Re: [PATCH][gdb/exp] Fix printing of type of optimized out vla

Simon Marchi
2018-07-18T19:53:12Z

On 2018-07-03 10:18, Tom de Vries wrote:
> Hi,
>
> Consider this snippet from gcc/testsuite/gcc.dg/guality/vla-1.c:
> ...
> int __attribute__((noinline))
> f1 (int i)
> {
> char a[i + 1];
> a[0] = 5; /* { dg-final { gdb-test .+1 "i" "5" } } */
> return a[0]; /* { dg-final { gdb-test . "sizeof (a)" "6" } }
> */
> }
> ...
>
> When we compile the test-case with -O1 -g, and query the size of
> optimized
> out vla 'a', we get:
> ...
> $ ./gdb -batch -ex "b f1" -ex "r" -ex "p sizeof (a)" vla-1.exe
> Breakpoint 1 at 0x4004a8: file vla-1.c, line 17.
>
> Breakpoint 1, f1 (i=i@entry=5) at vla-1.c:17
> 17 return a[0];
> $1 = 0
> ...
> while we expect a size of '6'.
>
> The problem is that default_read_var_value does not resolve the dynamic
> type
> of a variable if the variable is optimized out.
>
> This patch fixes that, and consequently gdb prints '6', as expected.
>
> Tested on x86_64-linux.
>
> OK for trunk?
>
> Thanks,
> - Tom

Thanks, that LGTM.

Simon