2007-01-12 David Smith <dsmith@redhat.com>

	* tapsets.cxx
	(dwarf_var_expanding_copy_visitor::visit_target_symbol): Since
	array behavior has changed (setting to 0 no longer deletes the
	array element), we delete the internal counter array element when
	providing target variable access in return probes.

2 files changed, 32 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index b804f124..697a99cf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2007-01-12  David Smith  <dsmith@redhat.com>
+
+	* tapsets.cxx
+	(dwarf_var_expanding_copy_visitor::visit_target_symbol): Since
+	array behavior has changed (setting to 0 no longer deletes the
+	array element), we delete the internal counter array element when
+	providing target variable access in return probes.
+
 2007-01-11  Roland McGrath  <roland@redhat.com>
 
 	* systemtap.spec.in (elfutils_version): Bump to 0.125.
diff --git a/tapsets.cxx b/tapsets.cxx
index d08e8633..5869a318 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -3012,6 +3012,8 @@ dwarf_var_expanding_copy_visitor::visit_target_symbol (target_symbol *e)
       //                    _dwarf_tvar_{name}_{num}_ctr[_dwarf_tvar_tid]]
       //   delete _dwarf_tvar_{name}_{num}[_dwarf_tvar_tid,
       //                    _dwarf_tvar_{name}_{num}_ctr[_dwarf_tvar_tid]--]
+      //   if (! _dwarf_tvar_{name}_{num}_ctr[_dwarf_tvar_tid])
+      //       delete _dwarf_tvar_{name}_{num}_ctr[_dwarf_tvar_tid]
 
       // (2a) Synthesize the tid temporary expression, which will look
       // like this:
@@ -3117,6 +3119,28 @@ dwarf_var_expanding_copy_visitor::visit_target_symbol (target_symbol *e)
 
       add_block->statements.push_back (ds);
 
+      // (2d) Delete the counter value if it is 0.  It will look like
+      // this:
+      //   if (! _dwarf_tvar_{name}_{num}_ctr[_dwarf_tvar_tid])
+      //       delete _dwarf_tvar_{name}_{num}_ctr[_dwarf_tvar_tid]
+      
+      ds = new delete_statement;
+      ds->tok = e->tok;
+      ds->value = ai_ctr;
+
+      unary_expression *ue = new unary_expression;
+      ue->tok = e->tok;
+      ue->op = "!";
+      ue->operand = ai_ctr;
+
+      if_statement *ifs = new if_statement;
+      ifs->tok = e->tok;
+      ifs->condition = ue;
+      ifs->thenblock = ds;
+      ifs->elseblock = NULL;
+      
+      add_block->statements.push_back (ifs);
+
       // (3) We need an entry probe that saves the value for us in the
       // global array we created.  Create the entry probe, which will
       // look like this: