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Guido van Rossum 7d83f7bcc4
gh-118335: Configure Tier 2 interpreter at build time (#118339) 
The code for Tier 2 is now only compiled when configured
with `--enable-experimental-jit[=yes|interpreter]`.

We drop support for `PYTHON_UOPS` and -`Xuops`,
but you can disable the interpreter or JIT
at runtime by setting `PYTHON_JIT=0`.
You can also build it without enabling it by default
using `--enable-experimental-jit=yes-off`;
enable with `PYTHON_JIT=1`.

On Windows, the `build.bat` script supports
`--experimental-jit`, `--experimental-jit-off`,
`--experimental-interpreter`.

In the C code, `_Py_JIT` is defined as before
when the JIT is enabled; the new variable
`_Py_TIER2` is defined when the JIT *or* the
interpreter is enabled. It is actually a bitmask:
1: JIT; 2: default-off; 4: interpreter.
 		2024-04-30 18:26:34 -07:00
..
README.md Rename tier 2 redundancy eliminator to optimizer (#115888) 2024-02-26 08:42:53 -08:00
_typing_backports.py gh-104504: cases generator: Add `--warn-unreachable` to the mypy config (#108112) 2023-08-21 00:40:41 +01:00
analyzer.py gh-118335: Configure Tier 2 interpreter at build time (#118339) 2024-04-30 18:26:34 -07:00
cwriter.py GH-111485: Generate instruction and uop metadata (GH-113287) 2023-12-20 14:27:25 +00:00
generators_common.py Cases generator: Remove type_prop and passthrough (#117614) 2024-04-08 06:26:52 +08:00
interpreter_definition.md gh-115778: Add `tierN` annotation for instruction definitions (#115815) 2024-02-23 17:31:57 +00:00
lexer.py gh-115778: Add `tierN` annotation for instruction definitions (#115815) 2024-02-23 17:31:57 +00:00
mypy.ini GH-111485: Separate out parsing, analysis and code-gen phases of tier 1 code generator (GH-112299) 2023-12-07 12:49:40 +00:00
opcode_id_generator.py ``Tools/cases_generator``: Fix typos and incorrect comments. (#114892) 2024-02-02 17:52:58 -08:00
opcode_metadata_generator.py GH-116422: Tier2 hot/cold splitting (GH-116813) 2024-03-26 09:35:11 +00:00
optimizer_generator.py gh-115419: Change default sym to not_null (GH-116562) 2024-03-13 20:57:48 +08:00
parser.py GH-111485: Delete the old generator code. (GH-113321) 2023-12-21 12:46:28 +00:00
parsing.py GH-115457: Support splitting and replication of micro ops. (GH-115558) 2024-02-20 10:50:59 +00:00
plexer.py gh-106812: Refactor cases_generator to allow uops with array stack effects (#107564) 2023-08-04 09:35:56 -07:00
py_metadata_generator.py ``Tools/cases_generator``: Fix typos and incorrect comments. (#114892) 2024-02-02 17:52:58 -08:00
stack.py GH-115457: Support splitting and replication of micro ops. (GH-115558) 2024-02-20 10:50:59 +00:00
target_generator.py GH-111485: Generate `TARGET` table for computed goto dispatch. (GH-113319) 2023-12-20 15:09:12 +00:00
tier1_generator.py gh-115999: Disable the specializing adaptive interpreter in free-threaded builds (#116013) 2024-02-29 21:53:32 -05:00
tier2_generator.py GH-117457: Correct pystats uop "miss" counts (GH-117477) 2024-04-04 15:49:18 -07:00
uop_id_generator.py gh-115778: Add `tierN` annotation for instruction definitions (#115815) 2024-02-23 17:31:57 +00:00
uop_metadata_generator.py GH-116422: Tier2 hot/cold splitting (GH-116813) 2024-03-26 09:35:11 +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.