is clang better than gcc?

6 Continue this thread level 2 Or with WebP image encoding, AOCC was on-par with the upstream LLVM Clang releases. Clang is also built to be a drop-in replacement for GCC command. And with that better understanding, a warning can go away. Clang is mainly used to provide performance superior to that of GCC. Since now GCC is deprecated and Clang is new default, we would like to see Clang building binaries that are of similar size (when using same optimisation parameters). Answer (1 of 3): Hi, Let me clear some confusion, Visual Studio is not compiler, it is a complete IDE with all development tool inbuilt. On the Intel side, the Core i5 2500K interestingly had slightly better performance on Clang over GCC. 0 100 200 300 400 500 600 700 800 GCC GCC 32 ICC ICC 32 CLANG . The results are almost similar to Perlbench benchmark, the only difference between that ICC O2 & O3 have better runtime than corresponding GCC levels. GCC or clang are both great for C++ development as they are conforming C++14 implementations. This looks like something the clang needs to do better on, as I really don't see people adding these casts to future code. In both cases, the identity conversion sequence is involved: int to int, and int to const int& (the latter is considered the identity conversion sequence thanks to [over.ics.ref]/1). if you make a typo in a function name you call, Clang will report that this is likely a typo (and suggest the correct name), while GCC will complain about unknown function name. This will provide the symbolic link (softlink) to the default version of GCC. It makes my code that little bit better to run it through both compilers. Like for ps-uni (point-select uniform 128 threads), the highest throughput is seen with clang-o3 and lowest with clang-ofast Observations In most cases, clang O2/O3 has performed better than gcc. Beside this, is clang better than GCC? (1) When the company started & chose vxWorks, clang wasn't an option. E.g. Open a terminal window. Yes, I know things are a lot better in C++, but there may still be times when you can't escape from its C roots, such as when writing language bindings, or when using a library written in C. Really, this should have been fixed thirty years ago! However, Clang is more powerful and has been specifically designed for performance. GCC produces better code than clang - I'd consider both to be more or less the same w.r.t code quality for primary platforms like x86 or arm. Type "gcc -version" in command prompt to check whether C compiler is installed in your machine. A fine reason to stick with GCC / Clang is if you really can't be bothered learning how to use Microsoft their tools. But Clang would likely generate better code, and almost certainly generate more helpful errors/warnings/analysis. GCC is indifferent to -O3 optimization clang benefits very marginally from -O3 optimization clang beats GCC by a similarly important margin at each level of optimization. It's free, of course, and typically available in your Linux distribution's package repositories. The linux kernel now supports native clang builds, setting LLVM=1 enables t. Clang is much faster and uses far less memory than GCC. In most cases, clang O2/O3 has performed better than gcc. In GCC and Clang, I imagine a __builtin_arraysize function would probably make a whole lot of sense. GCC has some splendid warnings that MSVC does not offer, and vice versa. Comparing these results with those for GCC 4.7.2 and clang 3.2, it stands out that GCC has clawed back about a quarter of clang's lead at each optimization level. However, LLVM and the open source C-language compiler built on top of it (Clang) do not get a lot of attention in the embedded world. On the other hand, GCC is still actually a better compiler than Clang/LLVM is. Although GCC-7.1 is faster than GCC-6.3, all the GCC versions are slower than GCC-4.9.4 which is the fastest at compiling code . The -mno-bti-at-return-twice flag will make sure a BTI instruction won't be added after a setjmp or possible other return-twice construct (ARM backend only). And at each optimization level GCC now beats Clang by 17%. I thought I would deliver my few cents too. While GCC and ICC only have at max 50% increase in runtime between O0 and O1. While LLVM and GCC both support a wide variety languages and libraries, they are licensed and developed differently. I must admit that I was quite skeptical of the LLVM/Clang project when it started, but people have put an impressive amount of work . Clang is better than Gcc in several respects, but it has a tendency for excessive loop unrolling, which is a waste of code cache. GCC improved their diagnostics and released their comeback article, titled "Clang Diagnostics Comparison". Llvm s back-end is faster than gcc s. from question Xcode 3.2.1 GCC CLANG and LLVM demystification. Answer (1 of 2): This is pretty subjective, but let me address some common misconceptions: 1. If clang didnt depend on gcc.. it would have had less deps. Visual Studio is proprietary tool, so it does not use gcc/g++(which is Open source), whereas it u. GCC currently is more portable than Clang (Windows support being the major hole currently in clang) & more popular in the Linux world. GCC is the most popular compiler and is used by most major software companies. This hunk: > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c Here we see that Clang performance does not improve with O2 