Saxon

Created W3C XSLT30 test case for-each-group-085

Here's the -explain output:

OPT : At line 6 of file:/Users/mike/w3c/xslt30-test-B/tests/insn/for-each-group/for-each-group-085.xsl
OPT : Rewriting numeric filter expression with constant subscript
OPT : Expression after rewrite: child::element()[2]
OPT : At line 6 of file:/Users/mike/w3c/xslt30-test-B/tests/insn/for-each-group/for-each-group-085.xsl
OPT : Rewrote Filter Expression as:
OPT : Expression after rewrite: child::element()[2]
OPT : At line 12 of file:/Users/mike/w3c/xslt30-test-B/tests/insn/for-each-group/for-each-group-085.xsl
OPT : Inlined references to $t
OPT : Expression after rewrite: let $o := ForEachGroup(<t {FixedAttribute("T")}/>, let $g := one-or-more((current-group()) treat as element()) return ($g[(data(attribute::attribute(Q{}n))) = (data($c/attribute::attribute(Q{}n)))]), data(attribute::attribute(Q{}n)), "http://www.w3.org/2005/xpath-functions/collation/codepoint") return (ApplyTemplates(child::node(), $o))
OPT : At line 21 of file:/Users/mike/w3c/xslt30-test-B/tests/insn/for-each-group/for-each-group-085.xsl
OPT : Inlined references to $o
OPT : Expression after rewrite: ApplyTemplates(child::node(), ForEachGroup(<t {FixedAttribute("T")}/>, let $g := one-or-more((current-group()) treat as element()) return ($g[(data(attribute::attribute(Q{}n))) = (data($c/attribute::attribute(Q{}n)))]), data(attribute::attribute(Q{}n)), "http://www.w3.org/2005/xpath-functions/collation/codepoint"))
OPT : At line 15 of file:/Users/mike/w3c/xslt30-test-B/tests/insn/for-each-group/for-each-group-085.xsl
OPT : Lifted (let $g := ...) above (xsl:apply-templates) on line 21
OPT : Expression after rewrite: let $Q{http://saxon.sf.net/generated-variable}v0 := let $g := (one-or-more(current-group())) treat as element() return ($g[data(@n) = (data($c/attribute::attribute(Q{}n)))]) return (ApplyTemplates(child::node(), ForEachGroup(<t {FixedAttribute("T")}/>, $Q{http://saxon.sf.net/generated-variable}v0, data(@n), "http://www.w3.org/2005/xpath-functions/collation/codepoint")))
OPT : At line 17 of file:/Users/mike/w3c/xslt30-test-B/tests/insn/for-each-group/for-each-group-085.xsl
OPT : Lifted ($c / @n) above (let $vv:v0 := ...) on line 15
OPT : Expression after rewrite: let $Q{http://saxon.sf.net/generated-variable}v1 := data($c/attribute::attribute(Q{}n)) return (let $Q{http://saxon.sf.net/generated-variable}v0 := let $g := (one-or-more(current-group())) treat as element() return ($g[data(@n) = $Q{http://saxon.sf.net/generated-variable}v1]) return (ApplyTemplates(child::node(), ForEachGroup(<t {FixedAttribute("T")}/>, $Q{http://saxon.sf.net/generated-variable}v0, data(@n), "http://www.w3.org/2005/xpath-functions/collation/codepoint"))))
Stylesheet compilation time: 522.359446ms
<stylesheet xmlns:fn="http://www.w3.org/2005/xpath-functions"
            xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <globalVariables/>
  <mode onNo="TC" flags="dW" patternSlots="0">
    <ruleSet type="namedElements">
      <ruleChain key="c">
        <templateRule prec="0"
                      prio="0.5"
                      seq="0"
                      rank="1"
                      minImp="0"
                      slots="4"
                      flags="s"
                      line="5"
                      module="file:/Users/mike/w3c/xslt30-test-B/tests/insn/for-each-group/for-each-group-085.xsl">
          <p.withUpper role="match" axis="parent" upFirst="false">
            <p.nodeTest test="element(Q{}c)"/>
            <p.nodeTest test="document-node()"/>
          </p.withUpper>
          <let role="action"
               baseUri="file:/Users/mike/w3c/xslt30-test-B/tests/insn/for-each-group/for-each-group-085.xsl"
               ns="xsl=~ xs=~"
               line="6"
               var="c"
               as="element()?"
               slot="0"
               eval="7">
            <subscript>
              <axis name="child" nodeTest="element()"/>
              <int val="2"/>
            </subscript>
            <let xmlns:vv="http://saxon.sf.net/generated-variable"
