[SUBREG V4 0/4] Add DF_LIVE_SUBREG data and apply to IRA and LRA

[Juzhe-Zhong <juzhe.zhong@rivai.ai>]

V3: Address comments from Dimitar Dimitrov

V4: Move detailed function from subreg-live-range.h to subreg-live-range.cc.

These patches are used to add a new data flow DF_LIVE_SUBREG,
which will track subreg liveness and then apply it to IRA and LRA
passes (enabled via -O3 or -ftrack-subreg-liveness). These patches
are for GCC 15. And these codes are pushed to the devel/subreg-coalesce
branch. In addition, my colleague Shuo Chen will also be involved in some
of the remain work, thank you for your support.

These patches are separated from the subreg-coalesce patches submitted
a few months ago. I refactored the code according to comments. The next
patches will support subreg coalesce base on they. Here are some data
abot build time of SPEC INT 2017 (x86-64 target):

                          baseline   baseline(+track-subreg-liveness)
specint2017 build time :  1892s      1883s

Regarding build times, I've run it a few times, but they all seem to take
much less time. Since the difference is small, it's possible that it's just
a change in environment. But it's theoretically possible, since supporting
subreg-liveness could have reduced the number of living regs.

For memory usage, I trided PR 69609 by valgrind, peak memory size grow from
2003910656 to 2003947520, very small increase.

Note that these patches don't enable register coalesce with subreg liveness in IRA/LRA,
so no performance change as expected.

And we will enable register coalsece with subreg liveness tracking in the followup patches.

Bootstrap and Regtested on x86-64 no regression.

Co-authored-by: Lehua Ding <lehua.ding@rivai.ai>

Juzhe-Zhong (4):
  DF: Add -ftrack-subreg-liveness option
  DF: Add DF_LIVE_SUBREG problem
  IRA: Apply DF_LIVE_SUBREG data
  LRA: Apply DF_LIVE_SUBREG data

 gcc/Makefile.in          |   1 +
 gcc/common.opt           |   4 +
 gcc/common.opt.urls      |   3 +
 gcc/df-problems.cc       | 886 ++++++++++++++++++++++++++++++++++++++-
 gcc/df.h                 | 159 +++++++
 gcc/doc/invoke.texi      |   8 +
 gcc/ira-build.cc         |   7 +-
 gcc/ira-color.cc         |   8 +-
 gcc/ira-emit.cc          |  12 +-
 gcc/ira-lives.cc         |   7 +-
 gcc/ira.cc               |  19 +-
 gcc/lra-coalesce.cc      |  27 +-
 gcc/lra-constraints.cc   | 109 ++++-
 gcc/lra-int.h            |   4 +
 gcc/lra-lives.cc         | 357 ++++++++++++----
 gcc/lra-remat.cc         |   8 +-
 gcc/lra-spills.cc        |  27 +-
 gcc/lra.cc               |  10 +-
 gcc/opts.cc              |   1 +
 gcc/regs.h               |   5 +
 gcc/sbitmap.cc           |  98 +++++
 gcc/sbitmap.h            |   2 +
 gcc/subreg-live-range.cc | 233 ++++++++++
 gcc/subreg-live-range.h  |  60 +++
 gcc/timevar.def          |   1 +
 25 files changed, 1920 insertions(+), 136 deletions(-)
 create mode 100644 gcc/subreg-live-range.cc
 create mode 100644 gcc/subreg-live-range.h

-- 
2.36.3