GitLab

... again.
For now, I've added a TODO comment, but sooner or later this will have to
be made gcc-version-independent.

We need to use GNUC3_ATTRIBUTE(used) to force gcc to keep the
definition of StgRunIsImplementedInAssembler() around.  In some cases
we had already made this function external rather than static to get
around the problem, but GNUC3_ATTRIBUTE(used) is a better fix.

Now that we can handle using C argument registers as global registers,
extend the x86_64 register mapping.  We now have 5 integer argument
registers, 4 float, and 2 double (all caller-saves).  This results in a
reasonable speedup on x86_64.

Darwin/PPC:
Make StgRunIsImplementedInAssembler non-static; gcc has recently acquired
a habit of dead-stripping it.

MERGE TO STABLE

Two improvements to the SMP runtime:

  - support for 'par', aka sparks.  Load balancing is very primitive
    right now, but I have seen programs that go faster using par.

  - support for backing off when a thread is found to be duplicating
    a computation currently underway in another thread.  This also
    fixes some instability in SMP, because it turned out that when
    an update frame points to an indirection, which can happen if
    a thunk is under evaluation in multiple threads, then after GC
    has shorted out the indirection the update will trash the value.
    Now we suspend the duplicate computation to the heap before this
    can happen.

Additionally:

  - stack squeezing is separate from lazy blackholing, and now only
    happens if there's a reasonable amount of squeezing to be done
    in relation to the number of words of stack that have to be moved.
    This means we won't try to shift 10Mb of stack just to save 2
    words at the bottom (it probably never happened, but still).

  - update frames are now marked when they have been visited by lazy
    blackholing, as per the SMP paper.

  - cleaned up raiseAsync() a bit.

- change the type of StgRun(): now we return the Capability that the
  thread currently holds.  The return status of the thread is now
  stored in cap->r.rRet (a new slot in the reg table).

  This was necessary because on return from StgRun(), the current
  TSO may be blocked, so it no longer belongs to us.  If it is a bound
  thread, then the Task may have been already woken up on another
  Capability, so the scheduler can't use task->cap to find the
  capability it currently owns.

- when shutting down, allow a bound thread to remove its TSO from
  the run queue when exiting (eliminates an error condition in
  releaseCapability()).

Fix a warning

Darwin/x86:

Align the stack correctly when entering Haskell code.

Registerised support for Darwin/x86, both NCG and mangled.

*) -fPIC doesn't work yet with -fvia-C.
*) Apple officially requires the stack to be 16-byte-aligned,
   GHC ignores this for now.

Hack around a nasty bug on x86_64, caused by failing to align %rsp
correctly at a C call.  See the comment for details.

Rationalise the BUILD,HOST,TARGET defines.

Recall that:

  - build is the platform we're building on
  - host is the platform we're running on
  - target is the platform we're generating code for

The change is that now we take these definitions as applying from the
point of view of the particular source code being built, rather than
the point of view of the whole build tree.

For example, in RTS and library code, we were previously testing the
TARGET platform.  But under the new rule, the platform on which this
code is going to run is the HOST platform.  TARGET only makes sense in
the compiler sources.

In practical terms, this means that the values of BUILD, HOST & TARGET
may vary depending on which part of the build tree we are in.

Actual changes:

 - new file: includes/ghcplatform.h contains platform defines for
   the RTS and library code.

 - new file: includes/ghcautoconf.h contains the autoconf settings
   only (HAVE_BLAH).  This is so that we can get hold of these
   settings independently of the platform defines when necessary
   (eg. in GHC).

 - ghcconfig.h now #includes both ghcplatform.h and ghcautoconf.h.

 - MachRegs.h, which is included into both the compiler and the RTS,
   now has to cope with the fact that it might need to test either
   _TARGET_ or _HOST_ depending on the context.

 - the compiler's Makefile now generates
     stage{1,2,3}/ghc_boot_platform.h
   which contains platform defines for the compiler.  These differ
   depending on the stage, of course: in stage2, the HOST is the
   TARGET of stage1.  This was wrong before.

