[Bug target/119847] [13/14/15 Regression] RISC-V:GCC fail to optimize repeated patterns in volatile operations

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119847

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2025-04-17
   Target Milestone|---                         |13.4
             Status|UNCONFIRMED                 |NEW
            Summary|RISC-V:GCC fail to optimize |[13/14/15 Regression]
                   |repeated patterns in        |RISC-V:GCC fail to optimize
                   |volatile operations         |repeated patterns in
                   |                            |volatile operations

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

The problem is at combine we recreate the full constant into an insn:
(insn 8 3 9 2 (set (reg/f:DI 141)
        (const_int 4161536696 [0xf80c02b8])) "/app/example.cpp":5:23 275
{*mvconst_internal}
     (nil))
...
(insn 15 12 16 2 (set (reg/f:DI 146)
        (const_int 4161536692 [0xf80c02b4])) "/app/example.cpp":5:23 275
{*mvconst_internal}
     (nil))


Which caused by r13-4907-g2e886eef7f2b5a .