Add high-level support for @cast()ing

This handles all of the parsing, traversal, and optimization.  It
doesn't actually resolve the cast yet though.

* staptree.h (struct cast_op, visitor::visit_cast_op): New.
* staptree.cxx (cast_op::print/visit, various visitor::visit_cast_op's):
Incorporate cast_op into the basic tree operations.
* parse.cxx (parser::parse_symbol): Parse @cast operator with an
expression operand, type string, and optional module string.
* translate.cxx (c_unparser::visit_cast_op): Error out if a @cast
survives to translation.
* elaborate.cxx (typeresolution_info::visit_cast_op): Error out if a
@cast survives to type resolution.
(symbol_fetcher::visit_cast_op): treat @casts as a symbol target
(void_statement_reducer::visit_cast_op): unused @casts can be discarded,
but the operand should still be evaluated.

1 files changed, 15 insertions, 0 deletions

diff --git a/staptree.h b/staptree.h
index 0cd0ee0d..7092f980 100644
--- a/staptree.h
+++ b/staptree.h
@@ -238,6 +238,15 @@ struct target_symbol: public symbol
 };
 
 
+struct cast_op: public target_symbol
+{
+  expression *operand;
+  std::string type, module;
+  void print (std::ostream& o) const;
+  void visit (visitor* u);
+};
+
+
 struct arrayindex: public expression
 {
   std::vector<expression*> indexes;
@@ -680,6 +689,7 @@ struct visitor
   virtual void visit_print_format (print_format* e) = 0;
   virtual void visit_stat_op (stat_op* e) = 0;
   virtual void visit_hist_op (hist_op* e) = 0;
+  virtual void visit_cast_op (cast_op* e) = 0;
 };
 
 
@@ -720,6 +730,7 @@ struct traversing_visitor: public visitor
   void visit_print_format (print_format* e);
   void visit_stat_op (stat_op* e);
   void visit_hist_op (hist_op* e);
+  void visit_cast_op (cast_op* e);
 };
 
 
@@ -759,6 +770,7 @@ struct varuse_collecting_visitor: public functioncall_traversing_visitor
   void visit_pre_crement (pre_crement *e);
   void visit_post_crement (post_crement *e);
   void visit_foreach_loop (foreach_loop *s);
+  void visit_cast_op (cast_op* e);
 
   bool side_effect_free ();
   bool side_effect_free_wrt (const std::set<vardecl*>& vars);
@@ -808,6 +820,7 @@ struct throwing_visitor: public visitor
   void visit_print_format (print_format* e);
   void visit_stat_op (stat_op* e);
   void visit_hist_op (hist_op* e);
+  void visit_cast_op (cast_op* e);
 };
 
 // A visitor similar to a traversing_visitor, but with the ability to rewrite
@@ -868,6 +881,7 @@ struct update_visitor: public visitor
   virtual void visit_print_format (print_format* e);
   virtual void visit_stat_op (stat_op* e);
   virtual void visit_hist_op (hist_op* e);
+  virtual void visit_cast_op (cast_op* e);
 
 private:
   std::stack<void *> targets;
@@ -922,6 +936,7 @@ struct deep_copy_visitor: public update_visitor
   virtual void visit_print_format (print_format* e);
   virtual void visit_stat_op (stat_op* e);
   virtual void visit_hist_op (hist_op* e);
+  virtual void visit_cast_op (cast_op* e);
 };
 
 #endif // STAPTREE_H