Add documentation to bench.pl.

[bison.git] / ChangeLog

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+2008-11-03  Akim Demaille  <demaille@gostai.com>
+
+       Add documentation to bench.pl.
+       * etc/bench.pl.in: Comment changes.
+
+2008-11-03  Akim Demaille  <demaille@gostai.com>
+
+       Fuse the three stacks into a single one.
+       In order to make it easy to perform benchmarks to ensure that there are no
+       performance loss, lalr1.cc is forked into lalr1-fusion.cc.  Eventually,
+       lalr1-fusion.cc will replace lalr1.cc.
+       
+       Meanwhile, to make sure that lalr1-fusion.cc is correctly exercized by the
+       test suite, the user must install a symbolic link from lalr1.cc to it.
+       
+       Instead of having three stacks (state, value, location), use a stack
+       of triples.  This considerably simplifies the code (and it will be
+       easier not to require locations as currently does the C++ parser),
+       and also gives a 10% speedup according to etc/bench (probably mainly since
+       memory allocation is done once instead of three times).
+       
+       Another motivation is to make it easier to destruct properly
+       semantic values: now that they are bound to their state (hence
+       symbol type) it will be easier to call the appropriate destructor.
+       
+       These changes should probably benefit the C parser too.
+       
+       * data/lalr1.cc: Copy as...  * data/lalr1-fusion.cc: this new
+       file.
+       (b4_rhs_value, b4_rhs_location): New definitions overriding those
+       from c++.m4.
+       (state_stack_type, semantic_stack_type, location_stack_type)
+       (yystate_stack_, yysemantic_stack_, yylocation_stack_): Remove.
+       (data_type, stack_type, yystack_): New.
+       (YYLLOC_DEFAULT, yypush_): Adjust.
+       (yyerror_range): Now based on data_type, not location_type.
+
+2008-11-03  Akim Demaille  <demaille@gostai.com>
+
+       Push the state, value, and location at the same time.
+       This is needed to prepare a forthcoming patch that fuses the three
+       stacks into one.
+       
+       * data/lalr1.cc (parser::yypush_): New.
+       (parser::yynewstate): Change the semantics: instead of arriving to
+       this label when value and location have been pushed, but yystate
+       is to be pushed on the state stack, now the three of them must
+       have been pushed before.  yystate still must be the new state.
+       This allows to use yypush_ everywhere instead of individual
+       handling of the stacks.
+
 2008-11-03  Akim Demaille  <demaille@gostai.com>
 
        Prefer references to pointers.