[gcc r13-729] Mitigate -Wmaybe-uninitialized in expmed.cc.

[gcc r13-729] Mitigate -Wmaybe-uninitialized in expmed.cc.

[Martin Liska]

https://gcc.gnu.org/g:c5c523723149112d117a6d3b259dfd95b032a545

commit r13-729-gc5c523723149112d117a6d3b259dfd95b032a545
Author: Martin Liska <mliska@suse.cz>
Date:   Mon May 16 10:36:49 2022 +0200

    Mitigate -Wmaybe-uninitialized in expmed.cc.
    
    It's the warning I see every time I build GCC:
    
    In file included from /home/marxin/Programming/gcc/gcc/coretypes.h:478,
                     from /home/marxin/Programming/gcc/gcc/expmed.cc: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 /home/marxin/Programming/gcc/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 /home/marxin/Programming/gcc/gcc/expmed.cc:5728:56:
    /home/marxin/Programming/gcc/gcc/machmode.h:550:49: warning: ‘*(unsigned int*)((char*)&int_mode + offsetof(scalar_int_mode, scalar_int_mode::m_mode))’ may be used uninitialized [-Wmaybe-uninitialized]
      550 |           ? mode_size_inline (mode) : mode_size[mode]);
          |                                                 ^~~~
    /home/marxin/Programming/gcc/gcc/expmed.cc: In function ‘rtx_def* emit_store_flag_1(rtx, rtx_code, rtx, rtx, machine_mode, int, int, machine_mode)’:
    /home/marxin/Programming/gcc/gcc/expmed.cc:5657:19: note: ‘*(unsigned int*)((char*)&int_mode + offsetof(scalar_int_mode, scalar_int_mode::m_mode))’ was declared here
     5657 |   scalar_int_mode int_mode;
          |                   ^~~~~~~~
    
    Can we please mitigate it?
    
    gcc/ChangeLog:
    
            * expmed.cc (emit_store_flag_1): Mitigate -Wmaybe-uninitialized
            warning.

Diff:
---
 gcc/expmed.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/expmed.cc b/gcc/expmed.cc
index c3e4aa8019a..c890823b064 100644
--- a/gcc/expmed.cc
+++ b/gcc/expmed.cc
@@ -5658,7 +5658,7 @@ emit_store_flag_1 (rtx target, enum rtx_code code, rtx op0, rtx op1,
 
   /* If we are comparing a double-word integer with zero or -1, we can
      convert the comparison into one involving a single word.  */
-  scalar_int_mode int_mode;
+  scalar_int_mode int_mode = {};
   if (is_int_mode (mode, &int_mode)
       && GET_MODE_BITSIZE (int_mode) == BITS_PER_WORD * 2
       && (!MEM_P (op0) || ! MEM_VOLATILE_P (op0)))