https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715
--- Comment #10 from Arnd Bergmann <arnd at linaro dot org> ---
As far as I can tell, gcc doesn't merge stack slots that came from inline
functions, as in comment 1, or this example:
void baz (int *, int *, int *, int *, int *, int *);
static inline void foo (int a, int b, int c, int d, int e, int f)
{
baz (&a, &b, &c, &d, &e, &f);
}
void
bar (int a, int b, int c, int d, int e, int f)
{
foo (a, b, c, d, e, f);
foo (a, b, c, d, e, f);
foo (a, b, c, d, e, f);
foo (a, b, c, d, e, f);
foo (a, b, c, d, e, f);
foo (a, b, c, d, e, f);
foo (a, b, c, d, e, f);
foo (a, b, c, d, e, f);
}
The frame sizes I see here are
gcc-8 -O2: 192 bytes
gcc-8 -O2 -fsanitize=address: 3120 bytes
gcc-8 -O2 -fsanitize=kernel-address: 192 bytes
gcc-8 -O2 -fsanitize=address asan-stack=0: 192 bytes
gcc-8 -O2 -fsanitize=kernel-address asan-stack=1: 3120 bytes
clang -O2: 72 bytes
clang -O2 -fsanitize=address: 88 bytes
clang -O2 -fsanitize=kernel-address: 888 bytes
clang -O2 -fsanitize=address asan-stack=0: 104 bytes
clang -O2 -fsanitize=kernel-address asan-stack=0: 104 bytes
(note: clang -fsanitize=kernel-address defaults to asan-stack=1, while gcc
defaults to asan-stack=0. gcc-5 and gcc-8 have identical output).
