70d378cdaa | ||
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.. | ||
README.md | ||
_typing_backports.py | ||
analysis.py | ||
analyzer.py | ||
cwriter.py | ||
flags.py | ||
formatting.py | ||
generate_cases.py | ||
generators_common.py | ||
instructions.py | ||
interpreter_definition.md | ||
lexer.py | ||
mypy.ini | ||
opcode_id_generator.py | ||
parser.py | ||
parsing.py | ||
plexer.py | ||
stack.py | ||
stacking.py | ||
tier1_generator.py | ||
tier2_generator.py | ||
uop_id_generator.py |
README.md
Tooling to generate interpreters
Documentation for the instruction definitions in Python/bytecodes.c
("the DSL") is here.
What's currently here:
lexer.py
: lexer for C, originally written by Mark Shannonplexer.py
: OO interface on top of lexer.py; main class:PLexer
parsing.py
: Parser for instruction definition DSL; main classParser
generate_cases.py
: driver script to readPython/bytecodes.c
and writePython/generated_cases.c.h
(and several other files)analysis.py
:Analyzer
class used to read the input filesflags.py
: abstractions related to metadata flags for instructionsformatting.py
:Formatter
class used to write the output filesinstructions.py
: classes to analyze and write instructionsstacking.py
: code to handle generalized stack effects
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.