[Bug c/83172] -Wstack-size= doesn't detect the correct stack size with VLA or alloca

[hao.hou at utah dot edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83172

--- Comment #2 from Hao Hou <hao.hou at utah dot edu> ---
(In reply to Eric Botcazou from comment #1)
> What happens for -Wvla-larger-than= if you use -O0 or -O1 instead of -O3?

The same result:

$ gcc-7 -Wvla-larger-than=128 -Wstack-usage=102400 -O0 -c t.c 
t.c: In function ‘stack_usage_only’:
t.c:23:5: warning: stack usage might be unbounded [-Wstack-usage=]
 int stack_usage_only(unsigned x)
     ^~~~~~~~~~~~~~~~
t.c: In function ‘alloca_fails_even_with_const’:
t.c:32:5: warning: stack usage might be unbounded [-Wstack-usage=]
 int alloca_fails_even_with_const()
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

-O1 results the same.