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Add "%define assert" to variants.

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This is used to help the user catch cases where some value gets
ovewritten by a new one.  This should not happen, as this will
probably leak.

Unfortunately this uncovered a bug in the C++ parser itself: the
lookahead value was not destroyed between two calls to yylex.  For
instance if the previous lookahead was a std::string, and then an int,
then the value of the std::string was correctly taken (i.e., the
lookahead was now an empty string), but std::string structure itself
was not reclaimed.

This is now done in variant::build(other&) (which is used to take the
value of the lookahead): other is not only stolen from its value, it
is also destroyed.  This incurs a new performance penalty of a few
percent, and union becomes faster again.

	* data/lalr1-fusion.cc (variant::build(other&)): Destroy other.
	(b4_variant_if): New.
	(variant::built): New.
	Use it whereever the status of the variant changes.
	* etc/bench.pl.in: Check the penalty of %define assert.
This commit is contained in:
Akim Demaille
2008-07-25 22:48:42 +02:00
parent f6038cb8c3
commit 2d32fc9fe2
3 changed files with 52 additions and 5 deletions
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@@ -1,3 +1,28 @@
2008-11-07 Akim Demaille <demaille@gostai.com>
Add "%define assert" to variants.
This is used to help the user catch cases where some value gets
ovewritten by a new one. This should not happen, as this will
probably leak.
Unfortunately this uncovered a bug in the C++ parser itself: the
lookahead value was not destroyed between two calls to yylex. For
instance if the previous lookahead was a std::string, and then an int,
then the value of the std::string was correctly taken (i.e., the
lookahead was now an empty string), but std::string structure itself
was not reclaimed.
This is now done in variant::build(other&) (which is used to take the
value of the lookahead): other is not only stolen from its value, it
is also destroyed. This incurs a new performance penalty of a few
percent, and union becomes faster again.
* data/lalr1-fusion.cc (variant::build(other&)): Destroy other.
(b4_variant_if): New.
(variant::built): New.
Use it whereever the status of the variant changes.
* etc/bench.pl.in: Check the penalty of %define assert.
2008-11-07 Akim Demaille <demaille@gostai.com>
Use "%define variant" in bench.pl.