Produce new-style Cmm from the Cmm parser

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.

1 files changed, 21 insertions, 16 deletions

diff --git a/compiler/cmm/SMRep.lhs b/compiler/cmm/SMRep.lhs
index d9644488fc..ac021df761 100644
--- a/compiler/cmm/SMRep.lhs
+++ b/compiler/cmm/SMRep.lhs
@@ -30,6 +30,7 @@ module SMRep (
 
         -- ** Predicates
         isStaticRep, isConRep, isThunkRep, isFunRep, isStaticNoCafCon,
+        isStackRep,
 
         -- ** Size-related things
         heapClosureSize,
@@ -148,7 +149,7 @@ data SMRep
         Liveness
 
   | RTSRep              -- The RTS needs to declare info tables with specific
-        StgHalfWord     -- type tags, so this form lets us override the default
+        Int             -- type tags, so this form lets us override the default
         SMRep           -- tag for an SMRep.
 
 -- | True <=> This is a static closure.  Affects how we garbage-collect it.
@@ -166,10 +167,10 @@ data ClosureTypeInfo
   | ThunkSelector SelectorOffset
   | BlackHole
 
-type ConstrTag         = StgHalfWord
+type ConstrTag         = Int
 type ConstrDescription = [Word8] -- result of dataConIdentity
-type FunArity          = StgHalfWord
-type SelectorOffset    = StgWord
+type FunArity          = Int
+type SelectorOffset    = Int
 
 -------------------------
 -- We represent liveness bitmaps as a Bitmap (whose internal
@@ -188,7 +189,7 @@ type Liveness = [Bool]   -- One Bool per word; True  <=> non-ptr or dead
 
 data ArgDescr
   = ArgSpec             -- Fits one of the standard patterns
-        !StgHalfWord    -- RTS type identifier ARG_P, ARG_N, ...
+        !Int            -- RTS type identifier ARG_P, ARG_N, ...
 
   | ArgGen              -- General case
         Liveness        -- Details about the arguments
@@ -212,7 +213,7 @@ mkHeapRep dflags is_static ptr_wds nonptr_wds cl_type_info
      hdr_size     = closureTypeHdrSize dflags cl_type_info
      payload_size = ptr_wds + nonptr_wds
 
-mkRTSRep :: StgHalfWord -> SMRep -> SMRep
+mkRTSRep :: Int -> SMRep -> SMRep
 mkRTSRep = RTSRep
 
 mkStackRep :: [Bool] -> SMRep
@@ -229,6 +230,11 @@ isStaticRep (HeapRep is_static _ _ _) = is_static
 isStaticRep (StackRep {})             = False
 isStaticRep (RTSRep _ rep)            = isStaticRep rep
 
+isStackRep :: SMRep -> Bool
+isStackRep StackRep{}     = True
+isStackRep (RTSRep _ rep) = isStackRep rep
+isStackRep _              = False
+
 isConRep :: SMRep -> Bool
 isConRep (HeapRep _ _ _ Constr{}) = True
 isConRep _                        = False
@@ -314,11 +320,10 @@ closureTypeHdrSize dflags ty = case ty of
 -- Defines CONSTR, CONSTR_1_0 etc
 
 -- | Derives the RTS closure type from an 'SMRep'
-rtsClosureType :: DynFlags -> SMRep -> StgHalfWord
-rtsClosureType dflags rep
-    = toStgHalfWord dflags
-    $ case rep of
-      RTSRep ty _ -> fromStgHalfWord ty
+rtsClosureType :: SMRep -> Int
+rtsClosureType rep
+    = case rep of
+      RTSRep ty _ -> ty
 
       HeapRep False 1 0 Constr{} -> CONSTR_1_0
       HeapRep False 0 1 Constr{} -> CONSTR_0_1
@@ -355,11 +360,11 @@ rtsClosureType dflags rep
       _ -> panic "rtsClosureType"
 
 -- We export these ones
-rET_SMALL, rET_BIG, aRG_GEN, aRG_GEN_BIG :: DynFlags -> StgHalfWord
-rET_SMALL   dflags = toStgHalfWord dflags RET_SMALL
-rET_BIG     dflags = toStgHalfWord dflags RET_BIG
-aRG_GEN     dflags = toStgHalfWord dflags ARG_GEN
-aRG_GEN_BIG dflags = toStgHalfWord dflags ARG_GEN_BIG
+rET_SMALL, rET_BIG, aRG_GEN, aRG_GEN_BIG :: Int
+rET_SMALL   = RET_SMALL
+rET_BIG     = RET_BIG
+aRG_GEN     = ARG_GEN
+aRG_GEN_BIG = ARG_GEN_BIG
 \end{code}
 
 Note [Static NoCaf constructors]