See this answer. Is this even the correct approach here No: you can’t use mismatched versions of glibc as your link command does. You used crt0.o and ld-linux.so from new (system-installed) libc, but libc.so.6 from an old (copied from cluster) libc. That is just not going to work.
It turns out that when you compile without the -fPIC option multiplyComplex, sqComplex, isInSet and isMandelbrot are inlined automatically by the compiler. If you define those functions as static you will likely get the same performance when compiling with -fPIC because the compiler will be free to perform inlining. The reason why the compiler is … Read more
gcc can use builtin functions in many cases, their documentation says: Many of these functions are only optimized in certain cases; if they are not optimized in a particular case, a call to the library function is emitted. so therefore gcc will not need to link against the math library when using the builtin function … Read more
Interestingly, using -fdata-sections can make the literal pools of your functions, and thus your functions themselves larger. I’ve noticed this on ARM in particular, but it’s likely to be true elsewhere. The binary I was testing only grew by a quarter of a percent, but it did grow. Looking at the disassembly of the changed … Read more
As well as Intel’s vol.2 PDF manual, there is also an online intrinsics guide. The Intel® Intrinsics Guide contains reference information for Intel intrinsics, which provide access to Intel instructions such as Intel® Streaming SIMD Extensions (Intel® SSE), Intel® Advanced Vector Extensions (Intel® AVX), and Intel® Advanced Vector Extensions 2 (Intel® AVX2). It has a … Read more
You can write assert(x*x >= 0.f) as a compile-time promise instead of a runtime check as follows in GNU C: #include <cmath> float test1 (float x) { float tmp = x*x; if (!(tmp >= 0.0f)) __builtin_unreachable(); return std::sqrt(tmp); } (related: What optimizations does __builtin_unreachable facilitate? You could also wrap if(!x)__builtin_unreachable() in a macro and call … Read more
Yes, You can use gcc to compile your asm code. Use -c for compilation like this: gcc -c file.S -o file.o This will give object code file named file.o. To invoke linker perform following after above command: gcc file.o -o file
Here’s what’s going on: default_random_engine in libstdc++ (GCC’s standard library) is minstd_rand0, which is a simple linear congruential engine: typedef linear_congruential_engine<uint_fast32_t, 16807, 0, 2147483647> minstd_rand0; The way this engine generates random numbers is xi+1 = (16807xi + 0) mod 2147483647. Therefore, if the seeds are different by 1, then most of the time the first … Read more
The answer to this is platform-specific; what happens on Linux is different from what happens on Solaris, for example. The easy part (because it is not platform-specific) is the separation of ‘gcc’ and ‘g++’: gcc is the GNU C Compiler from the GCC (GNU Compiler Collection). g++ is the GNU C++ Compiler from the GCC. … Read more
Working for about 4-5 years with software/firmware development and environment testing of miniaturized satellites*, I would like to share my experience here. *(miniaturized satellites are a lot more prone to single event upsets than bigger satellites due to its relatively small, limited sizes for its electronic components) To be very concise and direct: there is … Read more