ARM GCC是否对汇编"REV"指令具有内置功能? [英] Does ARM GCC have a builtin function for the assembly 'REV' instruction?

问题描述

对于编译器来说，具有处理器功能的内在函数是很常见的，但是我很难找到它们.在ARM中是否可以使用"REV"(单词的反向字节顺序)指令?

It's pretty common for compilers to have builtin intrinsic functions for processor features, but I'm having trouble finding them. Is there one to get at the 'REV' (reverse byte order of a word) instruction in ARM?

在哪里可以找到内置函数的列表?

Where can I find the list of builtin functions?

推荐答案

在ARM中是否有一条指令可以实现"REV"(单词的反向字节顺序)指令?

Is there one to get at the 'REV' (reverse byte order of a word) instruction in ARM?

在所有体系结构上都有一种更便携"的形式.它是__builtin_bswap32.例如，编译器资源管理器具有

There is a more 'portable' form that is available on all architectures. It is __builtin_bswap32. For example the compiler explorer has,

unsigned int foo(unsigned int a)
{
  return __builtin_bswap32(a);
}

给予

foo(unsigned int):
        rev     r0, r0
        bx      lr

这比__builtin_rev更好，因为它将仅在某些ARM目标(当然也只有ARM CPU)上可用.您甚至可以在PowerPC，x86等上使用__builtin_bswap32.

This is better than __builtin_rev would be as it will only be available on certain ARM targets (and certainly only ARM CPUs). You can use __builtin_bswap32 even on PowerPC, x86, etc.

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