Missed ssa-copyrename optimization?

["Bin.Cheng" <amker dot cheng at gmail dot com>]

Hi,
For attached preprocessed file, dump file
lib_a-s_frexp.E.021t.copyrename1 contains gimple sequences like:

  <bb 4>:
  x_41 = x_8(D);
  goto <bb 8>;

  <bb 5>:
  if (ix_15 <= 1048575)
    goto <bb 6>;
  else
    goto <bb 7>;

  <bb 6>:
  x_19 = x_8(D) * 1.8014398509481984e+16;
  gh_u.value = x_19;
  _21 = gh_u.parts.msw;
  hx_22 = (__int32_t) _21;
  gh_u ={v} {CLOBBER};
  ix_24 = hx_22 & 2147483647;
  *eptr_16(D) = -54;

  <bb 7>:
  # x_1 = PHI <x_8(D)(5), x_19(6)>
  # hx_2 = PHI <hx_11(5), hx_22(6)>
  # ix_3 = PHI <ix_15(5), ix_24(6)>
  _26 = *eptr_16(D);
  _27 = ix_3 >> 20;
  _28 = _27 + -1022;
  _29 = _26 + _28;
  *eptr_16(D) = _29;
  hx.0_31 = (unsigned int) hx_2;
  _32 = hx.0_31 & 2148532223;
  _33 = _32 | 1071644672;
  hx_34 = (__int32_t) _33;
  sh_u.value = x_1;
  hx.1_36 = (unsigned int) hx_34;
  sh_u.parts.msw = hx.1_36;
  x_38 = sh_u.value;
  sh_u ={v} {CLOBBER};
  x_40 = x_38;

  <bb 8>:
  # _4 = PHI <x_41(4), x_40(7)>
  return _4;

I am not sure if phi node (_4, x_41, x_40) in basic block 8 should be
rename/partitioned into one partition.
Trunk does not do this rename/partition, which causing big regression
in code size on Thumb1.

BTW, the command line is:
arm-none-eabi-gcc -mthumb -mcpu=cortex-m0 -Os/-O2 ...

I noticed the behavior is intended by PR54200, but not sure how the
issue should be handled. Any suggestions?

--
Best Regards.

Attachment: lib_a-s_frexp.E
Description: Binary data