Add a new TypeBuilder helper class, which eases making LLVM IR types.

Patch by Jeffrey Yasskin!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70084 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 696 insertions, 0 deletions

diff --git a/include/llvm/Support/TypeBuilder.h b/include/llvm/Support/TypeBuilder.h
new file mode 100644
index 0000000000..df8bc5ea4b
--- /dev/null
+++ b/include/llvm/Support/TypeBuilder.h
@@ -0,0 +1,463 @@
+//===---- llvm/Support/TypeBuilder.h - Builder for LLVM types ---*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the TypeBuilder class, which is used as a convenient way to
+// create LLVM types with a consistent and simplified interface.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_TYPEBUILDER_H
+#define LLVM_SUPPORT_TYPEBUILDER_H
+
+#include "llvm/DerivedTypes.h"
+
+namespace llvm {
+
+/// TypeBuilder - This provides a uniform API for looking up types
+/// known at compile time.  To support cross-compilation, we define a
+/// series of tag types in the llvm::types namespace, like i<N>,
+/// ieee_float, ppc_fp128, etc.  TypeBuilder<T, false> allows T to be
+/// any of these, a native C type (whose size may depend on the host
+/// compiler), or a pointer, function, or struct type built out of
+/// these.  TypeBuilder<T, true> removes native C types from this set
+/// to guarantee that its result is suitable for cross-compilation.
+/// We define the primitive types, pointer types, and functions up to
+/// 5 arguments here, but to use this class with your own types,
+/// you'll need to specialize it.  For example, say you want to call a
+/// function defined externally as:
+///
+///   struct MyType {
+///     int32 a;
+///     int32 *b;
+///     void *array[1];  // Intended as a flexible array.
+///   };
+///   int8 AFunction(struct MyType *value);
+///
+/// You'll want to use
+///   Function::Create(TypeBuilder<types::i<8>(MyType*)>::get(), ...)
+/// to declare the function, but when you first try this, your compiler will
+/// complain that TypeBuilder<MyType>::get() doesn't exist. To fix this, write:
+///
+///   namespace llvm {
+///   using types::i;
+///   template<bool xcompile> class TypeBuilder<MyType, xcompile> {
+///   public:
+///     static const StructType *get() {
+///       // Using the static result variable ensures that the type is
+///       // only looked up once.
+///       static const StructType *const result = StructType::get(
+///         TypeBuilder<i<32>, xcompile>::get(),
+///         TypeBuilder<i<32>*, xcompile>::get(),
+///         TypeBuilder<i<8>*[], xcompile>::get(),
+///         NULL);
+///       return result;
+///     }
+///
+///     // You may find this a convenient place to put some constants
+///     // to help with getelementptr.  They don't have any effect on
+///     // the operation of TypeBuilder.
+///     enum Fields {
+///       FIELD_A,
+///       FIELD_B,
+///       FIELD_ARRAY
+///     };
+///   }
+///   }  // namespace llvm
+///
+/// Using the static result variable ensures that the type is only looked up
+/// once.
+///
+/// TypeBuilder cannot handle recursive types or types you only know at runtime.
+/// If you try to give it a recursive type, it will deadlock, infinitely
+/// recurse, or throw a recursive_init exception.
+template<typename T, bool cross_compilable> class TypeBuilder {};
+
+// Types for use with cross-compilable TypeBuilders.  These correspond
+// exactly with an LLVM-native type.
+namespace types {
+/// i<N> corresponds to the LLVM IntegerType with N bits.
+template<uint32_t num_bits> class i {};
+
+// The following classes represent the LLVM floating types.
+class ieee_float {};
+class ieee_double {};
+class x86_fp80 {};
+class fp128 {};
+class ppc_fp128 {};
+}  // namespace types
+
+// LLVM doesn't have const or volatile types.
