From 041e8e8b54ef5fa7e5b7f287fcd292e8c6d3935a Mon Sep 17 00:00:00 2001
From: David Nadlinger <code@klickverbot.at>
Date: Fri, 14 Jun 2013 21:49:44 +0200
Subject: [PATCH] Remove LDC-specific .classinfo AST rewrite.

Apart from reducing the diff to upstream DMD, this also fixes a
"cannot interpret" CTFE issue.
---
 dmd2/mtype.c | 43 +------------------------------------------
 gen/toir.cpp | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+), 42 deletions(-)

diff --git a/dmd2/mtype.c b/dmd2/mtype.c
index fdfebafd..eefbaa30 100644
--- a/dmd2/mtype.c
+++ b/dmd2/mtype.c
@@ -8703,47 +8703,9 @@ L1:
                 e->type = t;    // do this so we don't get redundant dereference
             }
             else
-            {
-                /* For class objects, the classinfo reference is the first
+            {   /* For class objects, the classinfo reference is the first
                  * entry in the vtbl[]
                  */
-#if IN_LLVM
-
-                Type* ct;
-                if (sym->isInterfaceDeclaration()) {
-                    ct = t->pointerTo()->pointerTo()->pointerTo();
-                }
-                else {
-                    ct = t->pointerTo()->pointerTo();
-                }
-
-                e = e->castTo(sc, ct);
-                e = new PtrExp(e->loc, e);
-                e->type = ct->nextOf();
-                e = new PtrExp(e->loc, e);
-                e->type = ct->nextOf()->nextOf();
-
-                if (sym->isInterfaceDeclaration())
-                {
-                    if (sym->isCOMinterface())
-                    {   /* COM interface vtbl[]s are different in that the
-                         * first entry is always pointer to QueryInterface().
-                         * We can't get a .classinfo for it.
-                         */
-                        error(e->loc, "no .classinfo for COM interface objects");
-                    }
-                    /* For an interface, the first entry in the vtbl[]
-                     * is actually a pointer to an instance of struct Interface.
-                     * The first member of Interface is the .classinfo,
-                     * so add an extra pointer indirection.
-                     */
-                    e = new PtrExp(e->loc, e);
-                    e->type = ct->nextOf()->nextOf()->nextOf();
-                }
-            }
-
-#else
-
                 e = new PtrExp(e->loc, e);
                 e->type = t->pointerTo();
                 if (sym->isInterfaceDeclaration())
@@ -8767,9 +8729,6 @@ L1:
                 }
                 e = new PtrExp(e->loc, e, t);
             }
-
-#endif // !LDC
-
             return e;
         }
 
diff --git a/gen/toir.cpp b/gen/toir.cpp
index 2ac4cbff..57e3615e 100644
--- a/gen/toir.cpp
+++ b/gen/toir.cpp
@@ -1333,6 +1333,30 @@ DValue* PtrExp::toElem(IRState* p)
     {
         V = e1->toElem(p)->getRVal();
     }
+
+    // The frontend emits dereferences of class/interfaces types to access the
+    // first member, which is the .classinfo property.
+    Type* origType = e1->type->toBasetype();
+    if (origType->ty == Tclass)
+    {
+        TypeClass* ct = static_cast<TypeClass*>(origType);
+
+        Type* resultType;
+        if (ct->sym->isInterfaceDeclaration())
+        {
+            // For interfaces, the first entry in the vtbl is actually a pointer
+            // to an Interface instance, which has the type info as its first
+            // member, so we have to add an extra layer of indirection.
+            resultType = Type::typeinfointerface->type->pointerTo();
+        }
+        else
+        {
+            resultType = Type::typeinfointerface->type;
+        }
+
+        V = DtoBitCast(V, DtoType(resultType->pointerTo()->pointerTo()));
+    }
+
     return new DVarValue(type, V);
 }