I am C-Reduce, the shrinker of C/C programs.
Joined June 2012
- Tweets 289
- Following 69
- Followers 481
- Likes 385
3 Photos and videos
Always happy to help!
10 Jul 2025
One contestant experimented with C-Reduce; a way to search for C programs that create unusual compiler behavior.
Maximizing the fitness function for error as a reward, no templates, no pre-processor hacks.
Just nested parenthesis causing exponential error output!
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C-Reduce retweeted
4 Mar 2025
Learn LLVM until I find a compiler job | Day 29
Both creduce and llvm-reduce are still running. Hopefully, the can finish by tomorrow morning.
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C-Reduce retweeted
16 Nov 2024
My favorite version of this is github.com/maleadt/creduce_j⦠which can take an entire tree of Julia packages and apply creduce to it .
Now I just need to figure out how to use Julia's parser to do smarter rewrites.
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"You can use C-Reduce for any language" by Max Bernstein.
bernsteinbear.com/blog/creduβ¦
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C-Reduce retweeted
16 Jul 2024
Running creduce to try to minimize a test case for "clang produces different binaries when building natively on i386 vs cross-building from amd64". Only reduced from 2346 to 1727 lines so far, which makes me think this bug is hard to trigger.
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I'll try anything!
9 Jan 2024
Does such a thing as CReduce for a Python script exist? (Or can CReduce be abused into working on Python code?)
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C-Reduce retweeted
7 Oct 2023
I tried creduce to reduce a segfaulting test case and it reduced it to this π #creduce #screenshotsaturday
ALT gdb disassembly output showing code for main function that basically calls itself, which is UB and causes segfault.
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I love working the night shift. π
Thanks for the shout out!
28 Jun 2023
I reduce a lot of compiler bugs, so I have a system that involves a directory full of stub stdlib/system headers, creduce, and some ready-made scripts.
I also have a 64-core machine. creduce takes it down to ~10k overnight, and I take it from there.
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C-Reduce retweeted
12 Jun 2023
You should use creduce to minimize that.
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Thanks for the shout out!
29 May 2023
creduce is good to know regardless, it's just especially good at this
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C-Reduce retweeted
16 Feb 2023
You can make minimal repros using creduce fairly easily. Even with msvc, just do it under WSL and take advantage of the fact you can call native win32 programs. No advanced C skills necessary
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C-Reduce retweeted
16 Feb 2023
creduce help text:
--shaddap Suppress output about non-fatal internal errors
[..]
--sllooww Try harder to reduce, but perhaps take a long time to do so
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C-Reduce retweeted
16 Feb 2023
Expectation: I have a bug, let me try to use C-Reduce to reduce it
Reality: Run into a bug with C-Reduce itself
Happy weekend I guess...
Oh wait, it's just Thursday.
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ALT Photograph of a glass award in box. Text: "ACM SIGPLAN / Most Influential Paper of PLDI 2012 / Awarded at PLDI 2022 / Test-Case Reduction for C Compiler Bugs / by / John Regehr, Yang Chen, Pascal Cuoq, Eric Eide, Chucky Ellison and Xuejun Yang"
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C-Reduce retweeted
15 Nov 2022
TFW the code creduce produces would probably not lead to a productive compiler bug report because it does weird things (like a null deref) that the original code doesn't do, but re-adding parts of the original code makes the bug you're trying to report not reproduce anymore...
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C-Reduce retweeted
13 Oct 2022
I'm having a @creduce problem: my source file has been preprocessed using clang-14, and now gcc-11 is complaining about it with errors like:
error: two or more data types in declaration specifiers
214 | typedef float _Float32;
Anyone know how to solve this?
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