> It broke GCC bootstrap:
>
> https://gcc.gnu.org/pipermail/gcc-regression/2021-November/075676.html
>
> In file included from ../../src-master/gcc/coretypes.h:474,
> from ../../src-master/gcc/expmed.c:26:
> In function ‘poly_uint16 mode_to_bytes(machine_mode)’,
> inlined from ‘typename if_nonpoly<typename
> T::measurement_type>::type GET_MODE_SIZE(const T&) [with T =
> scalar_int_mode]’ at ../../src-master/gcc/machmode.h:647:24,
> inlined from ‘rtx_def* emit_store_flag_1(rtx, rtx_code, rtx, rtx,
> machine_mode, int, int, machine_mode)’ at
> ../../src-master/gcc/expmed.c:5723:56:
> ../../src-master/gcc/machmode.h:550:49: warning: ‘*(unsigned
> int*)((char*)&int_mode + offsetof(scalar_int_mode,
> scalar_int_mode::m_mode))’ may be used uninitialized in this function
> [-Wmaybe-uninitialized]
> 550 | ? mode_size_inline (mode) : mode_size[mode]);
> | ^~~~
> ../../src-master/gcc/expmed.c: In function ‘rtx_def*
> emit_store_flag_1(rtx, rtx_code, rtx, rtx, machine_mode, int, int,
> machine_mode)’:
> ../../src-master/gcc/expmed.c:5652:19: note: ‘*(unsigned
> int*)((char*)&int_mode + offsetof(scalar_int_mode,
> scalar_int_mode::m_mode))’ was declared here
> 5652 | scalar_int_mode int_mode;
> | ^~~~~~~~
I seem to be able to bootstrap normally, so perhaps it is related to
--with-arch=native. I will try with that config.
However looking at the code
scalar_int_mode int_mode;
if (is_int_mode (mode, &int_mode)
&& GET_MODE_BITSIZE (int_mode) == BITS_PER_WORD * 2
the int_mode is indeed set conditionally and it is possible that this
may trigger false positive. I will however try again that we get same
modref summaries before and after patch.
There is PR103040 that shows wrong code bug in my earlier modref change
I am testinf fix for, but if that is the culprint it should have
reproduced earlier than with this commit.
Honza
