CBC - C B Compiler - https://github.com/xplshn/cbc
The predecesor of this B compiler, written in C11 and using QBE as its backend
(gbc) | The Go B Compiler
This compiler is a project aiming to make a valid B compiler, with optional syntax extensions, and a modules system like Go's
]~/Documents/TrulyMine/gbc@ ./gbc --help
Copyright (c) 2025: xplshn and contributors
For more details refer to <https://github.com/xplshn/gbc>
Synopsis
gbc <options> <input.b> ...
Description
A compiler for the B programming language with modern extensions. Like stepping into a time machine, but with better error messages.
Options
-C <arg>, --compiler-arg <arg> Pass a compiler-specific argument (e.g., -C linker_args='-s').
-d, --dump-ir Dump the intermediate representation and exit.
-h, --help Display this information
-I <path>, --include <path> Add a directory to the include path.
-L <arg>, --linker-arg <arg> Pass an argument to the linker.
-o <file>, --output <file> Place the output into <file>. |a.out|
--pedantic Issue all warnings demanded by the current B std.
--std=std Specify language standard (B, Bx) |Bx|
-t <backend/target>, --target <backend/target> Set the backend and target ABI. |qbe|
Feature Flags
-F<feature flag> Enable a specific feature flag
-Fno-<feature flag> Disable a specific feature flag
Available feature flags:
allow-uninitialized Allow declarations without an initializer (`var;` or `auto var;`) |x|
asm Allow `__asm__` blocks for inline assembly |x|
b-esc Recognize B-style '*' character escapes |-|
b-ops Recognize B-style assignment operators like '=+' |-|
bx-decl Enable Bx-style `auto name = val` declarations |x|
c-comments Recognize C-style '//' line comments |x|
c-esc Recognize C-style '\' character escapes |x|
c-ops Recognize C-style assignment operators like '+=' |x|
continue Allow the Bx keyword `continue` to be used |x|
extrn Allow the 'extrn' keyword |x|
float Enable support for floating-point numbers |x|
no-directives Disable `// [b]:` directives |-|
prom-types Enable type promotions - promote untyped literals to compatible types |-|
short-decl Enable Bx-style short declaration `:=` |x|
strict-decl Require all declarations to be initialized |-|
strict-types Disallow all incompatible type operations |-|
typed Enable the Bx opt-in & backwards-compatible type system |x|
Warning Flags
-W<warning flag> Enable a specific warning flag
-Wno-<warning flag> Disable a specific warning flag
Available Warning Flags:
b-esc Warn on usage of B-style '*' escapes |x|
b-ops Warn on usage of B-style assignment operators like '=+' |x|
c-comments Warn on usage of non-standard C-style '//' comments |-|
c-esc Warn on usage of C-style '\' escapes |-|
c-ops Warn on usage of C-style assignment operators like '+=' |-|
debug-comp Debug warning for type promotions and conversions |-|
extra Enable extra miscellaneous warnings |x|
float Warn when floating-point numbers are used |-|
implicit-decl Warn about implicit function or variable declarations |x|
local-address Warn when the address of a local variable is returned |x|
long-char-const Warn when a multi-character constant is too long for a word |x|
overflow Warn when an integer constant is out of range for its type |x|
pedantic Issue all warnings demanded by the strict standard |-|
prom-types Warn when type promotions occur |x|
truncated-char Warn when a character escape value is truncated |x|
u-esc Warn on unrecognized character escape sequences |x|
unreachable-code Warn about code that will never be executed |x|
]~/Documents/TrulyMine/gbc@
Progress Report:
- Capable of passing all tests
- Capable of compiling all examples. Producing the same output as the reference B compiler, against the same STDIN and argument inputs.
- Etc, these are just the most impressive examples
- I added a completely opt-in type system. It uses type first declarations like C, and uses the Go type names. (can also be used with strict B via
-std=B -Ftyped, the syntax is backwards compatible. Its so reliable it comes enabled by default.) gbc's warnings warn against common errors, poor decisions, etc- Directives are supported
- Meta-programming: W.I.P
- Borrow-checking: Working on that!!! Will probably be the last feature of GBC once the most essential stuff is addressed
- Portable and with multiple backends:
- QBE (default, via modernc.org/libQBE, a pure Go version of QBE)
- LLVM (via
llc) - TODO: GameBoy Color Target... Coming soon!!!
Demo
TODO: GIFs showcasing things properly
The project is currently in its infancy, and the long-term goals are very ambitious. This is the current roadmap:
ROADMAP
(i) Tests
Make a script that takes the tests from tsoding/b, and filters the tests.json to only include the IR testsMake a Go program that runs each test, displays the passing/failing ones(ii) Compatibility with tsoding/b
Support the "extrn" keyword, as well as inline assemblyUse the same warning & error messages tsoding/b/ our warnings n errors are much betterBe able to pass the IR tests of tsoding/b- A gameboy color target once all examples can be compiled and work as expected (WIP)
(iii) Packages / Modules inspired by Go
- ¿.. Namespaces based on .mod file ..?
- Implement a way to import/export symbols from different .B files, in different namespaces
Contributions are hyper-mega welcome
Acknowledgments
References
- https://research.swtch.com/b-lang
- https://www.nokia.com/bell-labs/about/dennis-m-ritchie/kbman.html
- https://www.nokia.com/bell-labs/about/dennis-m-ritchie/bref.html
- https://www.nokia.com/bell-labs/about/dennis-m-ritchie/btut.html
- https://github.com/Spydr06/BCause
- https://github.com/kparc/bcc
Not B-related, but I did find these helpful for learning how to write the compiler:
- comp-bib: "Resources for Amateur Compiler Writers"
- qcc: dead-simple C compiler
- scc: The best C99 compiler out there. QBE-backed.
- cproc: QBE-backed compiler written in C99, with support for some C23 & GNU C extensions
Cool stuff used by this project:
- QBE: The QBE compiler backend
- modernc.org/libqbe: A pure-go convertion of QBE, this allows
gbcto be self-contained