[Bug rtl-optimization/78575] [7 Regression] ICE: in trunc_int_for_mode, at explow.c:55 with -O2 -g

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78575

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2016-11-29
                 CC|                            |msebor at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
Confirmed.  Bisection identified r239378 as the first revision to ICE:

r239378 (gcc 7.0.0) failed (status 4):
------------------------------------------------------------------------
r239378 | hjl | 2016-08-11 11:51:01 -0400 (Thu, 11 Aug 2016) | 21 lines

Use TImode for piecewise move in 64-bit mode

Use TImode for piecewise move in 64-bit mode.  We should use TImode in
32-bit mode and use OImode or XImode if they are available.  But since
by_pieces_ninsns determines the widest mode with MAX_FIXED_MODE_SIZE,
we can only use TImode in 64-bit mode.

gcc/

        * config/i386/i386.h (MOVE_MAX_PIECES): Use TImode in 64-bit
        mode if unaligned SSE load and store are optimal.