llvmkit-asmparser

Lexer and parser for LLVM textual IR (.ll).

The Rust files mirror llvm/lib/AsmParser/ and llvm/include/llvm/AsmParser/ file-for-file: LLLexer.{h,cpp} → ll_lexer.rs, LLToken.h → ll_token.rs. Tracking LLVM 22.1.4.

What's implemented

• .ll lexer — borrows from a pre-loaded &[u8]; tokens carry Cow<[u8]> payloads that allocate only when an escape sequence actually changes bytes.
• .ll parser — recursive-descent, one-token lookahead. Builds into an existing Module<'ctx, _, Unverified> from llvmkit-ir; the 'ctx brand prevents cross-module mixing at compile time. Covers target datalayout / target triple, source_filename, module asm, type definitions, globals, declarations, definitions, function attributes/comdats/header operands, metadata and debug records, use-list directives, summaries, every shipped opcode, and represented ConstantExpr forms needed by upstream fixtures, including folded vector GEP, bitcast, cast, and select cases. Remaining parser work is tracked by the workspace roadmap rather than by empty parser stubs.

Bitcode is out of scope for this crate today; see the workspace README for the roadmap.

Usage

use llvmkit_asmparser::ll_lexer::Lexer;

let mut lex = Lexer::from("@x = i32 42");
while let Some(tok) = lex.next() {
    println!("{:?}", tok.expect("lex error"));
}

For a Read-based entry point, use the read_to_owned helper:

use llvmkit_asmparser::{ll_lexer::Lexer, read_to_owned};
use std::fs::File;

let bytes = read_to_owned(File::open("foo.ll")?)?;
let lex   = Lexer::new(&bytes);
# Ok::<_, std::io::Error>(())

End-to-end examples:

• cargo run --example lex_file -- examples/demo.ll
• cargo run --example parse_file -- examples/parser_demo.ll

The parser example prints the round-tripped module via the AsmWriter on success and a (line:col) diagnostic with a caret underline on failure.

Parser corpus

tests/parser_corpus.rs reads tests/fixtures/parser_corpus_manifest.txt. Each row names an llvmkit fixture, its upstream provenance, optional expect=<file> canonical AsmWriter output, and status=pass|xfail-parse|xfail-verify. The xfail-* rows are the explicit allowlist for upstream-negative or not-yet-supported shapes; passing rows must parse, verify, and match the checked-in expected output when one is listed. Fixture comments cite upstream inputs as provenance, not as a claim that upstream's FileCheck text is identical to llvmkit's current expected output.

License

Apache-2.0 WITH LLVM-exception (same as upstream LLVM). See the workspace LICENSE.