February 8, 2026
Kernel dreams, reality checks
Claude's C Compiler vs. GCC
AI builds a 'compiler' in hours—devs split between awe, eye-rolls, and 90% jokes
TLDR: Anthropic’s AI built a C compiler and claims it can build the Linux kernel, but early tests show up to 20× slowdowns versus GCC. Commenters are split: some cheer the rapid AI build, others say it only counts when it’s fast and reliable—making this a must-watch AI vs. legacy showdown.
Anthropic says its AI-made C tool, Claude’s C Compiler (CCC), can even build the Linux kernel. The code was written by Claude Opus 4.6, in Rust, and the internet immediately grabbed popcorn. Then the speed tests hit: a popular database ran 12× slower without tuning and 20× slower even with it. Cue gasp. One camp cheered the feat—an AI scaffolding a whole compiler in hours is wild—while skeptics fired back that slow and flaky means “not ready.” The vibe: demo magic vs. real-world pain.
Technical diehards explained the gap in plain terms: GCC (the veteran GNU Compiler Collection from 1987) has decades of tricks to juggle computer registers and turbocharge code, and CCC doesn’t—yet. Over on the “is this original?” beat, a commenter wondered if Claude just browsed and rewrote classic compiler ideas into Rust, poking at the “AI remix” question. Meanwhile, Anthropic’s post and the repo became the arena for memes and the timeless joke: the last 10% takes the other 90% of the time.
Bottom line: CCC looks like a flashy first draft—impressive build, messy results. The community is split between wow and whoa, slow, and the drama is delicious: can an AI fix the hard parts, or is GCC still king for a reason?
Key Points
- •Anthropic introduced Claude’s C Compiler (CCC), claiming it can compile the Linux kernel, with all code generated by Claude Opus 4.6 and humans providing tests.
- •CCC’s Rust codebase targets x86-64, i686, AArch64, and RISC-V 64, and includes a frontend, SSA-based IR, optimizer, code generator, peephole optimizers, assembler, linker, and DWARF debug info, built from scratch.
- •The article sets out to verify Anthropic’s claim and benchmark CCC against GCC, the long-standing industry standard.
- •It outlines the four stages of building a C program: preprocessing, compilation to assembly, assembling to machine code, and linking into an executable.
- •The article explains that while parsing and translating C is notable, matching GCC’s decades of optimizations and handling complex instruction encodings—especially on x86-64—remains a major challenge.