escape: Avoid allocation of varargs parameter.

    
    There was a bug in the escape analysis that would cause
    the slice implicitly created to hold varargs parameters to always
    escape, as well as the appended to slice argument.  The intended
    behavior was that the elements of the appendee and appended to
    slice would escape to the heap.  Alongside of these issues,
    the varargs slice would also have a chance to be initialized to an
    invalid memory location if it were stack-allocated.  This has been
    fixed as well.
    
    Reviewed-on: https://go-review.googlesource.com/30450


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@240826 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 31 insertions, 1 deletions

diff --git a/gcc/go/gofrontend/escape.cc b/gcc/go/gofrontend/escape.cc
index 1c810769d22..ba82d8055d4 100644
--- a/gcc/go/gofrontend/escape.cc
+++ b/gcc/go/gofrontend/escape.cc
@@ -1215,7 +1215,7 @@ Escape_analysis_assign::expression(Expression** pexpr)
 			     "special treatment of append(slice1, slice2...)");
 
 		  // The content of the original slice leaks as well.
-		  Node* appendee = Node::make_node(call->args()->back());
+		  Node* appendee = Node::make_node(call->args()->front());
 		  this->assign_deref(this->context_->sink(), appendee);
 		}
 		break;
@@ -2088,6 +2088,36 @@ Escape_analysis_assign::assign_deref(Node* dst, Node* src)
 	  // or numeric constants.
 	  return;
 
+	case Expression::EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
+	case Expression::EXPRESSION_SLICE_CONSTRUCTION:
+	case Expression::EXPRESSION_STRUCT_CONSTRUCTION:
+	  {
+	    // Dereferencing an array, slice, or struct is like accessing each
+	    // of its values.  In this situation, we model the flow from src to
+	    // dst where src is one of the above as a flow from each of src's
+	    // values to dst.
+	    Expression* e = src->expr();
+	    Expression_list* vals = NULL;
+	    if (e->slice_literal() != NULL)
+	      vals = e->slice_literal()->vals();
+	    else if (e->array_literal() != NULL)
+	      vals = e->array_literal()->vals();
+	    else
+	      vals = e->struct_literal()->vals();
+
+	    if (vals != NULL)
+	      {
+		for (Expression_list::const_iterator p = vals->begin();
+		     p != vals->end();
+		     ++p)
+		  {
+		    if ((*p) != NULL)
+		      this->assign(dst, Node::make_node(*p));
+		  }
+	      }
+	  }
+	  return;
+
 	default:
 	  break;
         }