Expand @defined to support more cases

* tapsets.cxx (var_expanding_visitor::visit_defined_op): If no error was
  raised or replacement made on a target_symbol, then its @defined state
  is still indeterminate.  Some later pass (like @cast) might handle it.
* elaborate.cxx (const_folder::visit_defined_op): Squash any escapees.
* testsuite/semok/thirtysix.stp: Add more variants.

3 files changed, 34 insertions, 1 deletions

diff --git a/elaborate.cxx b/elaborate.cxx
index 5f3cc8ae..12dbce3a 100644
--- a/elaborate.cxx
+++ b/elaborate.cxx
@@ -3010,6 +3010,7 @@ struct const_folder: public update_visitor
   void visit_comparison (comparison* e);
   void visit_concatenation (concatenation* e);
   void visit_ternary_expression (ternary_expression* e);
+  void visit_defined_op (defined_op* e);
 };
 
 void
@@ -3471,6 +3472,20 @@ const_folder::visit_ternary_expression (ternary_expression* e)
     }
 }
 
+void
+const_folder::visit_defined_op (defined_op* e)
+{
+  // If a @defined makes it this far, then it is, de facto, undefined.
+
+  if (session.verbose>2)
+    clog << "Collapsing untouched @defined check " << *e->tok << endl;
+  relaxed_p = false;
+
+  literal_number* n = new literal_number (0);
+  n->tok = e->tok;
+  n->visit (this);
+}
+
 static void semantic_pass_const_fold (systemtap_session& s, bool& relaxed_p)
 {
   // Let's simplify statements with constant values.
diff --git a/tapsets.cxx b/tapsets.cxx
index ca439ede..d470b043 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -1982,7 +1982,12 @@ var_expanding_visitor::visit_defined_op (defined_op* e)
     else if (foo2 && foo2->probe_context_var != "") // successful
       resolved = true;
     else if (foo2) // unresolved but not marked either way
-      assert (0); // should not happen
+      {
+        // it might be resolved by some other pass
+        e->operand = foo2;
+        provide (e);
+        return;
+      }
     else // resolved, rewritten to some other expression type
       resolved = true;
   } catch (const semantic_error& e) { 
diff --git a/testsuite/semok/thirtysix.stp b/testsuite/semok/thirtysix.stp
index e31a51ce..5965a7df 100755
--- a/testsuite/semok/thirtysix.stp
+++ b/testsuite/semok/thirtysix.stp
@@ -19,3 +19,16 @@ probe process("stap").syscall { println(@defined($argZZ)?$argZZ:0) } # invalid
 probe process("stap").syscall.return { println(@defined($nosuchvar)?$nosuchvar:0) } # invalid
 probe process("stap").syscall.return { println(@defined($syscall)?$syscall:0) } # valid
 %)
+
+probe begin,end,error,never { println(@defined($nosuchvar)?$nosuchvar:0) } # invalid
+probe timer.s(1),timer.jiffies(1) { println(@defined($nosuchvar)?$nosuchvar:0) } # invalid
+probe timer.profile { println(@defined($nosuchvar)?$nosuchvar:0) } # invalid
+
+probe begin { println(@defined(@cast(0, "task_struct")->foo)?$nosuchvar:0) } # invalid
+probe begin { println(@defined(@cast(0, "task_struct")->pid)?1:0) } # valid
+probe kernel.function("sys_open") { println(@defined(@cast(0, "task_struct")->foo)?$nosuchvar:0) } # invalid
+probe kernel.function("sys_open") { println(@defined(@cast(0, "task_struct")->pid)?1:0) } # valid
+
+function foo1() { println(@defined(@cast(0, "task_struct")->foo)?$nosuchvar:0) } # invalid
+function foo2() { println(@defined(@cast(0, "task_struct")->pid)?1:0) } # valid
+probe begin { foo1(); foo2(); }