2007-03-28 David Smith <dsmith@redhat.com>

        PR 2341 (partial fix)
        * elaborate.h (struct derived_probe): Added needs_global_locks()
        member function.  Unless overridden, will return true indicating
        that this probe needs locks around global variable references.
        * tapsets.cxx (struct be_derived_probe): Added override of default
        needs_global_locks() returning false.  begin/end probes don't
        need locks around global variables, since they aren't run
        concurrently with any other probes.
        * translate.cxx (c_unparser::emit_common_header): Updated
        probe_contents logic to match the logic in emit_probe.
        (c_unparser::emit_probe): Added whether the probe needs global
        variable locks to the probe string (that helps eliminate duplicate
        probes).  The generated C changes based on whether or not global
        variable locks are needed, but the pass 2 output doesn't differ
        between a probe that needs global variable locks and one that
        doesn't.  If the probe doesn't need global variable locks, doesn't
        output them.

1 files changed, 12 insertions, 3 deletions

diff --git a/translate.cxx b/translate.cxx
index e656c5ee..b7c21032 100644
--- a/translate.cxx
+++ b/translate.cxx
@@ -845,6 +845,7 @@ c_unparser::emit_common_header ()
       ostringstream oss;
       oss << "c->statp = & time_" << dp->basest()->name << ";" << endl;  // -t anti-dupe
       dp->body->print(oss);
+      oss << "# needs_global_locks: " << dp->needs_global_locks () << endl;
 
       if (tmp_probe_contents.count(oss.str()) == 0) // unique
         {
@@ -1357,6 +1358,10 @@ c_unparser::emit_probe (derived_probe* v)
 
   v->body->print(oss);
 
+  // Since the generated C changes based on whether or not the probe
+  // needs locks around global variables, this needs to be reflected
+  // in the probe string.
+  oss << "# needs_global_locks: " << v->needs_global_locks () << endl;
 
   // If an identical probe has already been emitted, just call that
   // one.
@@ -1415,8 +1420,11 @@ c_unparser::emit_probe (derived_probe* v)
 
       // emit all read/write locks for global variables
       varuse_collecting_visitor vut;
-      v->body->visit (& vut);
-      emit_locks (vut);
+      if (v->needs_global_locks ())
+        {
+	  v->body->visit (& vut);
+	  emit_locks (vut);
+	}
 
       // initialize locals
       for (unsigned j=0; j<v->locals.size(); j++)
@@ -1443,7 +1451,8 @@ c_unparser::emit_probe (derived_probe* v)
       // included a print/printf/etc. routine!
       o->newline(1) << "_stp_print_flush();";
 
-      emit_unlocks (vut);
+      if (v->needs_global_locks ())
+	emit_unlocks (vut);
 
       o->newline(-1) << "}\n";
     }