Ada83

A single-file Ada 83 LLVM compiler.

Compiler	ada83.c, 64k lines, no generated code, no third-party source
Runtime	ada83-runtime.ada, 3k lines of Ada
Language	all of MIL-STD-1815A: tasking, generics, fixed point, representation clauses
Conformance	3561 / 3561, ACATS 1.11
Targets	Linux, macOS, Windows

Quick start

From the latest release, unpack the archive for your platform: bin-linux.zip, bin-macos.zip or bin-windows.zip

with Text_IO; use Text_IO;
procedure Hello is
begin
   Put_Line ("Hello, Ada 83!");
end;

$ ./ada83 hello.ada -o hello
Compiled 'hello.ada' -> 'hello.native.ll'
Generated ALI file 'hello.native.ali'
$ ./hello
Hello, Ada 83!

For the editor, install the extension that came in the same archive:

code --install-extension ada83.vsix

It needs ada83 on your PATH, or ada83.compilerPath set to where you unpacked it.

Building

Platform	Command	Notes
Linux	make	GCC or Clang; installs libLLVM via the system package manager if absent
macOS	make.applescript	Apple Clang; libLLVM via Homebrew
Windows	make.bat	GCC or Clang; offers to fetch Zig if neither is installed

Every script writes what it builds into bin-<target>/ - bin-linux/ada83, bin-macos/ada83, bin-windows\ada83.exe with the DLLs it loads beside it. The DLLs are vendored in bin-dll.zip, which holds nothing else; the release workflow zips each finished bin-<target>/ into the archives it publishes.

ada83-runtime.ada holds the standard library, and the compiler looks for it beside its own executable.

Platform	Command	Produces
Linux	make package	bin-linux/, extension and artwork included
macOS	osascript make.applescript package	bin-macos/, both slices together
Windows	make.bat package	bin-windows/, DLLs included

Conformance

Under ACATS 1.11 all 3561 tests pass

Suite	Category	Passed	Completion
A	Acceptance	140 / 140	100% ✅
B	Illegality	1350 / 1350	100% ✅
C	Executable	1973 / 1973	100% ✅
D	Numerics	17 / 17	100% ✅
E	Inspection	34 / 34	100% ✅
L	Post-compilation	47 / 47	100% ✅
	Total	3561 / 3561	100% ✅

Benchmarks

Run time of the generated code at -O2, against GNAT 13.3.0 (GCC 13.3.0-6ubuntu2~24.04.1), on Linux x86_64 with 4 cpus (Intel Xeon @ 2.10 GHz), with libLLVM 20.1.2 behind ada83's back end.

Program	Stresses	ada83 (s)	gnat (s)	Ratio	Result
lu	LU decomposition, float division	0.058 ± 0.001	0.205 ± 0.004	0.28	3.5× faster
strings	slices and character work	0.057 ± 0.001	0.055 ± 0.001	—	indistinguishable
numerics	fixed point and 12-digit float *	0.122 ± 0.002	0.090 ± 0.001	1.36	1.4× slower
memory	allocation and deallocation	0.382 ± 0.009	0.257 ± 0.009	1.49	1.5× slower
checks	range and index checks in a hot loop	0.258 ± 0.004	0.164 ± 0.004	1.57	1.6× slower
sieve	integer arrays, index checks	0.087 ± 0.003	0.051 ± 0.001	1.71	1.7× slower
recurse	call and return	0.057 ± 0.001	0.023 ± 0.000	2.48	2.5× slower
matmul	dense float, nested loops	0.049 ± 0.001	0.017 ± 0.001	2.88	2.9× slower

VSCode Extension

ada83 --lsp serves the Language Server Protocol on stdin and stdout.

Error messages can be read in another language. ada83.language picks one, and anything but English hands the message to the editor's model.

ada83.language
en	English, as the compiler writes it — no model, no request
es	Spanish
fr	French
de	German
zh-CN	Chinese (Simplified)
ja	Japanese
hi	Hindi
lolcat	O NOES 'Put_Lin' IS NOT CALLABUL. SRSLY.

Setting
ada83.compilerPath	Location of ada83 and where ${workspaceFolder} gets substituted
ada83.includePaths	Directories for with-ed units
ada83.language	Language error messages are read in
ada83.formatOnType	Reindent each line as you type it
ada83.formatOnSave	Reformat the whole file as it is saved, by asking a model
ada83.formatStrength	How much a reformat may change: indentation, layout or style
ada83.trace.server	Write the protocol traffic to the output channel

Use

The compiler emits LLVM IR, so the IR can be taken directly:

./ada83 --ir hello.ada -o hello.ll      # Textual LLVM IR
./ada83 --emit-llvm hello.ada -o hello  # Native, keeping the optimised IR
./ada83 --ir a.ada b.ada c.ada          # Several units, one process each
./ada83 hello.ll world.ll -o hello      # Link .ll modules, no source needed
lli hello.ll                            # Interpret the IR

Tests

The ACATS tests are in tests.zip and unzipped on first use.

bash test.sh         # Every class, the default
bash test.sh run c   # One class
bash test.sh run c45 # One group
bash test.sh check   # Run, then diff against the baseline
bash test.sh help

Release Workflow

1. Update ada83.c with ADA83_VERSION_MINOR or ADA83_VERSION_MAJOR through a normal PR and merge to main.
2. Update git with git tag v1.0 && git push origin v1.0
3. Allow release.yml to verify the tag, build and packages all platforms and publishes.

The tag gate refuses to publish unless the tag matches ADA83_VERSION_* and no release exists under that tag. So a tag on an unmerged branch, or one that disagrees.