+template<typename T, bool cross> class TypeBuilder<const T, cross>
+  : public TypeBuilder<T, cross> {};
+template<typename T, bool cross> class TypeBuilder<volatile T, cross>
+  : public TypeBuilder<T, cross> {};
+template<typename T, bool cross> class TypeBuilder<const volatile T, cross>
+  : public TypeBuilder<T, cross> {};
+
+// Pointers
+template<typename T, bool cross> class TypeBuilder<T*, cross> {
+public:
+  static const PointerType *get() {
+    static const PointerType *const result =
+      PointerType::getUnqual(TypeBuilder<T,cross>::get());
+    return result;
+  }
+};
+
+/// There is no support for references
+template<typename T, bool cross> class TypeBuilder<T&, cross> {};
+
+// Arrays
+template<typename T, size_t N, bool cross> class TypeBuilder<T[N], cross> {
+public:
+  static const ArrayType *get() {
+    static const ArrayType *const result =
+      ArrayType::get(TypeBuilder<T, cross>::get(), N);
+    return result;
+  }
+};
+/// LLVM uses an array of length 0 to represent an unknown-length array.
+template<typename T, bool cross> class TypeBuilder<T[], cross> {
+public:
+  static const ArrayType *get() {
+    static const ArrayType *const result =
+      ArrayType::get(TypeBuilder<T, cross>::get(), 0);
+    return result;
+  }
+};
+
+// Define the C integral types only for TypeBuilder<T, false>.
+//
+// C integral types do not have a defined size. It would be nice to use the
+// stdint.h-defined typedefs that do have defined sizes, but we'd run into the
+// following problem:
+//
+// On an ILP32 machine, stdint.h might define:
+//
+//   typedef int int32_t;
+//   typedef long long int64_t;
+//   typedef long size_t;
+//
+// If we defined TypeBuilder<int32_t> and TypeBuilder<int64_t>, then any use of
+// TypeBuilder<size_t> would fail.  We couldn't define TypeBuilder<size_t> in
+// addition to the defined-size types because we'd get duplicate definitions on
+// platforms where stdint.h instead defines:
+//
+//   typedef int int32_t;
+//   typedef long long int64_t;
+//   typedef int size_t;
+//
+// So we define all the primitive C types and nothing else.
+#define DEFINE_INTEGRAL_TYPEBUILDER(T) \
+template<> class TypeBuilder<T, false> { \
+public: \
+  static const IntegerType *get() { \
+    static const IntegerType *const result = \
+      IntegerType::get(sizeof(T) * CHAR_BIT); \
+    return result; \
+  } \
+}; \
+template<> class TypeBuilder<T, true> { \
+  /* We provide a definition here so users don't accidentally */ \
+  /* define these types to work. */ \
+}
+DEFINE_INTEGRAL_TYPEBUILDER(char);
+DEFINE_INTEGRAL_TYPEBUILDER(signed char);
+DEFINE_INTEGRAL_TYPEBUILDER(unsigned char);
+DEFINE_INTEGRAL_TYPEBUILDER(short);
+DEFINE_INTEGRAL_TYPEBUILDER(unsigned short);
+DEFINE_INTEGRAL_TYPEBUILDER(int);
+DEFINE_INTEGRAL_TYPEBUILDER(unsigned int);
+DEFINE_INTEGRAL_TYPEBUILDER(long);
+DEFINE_INTEGRAL_TYPEBUILDER(unsigned long);
+#ifdef _MSC_VER
+DEFINE_INTEGRAL_TYPEBUILDER(__int64);
+DEFINE_INTEGRAL_TYPEBUILDER(unsigned __int64);
+#else /* _MSC_VER */
+DEFINE_INTEGRAL_TYPEBUILDER(long long);
+DEFINE_INTEGRAL_TYPEBUILDER(unsigned long long);
+#endif /* _MSC_VER */
+#undef DEFINE_INTEGRAL_TYPEBUILDER
+
+template<uint32_t num_bits, bool cross>
+class TypeBuilder<types::i<num_bits>, cross> {
+public:
+  static const IntegerType *get() {
+    static const IntegerType *const result = IntegerType::get(num_bits);
+    return result;
+  }
+};
+
+template<> class TypeBuilder<float, false> {
+public:
+  static const Type *get() {
+    return Type::FloatTy;
+  }
+};
+template<> class TypeBuilder<float, true> {};
+
+template<> class TypeBuilder<double, false> {
+public:
+  static const Type *get() {
+    return Type::DoubleTy;
+  }
+};
+template<> class TypeBuilder<double, true> {};
+
+template<bool cross> class TypeBuilder<types::ieee_float, cross> {
+public:
+  static const Type *get() { return Type::FloatTy; }
+};
+template<bool cross> class TypeBuilder<types::ieee_double, cross> {
+public:
+  static const Type *get() { return Type::DoubleTy; }
+};
+template<bool cross> class TypeBuilder<types::x86_fp80, cross> {
+public:
+  static const Type *get() { return Type::X86_FP80Ty; }
+};
+template<bool cross> class TypeBuilder<types::fp128, cross> {
+public:
+  static const Type *get() { return Type::FP128Ty; }
+};
+template<bool cross> class TypeBuilder<types::ppc_fp128, cross> {
+public:
+  static const Type *get() { return Type::PPC_FP128Ty; }
+};
+
+template<bool cross> class TypeBuilder<void, cross> {
+public:
+  static const Type *get() {
+    return Type::VoidTy;
+  }
+};
+
+/// void* is disallowed in LLVM types, but it occurs often enough in C code that
+/// we special case it.
