Unused gdb variable

Question

Is it possible to get the value of an unused variable using gdb? Is there any configuration for GCC so that the garbage value for an unused variable is not displayed "optimized"?

c file:

#include<stdio.h> void main() { int x; int y; printf("value of x: %d",x); } 

In gdb, I want to get the garbage value of the variable y.

 (gdb) run Starting program: /home/charmae/workspace/AVT/a.out Breakpoint 1, main () at file4.c:7 7 printf("value of x: %d",x); (gdb) info locals x = 2789364 (gdb) py $1 = <optimized out> (gdb) px $2 = 2789364 

Answer 1

This has nothing to do with GDB. The object that optimized this variable is the compiler (maybe GCC in your case). You can force it to save it by declaring the variable as mutable

Best question: why are you trying to do?

Answer 2

This is not related to gcc. Either the compiler has compiled code to maintain the value, or it does not.

Answer 3

You can add the operator y=y; . This would force the use of y and gcc -O0 -g track it (at least on my Linux / Debian / Sid / AMD64 with gcc 4.6.2 and gdb 7.3.50 )