Filip Jerzy Pizło
@filpizlo
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In my spare time, I made a memory-safe C that I call Fil-C.
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I wrote a blog post about C++ transactional memory.
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I wrote a detailed post documenting how JavaScriptCore uses speculation to infer types.
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Memory-safe SQLite, everyone. It took a 15KB patch to SQLite to get this far. Fil-C is where it's at, holy fugc!
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Some folks get religious about C versus C++. I love both languages. Favorite thing about C: transparency - every expression has a clear meaning. Favorite thing about C++: abstraction - you can say so much with so few bytes. What's important is they're both better than Rust.
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Memory safe OpenSSH client just made its first login and it was beautiful. Also memory safe OpenSSL. And libc. It all works in Fil-C.
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Introducing Riptide: WebKit's Retreating Wavefront Concurrent Garbage Collector.
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A demo of memory-safe C.
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I came up with a scheme that makes it possible to add threads to JavaScript with super low overhead!
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This was a fun project to watch. And what a gloriously huge patch. Our bet that certain interpreter speed optimizations are inconsequential to JIT perf and so only cost memory paid off.
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I just wrote a concurrent GC.
It doesn’t work at all lol.
Life is good. 🤘
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Memory-safe CPython running in Fil-C has something to say!
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Memory-safe C++! Thanks to Fil-C now being able to compile libcxxabi and libcxx and being able to handle the (pizlonated version of the) Itanium C++ ABI, including member function ptrs, vtables with virtual base classes, etc.
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What a cool write up of Riptide.
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I wrote a concurrent GC in one hour and it's 333 lines long. New personal record.
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Fil-C is now only 10x slower than C on average. Best case, XZ utils decompress, is only 3x slower.
Recall I started at 200x slower. And I'm not done optimizing. This is only the beginning of my rampage.
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I've got a memory-safe OpenSSH sshd that just accepted a connection from a memory-safe OpenSSH ssh client. Fil-C is the real deal, y'all. Fuck yeah!
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I ported zsh to Fil-C and got it to work well enough that Oh My Zsh works. Say hello to my super feature-rich and totally memory-safe Linux shell!
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Fun fact: JSC’s top tier JIT, the FTL, executes our bytecode instructions faster than the CPU it’s running on executes machine code instructions.
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I got Lynx to compile with Fil-C. Only had to disable one case of a pool allocator to get there. Say hello to my totally memory safe web browser. 🕺🤘🙃
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Fil-C wouldn't be possible without the awesomeness of the clang/llvm codebase. I love how anytime I have a complex question about how C or C++ semantics are handled, the answer is in the code, clear as day, written in a wonderful hacker-friendly style.
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So cool to see this write up!
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2020 is handing me one bad hand after another. Could use y’all’s support.
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This doesn’t get said enough: the ES spec is really great. The best language spec I’ve had the pleasure of implementing to. So unambiguous, even when that wasn’t the easiest thing to do.
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Introducing the WebKit B3 compiler: Includes lots of details and empitical evaluations.
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Spectre means that you now need next-level talent to write a secure language VM. It’s game changing. It’s the most exciting thing I have seen in my life.
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Just made Fil-C ~10x faster. Less than a week of work (started on Saturday). Just two optimizations got me there, and there's still a ton of obvious stuff to do.
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Fil-C update: FreeBSD, X86_64, X11 tunneling, and C++.
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My view: I prefer to publish blogs these days because I get *more* peer review than if I submitted for publication. I get reviews faster, from more people, and those reviews lead to more constructive conversations. That's how peer review should be.
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Ever wanted to know how polymorphic inline caches work in JSC? This post about `delete` is a really good tour:
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Fil-C did find a small bug in CPython! So cool to see if fixed already!
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Memory-safe shared memory IPC with mmap in Fil-C!
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Memory safe XZ Utils with Fil-C in less than 5 minutes of work. 🤘💪
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WebKit IsoHeap = C++ template program that generates a first-fit amortized O(1) malloc with atomicless fast paths specialized for a type (size + alignment), which guarantees that once a virtual address gets used for a type, it never gets used for any other type.
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Fil’s Unbelievable C Compiler now runs an inlining pipeline before the program gets pizlonated.
This makes Fil-C ~40% faster than before on the PizBench benchmark suite geomean.
On stepanov_container, Fil-C++ is now only ~2x slower than Yolo-C++.
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Great news everyone. My compiler can compile hello.cpp with exceptions enabled without crashing!
(Don't ask me if it actually runs. I'm too scared to find out. I'll save that for another day.)
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Fil-C++ now supports exceptions. Cool fact: even the libc++abi personality function is memory safe (if it gets anything wrong then filc panic).
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Fugc it, I'm moving my development to Linux. And shooting for a PoC that involves an Awesome App (TM).
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This is what UAF looks like with FUGC. This is guaranteed. It'll always trap. No tagging. No probabilities. No shenanigans. No way around it. Your program just gets fugced.
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@NovallSwift
My philosophy: If you make a mistake in production just remind yourself how cool it is that your code is in production and then skip the part where you fault/blame.
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I can now compile *and* run hello.cpp with exceptions enabled. Note that this means I can compile and run libc++ and libc++abi with exceptions enabled.