+template<> class TypeBuilder<void*, false>
+  : public TypeBuilder<types::i<8>*, false> {};
+
+template<typename R, bool cross> class TypeBuilder<R(), cross> {
+public:
+  static const FunctionType *get() {
+    static const FunctionType *const result = create();
+    return result;
+  }
+
+private:
+  static const FunctionType *create() {
+    std::vector<const Type*> params;
+    return FunctionType::get(TypeBuilder<R, cross>::get(), params, false);
+  }
+};
+template<typename R, typename A1, bool cross> class TypeBuilder<R(A1), cross> {
+public:
+  static const FunctionType *get() {
+    static const FunctionType *const result = create();
+    return result;
+  }
+
+private:
+  static const FunctionType *create() {
+    std::vector<const Type*> params;
+    params.reserve(1);
+    params.push_back(TypeBuilder<A1, cross>::get());
+    return FunctionType::get(TypeBuilder<R, cross>::get(), params, false);
+  }
+};
+template<typename R, typename A1, typename A2, bool cross>
+class TypeBuilder<R(A1, A2), cross> {
+public:
+  static const FunctionType *get() {
+    static const FunctionType *const result = create();
+    return result;
+  }
+
+private:
+  static const FunctionType *create() {
+    std::vector<const Type*> params;
+    params.reserve(2);
+    params.push_back(TypeBuilder<A1, cross>::get());
+    params.push_back(TypeBuilder<A2, cross>::get());
+    return FunctionType::get(TypeBuilder<R, cross>::get(), params, false);
+  }
+};
+template<typename R, typename A1, typename A2, typename A3, bool cross>
+class TypeBuilder<R(A1, A2, A3), cross> {
+public:
+  static const FunctionType *get() {
+    static const FunctionType *const result = create();
+    return result;
+  }
+
+private:
+  static const FunctionType *create() {
+    std::vector<const Type*> params;
+    params.reserve(3);
+    params.push_back(TypeBuilder<A1, cross>::get());
+    params.push_back(TypeBuilder<A2, cross>::get());
+    params.push_back(TypeBuilder<A3, cross>::get());
+    return FunctionType::get(TypeBuilder<R, cross>::get(), params, false);
+  }
+};
+
+template<typename R, typename A1, typename A2, typename A3, typename A4,
+         bool cross>
+class TypeBuilder<R(A1, A2, A3, A4), cross> {
+public:
+  static const FunctionType *get() {
+    static const FunctionType *const result = create();
+    return result;
+  }
+
+private:
+  static const FunctionType *create() {
+    std::vector<const Type*> params;
+    params.reserve(4);
+    params.push_back(TypeBuilder<A1, cross>::get());
+    params.push_back(TypeBuilder<A2, cross>::get());
+    params.push_back(TypeBuilder<A3, cross>::get());
+    params.push_back(TypeBuilder<A4, cross>::get());
+    return FunctionType::get(TypeBuilder<R, cross>::get(), params, false);
+  }
+};
+
+template<typename R, typename A1, typename A2, typename A3, typename A4,
+         typename A5, bool cross>
+class TypeBuilder<R(A1, A2, A3, A4, A5), cross> {
+public:
+  static const FunctionType *get() {
+    static const FunctionType *const result = create();
