llvm/llvm-project on Hacker News

…And the reason why I got so many "./" was due to a clang preprocessor bug that modifies __FILE__: https://github.com/llvm/llvm-project/issues/43825

comment by omoikane · 2024-07-31 · in `find` + `mkdir` is Turing complete

…assembler patch that will eliminate almost all mapping symbols without breaking disassemblers https://github.com/llvm/llvm-project/pull/99718 - RISC-V ISA extension `$x<ISA>` (unimplemented yet) would raise question where the relocatable…

comment by MaskRay · 2024-07-22 · in Mapping Symbols: Rethinking for Efficiency

…indices that each select a separate register, and blend those shuffled together all in one uop. https://github.com/llvm/llvm-project/issues/79196 also mentions this in "we want the elements to come from as few DLENs of the source vector as…

comment by dzaima · 2024-07-21 · in Linus Torvalds says RISC-V will make the same mistakes as Arm and x86

…bisecting functions when given assembly produced by working baseline and “bad” compiler to compare: https://github.com/llvm/llvm-project/blob/main/llvm/utils/ab...

comment by MatzeBraun · 2024-07-19 · in Hash-based bisect debugging in compilers and runtimes

Ok, 18.1.8 uploaded [1] [2]. [1] https://github.com/llvm/llvm-project/releases/tag/llvmorg-18... [2] https://discourse.llvm.org/t/18-1-8-has-been-tagged/79726/10...

comment by quic_bcain · 2024-07-06 · in Integrated assembler improvements in LLVM 19

▲ 12

Guide on optimizing Linux kernel with BOLT

story by dist1ll · 2024-07-03 · 0 comments

This looks like iffy blogspam of https://github.com/llvm/llvm-project/blob/main/bolt/docs/Opt... The claim in it is 'up to 5% improvement' so the title seems overstated as well.

comment by pvg · 2024-07-03 · in Meta Sees ~5% Performance Gains to Optimizing the Linux Kernel with Bolt

…knows where else there might be pre-builts? There used to be something just like that for v17, like https://github.com/llvm/llvm-project/releases/download/llvmo...

comment by Keyframe · 2024-07-01 · in Integrated assembler improvements in LLVM 19

…planned: - Removing per-instruction timers, which add a measurable overhead even when disabled ( https://github.com/llvm/llvm-project/pull/97046 ) - Splitting AsmPrinterHandler (used for unwind info) and DebugHandler (used also for…

comment by aengelke · 2024-07-01 · in Integrated assembler improvements in LLVM 19

…However, due to complex interactions in the backend, this does not actually happen in this case ( https://github.com/llvm/llvm-project/issues/94829 ).

comment by nikic · 2024-06-09 · in Compilers are too smart

…the output back to an object file. The test cases are a good way to explore the functionality: https://github.com/llvm/llvm-project/tree/main/llvm/test/too... https://github.com/llvm/llvm-project/tree/main/llvm/test/too...

comment by MaskRay · 2024-05-28 · in Evolution of the ELF object file format

To answer my own question, it appears the Oryon CPUs do not according to this LLVM patch: https://github.com/llvm/llvm-project/blob/8aebe46d7fdd15f02a... There's a pretty good interpretation of it here:…

comment by 201984 · 2024-05-23 · in Introducing Copilot+ PCs

…it to enable partial and runtime unrolling for in-order models. I've left a review comment https://github.com/llvm/llvm-project/pull/91022/files#r16026... and as I note there, the setting seems to have become very divorced from…

comment by asb · 2024-05-16 · in Qualcomm's Oryon LLVM Patches

…to in that GH issue is showing that LLVM will attempt constant folding of various trig functions: https://github.com/llvm/llvm-project/blob/faa43a80f70c639f40... but the IEEE-754 spec does also recommend correctly rounded results for those…

comment by boulos · 2024-05-11 · in Why the CORDIC algorithm lives rent-free in my head

…people have written tooling for those checks for various CPUs? Also, is it that ‘simple’? Reading https://github.com/llvm/llvm-project/issues/62479 , calculations that the compiler does and that only end up in the executable as constants…

comment by Someone · 2024-05-11 · in Why the CORDIC algorithm lives rent-free in my head

…[1] to libc++ [2]. [1]: https://github.com/gcc-mirror/gcc/blob/065dddc/libstdc++-v3/... [2]: https://github.com/llvm/llvm-project/blob/1a96179/libcxx/inc... Basically libstdc++ is paying an extra 8 bytes of storage, and losing trivial…

comment by quuxplusone · 2024-05-08 · in Qt and C++ Trivial Relocation (Part 1)

