94 lines
3.7 KiB
Plaintext
94 lines
3.7 KiB
Plaintext
An informal guide to reading and working on the rustc compiler.
|
|
==================================================================
|
|
|
|
If you wish to expand on this document, or have a more experienced
|
|
Rust contributor add anything else to it, please get in touch:
|
|
|
|
https://github.com/mozilla/rust/wiki/Note-development-policy
|
|
("Communication" subheading)
|
|
|
|
or file a bug:
|
|
|
|
https://github.com/mozilla/rust/issues
|
|
|
|
Your concerns are probably the same as someone else's.
|
|
|
|
|
|
High-level concepts
|
|
===================
|
|
|
|
Rustc consists of the following subdirectories:
|
|
|
|
front/ - front-end: attributes, conditional compilation
|
|
middle/ - middle-end: name resolution, typechecking, LLVM code
|
|
generation
|
|
back/ - back-end: linking and ABI
|
|
metadata/ - encoder and decoder for data required by
|
|
separate compilation
|
|
driver/ - command-line processing, main() entrypoint
|
|
util/ - ubiquitous types and helper functions
|
|
lib/ - bindings to LLVM
|
|
|
|
The files concerned purely with syntax -- that is, the AST, parser,
|
|
pretty-printer, lexer, macro expander, and utilities for traversing
|
|
ASTs -- are in a separate crate called "syntax", whose files are in
|
|
./../libsyntax, where . is the current directory (that is, the parent
|
|
directory of front/, middle/, back/, and so on).
|
|
|
|
The entry-point for the compiler is main() in driver/rustc.rs, and
|
|
this file sequences the various parts together.
|
|
|
|
|
|
The 3 central data structures:
|
|
------------------------------
|
|
|
|
#1: ../libsyntax/ast.rs defines the AST. The AST is treated as immutable
|
|
after parsing, but it depends on mutable context data structures
|
|
(mainly hash maps) to give it meaning.
|
|
|
|
- Many -- though not all -- nodes within this data structure are
|
|
wrapped in the type spanned<T>, meaning that the front-end has
|
|
marked the input coordinates of that node. The member .node is
|
|
the data itself, the member .span is the input location (file,
|
|
line, column; both low and high).
|
|
|
|
- Many other nodes within this data structure carry a
|
|
def_id. These nodes represent the 'target' of some name
|
|
reference elsewhere in the tree. When the AST is resolved, by
|
|
middle/resolve.rs, all names wind up acquiring a def that they
|
|
point to. So anything that can be pointed-to by a name winds
|
|
up with a def_id.
|
|
|
|
#2: middle/ty.rs defines the datatype sty. This is the type that
|
|
represents types after they have been resolved and normalized by
|
|
the middle-end. The typeck phase converts every ast type to a
|
|
ty::sty, and the latter is used to drive later phases of
|
|
compilation. Most variants in the ast::ty tag have a
|
|
corresponding variant in the ty::sty tag.
|
|
|
|
#3: lib/llvm.rs defines the exported types ValueRef, TypeRef,
|
|
BasicBlockRef, and several others. Each of these is an opaque
|
|
pointer to an LLVM type, manipulated through the lib::llvm
|
|
interface.
|
|
|
|
|
|
Control and information flow within the compiler:
|
|
-------------------------------------------------
|
|
|
|
- main() in rustc.rc assumes control on startup. Options are
|
|
parsed, platform is detected, etc.
|
|
|
|
- libsyntax/parse/parser.rs parses the input files and produces an AST
|
|
that represents the input crate.
|
|
|
|
- Multiple middle-end passes (middle/resolve.rs, middle/typeck.rs)
|
|
analyze the semantics of the resulting AST. Each pass generates new
|
|
information about the AST and stores it in various environment data
|
|
structures. The driver passes environments to each compiler pass
|
|
that needs to refer to them.
|
|
|
|
- Finally middle/trans.rs translates the Rust AST to LLVM bitcode in a
|
|
type-directed way. When it's finished synthesizing LLVM values,
|
|
rustc asks LLVM to write them out in some form (.bc, .o) and
|
|
possibly run the system linker.
|