+    return result;
+  }
+
+private:
+  static const FunctionType *create() {
+    std::vector<const Type*> params;
+    params.reserve(5);
+    params.push_back(TypeBuilder<A1, cross>::get());
+    params.push_back(TypeBuilder<A2, cross>::get());
+    params.push_back(TypeBuilder<A3, cross>::get());
+    params.push_back(TypeBuilder<A4, cross>::get());
+    params.push_back(TypeBuilder<A5, cross>::get());
+    return FunctionType::get(TypeBuilder<R, cross>::get(), params, false);
+  }
+};
+
+template<typename R, bool cross> class TypeBuilder<R(...), cross> {
+public:
+  static const FunctionType *get() {
+    static const FunctionType *const result = create();
+    return result;
+  }
+
+private:
+  static const FunctionType *create() {
+    std::vector<const Type*> params;
+    return FunctionType::get(TypeBuilder<R, cross>::get(), params, true);
+  }
+};
+template<typename R, typename A1, bool cross>
+class TypeBuilder<R(A1, ...), cross> {
+public:
+  static const FunctionType *get() {
+    static const FunctionType *const result = create();
+    return result;
+  }
+
+private:
+  static const FunctionType *create() {
+    std::vector<const Type*> params;
+    params.reserve(1);
+    params.push_back(TypeBuilder<A1, cross>::get());
+    return FunctionType::get(TypeBuilder<R, cross>::get(), params, true);
+  }
+};
+template<typename R, typename A1, typename A2, bool cross>
+class TypeBuilder<R(A1, A2, ...), cross> {
+public:
+  static const FunctionType *get() {
+    static const FunctionType *const result = create();
+    return result;
+  }
+
+private:
+  static const FunctionType *create() {
+    std::vector<const Type*> params;
+    params.reserve(2);
+    params.push_back(TypeBuilder<A1, cross>::get());
+    params.push_back(TypeBuilder<A2, cross>::get());
+    return FunctionType::get(TypeBuilder<R, cross>::get(), params, true);
+  }
+};
+template<typename R, typename A1, typename A2, typename A3, bool cross>
+class TypeBuilder<R(A1, A2, A3, ...), cross> {
+public:
+  static const FunctionType *get() {
+    static const FunctionType *const result = create();
+    return result;
+  }
+
+private:
+  static const FunctionType *create() {
+    std::vector<const Type*> params;
+    params.reserve(3);
+    params.push_back(TypeBuilder<A1, cross>::get());
+    params.push_back(TypeBuilder<A2, cross>::get());
+    params.push_back(TypeBuilder<A3, cross>::get());
+    return FunctionType::get(TypeBuilder<R, cross>::get(), params, true);
+  }
+};
+
+template<typename R, typename A1, typename A2, typename A3, typename A4,
+         bool cross>
+class TypeBuilder<R(A1, A2, A3, A4, ...), cross> {
+public:
+  static const FunctionType *get() {
+    static const FunctionType *const result = create();
+    return result;
+  }
+
+private:
+  static const FunctionType *create() {
+    std::vector<const Type*> params;
+    params.reserve(4);
+    params.push_back(TypeBuilder<A1, cross>::get());
+    params.push_back(TypeBuilder<A2, cross>::get());
+    params.push_back(TypeBuilder<A3, cross>::get());
