From c238a79a97ad35227a28acf16028ab63127c2fb7 Mon Sep 17 00:00:00 2001
From: Fariborz Jahanian <fjahanian@apple.com>
Date: Thu, 30 Jul 2009 00:10:25 +0000
Subject: [PATCH] ir-gen for nested non-virtual base member access in current
 class.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@77554 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/CGCXX.cpp                         | 52 +++++++++++++++++--
 test/CodeGenCXX/nested-base-member-access.cpp | 51 ++++++++++++++++++
 2 files changed, 98 insertions(+), 5 deletions(-)
 create mode 100644 test/CodeGenCXX/nested-base-member-access.cpp

diff --git a/lib/CodeGen/CGCXX.cpp b/lib/CodeGen/CGCXX.cpp
index f80956b93f..bce22e5ec3 100644
--- a/lib/CodeGen/CGCXX.cpp
+++ b/lib/CodeGen/CGCXX.cpp
@@ -155,19 +155,61 @@ llvm::Value *CodeGenFunction::LoadCXXThis() {
   return Builder.CreateLoad(LocalDeclMap[CXXThisDecl], "this");
 }
 
+static bool
+GetNestedPaths(llvm::SmallVectorImpl<const CXXRecordDecl *> &NestedBasePaths,
+               const CXXRecordDecl *ClassDecl,
+               const CXXRecordDecl *BaseClassDecl) {
+  assert(!ClassDecl->isPolymorphic() && 
+         "FIXME: We don't support polymorphic classes yet!");
+  for (CXXRecordDecl::base_class_const_iterator i = ClassDecl->bases_begin(),
+      e = ClassDecl->bases_end(); i != e; ++i) {
+    if (i->isVirtual())
+      continue;
+    const CXXRecordDecl *Base = 
+        cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
+    if (Base == BaseClassDecl) {
+      NestedBasePaths.push_back(BaseClassDecl);
+      return true;
+    }
+  }
+  // BaseClassDecl not an immediate base of ClassDecl.
+  for (CXXRecordDecl::base_class_const_iterator i = ClassDecl->bases_begin(),
+       e = ClassDecl->bases_end(); i != e; ++i) {
+    if (i->isVirtual())
+      continue;
+    const CXXRecordDecl *Base = 
+      cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
+    if (GetNestedPaths(NestedBasePaths, Base, BaseClassDecl)) {
+      NestedBasePaths.push_back(Base);
+      return true;
+    }
+  }
+  return false;
+}
+
 llvm::Value *CodeGenFunction::AddressCXXOfBaseClass(llvm::Value *BaseValue,
                                           const CXXRecordDecl *ClassDecl, 
                                           const CXXRecordDecl *BaseClassDecl) {
   if (ClassDecl == BaseClassDecl)
     return BaseValue;
   
+  llvm::Type *I8Ptr = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
+  llvm::SmallVector<const CXXRecordDecl *, 16> NestedBasePaths;
+  GetNestedPaths(NestedBasePaths, ClassDecl, BaseClassDecl);
+  assert(NestedBasePaths.size() > 0 && 
+         "AddressCXXOfBaseClass - inheritence path failed");
+  NestedBasePaths.push_back(ClassDecl);
+  uint64_t Offset = 0;
+  
   // Accessing a member of the base class. Must add delata to
   // the load of 'this'.
-  // FIXME. Once type layout is complete, this will probably change.
-  const ASTRecordLayout &Layout = 
-  getContext().getASTRecordLayout(ClassDecl);
-  llvm::Type *I8Ptr = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
-  uint64_t Offset = Layout.getBaseClassOffset(BaseClassDecl) / 8;
+  for (unsigned i = NestedBasePaths.size()-1; i > 0; i--) {
+    const CXXRecordDecl *DerivedClass = NestedBasePaths[i];
+    const CXXRecordDecl *BaseClass = NestedBasePaths[i-1];
+    const ASTRecordLayout &Layout = 
+      getContext().getASTRecordLayout(DerivedClass);
+    Offset += Layout.getBaseClassOffset(BaseClass) / 8;
+  }
   llvm::Value *OffsetVal = 
     llvm::ConstantInt::get(
                   CGM.getTypes().ConvertType(CGM.getContext().LongTy), Offset);
diff --git a/test/CodeGenCXX/nested-base-member-access.cpp b/test/CodeGenCXX/nested-base-member-access.cpp
new file mode 100644
index 0000000000..aee7a12232
--- /dev/null
+++ b/test/CodeGenCXX/nested-base-member-access.cpp
@@ -0,0 +1,51 @@
+// RUN: clang-cc %s -emit-llvm -o %t
+
+extern "C" int printf(...);
+
+struct M {
+  M(int i){ iM = i; }
+  int iM;
+  void MPR() { printf("iM = %d\n", iM); }
+
+};
+
+struct Q {
+  Q(int i){ iQ = i; }
+  int iQ;
+  void QPR() { printf("iQ = %d\n", iQ); }
+};
+
+struct IQ {
+  IQ(int i) { iIQ = i; }
+  void IQPR() { printf("iIQ = %d\n", iIQ); }
+  int iIQ;
+};
+
+struct L : IQ {
+  L(int i) : IQ(i+100) { iL = i; }
+  int iL;
+};
+
+struct P : Q, L  {
+  P(int i) : Q(i+100), L(i+200) { iP = i; }
+  int iP;
+  void PPR() { printf("iP = %d\n", iP); }
+};
+
+
+struct N : M,P {
+  N() : M(100), P(200) {}
+  void PR() { this->MPR(); this->PPR(); this->QPR(); 
+	      IQPR();
+	      printf("iM = %d\n", iM); 
+	      printf("iP = %d\n", iP);
+ 	      printf("iQ = %d\n", iQ);
+ 	      printf("iL = %d\n", iL);
+ 	      printf("iIQ = %d\n", iIQ);
+	      }
+};
+
+int main() {
+  N n1;
+  n1.PR();
+}
-- 
2.40.0