gh-148219: Fix JIT+pystats crash: is_terminator fails for base opcodes#148220
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eendebakpt wants to merge 1 commit intopython:mainfrom
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gh-148219: Fix JIT+pystats crash: is_terminator fails for base opcodes#148220eendebakpt wants to merge 1 commit intopython:mainfrom
eendebakpt wants to merge 1 commit intopython:mainfrom
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Two bugs when building with --enable-experimental-jit --enable-pystats:
1. `is_terminator()` uses `_PyUop_Uncached[opcode]` to map replicated
variants back to base opcodes, but the array only contains entries
for replicated variants (e.g. `_JUMP_TO_TOP_r00`). For base opcodes
like `_JUMP_TO_TOP` itself, it returns 0, so the terminator is not
recognized. This causes `effective_trace_length()` to hit
`Py_FatalError("No terminating instruction")`.
Fix: fall back to the raw opcode when `_PyUop_Uncached` returns 0.
2. `jit.c` references `jit_got_size` in `OPT_STAT_ADD` but the field
is missing from `OptimizationStats` in `pystats.h`, causing a build
failure.
Fix: add the missing `jit_got_size` field.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
diegorusso
reviewed
Apr 7, 2026
| uint64_t jit_code_size; | ||
| uint64_t jit_trampoline_size; | ||
| uint64_t jit_data_size; | ||
| uint64_t jit_got_size; |
markshannon
reviewed
Apr 7, 2026
| is_terminator(const _PyUOpInstruction *uop) | ||
| { | ||
| int opcode = _PyUop_Uncached[uop->opcode]; | ||
| if (opcode == 0) { |
Member
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We probably should remove the line int opcode = _PyUop_Uncached[uop->opcode]; as the only time we should see a TOS caching uop is in the sanity_check function.
Maybe move that line there, and just assert(opcode <= MAX_UOP_ID) here?
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Two bugs when building with --enable-experimental-jit --enable-pystats:
is_terminator()uses_PyUop_Uncached[opcode]to map replicated variants back to base opcodes, but the array only contains entries for replicated variants (e.g._JUMP_TO_TOP_r00). For base opcodes like_JUMP_TO_TOPitself, it returns 0, so the terminator is not recognized.jit.creferencesjit_got_sizeinOPT_STAT_ADDbut the field is missing fromOptimizationStatsinpystats.h, causing a build failure.