+    params.push_back(TypeBuilder<A4, cross>::get());
+    return FunctionType::get(TypeBuilder<R, cross>::get(), params, true);
+  }
+};
+
+template<typename R, typename A1, typename A2, typename A3, typename A4,
+         typename A5, bool cross>
+class TypeBuilder<R(A1, A2, A3, A4, A5, ...), cross> {
+public:
+  static const FunctionType *get() {
+    static const FunctionType *const result = create();
+    return result;
+  }
+
+private:
+  static const FunctionType *create() {
+    std::vector<const Type*> params;
+    params.reserve(5);
+    params.push_back(TypeBuilder<A1, cross>::get());
+    params.push_back(TypeBuilder<A2, cross>::get());
+    params.push_back(TypeBuilder<A3, cross>::get());
+    params.push_back(TypeBuilder<A4, cross>::get());
+    params.push_back(TypeBuilder<A5, cross>::get());
+    return FunctionType::get(TypeBuilder<R, cross>::get(), params, true);
+  }
+};
+
+}  // namespace llvm
+
+#endif
diff --git a/unittests/Support/TypeBuilderTest.cpp b/unittests/Support/TypeBuilderTest.cpp
new file mode 100644
index 0000000000..425ee6bf54
--- /dev/null
+++ b/unittests/Support/TypeBuilderTest.cpp
@@ -0,0 +1,233 @@
+//===- llvm/unittest/Support/TypeBuilderTest.cpp - TypeBuilder tests -----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/TypeBuilder.h"
+
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+TEST(TypeBuilderTest, Void) {
+  EXPECT_EQ(Type::VoidTy, (TypeBuilder<void, true>::get()));
+  EXPECT_EQ(Type::VoidTy, (TypeBuilder<void, false>::get()));
+  // Special case for C compatibility:
+  EXPECT_EQ(PointerType::getUnqual(Type::Int8Ty),
+            (TypeBuilder<void*, false>::get()));
+}
+
+TEST(TypeBuilderTest, HostIntegers) {
+  EXPECT_EQ(Type::Int8Ty, (TypeBuilder<int8_t, false>::get()));
+  EXPECT_EQ(Type::Int8Ty, (TypeBuilder<uint8_t, false>::get()));
+  EXPECT_EQ(Type::Int16Ty, (TypeBuilder<int16_t, false>::get()));
+  EXPECT_EQ(Type::Int16Ty, (TypeBuilder<uint16_t, false>::get()));
+  EXPECT_EQ(Type::Int32Ty, (TypeBuilder<int32_t, false>::get()));
+  EXPECT_EQ(Type::Int32Ty, (TypeBuilder<uint32_t, false>::get()));
+  EXPECT_EQ(Type::Int64Ty, (TypeBuilder<int64_t, false>::get()));
+  EXPECT_EQ(Type::Int64Ty, (TypeBuilder<uint64_t, false>::get()));
+
+  EXPECT_EQ(IntegerType::get(sizeof(size_t) * CHAR_BIT),
+            (TypeBuilder<size_t, false>::get()));
+  EXPECT_EQ(IntegerType::get(sizeof(ptrdiff_t) * CHAR_BIT),
+            (TypeBuilder<ptrdiff_t, false>::get()));
+}
+
+TEST(TypeBuilderTest, CrossCompilableIntegers) {
+  EXPECT_EQ(IntegerType::get(1), (TypeBuilder<types::i<1>, true>::get()));
+  EXPECT_EQ(IntegerType::get(1), (TypeBuilder<types::i<1>, false>::get()));
+  EXPECT_EQ(IntegerType::get(72), (TypeBuilder<types::i<72>, true>::get()));
+  EXPECT_EQ(IntegerType::get(72), (TypeBuilder<types::i<72>, false>::get()));
+}
+
+TEST(TypeBuilderTest, Float) {
+  EXPECT_EQ(Type::FloatTy, (TypeBuilder<float, false>::get()));
+  EXPECT_EQ(Type::DoubleTy, (TypeBuilder<double, false>::get()));
+  // long double isn't supported yet.