▲ 2

Add support for Qualcomm Oryon processor

story by gok · 2024-05-04 · 0 comments

…is still in preview[2], and GCC 14 isn't even out yet. This can't be nearer the bleeding edge. [1]: https://github.com/llvm/llvm-project/releases/tag/llvmorg-18... [2]: https://learn.microsoft.com/en-us/visualstudio/releases/2022...

comment by delta_p_delta_x · 2024-04-29 · in Speeding up C++ build times

See https://github.com/llvm/llvm-project/issues/88344 https://fortran-lang.discourse.group/t/flang-new-how-to-forc...

comment by zaikunzhang · 2024-04-14 · in Flang-new: How to force arrays to be allocated on the heap?

…guarantees (like memory fences) from loops, not just the data as it appears to a single thread. [1] https://github.com/llvm/llvm-project/issues/64188

comment by dataflow · 2024-04-07 · in A memory model for Rust code in the kernel

Pull requests are always welcome ( https://github.com/llvm/llvm-project ), and one can contact the general LLVM Fortran development community ( https://discourse.llvm.org/c/subprojects/flang/33 ) for help. I am focused on things needed to…

comment by pklausler · 2024-04-05 · in Fortran on WebAssembly

…ifunc has real uses and it indeed does not work when sanitizer is enabled. Similar change in llvm: https://github.com/llvm/llvm-project/commit/1ef3de6b09f6b21a...

comment by nialv7 · 2024-03-29 · in Backdoor in upstream xz/liblzma leading to SSH server compromise

There is a related issue for LLVM/clang by this person: https://github.com/llvm/llvm-project/issues/63957

comment by mxmlnkn · 2024-03-29 · in Backdoor in upstream xz/liblzma leading to SSH server compromise

…being able to cache and reuse compiled queries. Actually, it's implemented in LLVM for years :) https://github.com/llvm/llvm-project/commit/a98546ebcd2a692e...

comment by weliveindetail · 2024-03-18 · in I wrote a new JIT compiler for PostgreSQL

…fixed in both major C++ libraries: https://github.com/gcc-mirror/gcc/commit/ebf6175464768983a2d... https://github.com/llvm/llvm-project/commit/4f67a909902d8ab9... So what C++ community refused to regard this as an issue and refused to fix…

comment by kllrnohj · 2024-03-12 · in C++ Safety, in Context

…a bit on this aspect. [^1]: https://github.com/gcc-mirror/gcc/commit/ebf6175464768983a2d... [^2]: https://github.com/llvm/llvm-project/commit/4f67a909902d8ab9...

comment by adev_ · 2024-03-12 · in C++ Safety, in Context

Ok, I've restored the URL you submitted ( https://github.com/llvm/llvm-project/blob/8ec28af8eaff5acd0d... ).

comment by dang · 2024-03-02 · in Clang accepts MSVC arguments and targets Windows if its binary is named clang-cl

…from several other places as well. `IsClangCL()` that returns true if the driver mode is "cl": https://github.com/llvm/llvm-project/blob/8ec28af8eaff5acd0d... `setDriverMode()` which sets the above: https://github.com/llvm/llvm-project/blob…

comment by delta_p_delta_x · 2024-03-02 · in Clang accepts MSVC arguments and targets Windows if its binary is named clang-cl

For everyone else looking for the magic in this almost 7k lines monster, look at line 6610 [1]. [1] https://github.com/llvm/llvm-project/blob/8ec28af8eaff5acd0d...

comment by mschuster91 · 2024-03-02 · in Clang accepts MSVC arguments and targets Windows if its binary is named clang-cl

▲ 27

Clang accepts MSVC arguments and targets Windows if its binary is named clang-cl

story by delta_p_delta_x · 2024-03-02 · 6 comments

…I don't know, and apparently it's so complex that it requires over 9000 lines of C++ to express: https://github.com/llvm/llvm-project/blob/main/llvm/lib/Anal...

comment by tinco · 2024-02-28 · in Rewrite the VP9 codec library in Rust

https://github.com/llvm/llvm-project/blob/main/flang/docs/F2...

comment by pklausler · 2024-02-22 · in Fortran 2023

…from memory, even when the original location is still available, as can be seen in this issue: https://github.com/llvm/llvm-project/issues/53348 I vaguely remember that it could allow high-end CPUs to use something similar to register…

comment by newpavlov · 2024-02-06 · in Avoiding register spills in vectorized code with many constants

