[Bug rtl-optimization/104054] [9/10/11/12 Regression] '-fcompare-debug' failure (length) w/ -Os -funroll-loops since r8-3946-gfe94440235cfaa57

[ubizjak at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104054

--- Comment #3 from Uroš Bizjak <ubizjak at gmail dot com> ---
The first difference is in rnreg pass, w/o -g:

   28: L28:
   29: NOTE_INSN_BASIC_BLOCK 4
   30: [`i']=0
   63: di:DI=r9:DI       <--- here
   64: dx:DI=r10:DI
    9: r8:HI=0x5
      REG_EQUAL 0x5
   98: {cx:DI=0;clobber flags:CC;}
      REG_UNUSED flags:CC
   84: si:DI=0x1
   99: {r11:DI=0;clobber flags:CC;}
      REG_UNUSED flags:CC
   79: pc=L41


and w/ -g:

   34: L34:
   35: NOTE_INSN_BASIC_BLOCK 4
   36: debug begin stmt marker
   37: [`i']=0
   77: ax:DI=r9:DI
   78: dx:DI=r10:DI
    9: r8:HI=0x5
      REG_EQUAL 0x5
  112: {cx:DI=0;clobber flags:CC;}
      REG_UNUSED flags:CC
   98: si:DI=0x1
  113: {di:DI=0;clobber flags:CC;}
      REG_UNUSED flags:CC
   93: pc=L53

And indeed, the -fcompare-debug test succeeds with -fno-rename-registers