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Sam Gross 4759ba6eec
gh-127022: Simplify `PyStackRef_FromPyObjectSteal` (#127024) 
This gets rid of the immortal check in `PyStackRef_FromPyObjectSteal()`.
Overall, this improves performance about 2% in the free threading
build.

This also renames `PyStackRef_Is()` to `PyStackRef_IsExactly()` because
the macro requires that the tag bits of the arguments match, which is
only true in certain special cases.
 		2024-11-22 12:55:33 -05:00
..
README.md
…
_typing_backports.py
…
analyzer.py gh-127022: Simplify `PyStackRef_FromPyObjectSteal` (#127024) 2024-11-22 12:55:33 -05:00
cwriter.py GH-119866: Spill the stack around escaping calls. (GH-124392) 2024-10-07 14:56:39 +01:00
generators_common.py gh-118423: Add `INSTRUCTION_SIZE` macro to code generator (GH-125467) 2024-10-29 17:25:05 +00:00
interpreter_definition.md gh-118423: Add `INSTRUCTION_SIZE` macro to code generator (GH-125467) 2024-10-29 17:25:05 +00:00
lexer.py GH-119866: Spill the stack around escaping calls. (GH-124392) 2024-10-07 14:56:39 +01:00
mypy.ini
…
opcode_id_generator.py GH-122390: Replace `_Py_GetbaseOpcode` with `_Py_GetBaseCodeUnit` (GH-122942) 2024-08-13 14:22:57 +01:00
opcode_metadata_generator.py gh-124285: Fix bug where bool() is called multiple times for the same part of a boolean expression (#124394) 2024-09-25 15:51:25 +01:00
optimizer_generator.py gh-120619: Strength reduce function guards, support 2-operand uop forms (GH-124846) 2024-11-09 11:35:33 +08:00
parser.py gh-120417: Remove unused imports in cases_generator (#120622) 2024-06-17 21:58:56 +02:00
parsing.py gh-124285: Fix bug where bool() is called multiple times for the same part of a boolean expression (#124394) 2024-09-25 15:51:25 +01:00
plexer.py
…
py_metadata_generator.py GH-120024: Tidy up case generator code a bit. (GH-122780) 2024-08-08 10:57:59 +01:00
stack.py GH-119866: Spill the stack around escaping calls. (GH-124392) 2024-10-07 14:56:39 +01:00
target_generator.py GH-120024: Tidy up case generator code a bit. (GH-122780) 2024-08-08 10:57:59 +01:00
tier1_generator.py gh-118423: Add `INSTRUCTION_SIZE` macro to code generator (GH-125467) 2024-10-29 17:25:05 +00:00
tier2_generator.py gh-120619: Strength reduce function guards, support 2-operand uop forms (GH-124846) 2024-11-09 11:35:33 +08:00
uop_id_generator.py gh-120417: Remove unused imports in cases_generator (#120622) 2024-06-17 21:58:56 +02:00
uop_metadata_generator.py GH-126222: Fix `_PyUop_num_popped` (GH-126507) 2024-11-07 10:48:27 +00:00

README.md

Tooling to generate interpreters

Documentation for the instruction definitions in Python/bytecodes.c ("the DSL") is here.

What's currently here:

  • analyzer.py: code for converting AST generated by Parser to more high-level structure for easier interaction
  • lexer.py: lexer for C, originally written by Mark Shannon
  • plexer.py: OO interface on top of lexer.py; main class: PLexer
  • parsing.py: Parser for instruction definition DSL; main class: Parser
  • parser.py helper for interactions with parsing.py
  • tierN_generator.py: a couple of driver scripts to read Python/bytecodes.c and write Python/generated_cases.c.h (and several other files)
  • optimizer_generator.py: reads Python/bytecodes.c and Python/optimizer_bytecodes.c and writes Python/optimizer_cases.c.h
  • stack.py: code to handle generalized stack effects
  • cwriter.py: code which understands tokens and how to format C code; main class: CWriter
  • generators_common.py: helpers for generators
  • opcode_id_generator.py: generate a list of opcodes and write them to Include/opcode_ids.h
  • opcode_metadata_generator.py: reads the instruction definitions and write the metadata to Include/internal/pycore_opcode_metadata.h
  • py_metadata_generator.py: reads the instruction definitions and write the metadata to Lib/_opcode_metadata.py
  • target_generator.py: generate targets for computed goto dispatch and write them to Python/opcode_targets.h
  • uop_id_generator.py: generate a list of uop IDs and write them to Include/internal/pycore_uop_ids.h
  • uop_metadata_generator.py: reads the instruction definitions and write the metadata to Include/internal/pycore_uop_metadata.h

Note that there is some dummy C code at the top and bottom of Python/bytecodes.c to fool text editors like VS Code into believing this is valid C code.

A bit about the parser

The parser class uses a pretty standard recursive descent scheme, but with unlimited backtracking. The PLexer class tokenizes the entire input before parsing starts. We do not run the C preprocessor. Each parsing method returns either an AST node (a Node instance) or None, or raises SyntaxError (showing the error in the C source).

Most parsing methods are decorated with @contextual, which automatically resets the tokenizer input position when None is returned. Parsing methods may also raise SyntaxError, which is irrecoverable. When a parsing method returns None, it is possible that after backtracking a different parsing method returns a valid AST.

Neither the lexer nor the parsers are complete or fully correct. Most known issues are tersely indicated by # TODO: comments. We plan to fix issues as they become relevant.