commit d6338c94e5574b63469c740159d064e89c6718bf
author Cherry Zhang <cherryyz@google.com> Fri Jul 13 11:22:56 2018 -0400
committer Ian Lance Taylor <iant@golang.org> Tue Jul 17 17:20:32 2018 +0000
tree 691493f8a9f97d83b6aaa0d0e432273955973f55
parent db991403fc97854201b3f40492f4f6b9d471cabc

compiler: connect the concrete type and the placeholder for circular types

Previously, when creating the backend representation of a
circular type, we resolve the placeholder to a
circular_pointer_type. The backend doesn't know what the
concrete type is.

This CL changes it to resolve the placeholder to the concrete
type instead, so the backend may have better knowledge of the
concrete type.

Change-Id: I8fe458b71b6d4ac5f22d2f5e823c0af4f0320cb9
Reviewed-on: https://go-review.googlesource.com/123738
Reviewed-by: Ian Lance Taylor <iant@golang.org>

go/types.cc

diff --git a/go/types.cc b/go/types.cc
index 07819e2..fa8c0ad 100644
--- a/go/types.cc
+++ b/go/types.cc
@@ -10786,15 +10786,10 @@
       // Don't build a circular data structure.  GENERIC can't handle
       // it.
       if (this->seen_in_get_backend_)
-	{
-	  this->is_circular_ = true;
-	  return gogo->backend()->circular_pointer_type(bt, true);
-	}
+        return gogo->backend()->circular_pointer_type(bt, true);
       this->seen_in_get_backend_ = true;
       bt1 = Type::get_named_base_btype(gogo, base);
       this->seen_in_get_backend_ = false;
-      if (this->is_circular_)
-	bt1 = gogo->backend()->circular_pointer_type(bt, true);
       if (!gogo->backend()->set_placeholder_pointer_type(bt, bt1))
 	bt = gogo->backend()->error_type();
       return bt;
@@ -10803,15 +10798,10 @@
       // Don't build a circular data structure. GENERIC can't handle
       // it.
       if (this->seen_in_get_backend_)
-	{
-	  this->is_circular_ = true;
-	  return gogo->backend()->circular_pointer_type(bt, false);
-	}
+        return gogo->backend()->circular_pointer_type(bt, false);
       this->seen_in_get_backend_ = true;
       bt1 = Type::get_named_base_btype(gogo, base);
       this->seen_in_get_backend_ = false;
-      if (this->is_circular_)
-	bt1 = gogo->backend()->circular_pointer_type(bt, false);
       if (!gogo->backend()->set_placeholder_pointer_type(bt, bt1))
 	bt = gogo->backend()->error_type();
       return bt;

go/types.h

diff --git a/go/types.h b/go/types.h
index 234e0a6..0f85c3a 100644
--- a/go/types.h
+++ b/go/types.h
@@ -3243,8 +3243,8 @@
       interface_method_tables_(NULL), pointer_interface_method_tables_(NULL),
       location_(location), named_btype_(NULL), dependencies_(),
       is_alias_(false), is_visible_(true), is_error_(false), in_heap_(true),
-      is_placeholder_(false), is_converted_(false), is_circular_(false),
-      is_verified_(false), seen_(false), seen_in_compare_is_identity_(false),
+      is_placeholder_(false), is_converted_(false), is_verified_(false),
+      seen_(false), seen_in_compare_is_identity_(false),
       seen_in_get_backend_(false), seen_alias_(false)
   { }
 
@@ -3345,12 +3345,6 @@
   is_valid() const
   { return !this->is_error_; }
 
-  // Whether this is a circular type: a pointer or function type that
-  // refers to itself, which is not possible in C.
-  bool
-  is_circular() const
-  { return this->is_circular_; }
-
   // Return the base type for this type.
   Type*
   named_base();
@@ -3557,9 +3551,6 @@
   // Whether this type has been converted to the backend
   // representation.  Implies that is_placeholder_ is false.
   bool is_converted_;
-  // Whether this is a pointer or function type which refers to the
-  // type itself.
-  bool is_circular_;
   // Whether this type has been verified.
   bool is_verified_;
   // In a recursive operation such as has_pointer, this flag is used