https://github.com/python/cpython/commit/668c5723ebf30441961fceb7795566c17222c04b commit: 668c5723ebf30441961fceb7795566c17222c04b branch: main author: Chris Eibl <[email protected]> committer: Fidget-Spinner <[email protected]> date: 2026-04-05T23:25:14+08:00 summary:
GH-139922: add interpreter types to InternalDocs/interpreter.md (GH-148035) files: M InternalDocs/interpreter.md diff --git a/InternalDocs/interpreter.md b/InternalDocs/interpreter.md index 75acdf596a7f30..7fc41a807dd566 100644 --- a/InternalDocs/interpreter.md +++ b/InternalDocs/interpreter.md @@ -507,6 +507,38 @@ After the last `DEOPT_IF` has passed, a hit should be recorded with After an optimization has been deferred in the adaptive instruction, that should be recorded with `STAT_INC(BASE_INSTRUCTION, deferred)`. +## Interpreter types +There are three different types of interpreters to choose from based on compiler support: + + * traditional switch-case interpreter + + Supported by all compilers covered in PEP 7. + + * computed-gotos interpreter + + Enabled using configure option `--with-computed-gotos` and used by default on supported compilers. + It uses [Labels as Values](https://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html) + for more efficient dispatching. + + * tail-calling interpreter + + Enabled using configure option `--with-tail-call-interp` (or `--tail-call-interp` for build.bat on Windows). + It uses [tail calls](https://clang.llvm.org/docs/AttributeReference.html#musttail) and the + [preserve_none](https://clang.llvm.org/docs/AttributeReference.html#preserve-none) + calling convention between the small C functions that implement individual Python opcodes. + + Not all compilers support these and if they do not all targets might be supported (for example, + MSVC currently only supports x64 and only in optimized builds). + + In addition, compilers must do [escape analysis](https://gcc.gnu.org/onlinedocs/gcc/Common-Attributes.html#index-musttail) + of the lifetimes of automatic variables, function parameters, and temporaries to ensure proper tail-calls. They + emit a compile error in case of a violation or detection failure. The ability to detect this varies depending on the compiler and + also on the optimization level. Following techniques are particularly helpful to the MSVC compiler in this regard + * [Introducing additional scopes](https://github.com/python/cpython/blob/3908593039bde9d4b591ab09919003ee57418d64/Python/bytecodes.c#L2526) + * [extracting problematic code paths into a separate function](https://github.com/python/cpython/pull/143068/files#diff-729a985b0cb8b431cb291f1edb561bbbfea22e3f8c262451cd83328a0936a342R3724) + * [returning a pointer instead of taking it as an output parameter](https://github.com/python/cpython/blob/3908593039bde9d4b591ab09919003ee57418d64/Include/internal/pycore_ceval.h#L489-L492) + + Using `restrict` is another (currently unused) remedy. Additional resources -------------------- _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
