[MS-ABI] Implement dynamic_cast

This patch implements call lower from dynamic_cast to __RTDynamicCast 
and __RTCastToVoid.  Test cases are included.  A feature of note is that 
helper function getPolymorphicOffset is placed in such a way that it can 
be used by EmitTypeid (to be implemented in a later patch) without being 
moved.  Details are included as comments directly in the code.

llvm-svn: 210377

1 files changed, 157 insertions, 0 deletions

diff --git a/clang/test/CodeGenCXX/microsoft-abi-dynamic-cast.cpp b/clang/test/CodeGenCXX/microsoft-abi-dynamic-cast.cpp
new file mode 100644
index 00000000000..9fceaae9fc8
--- /dev/null
+++ b/clang/test/CodeGenCXX/microsoft-abi-dynamic-cast.cpp
@@ -0,0 +1,157 @@
+// RUN: %clang_cc1 -emit-llvm -O2 -optzns -o - -triple=i386-pc-win32 2>/dev/null %s | FileCheck %s
+
+struct S { char a; };
+struct V { virtual void f(){} };
+struct A : virtual V {};
+struct B : S, virtual V {};
+struct T {};
+
+T* test0() { return dynamic_cast<T*>((B*)0); }
+// CHECK: define noalias %struct.T* @"\01?test0@@YAPAUT@@XZ"() #0 {

+// CHECK-NEXT: entry:

