Identical basic blocks live long in RTL flow.

[Bin.Cheng]

Hi,
For below simple function from newlib:

static int
is_option (char *argv_element, int only)
{
  return ((argv_element == 0)
      || (argv_element[0] == '-') || (only && argv_element[0] == '+'));
}

The expanded rtl is like:

    9: NOTE_INSN_BASIC_BLOCK 2
    2: r113:SI=r0:SI
    3: r114:SI=r1:SI
    4: NOTE_INSN_FUNCTION_BEG
   11: pc={(r113:SI==0)?L39:pc}
      REG_BR_PROB 0x3f6
   12: NOTE_INSN_BASIC_BLOCK 3
   13: r111:SI=zero_extend([r113:SI])
   14: pc={(r111:SI==0x2d)?L43:pc}
      REG_BR_PROB 0x7c7
   15: NOTE_INSN_BASIC_BLOCK 4
   16: pc={(r114:SI!=0)?L20:pc}
      REG_BR_PROB 0x1388
   22: L22:
   17: NOTE_INSN_BASIC_BLOCK 5
    6: r110:SI=0
   20: L20:
   21: NOTE_INSN_BASIC_BLOCK 6
   23: pc={(r111:SI!=0x2b)?L22:pc}
      REG_BR_PROB 0x1f49
   35: NOTE_INSN_BASIC_BLOCK 7
    8: r110:SI=0x1
   39: L39:
   38: NOTE_INSN_BASIC_BLOCK 8
    7: r110:SI=0x1
   43: L43:
   42: NOTE_INSN_BASIC_BLOCK 9
    5: r110:SI=0x1
   24: L24:
   25: NOTE_INSN_BASIC_BLOCK 10
   26: r112:SI=r110:SI
   30: r0:SI=r112:SI
   33: use r0:SI

Basic blocks 8/9/10 are identical and live until pass jump2, which is
after register allocation.
I think these duplicated BBs do not contain additional information and
should be better to be removed ASAP, because they might interfere with
other passes like ifcvt.

So should this issue be handled like in jump pass?

Thanks in advance.
BTW, The compilation command line is:
arm-none-eabi-gcc -mthumb -mcpu=cortex-m0 -Os ...
--
Best Regards.