+  EXPECT_EQ(Type::FloatTy, (TypeBuilder<types::ieee_float, true>::get()));
+  EXPECT_EQ(Type::FloatTy, (TypeBuilder<types::ieee_float, false>::get()));
+  EXPECT_EQ(Type::DoubleTy, (TypeBuilder<types::ieee_double, true>::get()));
+  EXPECT_EQ(Type::DoubleTy, (TypeBuilder<types::ieee_double, false>::get()));
+  EXPECT_EQ(Type::X86_FP80Ty, (TypeBuilder<types::x86_fp80, true>::get()));
+  EXPECT_EQ(Type::X86_FP80Ty, (TypeBuilder<types::x86_fp80, false>::get()));
+  EXPECT_EQ(Type::FP128Ty, (TypeBuilder<types::fp128, true>::get()));
+  EXPECT_EQ(Type::FP128Ty, (TypeBuilder<types::fp128, false>::get()));
+  EXPECT_EQ(Type::PPC_FP128Ty, (TypeBuilder<types::ppc_fp128, true>::get()));
+  EXPECT_EQ(Type::PPC_FP128Ty, (TypeBuilder<types::ppc_fp128, false>::get()));
+}
+
+TEST(TypeBuilderTest, Derived) {
+  EXPECT_EQ(PointerType::getUnqual(PointerType::getUnqual(Type::Int8Ty)),
+            (TypeBuilder<int8_t**, false>::get()));
+  EXPECT_EQ(ArrayType::get(Type::Int8Ty, 7),
+            (TypeBuilder<int8_t[7], false>::get()));
+  EXPECT_EQ(ArrayType::get(Type::Int8Ty, 0),
+            (TypeBuilder<int8_t[], false>::get()));
+
+  EXPECT_EQ(PointerType::getUnqual(PointerType::getUnqual(Type::Int8Ty)),
+            (TypeBuilder<types::i<8>**, false>::get()));
+  EXPECT_EQ(ArrayType::get(Type::Int8Ty, 7),
+            (TypeBuilder<types::i<8>[7], false>::get()));
+  EXPECT_EQ(ArrayType::get(Type::Int8Ty, 0),
+            (TypeBuilder<types::i<8>[], false>::get()));
+
+  EXPECT_EQ(PointerType::getUnqual(PointerType::getUnqual(Type::Int8Ty)),
+            (TypeBuilder<types::i<8>**, true>::get()));
+  EXPECT_EQ(ArrayType::get(Type::Int8Ty, 7),
+            (TypeBuilder<types::i<8>[7], true>::get()));
+  EXPECT_EQ(ArrayType::get(Type::Int8Ty, 0),
+            (TypeBuilder<types::i<8>[], true>::get()));
+
+
+  EXPECT_EQ(Type::Int8Ty,
+            (TypeBuilder<const int8_t, false>::get()));
+  EXPECT_EQ(Type::Int8Ty,
+            (TypeBuilder<volatile int8_t, false>::get()));
+  EXPECT_EQ(Type::Int8Ty,
+            (TypeBuilder<const volatile int8_t, false>::get()));
+
+  EXPECT_EQ(Type::Int8Ty,
+            (TypeBuilder<const types::i<8>, false>::get()));
+  EXPECT_EQ(Type::Int8Ty,
+            (TypeBuilder<volatile types::i<8>, false>::get()));
+  EXPECT_EQ(Type::Int8Ty,
+            (TypeBuilder<const volatile types::i<8>, false>::get()));
+
+  EXPECT_EQ(Type::Int8Ty,
+            (TypeBuilder<const types::i<8>, true>::get()));
+  EXPECT_EQ(Type::Int8Ty,
+            (TypeBuilder<volatile types::i<8>, true>::get()));
+  EXPECT_EQ(Type::Int8Ty,
+            (TypeBuilder<const volatile types::i<8>, true>::get()));
+
+  EXPECT_EQ(PointerType::getUnqual(Type::Int8Ty),
+            (TypeBuilder<const volatile int8_t*const volatile, false>::get()));
+}
+
+TEST(TypeBuilderTest, Functions) {
+  std::vector<const Type*> params;
+  EXPECT_EQ(FunctionType::get(Type::VoidTy, params, false),
+            (TypeBuilder<void(), true>::get()));
+  EXPECT_EQ(FunctionType::get(Type::Int8Ty, params, true),
+            (TypeBuilder<int8_t(...), false>::get()));
+  params.push_back(TypeBuilder<int32_t*, false>::get());
+  EXPECT_EQ(FunctionType::get(Type::Int8Ty, params, false),
+            (TypeBuilder<int8_t(const int32_t*), false>::get()));
+  EXPECT_EQ(FunctionType::get(Type::Int8Ty, params, true),
+            (TypeBuilder<int8_t(const int32_t*, ...), false>::get()));
+  params.push_back(TypeBuilder<char*, false>::get());
+  EXPECT_EQ(FunctionType::get(Type::Int8Ty, params, false),
+            (TypeBuilder<int8_t(int32_t*, void*), false>::get()));
+  EXPECT_EQ(FunctionType::get(Type::Int8Ty, params, true),
+            (TypeBuilder<int8_t(int32_t*, char*, ...), false>::get()));
+  params.push_back(TypeBuilder<char, false>::get());
+  EXPECT_EQ(FunctionType::get(Type::Int8Ty, params, false),
