PR2049: support arbitrary $target-array indexing

Rather than just numeric literals, we can now support arbitrary
expressions for the index value.  Note that loc2c won't allow this for
noncontiguous arrays, as the access methods need to be statically
computed, but for contiguous arrays and pointers-as-arrays it works
just fine.

* staptree.h (target_symbol::component): Add expression_array_index.
* staptree.cxx (target_symbol::visit_components): New helper.
  (target_symbol::assert_no_components): Recognize new array type.
  (target_symbol::component::print): Print subexpressions.
  (traversing_visitor::visit_target_symbol, visit_cast_op): Visit the
  indexing components too.
  (varuse_collecting_visitor::visit_target_symbol): Ditto.
  (update_visitor::visit_target_symbol, visit_cast_op): Ditto.
* elaborate.cxx (void_statement_reducer::visit_target_symbol): New.
  (void_statement_reducer::visit_cast_op): Save indexes too.
* parse.cxx (parser::parse_target_symbol_components): Parse expressions.
* tapsets.cxx (dwarf_var_expanding_visitor::visit_target_symbol): Pass
  expression-indexes as parameters (indexN) to the dwarf function.
  (dwarf_cast_expanding_visitor::visit_cast_op): Ditto.
  (tracepoint_var_expanding_visitor::visit_target_symbol_arg): Ditto.
  (sdt_var_expanding_visitor::visit_target_symbol): Visit the new @cast.
* dwflpp.cxx (dwflpp::translate_components): Use THIS->indexN.
* translate.cxx (c_unparser::visit_target_symbol): Correct error msg.
* testsuite/systemtap.base/pointer_array.stp: Use a simple index.

1 files changed, 9 insertions, 2 deletions

diff --git a/staptree.h b/staptree.h
index 9ade2a42..146d0e34 100644
--- a/staptree.h
+++ b/staptree.h
@@ -58,6 +58,7 @@ std::ostream& operator << (std::ostream& o, const exp_type& e);
 
 struct token;
 struct visitor;
+struct update_visitor;
 
 struct expression
 {
@@ -227,7 +228,8 @@ struct target_symbol: public symbol
   enum component_type
     {
       comp_struct_member,
-      comp_literal_array_index
+      comp_literal_array_index,
+      comp_expression_array_index,
     };
 
   struct component
@@ -236,11 +238,14 @@ struct target_symbol: public symbol
       component_type type;
       std::string member; // comp_struct_member
       int64_t num_index; // comp_literal_array_index
+      expression* expr_index; // comp_expression_array_index
 
       component(const token* t, const std::string& m):
-        tok(t), type(comp_struct_member), member(m), num_index(0) {}
+        tok(t), type(comp_struct_member), member(m) {}
       component(const token* t, int64_t n):
         tok(t), type(comp_literal_array_index), num_index(n) {}
+      component(const token* t, expression* e):
+        tok(t), type(comp_expression_array_index), expr_index(e) {}
       void print (std::ostream& o) const;
     };
 
@@ -252,6 +257,8 @@ struct target_symbol: public symbol
   target_symbol(): addressof(false), saved_conversion_error (0) {}
   void print (std::ostream& o) const;
   void visit (visitor* u);
+  void visit_components (visitor* u);
+  void visit_components (update_visitor* u);
   void assert_no_components(const std::string& tapset);
 };