+// CHECK-NEXT:   ret %struct.T* null

+// CHECK-NEXT: }

+
+T* test1(V* x) { return &dynamic_cast<T&>(*x); }
+// CHECK: define %struct.T* @"\01?test1@@YAPAUT@@PAUV@@@Z"(%struct.V* %x) #1 {
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   %0 = bitcast %struct.V* %x to i8*
+// CHECK-NEXT:   %1 = tail call i8* @__RTDynamicCast(i8* %0, i32 0, i8* bitcast (%"MSRTTITypeDescriptor\07"* @"\01??_R0?AUV@@@8" to i8*), i8* bitcast (%"MSRTTITypeDescriptor\07"* @"\01??_R0?AUT@@@8" to i8*), i32 1) #2
+// CHECK-NEXT:   %2 = bitcast i8* %1 to %struct.T*
+// CHECK-NEXT:   ret %struct.T* %2
+// CHECK-NEXT: }
+
+T* test2(A* x) { return &dynamic_cast<T&>(*x); }
+// CHECK: define %struct.T* @"\01?test2@@YAPAUT@@PAUA@@@Z"(%struct.A* %x) #1 {
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   %0 = bitcast %struct.A* %x to i8*
+// CHECK-NEXT:   %1 = bitcast %struct.A* %x to i8**
+// CHECK-NEXT:   %vbtable = load i8** %1, align 4
+// CHECK-NEXT:   %2 = getelementptr inbounds i8* %vbtable, i32 4
+// CHECK-NEXT:   %3 = bitcast i8* %2 to i32*
+// CHECK-NEXT:   %vbase_offs = load i32* %3, align 4
+// CHECK-NEXT:   %4 = getelementptr inbounds i8* %0, i32 %vbase_offs
+// CHECK-NEXT:   %5 = tail call i8* @__RTDynamicCast(i8* %4, i32 %vbase_offs, i8* bitcast (%"MSRTTITypeDescriptor\07"* @"\01??_R0?AUA@@@8" to i8*), i8* bitcast (%"MSRTTITypeDescriptor\07"* @"\01??_R0?AUT@@@8" to i8*), i32 1) #2
+// CHECK-NEXT:   %6 = bitcast i8* %5 to %struct.T*
+// CHECK-NEXT:   ret %struct.T* %6
+// CHECK-NEXT: }
+
+T* test3(B* x) { return &dynamic_cast<T&>(*x); }
+// CHECK: define %struct.T* @"\01?test3@@YAPAUT@@PAUB@@@Z"(%struct.B* %x) #1 {
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   %0 = getelementptr inbounds %struct.B* %x, i32 0, i32 0, i32 0
+// CHECK-NEXT:   %vbptr = getelementptr inbounds i8* %0, i32 4
+// CHECK-NEXT:   %1 = bitcast i8* %vbptr to i8**
+// CHECK-NEXT:   %vbtable = load i8** %1, align 4
+// CHECK-NEXT:   %2 = getelementptr inbounds i8* %vbtable, i32 4
+// CHECK-NEXT:   %3 = bitcast i8* %2 to i32*
+// CHECK-NEXT:   %vbase_offs = load i32* %3, align 4
+// CHECK-NEXT:   %4 = add nsw i32 %vbase_offs, 4
+// CHECK-NEXT:   %5 = getelementptr inbounds i8* %0, i32 %4
+// CHECK-NEXT:   %6 = tail call i8* @__RTDynamicCast(i8* %5, i32 %4, i8* bitcast (%"MSRTTITypeDescriptor\07"* @"\01??_R0?AUB@@@8" to i8*), i8* bitcast (%"MSRTTITypeDescriptor\07"* @"\01??_R0?AUT@@@8" to i8*), i32 1) #2
+// CHECK-NEXT:   %7 = bitcast i8* %6 to %struct.T*
+// CHECK-NEXT:   ret %struct.T* %7
+// CHECK-NEXT: }
+
+T* test4(V* x) { return dynamic_cast<T*>(x); }
+// CHECK: define %struct.T* @"\01?test4@@YAPAUT@@PAUV@@@Z"(%struct.V* %x) #1 {
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   %0 = bitcast %struct.V* %x to i8*
+// CHECK-NEXT:   %1 = tail call i8* @__RTDynamicCast(i8* %0, i32 0, i8* bitcast (%"MSRTTITypeDescriptor\07"* @"\01??_R0?AUV@@@8" to i8*), i8* bitcast (%"MSRTTITypeDescriptor\07"* @"\01??_R0?AUT@@@8" to i8*), i32 0) #2
+// CHECK-NEXT:   %2 = bitcast i8* %1 to %struct.T*
+// CHECK-NEXT:   ret %struct.T* %2
+// CHECK-NEXT: }
+
+T* test5(A* x) { return dynamic_cast<T*>(x); }
+// CHECK: define %struct.T* @"\01?test5@@YAPAUT@@PAUA@@@Z"(%struct.A* %x) #1 {
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   %0 = icmp eq %struct.A* %x, null
+// CHECK-NEXT:   br i1 %0, label %dynamic_cast.call, label %dynamic_cast.valid
+// CHECK: dynamic_cast.valid:                               ; preds = %entry
