Ping: https://gcc.gnu.org/ml/gcc-patches/2018-01/msg01131.html
This was submitted in stage 3 but if fixing xfailed assertions
in tests by enhancing optimizations is out of scope for the
current stage let me know so I can schedule this change for
GCC 9.
On 01/12/2018 02:30 PM, Martin Sebor wrote:
A failure in a test for the recently enhanced -Warray-bounds
warning exposed an unnecessarily broad restriction in the strlen
pass that prevents it from tracking the length of a member string
of locally defined and initialized struct:
void f (void)
{
struct { char s[8]; int i } a = { "1234", 5 };
if (strlen (a.s) != 4) // not folded
abort ();
}
IIUC, the restriction was in place to account for writes into
an array changing or invalidating the length of a string stored
in its initial elements. This would happen if the write either
changed the string's terminating nul byte, or if it reset one
of the prior non-nul bytes.
To reflect just this intent the restriction can be tightened
up to improve the pass' ability to track even the lengths of
string members of locally initialized aggregates. Besides
leading to better code this change also clears up the test
failure.
Tested on x86_64-linux.
Martin