                 line="17"
                 var="vv:v1"
                 as="xs:untypedAtomic?"
                 slot="1"
                 eval="13">
              <data>
                <slash simple="1">
                  <varRef name="c" slot="0"/>
                  <axis name="attribute" nodeTest="attribute(Q{}n)"/>
                </slash>
              </data>
              <let line="15" var="vv:v0" as="element()*" slot="2" eval="4">
                <let var="g"
                     as="(element() intersect element(Q{}t, Q{http://www.w3.org/2001/XMLSchema}untyped))+"
                     slot="3"
                     eval="8">
                  <treat as="element()" diag="3|0|XTTE0570|g">
                    <check card="+" diag="3|0|XTTE0570|g">
                      <currentGroup/>
                    </check>
                  </treat>
                  <filter line="17" flags="b">
                    <varRef name="g" slot="3"/>
                    <gc op="=" card="1:1" comp="CCC">
                      <attVal name="Q{}n" chk="0"/>
                      <varRef name="vv:v1" slot="1"/>
                    </gc>
                  </filter>
                </let>
                <applyT line="21" flags="i" bSlot="0">
                  <axis role="select" name="child" nodeTest="node()"/>
                  <withParam name="o" flags="t" as="element()*">
                    <forEachGroup line="9" algorithm="by">
                      <elem role="select" name="t" namespaces="xs">
                        <att name="n" flags="l">
                          <str val="T"/>
                        </att>
                      </elem>
                      <attVal role="key" line="13" name="Q{}n" chk="0"/>
                      <str role="collation"
                           val="http://www.w3.org/2005/xpath-functions/collation/codepoint"/>
                      <varRef role="content" line="15" name="vv:v0" slot="2"/>
                    </forEachGroup>
                  </withParam>
                </applyT>
              </let>
            </let>
          </let>
        </templateRule>
      </ruleChain>
      <ruleChain key="t">
        <templateRule prec="0"
                      prio="0.0"
                      seq="1"
                      rank="0"
                      minImp="0"
                      slots="1"
                      flags="s"
                      line="26"
                      module="file:/Users/mike/w3c/xslt30-test-B/tests/insn/for-each-group/for-each-group-085.xsl">
          <p.nodeTest role="match" test="element(Q{}t)"/>
          <param role="action"
                 baseUri="file:/Users/mike/w3c/xslt30-test-B/tests/insn/for-each-group/for-each-group-085.xsl"
                 ns="xsl=~ xs=~"
                 line="27"
                 name="o"
                 slot="0"
                 flags="t"
                 as="element()*">
            <empty role="select"/>
            <treat role="conversion" as="element()" diag="8|0|XTTE0590|o">
              <supplied slot="0"/>
            </treat>
          </param>
        </templateRule>
      </ruleChain>
    </ruleSet>
  </mode>
  <namedTemplates/>
  <accumulators/>
  <functions/>
</stylesheet>

The critical thing here is:

OPT : Lifted (let $g := ...) above (xsl:apply-templates) on line 21

This loop-lifting is clearly incorrect. (Note, the loop-lifting code is completely rewritten in 9.8)

The loop-lifting error is a consequence of an earlier incorrect tree rewrite: the "controlling instruction" held in the current-group() call is not the xsl:for-each-group instruction that is currently its container in the expression tree. This basically means that the cached information has become out-of-date.

This happens when the ForEachGroup instruction is copied, when its containing variable is inlined. The copy operation fails to rebind the link from the current-group call to the ForEachGroup instruction. Added a call on fixupGroupReferences() after the copy() operation to solve the problem.