and O3, but slightly decreases. O3 have better runtime than corresponding GCC levels. The -aarch64-none-elf target now uses the BareMetal driver rather than the GNU driver. On macOS, Clang is the default choice, installed with the Xcode command-line tools. But their licenses differ quite a bit. So it shouldnt depend on gcc. Is . For now, only… Currently, binaries produced by Clang are up to 15% larger than binaries produced by GCC. The choice of which one to use really depends on what things are important to you. Both builds can't use -march=native so It may be an equal comparsion. GCC Vs Clang comparison under the head of the license should be best left to the lawyers. I would say that, if you are already familiar with GCC / Clang, not familiar with MSVC, and plan on targeting both *nix and Windows, then I don't really see why you should bother to learn MSVC . The difference is less than 3%. Is clang better than GCC? GCC's warnings are sometimes acceptable, but are often confusing and it does not support expressive diagnostics. . It producers faster code, it produces smaller code, it correctly compiles more code, (the linux kernel is a notable example) etc. Programs that depend on clang invoking GCC as the linker driver should use GCC as the linker in the build system. But Intel's compilers include lots of proprietary optimizations for its own chips, and can often output executable code that performs better than that produced by third-party compilers such as GCC. Through long-term development and iteration, GCC, Clang, and LLVM have become mature compilers in the industry. If you are running Linux, the GNU Compiler Collection (GCC) is a popular choice. In both cases, the identity conversion sequence is involved: int to int, and int to const int& (the latter is considered the identity conversion sequence thanks to [over.ics.ref]/1). default (gcc-O2) tend to perform worse/average for most cases. Is clang better than gcc? Indeed, clang-4.0.1 is much faster for compilation than clang-3.9. GCC more than reverses Clang's former superiority. Is Clang better than Msvc? GCC has some splendid warnings that MSVC does not offer, and vice versa. GCC is licensed under GPL (GNU public license) whereas Clang/LLVM is licensed under Apache License. It turns out that gcc can now do more or less as good a job as the hand-crafted asm. FOSS software - It is true that both GCC and Clang are free and open-source software. I would say that, if you are already familiar with GCC / Clang, not familiar with MSVC, and plan on targeting both *nix and Windows, then I don't really see why you should bother to learn MSVC . But where it differs from the Intel Rocket Lake results is that at "-O3 -march=native" the Clang compiler still squeaked past GCC 11, including when making use of Link Time Optimizations. MinGW also compiles significantly slower than MSVC (though precompiled headers help a little). Clang has much better error reporting. Enter the command (clang — version) to confirm if the Clang Compilers had already been installed. With Haswell and Ivy Bridge era systems the GCC vs. Clang performance was the same. Is LLVM better than GCC? We use GCC. MSVC is fine if you are actually targeting Windows; MSVC is not nearly as bad as some here would have you believe. Clang developers have spend a hughe amount of work to make sure you can (usually) use clang as a drop in replacement for gcc. The current version of the Android NDK uses version 4.6 of the open source Gnu Compiler Collection (GCC) toolchain by default. Again to compile C++ program you need g++ compiler not gcc. Let's see who is really better by testing common errors in Clang 6.0.0, GCC 7.3.0, and, via the Compiler Explorer, MSVC 2017 19.10.25107. About Clang, It depends on gcc which includes gcc dependencies. After some consideration I think we'll stay with GCC for now and I'm going compare Fedora GCC 8 builds with the Mozilla LLVM Clang ones when there are available. Advantages of GCC GCC supports more traditional languages than Clang and LLVM, such as Ada, Fortran, and Go. Is clang better than gcc? Clang is faster than GCC - While historically true, this isn't the case anymore. It's ambiguous. (2) No-one has felt strongly enough about switching to clang to put forth the argument for switching. Better Firmware with LLVM/Clang. GCC supports more less-popular architectures, and supported RISC-V earlier than Clang and LLVM. If you need to analyze or modify code at the source level, Clang is better than LLVM. AOCC 3.2 did come out technically in front for this benchmark but with no meaningful difference against the newer GCC and Clang releases. > This patch now works with both gcc and clang. If there's a project that caught my interest lately, it's Clang, a front-end for the LLVM compiler created as a "drop-in" replacement for gcc. In general, Clang-produced binaries run more slowly than the equivalent GCC binaries: While using LLVM is faster at building code than GCC. gcc: 2.41888s clang: 0.0396217s Timing -O2: gcc: 2.41024s clang: 0.0395114s Timing -O1: gcc: 2.41766s clang: 2.43113s So it seems that gcc does not optimize this function at all even at higher optimization levels. Ofast fails to perform for both gcc or clang. Both GCC and Clang support using ld.lld instead of the system linker (which may well be lld, like on FreeBSD) via the command line switch -fuse-ld=lld. DoDoENT commented on Mar 15, 2016. It's ambiguous. Clang is much faster and