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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
<html>
  <head>
    <title>SML/NJ Version 110.19 NEWS</title>
  </head>

  <body bgcolor="white">
   <center><h1>Standard ML of New Jersey<BR>
        Version 110.19, July 8, 1999</h1>
   </center>

   <center>
      <tt> http://cm.bell-labs.com/cm/cs/what/smlnj/index.html </tt>
   </center>

<blockquote>
<center>
<h2> Warning </h2>
</center>
 <blockquote>
 <blockquote>
    <em>
  	This version is intended for compiler hackers.  
	We are in the midst of substantial structural changes, 
	and this is a snapshot. 
    </em>
 </blockquote> 
 </blockquote>
      
<hr>

<center><h2>Summary:</h2></center>
  This version has a large number of MLRISC changes done primarily by
  Allen Leung. Salient features are:
  <ul>
   <li><font color="#aa0000"> MLTree:</font> All operations are explicitly typed by the data width,
	allowing better support for 16/64 bit operations (or any other
	width).  

   <li><font color="#aa0000"> Register encodings:</font> All physical
   registers are encoded uniquely.

   <li><font color="#aa0000"> Machine Descriptions: </font> Nearly all
   the target specific MLRISC files are now generated from a machine
   description.

   <li><font color="#aa0000"> Annotations:</font> Target machine
   instructions can be marked with client specific annotations.

   <li><font color="#aa0000"> Regions:</font> There is a new way to
   describing memory aliasing.

   <li><font color="#aa0000"> Multiplication/division:</font> There is
   better support for generating code involving constant operands.

   <li><font color="#aa0000"> Documentation:</font> Is in progress but
   not ready for prime time.

   <li> Execution time improves. 
  </ul>
<p>
 Other Changes include:

  <ul>
    <li> <font color="#aa0000">alpha32x</font> is no longer supported.
    <li> changes to support sockets under win32.
  </ul>
<hr>

<center><h2> MLRISC Changes</h2></center>

  <h4> MLTree </h4>

   <ul>
     <li>
        All operators in MLTREE are now typed by the data width.  For example,
        previously to compute <tt>x := y + 1</tt> we would write:
        <pre>
                MV(x,ADD(REG y,LI 1)) 
	</pre>
        Now we write:
	<pre>
            MV(x, 32, ADD(32, REG(32, y), LI 1))
	</pre>
        instead (assuming that x and y are both 32-bit quantities.)

        To translate old MLTREE to new MLTREE should be a straight
        forward process.

      <li> There is a larger set of operators.  Also, some of the operation
        names have been changed.  For example, we had:
	<pre>
            LOAD32 of rexp * region
	</pre>
        Now, we have
	<pre>
            LOAD of ty * rexp * region
	</pre>
        instead.  The ty (data width) parameter specifies the width of the
        data to be loaded.

      <li> New integer operators are:
	  <pre>
          MULS   of ty * rexp * rexp (* signed multiplication/division *)
          DIVS   of ty * rexp * rexp
          REMS   of ty * rexp * rexp
          REMU   of ty * rexp * rexp (* unsigned remainder *)
          NOTB   of ty * rexp        (* ones complement *) 
          CVTI2I of ty * ext * rexp  (* type promotion and conversion *)
          CVTF2I of ty * rounding_mode * fexp

           (* 
            * COND(ty,cc,e1,e2):
            * Evaluate into either e1 or e2, depending on cc.  
            * Both e1 and e2 can be evaluated eagerly.
            *)
          COND of ty * ccexp * rexp * rexp
          LOAD_UNALIGNED of ty * rexp * Region.region (* unaligned load *)
          MARK of rexp * Annotations.annotation
         </pre>
      <li> New floating-point operators are:
	  <pre>
          FLOAD_UNALIGNED  of fty * rexp * Region.region
          FABS of fty * fexp
          FNEG of fty * fexp
          FSQRT of fty * fexp
          CVTI2F of fty * ext * rexp
          CVTF2F of fty * rounding_mode * fexp
          FMARK of fexp * Annotations.annotation
	  </pre>
      <li> Note: not all the new operators have been implemented.

