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Restrict bitwise comparisons to sets with at least 3 elements (direct equality is cheaper for 1-2 elements)

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Sam Harwell 2012-11-27 08:27:14 -06:00
parent 88dbee6352
commit 7c5ec45054
1 changed files with 11 additions and 1 deletions
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12
tool/resources/org/antlr/v4/tool/templates/codegen/Java/Java.stg
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@ -453,7 +453,7 @@ Sync(s) ::= "sync(<s.expecting.name>);"
ThrowNoViableAlt(t) ::= "throw new NoViableAltException(this);" ThrowNoViableAlt(t) ::= "throw new NoViableAltException(this);"
TestSetInline(s) ::= << TestSetInline(s) ::= <<
<s.bitsets:{bits | <testShiftInRange({<s.varName> - <bits.shift>})> && ((1L \<\< (<s.varName> - <bits.shift>)) & (<bits.ttypes:{ttype | (1L \<\< (<ttype> - <bits.shift>))}; separator=" | ">)) != 0}; separator=" || "> <s.bitsets:{bits | <if(rest(rest(bits.ttypes)))><bitsetBitfieldComparison(s, bits)><else><bitsetInlineComparison(s, bits)><endif>}; separator=" || ">
>> >>
// Java language spec 15.19 - shift operators mask operands rather than overflow to 0... need range test // Java language spec 15.19 - shift operators mask operands rather than overflow to 0... need range test
@ -461,6 +461,16 @@ testShiftInRange(shiftAmount) ::= <<
((<shiftAmount>) & ~0x3f) == 0 ((<shiftAmount>) & ~0x3f) == 0
>> >>
// produces smaller bytecode only when bits.ttypes contains more than two items
bitsetBitfieldComparison(s, bits) ::= <%
(<testShiftInRange({<s.varName> - <bits.shift>})> && ((1L \<\< (<s.varName> - <bits.shift>)) & (<bits.ttypes:{ttype | (1L \<\< (<ttype> - <bits.shift>))}; separator=" | ">)) != 0)
%>
// produces more efficient bytecode when bits.ttypes contains at most two items
bitsetInlineComparison(s, bits) ::= <%
<bits.ttypes:{ttype | <s.varName>==<ttype>}; separator=" || ">
%>
cases(ttypes) ::= << cases(ttypes) ::= <<
<ttypes:{t | case <t>:}; separator="\n"> <ttypes:{t | case <t>:}; separator="\n">
>> >>