uses far less memory than GCC. __attribute__ will not really suppress a warning. If you have ever done software development that involves Apple products, FreeBSD, WebAssembly, or Rust, you have used the wildly popular compiler toolchain known as LLVM. Observations. Change the softlink to point to the version of GCC that you want to use. While LLVM's Clang C/C++ compiler was traditionally known for its faster build speeds than GCC, in recent releases of GCC the build speeds have improved and in some areas LLVM/Clang has slowed down with further optimization passes and other work added to its growing code-base. DoDoENT commented on Mar 15, 2016. It's been quite a while since I did measurements, but I've seen compile times up to twice as fast . Clang aims to provide extremely clear and concise diagnostics (error and warning messages), and includes support for expressive diagnostics. But it's possible that Firefox codebase somehow fits better LLVM Clang than GCC. Is Clang Better Than GCC? To update or install the Clang Compilers, you need to type in the following command: command xcode-select-install For ARM the situation is ambiguous, often Clang optimizes better. I can't see any rational reason to prefer Gcc. Ofast fails to perform for both gcc or clang. (For no scenario, it is able to perform . The advantage of this is that you can "mix and match" your code; compiling some parts with gcc and other parts with clang, and link them all together and they will work. So the gcc vs. clang debate flamed up again. Sometimes Clang is faster, sometimes Gcc is faster. GCC's warnings are sometimes acceptable, but are often confusing and it does not support expressive diagnostics. As part of our ongoing benchmarks of GCC 11 vs. LLVM Clang 12 given these fresh open-source compiler releases, today's comparison is looking at the Core i9 11900K "Rocket Lake" performance. Type "g++ -version" in command prompt to check whether C++ compiler is installed in your machine. Here are sizes of our barcode library when compiled . This means that switching to clang is going to be really easy, but it also provides at least two useful features which make it really better than gcc for local development: Compilation speed. Answer (1 of 11): If you're doing compiler research, LLVM/Clang is much, much easier to modify as plugins were part of the original architecture. In its design, the Clang compiler has been constructed to work very similarly to GCC to ensure that portability is maximized. First, we have to look at the implicit conversion sequences. In fact in the clang compiler it plays a major role but that s entirely internal - what comes out of clang is pure native arm ios machine code;llvm is not a virtual machine in that sense of the word. Clang first dissed GCC in their "Expressive Diagnostics"article. Currently, binaries produced by Clang are up to 15% larger than binaries produced by GCC. Clang is a C, C++, Objective-C, or Objective-C++ compiler that is compiled in C++ based on LLVM and released under the Apache 2.0 license. Despite all that, GCC/MinGW is an entirely reliable quality compiler, which in my opinion outperforms any to date available version of MSVC in terms of quality of generated code. I'm trying to build various dkms packages using clang rather than gcc and I don't know how to override the default gcc setting and get dkms to use clang instead. GCC supports more language extensions and more assembly language features than Clang and LLVM. It's a brand new, state of the art, modern, BSD-licensed open-source compiler that is a lot faster, optimizes more aggressively while using far less memory than the competition. Navigate to the directory which has this softlink. Of course there are differences, for example LLVM enables auto-vectorizer at -O2 while GCC only enables it by default at -O3, however Continue Reading Related Answer Amlan Dutta With the newer Intel CPUs like the Xeon Silver 4108, Core i7 8700K, and Core i9 7980XE, these newer Intel CPUs were siding with the GCC 8/9 compilers over Clang . In the case of GCC and Clang, that is __attribute__. default (gcc-O2) tend to perform worse/average for most cases. clang used to be incredibly fast and used little memory consumption, but recent versions have seen the compiler regress in both areas. Since now GCC is deprecated and Clang is new default, we would like to see Clang building binaries that are of similar size (when using same optimisation parameters). For a large app, they would likely be about even in compile time. There are multiple factors to consider when choosing a compiler. It makes my code that little bit better to run it through both compilers. I'm trying to build various dkms packages using clang rather than gcc and I don't know how to override the default gcc setting and get dkms to use clang instead. Like for ps-uni (point-select uniform 128 threads), the highest throughput is seen with clang-o3 and lowest with clang-ofast. With both GCC and LLVM Clang, the benchmarks were carried out three times with varying CFLAGS/CXXFLAGS. In the most optimized configuration tested, Clang 12 was still about 4% faster than GCC 11 on this Zen 3 system, unlike GCC leading on the Intel side. Comonly (on Linux) you can use clang to compile a program and link it against a program compiled by gcc. On the other hand clang does a lot more now than it used to so it's somewhat justified. On wikipedia Clang states that it is a replacement for gnu c compiler. Visual Studio is a little bit lagging but it's catching up. in the rest of the tests the performance was either close to that of GCC or well behind. Second, we look at the tie-breaker rules regarding standard conversion sequences, [over.ics.ref]/3.2. They're ugly and redundant (or GCC). 