Import Upstream version 20180207
[hcoop/debian/mlton.git] / doc / guide / localhost / PolyHash
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22<a href="./Home">MLton 20180207</a>\r
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25<div id="header">\r
26<h1>PolyHash</h1>\r
27</div>\r
28<div id="content">\r
29<div id="preamble">\r
30<div class="sectionbody">\r
31<div class="paragraph"><p><a href="PolyHash">PolyHash</a> is an optimization pass for the <a href="SSA">SSA</a>\r
32<a href="IntermediateLanguage">IntermediateLanguage</a>, invoked from <a href="SSASimplify">SSASimplify</a>.</p></div>\r
33</div>\r
34</div>\r
35<div class="sect1">\r
36<h2 id="_description">Description</h2>\r
37<div class="sectionbody">\r
38<div class="paragraph"><p>This pass implements polymorphic, structural hashing.</p></div>\r
39</div>\r
40</div>\r
41<div class="sect1">\r
42<h2 id="_implementation">Implementation</h2>\r
43<div class="sectionbody">\r
44<div class="ulist"><ul>\r
45<li>\r
46<p>\r
47<a href="https://github.com/MLton/mlton/blob/master/mlton/ssa/poly-hash.fun"><span class="monospaced">poly-hash.fun</span></a>\r
48</p>\r
49</li>\r
50</ul></div>\r
51</div>\r
52</div>\r
53<div class="sect1">\r
54<h2 id="_details_and_notes">Details and Notes</h2>\r
55<div class="sectionbody">\r
56<div class="paragraph"><p>For each datatype, tycon, and vector type, it builds and equality\r
57function and translates calls to <span class="monospaced">MLton_hash</span> into calls to that\r
58function.</p></div>\r
59<div class="paragraph"><p>For tuples, it does the equality test inline; i.e., it does not create\r
60a separate equality function for each tuple type.</p></div>\r
61<div class="paragraph"><p>All equality functions are created only if necessary, i.e., if\r
62equality is actually used at a type.</p></div>\r
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