      <li> Order of evaluation:
	   <pre>
	   datatype order = 
		RL (* right-to-left *) | LR (* left-to-right *)
	   </pre>
          has been removed from arithmetic operators. Where order of
          evaluation is important, it should be made explicit by
	  sequentially assigning values to temporary registers.
      </ul>

   <h4>Register encodings</h4>

      <strong>EXTREMELY IMPORTANT:</strong> The encoding of physical
      registers has been changed. All physical registers are now
      encoded uniquely.  For example, on the Sparc, %g0 is encoding as
      0 and %f0 is encoding as 32.  Previously %f0 was encoded as 0.
      An MLRISC client should use the function Reg provided by the
      CELLS interface to compute these new encoding.
      <pre>
	   val Reg : cellkind -> int -> register
      </pre>
      For example, to describe %f0, use 
      <pre>
	  SparcCells.Reg SparcCells.FP 0
      </pre>

  <h4> Annotations</h4>
   
      There is a new mechanism to inject client-defined annotations into 
      the program.  Annotations can be attached to instructions, basic blocks,
      control flow edges or an entire cluster/CFG.
      <p>
      These MLTREE constructors:
	
	<ul>
	 <li> <tt>MARK of rexp * Annotations.annotation</tt>
	 <li> <tt>FMARK of fexp * Annotations.annotation</tt>
	 <li> <tt>CCMARK of ccexp * Annotations.annotation</tt>
        </ul>

      inject instruction level annotations.  
      (See MLRISC/instructions/insnProps.sig)
      <p>
      The term
	<pre>
	 BLOCK_ANNOTATION of Annotations.annotation
	</pre>
      inject a basic block level annotation.
      <p>
      Finally, 
	 <pre>
	 ENDCLUSTER of int Intmap.intmap * Annotations.annotations
	 </pre>
      can be used to attach a list of cluster level annotations.
      <p>
      Certain annotations are interpreted specially by the MLRISC
      system.  For example, there is an annotation that specifies
      branch probability, another that specifies control-dependence
      etc.  (See <tt>MLRISC/instructions/basicAnnotations.sig</tt>).
      Annotations are not restricted to the ones that we have
      predefined; an MLRISC client can freely define its own
      annotations (annotations are just ML exceptions).
      Client-defined annotations are propagated and are semantically
      null -- unless you write a new optimization phase to recognize a
      new annotation.


  <h4> Execution time</h4>

   Compilation and execution time on the HPPA, which has been the
      most finely tuned architecture in this release, improves from
      0-20% depending on the benchmark. Your mileage with other
      architectures will vary, however, their fine tuning has been 
      deferred to the next version. All other architecture should
      eventually improve, as a result of the generic
      multiplication/division by constants, and strength reduction.
      Currently 110.19 is 6% slower at compiling the compiler than 
      110.18 on the DEC Alpha.

  <h4> Machine Descriptions </h4>

      Nearly all the target specific MLRISC files are generated from a
      machine description. (See <tt>MLRISC/[arch]/[arch].md</tt>,
      where <tt>[arch]</tt> is one of <tt>sparc</tt>, <tt>hppa</tt>,
      <tt>alpha</tt>, <tt>ppc</tt>, or <tt>x86</tt>). This borrows
      several ideas from the New Jersey Machine Code Toolkit, and
      others. The files that process the machine descriptions have not
      been included in this release.
 
  <h4> Regions</h4>

      Please see the files <tt>aliasing/mlriscRegion.{sig,sml}</tt>
      for details.
 
  <h4> Multiplication/Division</h4>

       Strength reduction is performed for integer multiplications and 
    divisions by constants (except on the x86 platform).  This almost
    always leads to faster code.  The algorithm that we currently use 
    for strength reduction is very simple; more improvements are possible. 

  <h4> Documentation </h4>

      Preliminary documentation is included in this version, but is
      not ready for prime time use. It can be accessed by pointing to
      <tt.MLRISC/Doc/index.html</tt>. This documentation will be
      continually updated, and the following page should be used for
      the latest documentation:
        <pre>
	http://cm.bell-labs.com/cm/cs/what/smlnj/MLRISC
	</pre>

  <h4> See Also </h4>

      For architecture specific changes, please see the files
       <tt>MLRISC/[arch]/README.[arch]</tt>
      where <tt>[arch]</tt> is the name of the architecture.

 
      For detailed changes to MLRISC, please see the files
      <tt>MLRISC/README</tt> and <tt>MLRISC/CHANGES</tt>.
<hr>
<center><h2> Other Changes </h2></center>
  <h4>Alpha32x </h4>

    The DEC Alpha under OSF 3.2 is no longer supported. A special code 
    generator was required for this because the OS would not emulate
    certain floating point instructions. For example, for floating
    point subtraction, FSUB with the /SUD extension is  generated.
    (/SUD for software completion, underflow enabled, and dynamic
    rounding mode). Instead OSF 3.2 would generate an illegal
    instruction error.

<hr>
    <font size=-2>
    <address><a href="mailto:george@research.bell-labs.com">
		Lal George</a></address>
<!-- Created: Thu Aug  6 00:13:09 EDT 1998 -->
<!-- hhmts start -->
Last modified: Mon Jul 12 16:01:06 EDT 1999
<!-- hhmts end -->
    </font>
</blockquote>
</body>
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