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Hoist any-all common predicate for binary conjunctive classifications 

See comments.  This is meant to help mitigate the damage done by one of our
code generation systems.  The benefit is significant, allowing the code
generator to remain simple.  By placing this optimization within the
compiler, hand-written and template-generated code also benefit.
master
Mike Gerwitz 2021-01-27 16:14:13 -05:00
parent 25d500fec5
commit 658e55f2fa
1 changed files with 71 additions and 0 deletions
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71
src/current/include/preproc/macros.xsl
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@ -314,6 +314,77 @@
</template>
<!--
A very specific optimization targeting a common scenario from template
expansions.
If there is an <any> expression of this form:
<any>
<all>
<match on="foo" />
<match on="bar" value="BAZ" />
</all>
<all>
<match on="foo" />
<match on="bar" value="QUUX" />
</all>
</any>
Then the common "foo" will be hoisted out and the expression will become:
<match on="foo" />
<any>
<match on="bar" value="BAZ" />
<match on="bar" value="QUUX" />
</any>
The goal of this optimization is primarily to significantly reduce the
number of wasteful intermediate classifications that are generated.
-->
<template mode="preproc:class-groupgen" priority="6"
match="lv:any[ count( lv:all[ count(lv:*) = 2 ] ) = count(lv:*) ]">
<!-- TODO: missing @value may not have been expanded yet...! -->
<variable name="ons" as="element( lv:match )*"
select="lv:all/lv:match[
@value = 'TRUE'
or (
not( @value )
and not( @anyOf )
and not( c:* ) ) ]" />
<variable name="distinct-ons" as="xs:string*"
select="distinct-values( $ons/@on )" />
<variable name="nall" as="xs:integer"
select="count( lv:all )" />
<choose>
<when test="count( $distinct-ons ) = 1
and count( $ons ) = $nall
and count( $ons/parent::lv:all ) = $nall">
<!-- they're all the same, so hoist the first one out of the <any>,
which must be in a universal context -->
<sequence select="$ons[1]" />
<!-- then replace the <alls> with their remaining predicate (which is
either before or after) -->
<copy>
<apply-templates mode="preproc:class-groupgen"
select="$ons/preceding-sibling::lv:match
| $ons/following-sibling::lv:match"/>
</copy>
</when>
<!-- none, or more than one -->
<otherwise>
<next-match />
</otherwise>
</choose>
</template>
<template match="lv:any|lv:all" mode="preproc:class-groupgen" priority="5">
<!-- this needs to be unique enough that there is unlikely to be a conflict
between generated ids in various packages; generate-id is not enough for