Is there a simd instruction/intrinsic/builtin for partial shift of elements?
A minimal example would be more beneficial:Say I have a sorted 8 ints = {10, 20, 30, 40, 50, 60, 70, 80} (My use case is for sorted integers but i am not sure if that information is valuable...
View Articleavr-gcc 8.1.0 uses `as` instead of `avr-as`
I want to use the newest version of avr-gcc (8.1.0) for a new project, which is not available from ubuntu's package-manager. So I compiled it myself using the build-script from this site:...
View ArticleGNU C inline asm input constraint for AVX512 mask registers (k1...k7)?
AVX512 introduced opmask feature for its arithmetic commands. A simple example: godbolt.org.#include <immintrin.h> __m512i add(__m512i a, __m512i b) { __m512i sum; asm( "mov ebx, 0xAAAAAAAA;...
View ArticleRed Hat: using compiles fine but linker can't find __atomic_store_16; what...
I'm using atomic<> for the first time, and just as using <thread> requires you to link a thread library, it seems like using <atomic> wants you to do... something. What?> uname -a...
View ArticleModulo operation with negative numbers
In a C program i was trying the below operations(Just to check the behavior ) x = 5 % (-3); y = (-5) % (3); z = (-5) % (-3); printf("%d ,%d ,%d", x, y, z); gave me output as (2, -2 , -2) in gcc . I was...
View ArticleMultiple shared library constructors not being called
I've stumbled onto an interesting phenomenon while exploring shared library constructors. If I have a program which links against multiple shared libraries, and each library has its own constructor, if...
View ArticleChoosing a gcc compiler on a Linux machine for compilation with "make"
I encountered the following error message on a Linux machine while attempting to compile a program with the command "make":build/chem/rdm.o: In function `RDM::get_2rdm_slow(std::vector<Det,...
View Articlehow to fix errors caused by -Wconversion?
I have a piece of fake/sample code:#include <stdint.h> uint8_t func(uint16_t val0, uint16_t val1, uint16_t val2) { uint8_t r; val0 += 0x7F; val1 += (uint16_t)0x7F; val2 += 0x7FU; r =...
View ArticleWhat is the use of matching constraints in inline assembly
From the following link, https://www.ibm.com/developerworks/library/l-ia/index.htmla single variable may serve as both the input and the output operand.I wrote the following code:#include...
View ArticleThere's one constructor, but two destructors [duplicate]
This question already has an answer here:Why does flowing off the end of a non-void function without returning a value not produce a compiler error? 9 answersIt took me some time to get the error but...
View ArticleWhat happens in the assembly output when we add "cc" to clobber list
I read that if we specify "cc" in clobber list it indicates that an assembler code modifies flags registerWrote a sample program to check the difference in between adding "cc" and not adding. Comparing...
View ArticleHow to prohibit GCC from dropping unused function when linked static library?
I have an application linked with a few static libraries. And this application will load a dynamic library through dlopen. And the dynamic library will call a function which came from one of the static...
View Articlepython3 cross compile error: missing binary operator before token "(" #if...
I am trying to cross compile on python3.6 from x86_64-pc-linux-gnu to i686-pc-linux-gnu. I have prepared an sdk with bin-utils, kernel headers, glibc & gcc.After downloading and extracting python...
View ArticleImplicit declaration of strnlen in FreeRTOS
While developing my FreeRTOS application targeting an ARM Cortex M3 with GCC, using the C99 dialect, I decided to use strnlen, assuming that it's a standard C function and that I just need to include...
View ArticleAligning gcc compilation output file to a specific size
for a very specific and not relevant reason, I need to compile a gcc file, in a way that it will have a certain file size alignment. For example, I'm compiling a file, and it has a size of 72148 bytes....
View ArticleC++ function`s declaration and definition are different but it works well
I'm writing some C++ code And I found a very strange thing Like below code, it works well even though a function's declaration and definition are different Does anyone know how can this is possible?...
View ArticleLua C Compiling -llua Error
I am attempting to compile some C code to run with Lua through the command:gcc -o first first.c -llua -lm and the output I receive:ld: library not found for -llua clang: error: linker command failed...
View ArticleHow to modify gcc command inside pip
During installation python-ldap using pip (pip install python-ldap) I receive error:Modules/common.h:9:20: fatal error: Python.h: No such file or directory #include "Python.h" ^ compilation terminated....
View ArticleTypedefs with tweaked alignment
The 'Type Attributes'page for gcc, gives a very interesting example of how to tweak the alignment on type aliases: typedef int more_aligned_int __attribute__ ((aligned (8))); //...
View Articlecannot compile multiple c files gcc [closed]
I have the following files in the same directory: main.c, game.c, player.c, queue.c I write gcc main.c game.c player.c queue.c -o server in terminal, it seams that it works ( I see all the warnings)...
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