 - The compiler doesn't get platform info from Config.hs any more.
   Previously it did (sometimes), but unless we want to generate
   a new Config.hs for each stage we can't do this.

 - GHC now helpfully defines *_{BUILD,HOST}_{OS,ARCH} automatically
   in CPP'd Haskell source.

 - ghcplatform.h defines *_TARGET_* for backwards compatibility
   (ghcplatform.h is included by ghcconfig.h, which is included by
   config.h, so code which still #includes config.h will get the TARGET
   settings as before).

 - The Users's Guide is updated to mention *_HOST_* rather than
   *_TARGET_*.

 - coding-style.html in the commentary now contains a section on
   platform defines.  There are further doc updates to come.

Thanks to Wolfgang Thaller for pointing me in the right direction.

Add support for the dead code stripping feature of recent Apple linkers.
If your code is compiled using the NCG, you can now specify
-optl-W,-dead_strip on the GHC command line when linking.
It will have basically the same effect as using split-objs to build the
libraries.

Advantages over split-objs:
    * No evil perl script involved
    * Requires no special handling when building libraries

Disadvantages:
    * The current version of Apple's linker is slow when given the
      -dead_strip flag. _REALLY_ slow.
    * Mac OS X only.

This works by making the NCG emit the .subsections_via_symbols directive.
Additionally, we have to add an extra label at the top of every info table,
and make sure that the entry code references it (otherwise the info table
will be considered part of the preceding entry code).
The mangler just removes the .subsections_via_symbols directive.

#ifdef powerpc64:
fixed errors in run/return code revealed by testing

Added an StgRun for powerpc64/Linux
Fixed a typo in the code for powerpc32 Linux and Darwin

Removed the annoying "Id" CVS keywords, they're a real PITA when it
comes to merging...

Cleanup: all (well, most) messages from the RTS now go through the
functions in RtsUtils: barf(), debugBelch() and errorBelch().  The
latter two were previously called belch() and prog_belch()
respectively.  See the comments for the right usage of these message
functions.

One reason for doing this is so that we can avoid spurious uses of
stdout/stderr by Haskell apps on platforms where we shouldn't be using
them (eg. non-console apps on Windows).

Various fixes and removal of dead code.

Merge backend-hacking-branch onto HEAD.  Yay!

PowerPC Linux support for registerised compilation and native code
generation. (object splitting and GHCi are still unsupported).

Code for other platforms is not affected, so MERGE TO STABLE.

Oops, forgot one file in the x86_64 commit.

Update IA64 port to work with gcc 3.3.

PowerPC bugfix: Don't forget to save GPR13
(Thanks to Ashley Yakeley for reporting this)

MERGE TO STABLE

Merge the eval-apply-branch on to the HEAD
------------------------------------------

This is a change to GHC's evaluation model in order to ultimately make
GHC more portable and to reduce complexity in some areas.

At some point we'll update the commentary to describe the new state of
the RTS.  Pending that, the highlights of this change are:

  - No more Su.  The Su register is gone, update frames are one
    word smaller.

  - Slow-entry points and arg checks are gone.  Unknown function calls
    are handled by automatically-generated RTS entry points (AutoApply.hc,
    generated by the program in utils/genapply).

  - The stack layout is stricter: there are no "pending arguments" on
    the stack any more, the stack is always strictly a sequence of
    stack frames.

    This means that there's no need for LOOKS_LIKE_GHC_INFO() or
    LOOKS_LIKE_STATIC_CLOSURE() any more, and GHC doesn't need to know
    how to find the boundary between the text and data segments (BIG WIN!).

  - A couple of nasty hacks in the mangler caused by the neet to
    identify closure ptrs vs. info tables have gone away.

  - Info tables are a bit more complicated.  See InfoTables.h for the
    details.

  - As a side effect, GHCi can now deal with polymorphic seq.  Some bugs
    in GHCi which affected primitives and unboxed tuples are now
    fixed.

  - Binary sizes are reduced by about 7% on x86.  Performance is roughly
    similar, some programs get faster while some get slower.  I've seen
    GHCi perform worse on some examples, but haven't investigated
    further yet (GHCi performance *should* be about the same or better
    in theory).

