下列代码的输出为哪个？（） #include int main() { /* val1+val2=val3 */ unsigned int val1=2; unsigned int val2=3; unsigned int val3=0; asm volatile( "movl $0,%%eax\t" "addl %1,%%eax\t" "addl %2,%%eax\t" "movl %%eax,%0\t" :"=m"(val3) :"c"(val1),"d"(val2) ); printf("%d",,val3); return 0; }