…support for debuginfod server topologies now, it would be great to see Rust tools get on the train. https://github.com/llvm/llvm-project/commit/36f01909a0e29c10... And naturally we already have a port: https://crates.io/crates/debuginfod-rs

comment by raggi · 2024-01-26 · in Making Rust binaries smaller by default

…false but still worthwhile. [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55522 (GCC), https://github.com/llvm/llvm-project/issues/57589 (LLVM)

comment by lifthrasiir · 2024-01-24 · in From slow to SIMD: A Go optimization story

Looks like llvm recently got some RISC-V fusion support via -mtune: https://github.com/llvm/llvm-project/commits/main/llvm/lib/T...

comment by camel-cdr · 2024-01-20 · in MRISC32 – An Open 32-Bit RISC/Vector ISA (Suitable for FPGA CPU)

https://github.com/llvm/llvm-project/issues/57589 Turn on fast-math, it flips the FTZ/DAZ bit for the entire application. Even if you turned it on for just a shared library!

comment by jcranmer · 2024-01-16 · in Std: Clamp generates less efficient assembly than std:min(max,std:max(min,v))

…and it gets loaded, it sets the register, causing the whole process to flush it's subnormals. i.e https://github.com/llvm/llvm-project/issues/57589

comment by borodi · 2024-01-16 · in Std: Clamp generates less efficient assembly than std:min(max,std:max(min,v))

…uses a functionally same but slightly different stub file [1] because it prints no newlines. [1] https://github.com/llvm/llvm-project/blob/d7642b2/lld/COFF/W...

comment by lifthrasiir · 2024-01-11 · in Research paper is also an executable x86 program [pdf]

…maybe it wasn't actually fixed--note: I only skimmed the comments and I probably misunderstood): https://github.com/llvm/llvm-project/issues/13989 Edit again: I forgot about the comment at the end of the article that clarifies that…

comment by schemescape · 2023-12-03 · in Clang now makes binaries an original Pi B+ can't run

…days. References: see the LLVM Flang documentation on extensions, non-standard features, &c. in https://github.com/llvm/llvm-project/blob/main/flang/docs/Ex... and a suite of various incompatible feature tests in…

comment by pklausler · 2023-11-30 · in Potential of the Julia programming language for high energy physics computing

…C or C++ I'd strongly recommend using `__builtin_popcount` (provided by both Clang and GCC). [1]: https://github.com/llvm/llvm-project/blob/08a6968127f04a40d7... [2]: https://llvm.org/docs/LangRef.html#llvm-ctpop-intrinsic

comment by asb · 2023-11-28 · in Designing a SIMD Algorithm from Scratch

flang [1], it's part of the LLVM project. [1] https://github.com/llvm/llvm-project/tree/main/flang

comment by rsecora · 2023-11-22 · in Fortran 2023

…because of long compile times, spooky action at a distance, etc. Take these two files from LLVM: https://github.com/llvm/llvm-project/blob/main/libcxx/includ... https://github.com/llvm/llvm-project/blob/main/libcxx/includ... Is this "clean…

comment by gizmo · 2023-11-08 · in Hard-to-swallow truths they won't tell you about software engineer job

▲ 1

Preprocessor Embed Support for Clang

story by sigsev_251 · 2023-10-09 · 0 comments

…all, I haven't checked 100%). For example, their libc stdio implementation is completely in C++. https://github.com/llvm/llvm-project/tree/main/libc/src/stdi... You could say the same thing about Rust and Relibc, but it seems much less…

comment by trealira · 2023-10-03 · in Glibc dynamic loader hit by a nasty local privilege escalation vulnerability

…of currently caught exceptions. For example in llvm this is available with a cxa_get_globals call: https://github.com/llvm/llvm-project/blob/b05f1d93469fbd6451... These need to be saved/restored when switching fibers, otherwise fiber…

comment by snaury · 2023-09-24 · in Fiber in C++: Understanding the Basics

…been to drag some of these issues into the sunlight, as it did for aliasing problems previously. https://github.com/llvm/llvm-project/issues/45725 Once the GCC work is closer to finished, I expect we'll see the same there. I disagree that…

comment by tialaramex · 2023-09-19 · in Changing the Rules of Rust

That would mean you can't use LLVM either. Similar issues exists there: https://github.com/llvm/llvm-project/labels/miscompilation

comment by wdb · 2023-09-07 · in Bun 1.0 announcement [video]

…This file implements an analysis, but the results of the analysis is used by transformations. https://github.com/llvm/llvm-project/blob/main/llvm/lib/Anal... > 3. there's no guarentee this malloc is a per-spec malloc, it can be a…

comment by nlewycky · 2023-09-04 · in Using uninitialized memory for fun and profit (2008)