  - Internally the code generator is rather better organised.  I've moved
    info-table generation from the NCG into the main codeGen where it is
    shared with the C back-end; info tables are now emitted as arrays
    of words in both back-ends.  The NCG is one step closer to being able
    to support profiling.

This has all been fairly thoroughly tested, but no doubt I've messed
up the commit in some way.

added a clarifying comment to the PowerPC version

STG to machine register mapping for IA64.

Initial mangling and tailcalls support for IA64.

Function prologues and epilogues are deleted and we use a single register
stack frame throughout (with a little register renaming in the mangler...)
Dropthrough from fast to slow entry point is also implemented.
Tailcalls are marked and converted into jumps at mangle time.

Bug-fixes for PowerPC
*) Rewrote StgRun in assembler (that seems to be the cleanest way to get it to work).
*) Fixed a small typo in createAdjustor.

Save $gp in StgRun() on the Alpha

Changes to support powerpc-apple-darwin

From: Wolfgang Thaller <wolfgang.thaller@gmx.net>

make sure stdout is flushed; unused arg wibble

Back out rev 1.28.  In retrospect saving the pre-messed-with %esp in a
global location is thread/reentrancy unsafe and a brain-dead thing to
do, and we can't think of a clean way to fix this.  So am backing it out.

x86 only: make %esp be 8-aligned before entering HC-world code.
This avoids misalignment penalties for C doubles stored on the C
stack.  A quick test using nofib/imaginary/rfib shows that getting
this wrong increases run time by about 10% on our 1 GHz PIII.

On the alpha, __divq() in libc.a clobbers $s6, so StgRun() needs to save
$s6.  While we are at it, let us save $f8 and $f9 as well.
MERGE TO STABLE

Change the story about POSIX headers in C compilation.

Until now, all C code in the RTS and library cbits has by default been
compiled with settings for POSIXness enabled, that is:
   #define _POSIX_SOURCE   1
   #define _POSIX_C_SOURCE 199309L
   #define _ISOC9X_SOURCE
If you wanted to negate this, you'd have to define NON_POSIX_SOURCE
before including headers.

This scheme has some bad effects:

* It means that ccall-unfoldings exported via interfaces from a
  module compiled with -DNON_POSIX_SOURCE may not compile when
  imported into a module which does not -DNON_POSIX_SOURCE.

* It overlaps with the feature tests we do with autoconf.

* It seems to have caused borkage in the Solaris builds for some
  considerable period of time.

The New Way is:

* The default changes to not-being-in-Posix mode.

* If you want to force a C file into Posix mode, #include as
  the **first** include the new file ghc/includes/PosixSource.h.
  Most of the RTS C sources have this include now.

* NON_POSIX_SOURCE is almost totally expunged.  Unfortunately
  we have to retain some vestiges of it in ghc/compiler so that
  modules compiled via C on Solaris using older compilers don't
  break.

Fixed (I hope, and have reason to believe) mysterious segfaulting problem
on the Alpha.

The problem (I hope, and have reason to believe) was that, during a few
instructions, the register saving/restoring code in StgRun() places data
below the current SP value.  (I.e., it should first reserve stack space,
then put data in said space, rather than first put data in, then reserve
the space.)

   "The SP value might be used by the hardware when raising exceptions and
    asynchronous interrupts. It must be assumed that the contents of the stack
    below the current SP value and within the stack for the current thread are
    continually and unpredictably modified, as specified in the _Alpha
    Architecture Reference Manual_, and as a result of asynchronous software
    actions."

   -- Compaq Computer Corporation, Houston. Tru64 UNIX Calling Standard for
      Alpha Systems, 5.1 edition, August 2000, section 3.2.1.  http://www.
      tru64unix.compaq.com/docs/base_doc/DOCUMENTATION/V51_PDF/ARH9MBTE.PDF

Fix typo in StgRun() for the Alpha

merge recent changes from before-ghci-branch onto the HEAD

merged from ghc-4-07-branch: don't save %i7 across the call.

Change the names of several RTS symbols so they don't potentially
clash with user code.  All the symbols that may clash now have an
"stg_" prefix.