c - 如何在 gdb 中打印 OpenMP 并行区域的局部变量？

Question

我一直在调试 OpenMP 并行区域内的局部变量。

考虑到这段代码:

#include<omp.h>
#include<stdio.h>

int main(){
    int a = 0;
    #pragma omp parallel shared(a)
    {
    int m_a = a + omp_get_thread_num();
    printf("%d\n",m_a); //breakpoint set here
    }
}

代码运行良好，但如果我在带有注释的行设置断点并在 gdb 上键入 info locals，它只会显示 a 变量。键入 print m_a 会导致 No symbol "m_a"in current context。

Answer 1

这什么也没回答，只是报告我不能重复它，代码是用

编译的

gcc x.c -W -Wall -fopenmp -ggdb

和gdb session如下，一切正常，我猜可能是编译标志的问题，尝试在-g或-ggdb之外加上-O0

Reading symbols from ./a.out...done.
(gdb) break 9
Breakpoint 1 at 0x40064d: file x.c, line 9.
(gdb) run
Starting program: /some/path/to/a.out 
[Thread debugging using libthread_db enabled]
Thread 3 "a.out" hit Breakpoint 1, main._omp_fn.0 () at x.c:9
9           printf("%d\n",m_a); //breakpoint set here
(gdb) info locals
m_a = 2
a = 0
(gdb) info threads
  Id   Target Id         Frame 
  1    Thread 0x2aaaaaaebb40 (LWP 31287) "a.out" main._omp_fn.0 () at x.c:9
  2    Thread 0x2aaaabab0700 (LWP 31516) "a.out" main._omp_fn.0 () at x.c:9
* 3    Thread 0x2aaaabcb1700 (LWP 31517) "a.out" main._omp_fn.0 () at x.c:9
  4    Thread 0x2aaaabeb2700 (LWP 31518) "a.out" main._omp_fn.0 () at x.c:9
(gdb) thread 1
[Switching to thread 1 (Thread 0x2aaaaaaebb40 (LWP 31287))]
#0  main._omp_fn.0 () at x.c:9
9           printf("%d\n",m_a); //breakpoint set here
(gdb) info locals
m_a = 0
a = 0
(gdb) thread 2
[Switching to thread 2 (Thread 0x2aaaabab0700 (LWP 31516))]
#0  main._omp_fn.0 () at x.c:9
9           printf("%d\n",m_a); //breakpoint set here
(gdb) info locals
m_a = 1
a = 0
(gdb)