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* [PATCH 0/4] Alignment option enhancements
@ 2018-07-16  8:53 marxin
  2018-07-16  8:53 ` [PATCH 3/4] Define MAX_CODE_ALIGN globally marxin
                   ` (4 more replies)
  0 siblings, 5 replies; 13+ messages in thread
From: marxin @ 2018-07-16  8:53 UTC (permalink / raw)
  To: gcc-patches

Hi.

As you probably noticed, current trunk accepts extended format
of -falign-FOO options.
However there are some limitations that are addressed in the patchset:

1) E.g. align_labels_max_skip and align_labels_log are separate
   values and targets can override them via LABEL_ALIGN and
   LABEL_ALIGN_MAX_SKIP.  If you take a look at code in final.c:

	 if (max_log < log)
		{
		  max_log = log;
		  max_skip = targetm.asm_out.label_align_max_skip (label);
		}

   It improves alignment, but max_skip can be zero and then we end up
   with no alignment.  Thus I see it saner to provide just a single hook
   and return align_flags class instance.

2) In final.c we mix label, jump and loop alignments. I believe when
   combining them together, one should do maximum and not rely on:

 #ifdef ASM_OUTPUT_MAX_SKIP_ALIGN
	      ASM_OUTPUT_MAX_SKIP_ALIGN (file, align, max_skip);
	      /* Above, we don't know whether a label, jump or loop
		 alignment was used.  Conservatively apply
		 label subalignment, not jump or loop
		 subalignment (they are almost always larger).  */

   That's implemented in align_flags::max function. When combining
   for instance -falign-labels=1000 and -falign-jumps=2000, I hope
   using alignment of 2000 is the right choice.

3) I removed various align_* defines and use directly
   align_{*}.

4) I ported visium target to provide always secondary alignment of 8B.
   That's the same what x86_64 does and was factored out in previous commits
   I did.
  
5) Globally MAX_CODE_ALIGN is introduced.

6) Various coding styles are fixes in target code.

7) OPT_falign_* is not set with -Os. Then --help=common -Q reports proper values.

I tested that on x86_64-linux-gnu and ppc64le-linux. And also I tested all targets
that I touched, these should provide equal results.

Martin

marxin (4):
  Clean up of new format of -falign-FOO.
  Fix coding style of ASM_OUTPUT_ALIGN.
  Define MAX_CODE_ALIGN globally.
  Do not enable OPT_falign_* for -Os.

 gcc/align.h                          |  80 ++++++++++++
 gcc/common/config/i386/i386-common.c |   3 -
 gcc/config/alpha/alpha.c             |   5 +-
 gcc/config/i386/att.h                |   2 +-
 gcc/config/i386/cygming.h            |   2 +-
 gcc/config/i386/gas.h                |   2 +-
 gcc/config/i386/i386.c               |   5 +-
 gcc/config/i386/x86-64.h             |   2 +-
 gcc/config/iq2000/iq2000.h           |   2 +-
 gcc/config/m32r/m32r.h               |   3 +-
 gcc/config/m68k/m68k.c               |  10 +-
 gcc/config/nds32/nds32.h             |   9 +-
 gcc/config/pa/pa.h                   |   2 +-
 gcc/config/powerpcspe/powerpcspe.c   |  18 +--
 gcc/config/rs6000/rs6000-protos.h    |   2 +-
 gcc/config/rs6000/rs6000.c           |  18 +--
 gcc/config/rx/rx-protos.h            |   2 +-
 gcc/config/rx/rx.c                   |  59 +++++----
 gcc/config/rx/rx.h                   |   6 +-
 gcc/config/s390/s390.c               |   9 +-
 gcc/config/sh/sh.c                   |  19 +--
 gcc/config/sparc/sol2.h              |   2 +-
 gcc/config/sparc/sparc.h             |   2 +-
 gcc/config/spu/spu.c                 |   6 +-
 gcc/config/spu/spu.h                 |   2 +-
 gcc/config/visium/visium.c           |   2 +-
 gcc/config/visium/visium.h           |  17 +--
 gcc/coretypes.h                      |   1 +
 gcc/doc/tm.texi                      |  24 ----
 gcc/doc/tm.texi.in                   |   8 --
 gcc/final.c                          | 189 ++++++++-------------------
 gcc/flags.h                          |  38 +-----
 gcc/opts.c                           |  12 +-
 gcc/output.h                         |   6 +-
 gcc/system.h                         |   2 -
 gcc/target.def                       |  40 ------
 gcc/targhooks.h                      |   4 -
 gcc/toplev.c                         |  44 ++-----
 gcc/varasm.c                         |  14 +-
 39 files changed, 262 insertions(+), 411 deletions(-)
 create mode 100644 gcc/align.h

-- 
2.18.0

^ permalink raw reply	[flat|nested] 13+ messages in thread
end of thread, other threads:[~2018-07-22 12:19 UTC | newest]

Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-07-16  8:53 [PATCH 0/4] Alignment option enhancements marxin
2018-07-16  8:53 ` [PATCH 3/4] Define MAX_CODE_ALIGN globally marxin
2018-07-16  8:53 ` [PATCH 2/4] Fix coding style of ASM_OUTPUT_ALIGN marxin
2018-07-16  8:53 ` [PATCH 4/4] Do not enable OPT_falign_* for -Os marxin
2018-07-16  8:53 ` [PATCH 1/4] Clean up of new format of -falign-FOO marxin
2018-07-16 19:52   ` Pat Haugen
2018-07-16 21:24   ` Jeff Law
2018-07-17  9:52     ` Martin Liška
2018-07-18 15:49   ` Martin Sebor
2018-07-22  8:32     ` Gerald Pfeifer
2018-07-22 11:04       ` Gerald Pfeifer
2018-07-22 12:19         ` Rainer Orth
2018-07-16 14:10 ` [PATCH 0/4] Alignment option enhancements Richard Biener

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