GCC内联汇编:跳转到模块外部的标签 [英] GCC Inline Assembly: Jump to label outside block

问题描述

在MSVC下使用嵌入式程序集时，可以通过引用C/C ++代码中的标签来跳出程序集块，如

When using inline assembly under MSVC, one is allowed to jump outside of the assembly block by referencing a label in the C/C++ code, as explained in this MSDN article.

在GCC下使用内联汇编可以做到这一点吗?

Can such thing be done when using inline assembly under GCC?

这是我要完成的工作的一个示例:

Here's an example of what I'm trying to accomplish:

__asm__ __volatile__ (
"   /* assembly code */ "
"   jz external_label;  "
);

/* some C code */

external_label:
/* C code coninues... */

但是，编译器抱怨没有定义"external_label".

The compiler, however, complains about "external_label" not being defined.

推荐答案

如果用汇编程序定义标签怎么办?

What if you define the label with the assembler?

asm("external_label:");

---

更新:此代码似乎有效:

---

Update: this code seems to work:

#include <stdio.h>

int
main(void)
{
  asm("jmp label");
  puts("You should not see this.");
  asm("label:");

  return 0;
}

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