linearscan

Linearscan register allocator

Linearscan.js

Linearscan register allocator for javascript

// Declare some instructions 
var linearscan = require('linearscan');
 
function gp(kindvalue) {
  return { kind: kind, group: 'gp', value: value };
}
 
function fp(kindvalue) {
  return { kind: kind, group: 'fp', value: value };
}
 
var config = linearscan.config.create({
  // Multiple register groups might be specified, they will be allocated 
  // separately 
  registers: {
    gp: [
      'rax', 'rbx', 'rcx', 'rdx'
    ],
    fp: [
      'xmm1', 'xmm2', 'xmm3', 'xmm4'
    ]
  },
  opcodes: {
    literal: {
      // 'any' means either 'register' or 'spill' 
      output: gp('any')
    },
    'literal-fp': {
      output: fp('any')
    },
 
    // Set `branch` to `true` to get links to other regions 
    if: { branch: true },
    jump: { branch: true },
 
    add: {
      output: gp('any'),
      inputs: [ gp('any'), gp('any') ]
    },
    'add-fp': {
      output: fp('any'),
      inputs: [ fp('any'), fp('any') ]
    },
    floor: {
      output: gp('any'),
      inputs: [ fp('any') ]
    },
    return: {
      // specify particular register that MUST be used here 
      inputs: [ gp('register', 'rax') ]
    },
    'rax-out': {
      inputs: [],
      output: gp('register', 'rax'),
      spills: []
    },
    'rbx-out': {
      inputs: [],
      output: gp('register', 'rbx'),
      spills: []
    },
    'rbx-call': {
      inputs: [],
      output: gp('register', 'rbx'),
 
      // Scratches are similar to spills, but neither input nor output will 
      // be allocated to this value. 
      scratches: [ gp('register', 'rdx') ],
      spills: [
        gp('register', 'rax'),
        gp('register', 'rbx'),
        gp('register', 'rcx')
      ]
    },
    call: {
      output: gp('register', 'rax'),
 
      // 'register' means just any GP register 
      inputs: [ gp('register'), gp('any') ],
      spills: [
        gp('register', 'rax'),
        gp('register', 'rbx'),
        gp('register', 'rcx'),
        gp('register', 'rdx')
      ]
    }
  }
});
 
// Get pipeline from previous stages of compiler 
// (see json-pipeline npm module) 
var pipeline = getPipeline();
 
// Make sure that pipeline is properly indexed 
pipeline.reindex();
 
var out = linearscan.allocate(pipeline, config);
console.log(out.render('printable'));

Will output something like this:

register {
  %rax = literal 1
  %rbx = literal 2
  %rcx = literal 3
  %rdx = literal 4
  [0] = ls:move %3
  %rdx = literal 5
  [1] = ls:move [0]
  [3] = ls:move %1
  [2] = ls:move %2
  [0] = ls:move %3
  %rax = call %rdx, %rax
  %rax = add [3], [3]
  %rax = add [2], [2]
  %rax = add [1], [1]
  %rax = add [0], [0]
}

out.spillType is the list of spill ranges of following format: { type: 'register-group', from: index, to: index }.

This software is licensed under the MIT License.

Copyright Fedor Indutny, 2015.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.