S  M  L   /   N  J

                  1  1  0  .  1  3      N  E  W  S
			
  		         January 16, 1999

				WARNING

        This version is intended for compiler hackers only.  
	We are in the midst of substantial structural changes, 
	and this is a snapshot.  It only  supports the Sparc, 
	Alpha, and HPPA architectures.  Furthermore, there are
	performance bugs that have to be fixed.

        http://cm.bell-labs.com/cm/cs/what/smlnj/index.html

Summary:
  This version provides support for loading the sources files for the
  MLRISC Optimizer, and hooking it into the interactive loop. For now, 
  the only source files that are loaded are ones that build all the 
  fundamental compiler optimization data structures, and graphically 
  viewers for them. 


Demo:
 
  Requires daVinci: ftp://ftp.uni-bremen.de/pub/graphics/daVinci, or
  vcg: http://www.cs.uni-sb.de/RW/users/sander/html/gsvcg1.html
  
  The following steps exercises the current changes.

    1. Loading the optimizer sources and set the hook using:

	  CM.make'{force_relink=false, 
	           group="src/compiler/MLRISC-OPTIMIZER.cm"};

    2. At the top level execute:

	 structure M = Compiler.Control.MLRISC;

	 M.mlrisc :=true;				(* enable optimizer *)
	 M.Visual.viewer := "daVinci";		(* set viewer *)
	 M.view_IR := true;			(* enable viewer *)
	 M.mlrisc_phases :=			(* set phases *)
	  ["cluster->cfg", "view-dom", "cfg->cluster"];


    3. Compiling anything from here onwards, will go through the 
       optimizer. 
 
  Currently, the optimizer uses two different representations:
  the cluster and the IR.  The cluster is the old representation used
  in the register allocator and instruction selection.  The IR
  is the new representation.  Most new optimizations operate on
  the new IR.

  Several phases are possible in the mlrisc_phases list such as:

   a. view-cfg  -- view control flow graph
   b. view-dom  -- view dominator tree
   c. view-pdom -- view post dominator tree
   d. view-doms -- view dominator tree and post dominator tree together.
                   The post dominator is upside down.
   e. view-cdg  -- view control dependence graph
   f. view-loop -- show loop nesting tree
   g. guess     -- apply static branch prediction
                   (this need better machine descriptions)
   h. reshape   -- reorder the branch structure using frequencies 
                    gathered by static branch prediction

  All phases above transform IR into IR, so 
  they must be enclosed in phases "cluster->cfg", and "cfg->cluster",
  which translate clusters into IRs and vice versa.  In addition,
  there is a phase "copy-prop", which performs copy propagation on
  clusters.

Changes:

 .  The compiler uses  compiler/MLRISC.cm instead of the full
    MLRISC/MLRISC.cm. 

 .  FLOWGEN (MLRISC/cluster/flowgen.sml) now takes two functions:

	val optimize : (cluster->cluster) option ref
	val output : cluster->unit

    Each of the CodeGen/<arch>/<arch>CG.sml file were changed to have
    these. 

 .  CodeGen/main/mlrisc-export.sml defines a structure of all modules
    that must currently be exported from within the compiler. This 
    structure is quite small (for now at least).

 .  To get (6) above to work, I needed to establish the MLRISC
    environment as normally seen
    (CodeGen/optimizer/mlrisc-environment.sml), and set the 
    interactive optimizer hook to the new optimizer
    (CodeGen/optimizer/mlrisc-optimizer.sml).

Files:
   Deleted:
	TopLevel/main/codes.sig 
	CodeGen/main/cpsgen.sig
   Added:
	MLRISC.cm
	MLRISC-OPTIMIZER.cm
	TopLevel/main/code-generator.sig
	CodeGen/main/machine.sig
	CodeGen/main/machine-gen.sig
	CodeGen/main/mlrisc-export.sml
	CodeGen/optimizer/mlrisc-environment.sml
	CodeGen/optimizer/mlrisc-optimizer.sml