[Bug debug/109676] [13/14 regression] ICE in simplify_subreg, at simplify-rtx.cc:7426 when building firefox with -O2 -march=alderlake -g since r13-3378-gf6c168f8c06047

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109676

--- Comment #12 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The mode is changed in:
1637        case REG:
1638          PUT_MODE (src, V1TImode);
1639          /* Call fix_debug_reg_uses only if SRC is never defined.  */
1640          if (!DF_REG_DEF_CHAIN (REGNO (src)))
1641            fix_debug_reg_uses (src);
but because DF_REG_DEF_CHAIN (REGNO (src)) - it contains the
(insn 97 96 98 9 (set (reg:V1TI 91 [ p ])
        (mem/c:TI (plus:DI (reg/f:DI 19 frame)
                (const_int -32 [0xffffffffffffffe0])) [0 p+0 S16 A128]))
"pr109676.C":26:12 87 {*movti_internal}
     (nil))
insn which sets it, fix_debug_reg_uses isn't called.