c - 如何使用 NDK 在 ARM 内联汇编中执行简单循环？

Question

我正在尝试在 ARM Assembly 中执行一个简单的循环，但每次运行时都会崩溃这是日志:

01-13 15:34:21.277: A/libc(27296): Fatal signal 11 (SIGSEGV) at 0x00000000 (code=1), thread 27312 (Thread-2932)

这是我的代码我做错了什么？

 void foo(int *pIn, int *pOut) {
    //pIn contains the number of iterations the loop will have
    asm volatile(
        "ldr r3, %[in];"
        "ldr r4, %[out];"
        "ldr r5, [r3];"

        "loop:; "
        //here would go the code inside the loop perhaps put something in output, in this case just do nothing
        "subs r5, r5, #1;"
        "bne loop"

        :[out] "=m" (pOut)
        :[in] "m" (pIn)
        :"r3","r4","r5","memory" 
    );
}

在 Android.mk 文件中我放置了 32 位指令

LOCAL_ARM_MODE := arm

有什么想法为什么会崩溃吗？仅当我放置循环时才会发生崩溃，在此之前我尝试移动东西并且它工作得非常好，给出了我预期的输出值。

Answer 1

问题已解决，将“r5”和“cc”添加到我的破坏列表中即可使其工作。这是工作代码:

void foo(int *pIn, int *pOut) {
     //pIn contains the number of iterations the loop will have
     asm volatile(
         "ldr r3, %[in];"
         "ldr r4, %[out];"
         "ldr r5, [r3];"

         "loop:; "
         //here would go the code inside the loop perhaps put something in output, in this case just do nothing
         "subs r5, r5, #1;"
         "bne loop"

         :[out] "=m" (pOut)
         :[in] "m" (pIn)
         :"r3","r4","r5","cc","memory" 
     );
 }