2006-04-24 Frank Ch. Eigler <fche@elastic.org>

	PR 2599.
	* elaborate.cxx (visit_assignment): Tolerate null current_expr.
	* testsuite/semok/optimize.stp: Add relevant tests.

3 files changed, 18 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 3bea623f..968abc24 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2006-04-24  Frank Ch. Eigler  <fche@elastic.org>
+
+	PR 2599.
+	* elaborate.cxx (visit_assignment): Tolerate null current_expr.
+	* testsuite/semok/optimize.stp: Add relevant tests.
+
 2006-04-23  Eugene Teo  <eteo@redhat.com>
 
 	PR 2149
diff --git a/elaborate.cxx b/elaborate.cxx
index 3db165d4..61e63cb1 100644
--- a/elaborate.cxx
+++ b/elaborate.cxx
@@ -1306,7 +1306,10 @@ struct dead_assignment_remover: public traversing_visitor
     session(s), relaxed_p(r), vut(v), current_expr(0) {}
 
   void visit_expr_statement (expr_statement* s);
-  // XXX: and other places where an assignment may be nested
+  // XXX: other places where an assignment may be nested should be
+  // handled too (e.g., loop/if conditionals, array indexes, function
+  // parameters).  Until then, they result in visit_assignment() being
+  // called with null current_expr.
 
   void visit_assignment (assignment* e);
 };
@@ -1328,7 +1331,9 @@ dead_assignment_remover::visit_assignment (assignment* e)
 {
   symbol* left = get_symbol_within_expression (e->left);
   vardecl* leftvar = left->referent;
-  if (*current_expr == e) // we're not nested any deeper than expected 
+  if (current_expr && // see XXX above: this case represents a missed
+                      // optimization opportunity
+      *current_expr == e) // we're not nested any deeper than expected 
     {
       // clog << "Checking assignment to " << leftvar->name << " at " << *e->tok << endl;
       if (vut.read.find(leftvar) == vut.read.end()) // var never read?
diff --git a/testsuite/semok/optimize.stp b/testsuite/semok/optimize.stp
index 28ccb46c..bcf8ac04 100755
--- a/testsuite/semok/optimize.stp
+++ b/testsuite/semok/optimize.stp
@@ -16,3 +16,8 @@ probe begin {
   b = "goodbye"
   no . $such . $target + $variable
 }
+
+# bug #2599
+probe begin{for(i=1;i-=2;i++);}
+probe begin{while(i+=2);}
+probe begin{if(i=j);}