compiler: Use backend interface for slice construction.

	* go-gcc.cc (Gcc_backend::implicit_variable): Rename from
	gc_root_variable.  Add name and is_constant parameters.

From-SVN: r210088

1 files changed, 15 insertions, 1 deletions

diff --git a/gcc/go/gofrontend/expressions.h b/gcc/go/gofrontend/expressions.h
index 0936e00..6f03e02 100644
--- a/gcc/go/gofrontend/expressions.h
+++ b/gcc/go/gofrontend/expressions.h
@@ -1305,7 +1305,7 @@ class Unary_expression : public Expression
   Unary_expression(Operator op, Expression* expr, Location location)
     : Expression(EXPRESSION_UNARY, location),
       op_(op), escapes_(true), create_temp_(false), is_gc_root_(false),
-      expr_(expr), issue_nil_check_(false)
+      is_slice_init_(false), expr_(expr), issue_nil_check_(false)
   { }
 
   // Return the operator.
@@ -1344,6 +1344,15 @@ class Unary_expression : public Expression
     this->is_gc_root_ = true;
   }
 
+  // Record that this is an address expression of a slice value initializer,
+  // which is mutable if the values are not copied to the heap.
+  void
+  set_is_slice_init()
+  {
+    go_assert(this->op_ == OPERATOR_AND);
+    this->is_slice_init_ = true;
+  }
+
   // Apply unary opcode OP to UNC, setting NC.  Return true if this
   // could be done, false if not.  Issue errors for overflow.
   static bool
@@ -1427,6 +1436,11 @@ class Unary_expression : public Expression
   // special struct composite literal that is mutable when addressed, meaning
   // it cannot be represented as an immutable_struct in the backend.
   bool is_gc_root_;
+  // True if this is an address expression for a slice value with an immutable
+  // initializer.  The initializer for a slice's value pointer has an array
+  // type, meaning it cannot be represented as an immutable_struct in the
+  // backend.
+  bool is_slice_init_;
   // The operand.
   Expression* expr_;
   // Whether or not to issue a nil check for this expression if its address