uclinux-2008R1-RC8(bf561)到VDSP5的移植(51)：fork.c编译失败

 

出现一个莫明奇妙的编译错误：

../../kernel/fork.c

At end of source: : internal error: Uncaught exception Assertion failed raised

          at ../../../bril/optimiser/dominators.c:910 (in pass

          cleanup_scalar_stores_nonopt during compilation of _copy_process).

          Please submit a bug report with this message, the command line used,

          type of machine and the output of the compiler when you add -ED -v

          to the command line. Please also send us the pre-processed file that

          is generated by the -ED option (the file generated is named

          <original_filename>.i)

 

1 catastrophic error detected in the compilation of "../../kernel/fork.c".

Compilation aborted.

cc3089: fatal error: Compilation failed

Tool failed with exit/exception code: 1.

Build was unsuccessful.

注释掉所有代码，一步步往上添加，问题出在copy_process函数，进一步查找终于发现问题在于这个函数中的这个语句：

     if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||

              !cpu_online(task_cpu(p))))

         set_task_cpu(p, smp_processor_id());

当不加这行时没有错误。当加上这个语句时，出现上述错误。

回顾一下unlikely的定义：

#define unlikely(x)    expected_false(!!(x))

确实是做优化用的，既然此处编译不过，就去了它，改为：

     if (/*unlikely(*/!cpu_isset(task_cpu(p), p->cpus_allowed) ||

              !cpu_online(task_cpu(p))/*)*/)

         set_task_cpu(p, smp_processor_id());