关于inline(内联) 正如 gcc 手册描述的那样(别的编译器需要查看具体的手册),gcc 不会真正内联任何函数,如果使用了 "-fno-inline" 选项,或者如果使用了 "-O0"(优化等级)。当然除此之外,gcc还有其他多种情况不会真正内联函数。 "-Winline" 选项 阻止内联 阻止inline,可以使用函数属性 __noinline__ 。即使使用...
Target Builtins - Using the GNU Compiler Collection (GCC) MIPS Loongson Built-in Functions x86 Built-in Functions t.cpp: #include <immintrin.h> gcc -E t.cpp /usr/lib/gcc/x86_64-linux-gnu/10/include/immintrin.h intrinsic: 固有的, 内在的, 本质的; built-in :-) /usr/lib/gcc/x86_64...
void* p = __builtin_return_address(0); // 得到当前函数的返回地址 void* rbp = __builtin_frame_address(0); // 得到当前函数的栈帧的栈底 void* last_rbp = __builtin_frame_address(1); // 得到调用函数的栈帧的栈底 asm volatile( "leaq 16(%1), %%rsp;" // 恢复 rsp 寄存器的值 ...
gcc手册中这样写道: The weak attribute causes the declaration to be emitted as a weak symbol rather than a global. This is primarily useful in defininglibrary functionswhich can be overridden in user code, though it can also be used with non-function declarations. Weak symbols are supported for...
5.47 Built-in functions for atomic memory access The following builtins are intended to be compatible with those described in theIntel Itanium Processor-specific Application Binary Interface, section 7.4. As such, they depart from the normal GCC practice of using the “__builtin_” prefix, and ...
其中记录了一个明显的代码bug,若不加这个-fno-common选项,那么程序简直就是明显的错误,但可能还未被发现。 举个栗子: int a[5]; int b[5]; memcpy(a,"1234567890",10); //明显越界了还不报错。 多出来的拷贝到哪了?可能在 b[5]中。甚至 b[6]= 1这样超过数组的赋值也不会报错。
gcc从4.1.2提供了__sync_*系列的built-in函数,用于提供加减和逻辑运算的原子操作。 5.47 Built-in functions for atomic memory access The following builtins are intended to be compatible with those described in the Intel Itanium Processor-specific Application Binary Interface, section 7.4. As such, the...
GCC的“-fno-common”也允许我们把所有未初始化的全局变量不以COMMON块的形式处理,或者使用“__attribute__”拓展. 一旦一个未初始化的全局变量不是以COMMON块的形式存在,那么它就相当于一个强符号,如果其他目标文件中还有同一个变量的强符号定义,链接时就会发生符号重复定义错误。
GCC编译器提供了-fomit-frame-pointer和-fno-omt-frame-pointer两个相对的编译选项。 GCC手册[1]里对-fomit-frame-pointer的说明: Omit the frame pointer in functions that don’t need one. This avoids the instructions to save, set up and restore the frame pointer; on many targets it also makes ...