+            (TypeBuilder<int8_t(int32_t*, void*, char), false>::get()));
+  EXPECT_EQ(FunctionType::get(Type::Int8Ty, params, true),
+            (TypeBuilder<int8_t(int32_t*, char*, char, ...), false>::get()));
+  params.push_back(TypeBuilder<char, false>::get());
+  EXPECT_EQ(FunctionType::get(Type::Int8Ty, params, false),
+            (TypeBuilder<int8_t(int32_t*, void*, char, char), false>::get()));
+  EXPECT_EQ(FunctionType::get(Type::Int8Ty, params, true),
+            (TypeBuilder<int8_t(int32_t*, char*, char, char, ...),
+                         false>::get()));
+  params.push_back(TypeBuilder<char, false>::get());
+  EXPECT_EQ(FunctionType::get(Type::Int8Ty, params, false),
+            (TypeBuilder<int8_t(int32_t*, void*, char, char, char),
+                         false>::get()));
+  EXPECT_EQ(FunctionType::get(Type::Int8Ty, params, true),
+            (TypeBuilder<int8_t(int32_t*, char*, char, char, char, ...),
+                         false>::get()));
+}
+
+class MyType {
+  int a;
+  int *b;
+  void *array[1];
+};
+
+class MyPortableType {
+  int32_t a;
+  int32_t *b;
+  void *array[1];
+};
+
+}  // anonymous namespace
+
+namespace llvm {
+template<bool cross> class TypeBuilder<MyType, cross> {
+public:
+  static const StructType *get() {
+    // Using the static result variable ensures that the type is
+    // only looked up once.
+    static const StructType *const result = StructType::get(
+      TypeBuilder<int, cross>::get(),
+      TypeBuilder<int*, cross>::get(),
+      TypeBuilder<void*[], cross>::get(),
+      NULL);
+    return result;
+  }
+
+  // You may find this a convenient place to put some constants
+  // to help with getelementptr.  They don't have any effect on
+  // the operation of TypeBuilder.
+  enum Fields {
+    FIELD_A,
+    FIELD_B,
+    FIELD_ARRAY
+  };
+};
+
+template<bool cross> class TypeBuilder<MyPortableType, cross> {
+public:
+  static const StructType *get() {
+    // Using the static result variable ensures that the type is
+    // only looked up once.
+    static const StructType *const result = StructType::get(
+      TypeBuilder<types::i<32>, cross>::get(),
+      TypeBuilder<types::i<32>*, cross>::get(),
+      TypeBuilder<types::i<8>*[], cross>::get(),
+      NULL);
+    return result;
+  }
+
+  // You may find this a convenient place to put some constants
+  // to help with getelementptr.  They don't have any effect on
+  // the operation of TypeBuilder.
+  enum Fields {
+    FIELD_A,
+    FIELD_B,
+    FIELD_ARRAY
+  };
+};
+}  // namespace llvm
+namespace {
+
+TEST(TypeBuilderTest, Extensions) {
+  EXPECT_EQ(PointerType::getUnqual(StructType::get(
+                                     TypeBuilder<int, false>::get(),
+                                     TypeBuilder<int*, false>::get(),
+                                     TypeBuilder<void*[], false>::get(),
+                                     NULL)),
+            (TypeBuilder<MyType*, false>::get()));
+  EXPECT_EQ(PointerType::getUnqual(StructType::get(
+                                     TypeBuilder<types::i<32>, false>::get(),
+                                     TypeBuilder<types::i<32>*, false>::get(),
+                                     TypeBuilder<types::i<8>*[], false>::get(),
+                                     NULL)),
+            (TypeBuilder<MyPortableType*, false>::get()));
+  EXPECT_EQ(PointerType::getUnqual(StructType::get(
+                                     TypeBuilder<types::i<32>, false>::get(),
+                                     TypeBuilder<types::i<32>*, false>::get(),
+                                     TypeBuilder<types::i<8>*[], false>::get(),
+                                     NULL)),
+            (TypeBuilder<MyPortableType*, true>::get()));
+}
+
+}  // anonymous namespace