Now.... I just need to see what happens when I actually throw an exception. 🙈😱
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My concurrent GC is so awesome right now that I get concurrent crashes in the main thread and the GC thread, and hilariously, neither threads' crash is caused by the third bug, where the GC deletes the entire heap (we don't get far enough to crash from that UAF).
VICTORY!!!
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Fun fact: JavaScriptCore’s concurrent/parallel JIT and concurrent/parallel GC use “cowboy races” liberally. They would not work in TSAN, Rust, clang thread safety analysis or anything that ties types/fields to mutexes or uses the classic definition of races.
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Working on adding “zero cost” C++ exception handling, libunwind, and setjmp/longjmp to Fil-C. Longjmp from signal handlers will be especially interesting. Wish me luck!
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We are now live with Verse runtime error telemetry! See bottom of for more info. Or, just go to , click the Verse tab, and if your project has errors in live, they will show up there. Happy debugging!
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AutoSTM = compiler hack to make C++ transactional. Wanna help me ship it?
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Fil-C on FreeBSD/X86_64 is now at parity with Darwin/AArch64. Here's a memory-safe ssh client on my Mac connecting to a memory-safe sshd server on my FreeBSD ec2 instance.
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Holy cow, XZ decompress with Fil-C is now only 1.4x slower than native C (since I started getting SIMD to work in Fil-C). That's seriously cool!
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My favorite thing about POSIX C programming is how many headers you have to include to do things.
Makes me feel so accomplished and professional for knowing all their stupid names.
Am I crazy?
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Nothing like writing a patch that spans malloc, GC, and the JITs. I fucking love WebKit.
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Fil-C now supports memory-safe setjmp/longjmp. 🤣😂🥳
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If you have an Apple Silicon Mac and you want to try memory-safe Fil-C and Fil-C++, here's a binary release. Just untar and run ./setup.sh. LMK if you run into problems, but no guarantees since nobody is paying me to work on this.
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@migueldeicaza
Because sausages don’t have a borrow checker. You can build binary trees with sausages, for example.
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I just wrote the world's shittiest liveness analysis an I'm so proud of myself.
(Yes, doing an accurate GC means writing a liveness analysis over llvm IR. No, llvm IR doesn't want you to do that. But I don't care what llvm thinks.)
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@jarredsumner
My view of why JSC has a cheaper and better embedding interface is that it's all about JSC's use of nonmoving, conservative-on-the-stack GC. That was a conscious bet on my part >10 years ago and I'm happy to see that it paid off.
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The JSC concurrent GC just ran Octane/splay to completion. 10x reduction in pause times already.
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My abstract interpreter has won the practice round. In a program like `int foo(int* x) { return x[0]+x[1]+x[2]+x[3] }`, it schedules only one combined check for all four accesses.
Lots of work remains before it can handle anything more complex...
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Benchmarks! We make them and we use them!
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curl+openssl now work on Fil-C/FreeBSD/X86_64. Getting closer to parity with Fil-C/Darwin/AArch64!
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@munificentbob
To its credit, it would still be a great language even if they were called “butt” and “potato”.
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This jpeg was encoded using memory-safe IJG libjpeg-6b. It only took a one line change to get it to build and run with Fil-C (ALIGN_TYPE in jmemmgr.c).
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BTW, this is what it looks like for Fil-C to find that bug. What a cool stacktrace! 😲😍
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Memory safe C with Fil-C running a bunch of stuff!
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I went to Hell for 3.5 years and came back with a tasty malloc. Worth it.
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I've got Fil-C on FreeBSD/x86_64 working well enough to print hello, but so far with out a stdlib (I haven't gotten a libc working yet, just libpizlo/libfilc_mincrt).
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OK, Fil-C is now a Linux/X86_64 project. Darwin and FreeBSD support is dropped. This allows me to use the Musl Sando architecture: same version of musl below and above libpizlo, allowing much cleaner syscall support. This will let me support a lot more stuff than before.
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Making the mg text editor memory safe with zero code changes thanks to Fil-C.
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Achievement unlocked: I taught Molly enough about programming that she's now able to understand what kind of programming I do (and she was curious enough to ask).
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@thingskatedid
It’s the state of the art of probabilistic GCs. Because there is some probability that it will work for some program, and that program will experience unbelievably short GC pauses with this technology.
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Super tempted to move all Fil-C development to Linux/x86_64.
If it becomes successful there, then it can always be ported to other platforms.
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I've been thinking about the algorithms in for about six years now. Feels good to have finally shared it.
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I wanted to know what it's like to use ES6 so I rewrote part of B3 in it. What fun! It's my new favorite language.
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Really proud of where I work and who I get to work with :-)
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Cool story: process shared pthread primitives work great in Fil-C! And it is in fact totally memory safe (the shared memory has int type, which is enough for pshared mutex/cond since they use int futexes for coordination).
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@agent_cooper
I think it's actually a super popular opinion held by a folks who are too busy building real systems instead of bitching on twitter/hackernews. I ❤️ C.
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The WebKit retreating wavefront concurrent/parallel/generational GC is enabled on 64-bit as of r209694. Hopefully for good this time!
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The best part of my personal project is that every commit message can be "more shit".
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