1 yr. ago. At -O2 optimization Clang's 619 build is 46% faster than its 301 build: at -O3 Clang's improvement is 31%. In fact, every data structure in Clang used to represent the code (AST, CFG, etc) can always relate back to the original source, which is quite useful for many analysis purposes (refactoring, etc). Clang would do well to add hyphens to "pointer to integer". However, the difference between the two is that while GCC defaults to gnu89, Clang defaults to gnu99. To download and install Clang, you need to apply the following instructions. In this case, we want to tell GCC and Clang that the parameter argc is not used. The Gcc and Clang compilers are clearly the best when it comes to code optimization. I don't see that one set of utter nonsense is better than the other and spending time colour coding the output shows a dubious set of priorities. Does Clang optimize better than GCC? The -mbranch-protection flag will now also work for the ARM backend. Indeed, clang-4.0.1 is much faster for compilation than clang-3.9. so whats going on? 5. level 1. From the last time I saw, gcc's LTO scaled better than LLVM for compiling large code-bases, although with the addition of. LKML Archive on lore.kernel.org help / color / mirror / Atom feed * [PATCH] Documentation/llvm: add documentation on building w/ Clang/LLVM @ 2020-02-24 17:41 Nick Desaulniers 2020-02-24 21:20 ` Randy Dunlap ` (3 more replies) 0 siblings, 4 replies; 26+ messages in thread From: Nick Desaulniers @ 2020-02-24 17:41 UTC (permalink / raw) To: corbet, masahiroy Cc: Nick Desaulniers, Kees Cook . First, we have to look at the implicit conversion sequences. With __attribute__, we can give GCC and Clang information to understand our source code better. GCC usually produces faster code if you target x86/x86-64. Those flags included: -O2 for the "standard . I value C++11 support and code generation quality more than I value convenience of compilation. Is GCC faster than MSVC? Meanwhile with the Etcpak ETC texture compressor, LLVM Clang upstream was performing better than the AOCC downstream. Really? There are only 2 possibilities: either Clang is really so much better than GCC, then it should become the preferred compiler distro-wide (and GCC used only for those packages that don't build with Clang), or it is not, then we should consistently stick to GCC. from question Clang is much faster and uses far less memory than GCC. Here are sizes of our barcode library when compiled . If you're wanting faster binaries, there's no substitute for trying them both and measuring the results. Clang aims to provide extremely clear and concise diagnostics (error and warning messages), and includes support for expressive diagnostics. Why is C++ compiler slow? Although GCC-7.1 is faster than GCC-6.3, all the GCC versions are slower than GCC-4.9.4 which is the fastest at compiling code . Good, but at each optimization level GCC's 619 build is more than twice as fast as its 301. How to download / Install Clang? Clang is popular on BSD. GCC is correct. The assembly output of clang is almost around 100 lines longer than gcc and I don't think it is necessary to post it here, all I can . The hand-crafted version understood (mis)alignment better than gcc from 15 years ago, but at this point, gcc's inner loop is 1 instruction less than the hand-crafted version, although its setup before reaching the inner loop is several instructions longer. So what GCC did here is in this case, instead of being efficient and using loop unrolling, which is better in this case, J ust went with -O3 to SIMD. For two reasons. W hat Clang did in this case, both with -O3 and -O2 is, I would say, a bit better using loop unrolling This is a very simple example. GCC is correct. in most instances the GCC 4.5 built binaries had performed better than LLVM-GCC or Clang. With the Blosc compressor, the Clang 10.0 performance was basically tied with GCC 10 while the Core i9 10980XE performance saw GCC delivering better performance than this latest Clang release. In my experience, I found that Clang's driver might get confused when picking the right linker on some uncommon platforms, especially before version 11.0. The problem is that the standard library that clang uses is the gcc standard (libstdc++) library that Apple ships (which is based on gcc 4.2). On the other hand, Clang often compiles code more quickly than GCC, and produces better error messages when there is something wrong with your code. Clang is much faster and uses far less memory than GCC. Because clang got a LOT slower and GCC got a bit faster. Is clang better than GCC? Clang is usually a lot faster to compile than gcc is. Also, the difference between O0 and O1 is more than 300%. Clang plugin arguments can now be passed through the compiler driver via -fplugin-arg-pluginname-arg, similar to GCC's -fplugin-arg. The linux kernel now supports native clang builds, setting LLVM=1 enables t. Second, we look at the tie-breaker rules regarding standard conversion sequences, [over.ics.ref]/3.2. So if they deviate in foo's binary representation, this seems like a bug.

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