
Always run the stub audit first — this catches no-op stubs (the #1 bug source):
python3 scripts/debug/stub_audit.py $ARGUMENTS
If an opcode name was given, this shows a side-by-side generic vs JIT diff.
If no arguments, it scans all functions and reports no-op stubs.
-
Run ./scripts/debug/check_interpreter_parity.sh
-
For any issues found:
- Commented-out ppc_exception(): These are bugs. The exception is silently dropped. Enable the call.
- GEN_INTERPRET with ppc_exception(): The exception will be silently dropped because GEN_INTERPRET doesn't check exception_pending. Need native gen_ function or change to GEN_INTERPRET_BRANCH/ENDBLOCK (but ENDBLOCK also doesn't work for synchronous exceptions — see doc/AGENT_DEBUGGING.md).
- Missing MSR_POW handling: Must strip POW bit in ppc_set_msr().
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For each GEN_INTERPRET warning, check the x86 JIT (src/cpu/cpu_jitc_x86/ppc_opc.cc) to see how it handles the same opcode. The x86 JIT is the reference for how gen_ functions should work.
Critical rule
GEN_INTERPRET CANNOT dispatch synchronous exceptions. The only correct approaches are:
- Native gen_ that jumps directly to ppc_program_exception_asm (like x86 JIT does)
- GEN_INTERPRET_BRANCH which dispatches to npc (works but forces a dispatch on every call)
