MLton 20210117

# MLRISCLibrary

The MLRISC Library is a framework for retargetable and optimizing compiler back ends. The MLRISC Library is distributed with SML/NJ. Due to differences between SML/NJ and MLton, this library will not work out-of-the box with MLton.

As of 20210117, MLton includes a port of the MLRISC Library synchronized with SML/NJ version 110.99.

## Usage

- You can import a sub-library of the MLRISC Library into an MLB file with:

  MLB file | Description
  --- | ---
  $(SML_LIB)/mlrisc-lib/mlb/ALPHA.mlb | The ALPHA backend
  $(SML_LIB)/mlrisc-lib/mlb/AMD64.mlb | The AMD64 backend
  $(SML_LIB)/mlrisc-lib/mlb/AMD64-Peephole.mlb | The AMD64 peephole optimizer
  $(SML_LIB)/mlrisc-lib/mlb/CCall.mlb |
  $(SML_LIB)/mlrisc-lib/mlb/CCall-sparc.mlb |
  $(SML_LIB)/mlrisc-lib/mlb/CCall-x86-64.mlb |
  $(SML_LIB)/mlrisc-lib/mlb/CCall-x86.mlb |
  $(SML_LIB)/mlrisc-lib/mlb/Control.mlb |
  $(SML_LIB)/mlrisc-lib/mlb/Graphs.mlb |
  $(SML_LIB)/mlrisc-lib/mlb/HPPA.mlb | The HPPA backend
  $(SML_LIB)/mlrisc-lib/mlb/IA32.mlb | The IA32 backend
  $(SML_LIB)/mlrisc-lib/mlb/IA32-Peephole.mlb | The IA32 peephole optimizer
  $(SML_LIB)/mlrisc-lib/mlb/Lib.mlb |
  $(SML_LIB)/mlrisc-lib/mlb/MLRISC.mlb |
  $(SML_LIB)/mlrisc-lib/mlb/MLTREE.mlb |
  $(SML_LIB)/mlrisc-lib/mlb/Peephole.mlb |
  $(SML_LIB)/mlrisc-lib/mlb/PPC.mlb | The PPC backend
  $(SML_LIB)/mlrisc-lib/mlb/RA.mlb |
  $(SML_LIB)/mlrisc-lib/mlb/SPARC.mlb | The Sparc backend
  $(SML_LIB)/mlrisc-lib/mlb/StagedAlloc.mlb |
  $(SML_LIB)/mlrisc-lib/mlb/Visual.mlb |

- If you are porting a project from SML/NJ’s CompilationManager to MLton’s ML Basis system using cm2mlb, note that the following map is included by default:

      # MLRISC Library
      $SMLNJ-MLRISC                           $(SML_LIB)/mlrisc-lib/mlb

  This will automatically convert a $SMLNJ-MLRISC/MLRISC.cm import in an input .cm file into a $(SML_LIB)/mlrisc-lib/mlb/MLRISC.mlb import in the output .mlb file.

## Details

The following changes were made to the MLRISC Library, in addition to deriving the .mlb files from the .cm files:

- eliminate sequential withtype expansions: Most could be rewritten as a sequence of type definitions and datatype definitions.

- eliminate higher-order functors: Every higher-order functor definition and application could be uncurried in the obvious way.

- eliminate where <str> = <str>: Quite painful to expand out all the flexible types in the respective structures. Furthermore, many of the implied type equalities aren’t needed, but it’s too hard to pick out the right ones.

- library/array-noneq.sml (added, not exported): Implements signature ARRAY_NONEQ, similar to signature ARRAY from the Basis Library, but replacing the latter’s eqtype 'a array = 'a array and type 'a vector = 'a Vector.vector with type 'a array and type 'a vector. Thus, array-like containers may match ARRAY_NONEQ, whereas only the pervasive 'a array container may match ARRAY. (SML/NJ’s implementation of signature ARRAY omits the type realizations.)

- library/dynamic-array.sml and library/hash-array.sml (modifed): Replace include ARRAY with include ARRAY_NONEQ; see above.

## Patch

- MLRISC.patch