| class OPTIMIZE < $OPTIMIZE |
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| **** | This optimizer moves as many expressions as possible out of loops. An expression is movable if it is either * a constant * a constant from the beginning of the loop to its first call
___and_it_is_not_in_a_conditional_expression._We_have_to_check_two_cases: ____if_it_is_possible_that_the_expression_is_never_evaluated,_because_the_loop ____terminates_early_(iter_call,_return,_raise),_we_have_to_make_sure_that ____during_the_evaluation_of_the_code_there_is_no_fatal_error._Hence_we_ ____move_only_local,_global_and_attr_expressions_out_of_the_loop._Attr_expressions ____are_guarded_against_void_accesses. * if the code is in a conditional expression, we check that all it consists only of ___local,_global_or_attr_expressions_that_are_constant_during_the_whole_loop ___Attr_expressions_have_to_be_guarded_against_void_accesses. NOTE: if an attr expression is guarded against void accesses, the program _______will_not_stop_with_an_"void_access"_but_silently_continue._Therefore _______you_should_not_use_-O_if_you_need_to_check_all_accesses. |
| $OPTIMIZE | OPT_HELPER |
| check_leftover_functions(am:$AM_EXPR) |
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| create(p:PROG):SAME |
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| cs_options:CS_OPTIONS |
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| do_loop_opt(func:AM_ROUT_DEF) |
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| **** | if func.sig.is_iter then mark_hot_args(func); end; unfortunatly it is very hard to do any optimizations within iters. The problem is that it not possible to move code or evaluate expressions before or after the yield statement where they were. It is for example impossible to move the expression 'a*b' out of a loop, as you don't know if the caller may change it or not:
____loop_yield_1.up!*a*b;_end; This assumes that either a or b are attributes, and not locals of course. As it seems not worth the trouble, iters are not optimized at all (but we do inlining in iters, of course); |
| finalize |
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| init |
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| is_local(am:$AM):BOOL |
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| m_one:AM_INT_CONST |
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| m_two:AM_INT_CONST |
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| make_sure_emitted(s:SIG) |
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| mark_hot_args(func:AM_ROUT_DEF) |
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| new_local(func:AM_ROUT_DEF,tp:$TP):AM_LOCAL_EXPR |
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| new_local(func:AM_ROUT_DEF,tp:$TP,source:SFILE_ID):AM_LOCAL_EXPR |
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| no_optimize(func:AM_ROUT_DEF) |
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| **** | if no optimization option is on, but opt_debug is on the compiler dumps the AM form of all functions. Handy to get them, but definitly the wrong place for this code. This will most certainly be deleted in future versions of the optimizer. |
| one:AM_INT_CONST |
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| optimize(func:AM_ROUT_DEF) |
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| prog:PROG |
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| tp_bool:$TP |
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| tp_char:$TP |
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| tp_int:$TP |
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| two:AM_INT_CONST |
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| zero:AM_INT_CONST |
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