[PATCH 0/6] Parallelize Intra-Procedural Optimizations using the LTO Engine.

Jan Hubicka hubicka@ucw.cz
Sat Aug 29 11:31:56 GMT 2020


> 
> It not only creates hidden symbols, but it also changes the original
> symbol name to avoid clashses with other object files. It could be
> very nice to avoid doing this at all.
> 
> There was once an idea (I don't remember if from Richi or Honza) to
> avoid using partial linking, but instead concatenate the generated
> assembler files into a single assembler file and assemble it.  This
> would remove the requirement of symbol promotion, as they would be
> in the same assembler file, but I am not sure if this would work out
> of the box (i.e. if GCC generates assembler that could be concatenated
> together).

Not out of the box, because we number labels which will clash but we
also do smarter tihngs like producing constant pools based on whole unit
knowledge.

But it should not be technically that hard: simply initialize asm output
before fork to one file, in each fork arrange separate file and avoid
priting the end of file stuff and then concatenate in the main compiler
and work out the places where this breaks...

Honza
> 
> > 
> > > Bootstrapped and Regtested on Linux x86_64.
> > >
> > > Giuliano Belinassi (6):
> > >   Modify gcc driver for parallel compilation
> > >   Implement a new partitioner for parallel compilation
> > >   Implement fork-based parallelism engine
> > >   Add `+' for Jobserver Integration
> > >   Add invoke documentation
> > >   New tests for parallel compilation feature
> > >
> > >  gcc/Makefile.in                               |    6 +-
> > >  gcc/cgraph.c                                  |   16 +
> > >  gcc/cgraph.h                                  |   13 +
> > >  gcc/cgraphunit.c                              |  198 ++-
> > >  gcc/common.opt                                |    4 +
> > >  gcc/doc/invoke.texi                           |   32 +-
> > >  gcc/gcc.c                                     | 1219 +++++++++++++----
> > >  gcc/ipa-fnsummary.c                           |    2 +-
> > >  gcc/ipa-icf.c                                 |    3 +-
> > >  gcc/ipa-visibility.c                          |    3 +-
> > >  gcc/ipa.c                                     |    4 +-
> > >  gcc/jobserver.cc                              |  168 +++
> > >  gcc/jobserver.h                               |   33 +
> > >  gcc/lto-cgraph.c                              |  172 +++
> > >  gcc/{lto => }/lto-partition.c                 |  463 ++++++-
> > >  gcc/{lto => }/lto-partition.h                 |    4 +-
> > >  gcc/lto-streamer.h                            |    4 +
> > >  gcc/lto/Make-lang.in                          |    4 +-
> > >  gcc/lto/lto.c                                 |    2 +-
> > >  gcc/params.opt                                |    8 +
> > >  gcc/symtab.c                                  |   46 +-
> > >  gcc/testsuite/driver/a.c                      |    6 +
> > >  gcc/testsuite/driver/b.c                      |    6 +
> > >  gcc/testsuite/driver/driver.exp               |   80 ++
> > >  gcc/testsuite/driver/empty.c                  |    0
> > >  gcc/testsuite/driver/foo.c                    |    7 +
> > >  .../gcc.dg/parallel-early-constant.c          |   22 +
> > >  gcc/testsuite/gcc.dg/parallel-static-1.c      |   21 +
> > >  gcc/testsuite/gcc.dg/parallel-static-2.c      |   21 +
> > >  .../gcc.dg/parallel-static-clash-1.c          |   23 +
> > >  .../gcc.dg/parallel-static-clash-aux.c        |   14 +
> > >  gcc/toplev.c                                  |   58 +-
> > >  gcc/toplev.h                                  |    3 +
> > >  gcc/tree.c                                    |   23 +-
> > >  gcc/varasm.c                                  |   26 +-
> > >  intl/Makefile.in                              |    2 +-
> > >  libbacktrace/Makefile.in                      |    2 +-
> > >  libcpp/Makefile.in                            |    2 +-
> > >  libdecnumber/Makefile.in                      |    2 +-
> > >  libiberty/Makefile.in                         |  212 +--
> > >  zlib/Makefile.in                              |   64 +-
> > >  41 files changed, 2539 insertions(+), 459 deletions(-)
> > >  create mode 100644 gcc/jobserver.cc
> > >  create mode 100644 gcc/jobserver.h
> > >  rename gcc/{lto => }/lto-partition.c (78%)
> > >  rename gcc/{lto => }/lto-partition.h (89%)
> > >  create mode 100644 gcc/testsuite/driver/a.c
> > >  create mode 100644 gcc/testsuite/driver/b.c
> > >  create mode 100644 gcc/testsuite/driver/driver.exp
> > >  create mode 100644 gcc/testsuite/driver/empty.c
> > >  create mode 100644 gcc/testsuite/driver/foo.c
> > >  create mode 100644 gcc/testsuite/gcc.dg/parallel-early-constant.c
> > >  create mode 100644 gcc/testsuite/gcc.dg/parallel-static-1.c
> > >  create mode 100644 gcc/testsuite/gcc.dg/parallel-static-2.c
> > >  create mode 100644 gcc/testsuite/gcc.dg/parallel-static-clash-1.c
> > >  create mode 100644 gcc/testsuite/gcc.dg/parallel-static-clash-aux.c
> > >
> > > --
> > > 2.28.0
> > >


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