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In some cases, the layout of the LANGUAGE/OPTIONS_GHC lines has been
reorganized, while following the convention, to

- place `{-# LANGUAGE #-}` pragmas at the top of the source file, before
  any `{-# OPTIONS_GHC #-}`-lines.

- Moreover, if the list of language extensions fit into a single
  `{-# LANGUAGE ... -#}`-line (shorter than 80 characters), keep it on one
  line. Otherwise split into `{-# LANGUAGE ... -#}`-lines for each
  individual language extension. In both cases, try to keep the
  enumeration alphabetically ordered.
  (The latter layout is preferable as it's more diff-friendly)

While at it, this also replaces obsolete `{-# OPTIONS ... #-}` pragma
occurences by `{-# OPTIONS_GHC ... #-}` pragmas.

  * the new StgCmmArgRep module breaks a dependency cycle; I also
    untabified it, but made no real changes

  * updated the documentation in the wiki and change the user guide to
    point there

  * moved the allocation enters for ticky and CCS to after the heap check

    * I left LDV where it was, which was before the heap check at least
      once, since I have no idea what it is

  * standardized all (active?) ticky alloc totals to bytes

  * in order to avoid double counting StgCmmLayout.adjustHpBackwards
    no longer bumps ALLOC_HEAP_ctr

  * I resurrected the SLOW_CALL counters

    * the new module StgCmmArgRep breaks cyclic dependency between
      Layout and Ticky (which the SLOW_CALL counters cause)

    * renamed them SLOW_CALL_fast_<pattern> and VERY_SLOW_CALL

  * added ALLOC_RTS_ctr and _tot ticky counters

    * eg allocation by Storage.c:allocate or a BUILD_PAP in stg_ap_*_info

    * resurrected ticky counters for ALLOC_THK, ALLOC_PAP, and
      ALLOC_PRIM

    * added -ticky and -DTICKY_TICKY in ways.mk for debug ways

  * added a ticky counter for total LNE entries

  * new flags for ticky: -ticky-allocd -ticky-dyn-thunk -ticky-LNE

    * all off by default

    * -ticky-allocd: tracks allocation *of* closure in addition to
       allocation *by* that closure

    * -ticky-dyn-thunk tracks dynamic thunks as if they were functions

    * -ticky-LNE tracks LNEs as if they were functions

  * updated the ticky report format, including making the argument
    categories (more?) accurate again

  * the printed name for things in the report include the unique of
    their ticky parent as well as if they are not top-level

The main change here is that the Cmm parser now allows high-level cmm
code with argument-passing and function calls.  For example:

foo ( gcptr a, bits32 b )
{
  if (b > 0) {
     // we can make tail calls passing arguments:
     jump stg_ap_0_fast(a);
  }

  return (x,y);
}

More details on the new cmm syntax are in Note [Syntax of .cmm files]
in CmmParse.y.

The old syntax is still more-or-less supported for those occasional
code fragments that really need to explicitly manipulate the stack.
However there are a couple of differences: it is now obligatory to
give a list of live GlobalRegs on every jump, e.g.

  jump %ENTRY_CODE(Sp(0)) [R1];

Again, more details in Note [Syntax of .cmm files].

I have rewritten most of the .cmm files in the RTS into the new
syntax, except for AutoApply.cmm which is generated by the genapply
program: this file could be generated in the new syntax instead and
would probably be better off for it, but I ran out of enthusiasm.

Some other changes in this batch:

 - The PrimOp calling convention is gone, primops now use the ordinary
   NativeNodeCall convention.  This means that primops and "foreign
   import prim" code must be written in high-level cmm, but they can
   now take more than 10 arguments.

 - CmmSink now does constant-folding (should fix #7219)

 - .cmm files now go through the cmmPipeline, and as a result we
   generate better code in many cases.  All the object files generated
   for the RTS .cmm files are now smaller.  Performance should be
   better too, but I haven't measured it yet.

 - RET_DYN frames are removed from the RTS, lots of code goes away

 - we now have some more canned GC points to cover unboxed-tuples with
   2-4 pointers, which will reduce code size a little.

I've switched to passing DynFlags rather than Platform, as (a) it's
simpler to not have to extract targetPlatform in so many places, and
(b) it may be useful to have DynFlags around in future.

We don't actually use it yet

No special-casing in any NCGs yet

This changes the new code generator to make use of the Hoopl package
for dataflow analysis.  Hoopl is a new boot package, and is maintained
in a separate upstream git repository (as usual, GHC has its own
lagging darcs mirror in http://darcs.haskell.org/packages/hoopl).

During this merge I squashed recent history into one patch.  I tried
to rebase, but the history had some internal conflicts of its own
which made rebase extremely confusing, so I gave up. The history I
squashed was:

  - Update new codegen to work with latest Hoopl
  - Add some notes on new code gen to cmm-notes
  - Enable Hoopl lag package.
  - Add SPJ note to cmm-notes
  - Improve GC calls on new code generator.

Work in this branch was done by:
   - Milan Straka <fox@ucw.cz>
   - John Dias <dias@cs.tufts.edu>
   - David Terei <davidterei@gmail.com>

Edward Z. Yang <ezyang@mit.edu> merged in further changes from GHC HEAD
and fixed a few bugs.