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/*
* phc -- the open source PHP compiler
* See doc/license/README.license for licensing information
*
* HACK TODO: Remove.
* This is exactly the sort of hacky thing we wanted
* to remove. This would be much better done with a data-flow
* framework, but is much easier than cleaning up the passes, which
* would otherwise be necessary.
*
* Count the uses and defs of each variable. Of course, it is very
* imprecise, only works for very certain cases, doesn't use any
* sort of data-flow techniques, won't work in the general case in
* the presence of any sort of features, doesn't take references
* into account, etc. This is only barely usable for the hacky dead
* code elimination and copy propagation I've hacked into place.
*
*/
#ifndef PHC_USE_DEF_COUNTER
#define PHC_USE_DEF_COUNTER
#include "process_ir/General.h"
#include "HIR_visitor.h"
#include "lib/Stack.h"
#include "lib/Map.h"
#include "HIR.h"
/* Entering at the method level, count the total occurences of a
* variable, and the number of defintions, and the uses is the
* difference of the two. */
class Use_def_counter : public HIR::Visitor, public virtual GC_obj
{
// For analysis
private:
Stack< Map<string, int>* > analysis_defs;
Stack< Map<string, int>* > analysis_occurences;
void pre_method (HIR::Method* in);
void pre_assign_var (HIR::Assign_var* in);
void pre_variable_name (HIR::VARIABLE_NAME* in);
void post_method (HIR::Method* in);
void children_php_script (HIR::PHP_script* in);
// start analysing a new method
void init_analysis ();
void finish_analysis (HIR::Statement_list* in);
public:
Use_def_counter ();
};
class Clear_use_defs : public HIR::Visitor, public virtual GC_obj
{
void pre_node (HIR::Node* in)
{
in->attrs->erase_with_prefix ("phc.use_defs");
}
};
#endif // PHC_USE_DEF_COUNTER
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