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Mark Shannon 3eacfc1a4d
GH-121784: Generate an error during code gen if a variable is marked `unused`, but is used and thus cached in a prior uop. (#121788) 
* Reject uop definitions that declare values as 'unused' that are already cached by prior uops

* Track which variables are defined and only load from memory when needed

* Support explicit `flush` in macro definitions. 

* Make sure stack is flushed in where needed.
 		2024-07-18 12:49:24 +01:00
..
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-121784: Generate an error during code gen if a variable is marked `unused`, but is used and thus cached in a prior uop. (#121788) 2024-07-18 12:49:24 +01:00
cwriter.py GH-111485: Generate instruction and uop metadata (GH-113287) 2023-12-20 14:27:25 +00:00
generators_common.py GH-118926: Better distinguish between pointer and arrays in interpreter generator (GH-121496) 2024-07-09 11:33:56 +01:00
interpreter_definition.md gh-119689: generate stack effect metadata for pseudo instructions (#119691) 2024-05-29 09:47:56 +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 gh-120417: Remove unused imports in cases_generator (#120622) 2024-06-17 21:58:56 +02:00
opcode_metadata_generator.py gh-120417: Remove unused imports in cases_generator (#120622) 2024-06-17 21:58:56 +02:00
optimizer_generator.py GH-121784: Generate an error during code gen if a variable is marked `unused`, but is used and thus cached in a prior uop. (#121788) 2024-07-18 12:49:24 +01:00
parser.py gh-120417: Remove unused imports in cases_generator (#120622) 2024-06-17 21:58:56 +02:00
parsing.py GH-118926: Better distinguish between pointer and arrays in interpreter generator (GH-121496) 2024-07-09 11:33:56 +01:00
plexer.py
…
py_metadata_generator.py gh-120417: Remove unused imports in cases_generator (#120622) 2024-06-17 21:58:56 +02:00
stack.py GH-121784: Generate an error during code gen if a variable is marked `unused`, but is used and thus cached in a prior uop. (#121788) 2024-07-18 12:49:24 +01:00
target_generator.py gh-120417: Remove unused imports in cases_generator (#120622) 2024-06-17 21:58:56 +02:00
tier1_generator.py GH-121784: Generate an error during code gen if a variable is marked `unused`, but is used and thus cached in a prior uop. (#121788) 2024-07-18 12:49:24 +01:00
tier2_generator.py GH-121784: Generate an error during code gen if a variable is marked `unused`, but is used and thus cached in a prior uop. (#121788) 2024-07-18 12:49:24 +01:00
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-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.