From 245e19e33a9ef0a1ec79f09c5948b219dde6f8c9 Mon Sep 17 00:00:00 2001
From: Martin Kinkelin <noone@nowhere.com>
Date: Fri, 6 Jul 2018 21:22:35 +0200
Subject: [PATCH] Add some support for classes without TypeInfos

For -betterC and/or a minimal object.d without TypeInfo:

* Skip TypeInfo emission for classes and interfaces.
* Emit null as first vtable member.

Makes dmd-testsuite's {compilable,runnable}/minimal2.d work.
---
 gen/classes.cpp           |  5 -----
 gen/declarations.cpp      | 25 ++++++++++++++-----------
 ir/irclass.cpp            | 30 ++++++++++++++++++++----------
 tests/baremetal/classes.d | 29 +++++++++++++++++++++++++++++
 tests/d2/dmd-testsuite    |  2 +-
 5 files changed, 64 insertions(+), 27 deletions(-)
 create mode 100644 tests/baremetal/classes.d

diff --git a/gen/classes.cpp b/gen/classes.cpp
index 6efe4406dcb..649731b7d4e 100644
--- a/gen/classes.cpp
+++ b/gen/classes.cpp
@@ -65,11 +65,6 @@ void DtoResolveClass(ClassDeclaration *cd) {
     getIrField(vd, true);
   }
 
-  // emit the interfaceInfosZ symbol if necessary
-  if (cd->vtblInterfaces && cd->vtblInterfaces->dim > 0) {
-    irAggr->getInterfaceArraySymbol(); // initializer is applied when it's built
-  }
-
   // interface only emit typeinfo and classinfo
   if (cd->isInterfaceDeclaration()) {
     irAggr->initializeInterface();
diff --git a/gen/declarations.cpp b/gen/declarations.cpp
index 1ca7af491fe..1c4abb6427f 100644
--- a/gen/declarations.cpp
+++ b/gen/declarations.cpp
@@ -89,14 +89,13 @@ class CodegenVisitor : public Visitor {
       }
 
       // Emit TypeInfo.
-      DtoTypeInfoOf(decl->type, /*base=*/false);
-
-      // Declare __InterfaceZ.
-      IrAggr *ir = getIrAggr(decl);
-      llvm::GlobalVariable *interfaceZ = ir->getClassInfoSymbol();
-      // Only define if not speculative.
-      if (!isSpeculativeType(decl->type)) {
-        defineGlobal(interfaceZ, ir->getClassInfoInit(), decl);
+      if (global.params.useTypeInfo && Type::dtypeinfo) {
+        IrAggr *ir = getIrAggr(decl);
+        llvm::GlobalVariable *interfaceZ = ir->getClassInfoSymbol();
+        // Only define if not speculative.
+        if (!isSpeculativeType(decl->type)) {
+          defineGlobal(interfaceZ, ir->getClassInfoInit(), decl);
+        }
       }
     }
   }
@@ -196,9 +195,13 @@ class CodegenVisitor : public Visitor {
 
       ir->defineInterfaceVtbls();
 
-      llvm::GlobalVariable *classZ = ir->getClassInfoSymbol();
-      if (!isSpeculativeType(decl->type)) {
-        defineGlobal(classZ, ir->getClassInfoInit(), decl);
+      // Emit TypeInfo.
+      if (global.params.useTypeInfo && Type::dtypeinfo) {
+        llvm::GlobalVariable *classZ = ir->getClassInfoSymbol();
+        // Only define if not speculative.
+        if (!isSpeculativeType(decl->type)) {
+          defineGlobal(classZ, ir->getClassInfoInit(), decl);
+        }
       }
     }
   }
diff --git a/ir/irclass.cpp b/ir/irclass.cpp
index 694a09bdd6d..75f70242748 100644
--- a/ir/irclass.cpp
+++ b/ir/irclass.cpp
@@ -164,8 +164,13 @@ LLConstant *IrAggr::getVtblInit() {
   // start with the classinfo
   llvm::Constant *c;
   if (!cd->isCPPclass()) {
-    c = getClassInfoSymbol();
-    c = DtoBitCast(c, voidPtrType);
+    if (global.params.useTypeInfo && Type::dtypeinfo) {
+      c = getClassInfoSymbol();
+      c = DtoBitCast(c, voidPtrType);
+    } else {
+      // use null if there are no TypeInfos
+      c = llvm::Constant::getNullValue(voidPtrType);
+    }
     constants.push_back(c);
   }
 
@@ -312,16 +317,21 @@ void IrAggr::defineInterfaceVtbl(BaseClass *b, bool new_instance,
   const auto voidPtrTy = getVoidPtrType();
 
   if (!b->sym->isCPPinterface()) { // skip interface info for CPP interfaces
-    // index into the interfaces array
-    llvm::Constant *idxs[2] = {DtoConstSize_t(0),
-                               DtoConstSize_t(interfaces_index)};
+    if (global.params.useTypeInfo && Type::dtypeinfo) {
+      // index into the interfaces array
+      llvm::Constant *idxs[2] = {DtoConstSize_t(0),
+                                 DtoConstSize_t(interfaces_index)};
 
-    llvm::GlobalVariable *interfaceInfosZ = getInterfaceArraySymbol();
-    llvm::Constant *c = llvm::ConstantExpr::getGetElementPtr(
-        isaPointer(interfaceInfosZ)->getElementType(),
-        interfaceInfosZ, idxs, true);
+      llvm::GlobalVariable *interfaceInfosZ = getInterfaceArraySymbol();
+      llvm::Constant *c = llvm::ConstantExpr::getGetElementPtr(
+          isaPointer(interfaceInfosZ)->getElementType(), interfaceInfosZ, idxs,
+          true);
 
-    constants.push_back(DtoBitCast(c, voidPtrTy));
+      constants.push_back(DtoBitCast(c, voidPtrTy));
+    } else {
+      // use null if there are no TypeInfos
+      constants.push_back(llvm::Constant::getNullValue(voidPtrTy));
+    }
   }
 
   // add virtual function pointers
diff --git a/tests/baremetal/classes.d b/tests/baremetal/classes.d
new file mode 100644
index 00000000000..bb673841b02
--- /dev/null
+++ b/tests/baremetal/classes.d
@@ -0,0 +1,29 @@
+// Use classes with virtual functions.
+
+// -betterC for C assert.
+// RUN: %ldc -betterC %baremetal_args -run %s
+
+class A
+{
+    int x;
+    bool isB() { return false; }
+}
+
+class B : A
+{
+    override bool isB() { return true; }
+}
+
+__gshared A a = new A();
+__gshared B b = new B();
+
+extern(C) int main()
+{
+    A obj = a;
+    assert(!obj.isB());
+
+    obj = b;
+    assert(obj.isB());
+
+    return 0;
+}
diff --git a/tests/d2/dmd-testsuite b/tests/d2/dmd-testsuite
index 977ef0696f7..a079cc80f4e 160000
--- a/tests/d2/dmd-testsuite
+++ b/tests/d2/dmd-testsuite
@@ -1 +1 @@
-Subproject commit 977ef0696f7941357385925c07617544c3527f4c
+Subproject commit a079cc80f4ebe3574fc50792d9c83b112dd08008