+// CHECK-NEXT:   %1 = bitcast %struct.A* %x to i8*
+// CHECK-NEXT:   %2 = bitcast %struct.A* %x to i8**
+// CHECK-NEXT:   %vbtable = load i8** %2, align 4
+// CHECK-NEXT:   %3 = getelementptr inbounds i8* %vbtable, i32 4
+// CHECK-NEXT:   %4 = bitcast i8* %3 to i32*
+// CHECK-NEXT:   %vbase_offs = load i32* %4, align 4
+// CHECK-NEXT:   %5 = getelementptr inbounds i8* %1, i32 %vbase_offs
+// CHECK-NEXT:   %6 = tail call i8* @__RTDynamicCast(i8* %5, i32 %vbase_offs, i8* bitcast (%"MSRTTITypeDescriptor\07"* @"\01??_R0?AUA@@@8" to i8*), i8* bitcast (%"MSRTTITypeDescriptor\07"* @"\01??_R0?AUT@@@8" to i8*), i32 0) #2
+// CHECK-NEXT:   %phitmp = bitcast i8* %6 to %struct.T*
+// CHECK-NEXT:   br label %dynamic_cast.call
+// CHECK: dynamic_cast.call:                                ; preds = %dynamic_cast.valid, %entry
+// CHECK-NEXT:   %7 = phi %struct.T* [ %phitmp, %dynamic_cast.valid ], [ null, %entry ]
+// CHECK-NEXT:   ret %struct.T* %7
+// CHECK-NEXT: }
+
+T* test6(B* x) { return dynamic_cast<T*>(x); }
+// CHECK: define %struct.T* @"\01?test6@@YAPAUT@@PAUB@@@Z"(%struct.B* %x) #1 {
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   %0 = icmp eq %struct.B* %x, null
+// CHECK-NEXT:   br i1 %0, label %dynamic_cast.call, label %dynamic_cast.valid
+// CHECK: dynamic_cast.valid:                               ; preds = %entry
+// CHECK-NEXT:   %1 = getelementptr inbounds %struct.B* %x, i32 0, i32 0, i32 0
+// CHECK-NEXT:   %vbptr = getelementptr inbounds i8* %1, i32 4
+// CHECK-NEXT:   %2 = bitcast i8* %vbptr to i8**
+// CHECK-NEXT:   %vbtable = load i8** %2, align 4
+// CHECK-NEXT:   %3 = getelementptr inbounds i8* %vbtable, i32 4
+// CHECK-NEXT:   %4 = bitcast i8* %3 to i32*
+// CHECK-NEXT:   %vbase_offs = load i32* %4, align 4
+// CHECK-NEXT:   %5 = add nsw i32 %vbase_offs, 4
+// CHECK-NEXT:   %6 = getelementptr inbounds i8* %1, i32 %5
+// CHECK-NEXT:   %7 = tail call i8* @__RTDynamicCast(i8* %6, i32 %5, i8* bitcast (%"MSRTTITypeDescriptor\07"* @"\01??_R0?AUB@@@8" to i8*), i8* bitcast (%"MSRTTITypeDescriptor\07"* @"\01??_R0?AUT@@@8" to i8*), i32 0) #2
+// CHECK-NEXT:   %phitmp = bitcast i8* %7 to %struct.T*
+// CHECK-NEXT:   br label %dynamic_cast.call
+// CHECK: dynamic_cast.call:                                ; preds = %dynamic_cast.valid, %entry
+// CHECK-NEXT:   %8 = phi %struct.T* [ %phitmp, %dynamic_cast.valid ], [ null, %entry ]
+// CHECK-NEXT:   ret %struct.T* %8
+// CHECK-NEXT: }
+
+void* test7(V* x) { return dynamic_cast<void*>(x); }
+// CHECK: define i8* @"\01?test7@@YAPAXPAUV@@@Z"(%struct.V* %x) #1 {
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   %0 = bitcast %struct.V* %x to i8*
+// CHECK-NEXT:   %1 = tail call i8* @__RTCastToVoid(i8* %0) #2
+// CHECK-NEXT:   ret i8* %1
+// CHECK-NEXT: }
+
+void* test8(A* x) { return dynamic_cast<void*>(x); }
+// CHECK: define i8* @"\01?test8@@YAPAXPAUA@@@Z"(%struct.A* %x) #1 {
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   %0 = icmp eq %struct.A* %x, null
+// CHECK-NEXT:   br i1 %0, label %dynamic_cast.call, label %dynamic_cast.valid
+// CHECK: dynamic_cast.valid:                               ; preds = %entry
+// CHECK-NEXT:   %1 = bitcast %struct.A* %x to i8*
+// CHECK-NEXT:   %2 = bitcast %struct.A* %x to i8**
+// CHECK-NEXT:   %vbtable = load i8** %2, align 4
+// CHECK-NEXT:   %3 = getelementptr inbounds i8* %vbtable, i32 4
+// CHECK-NEXT:   %4 = bitcast i8* %3 to i32*
+// CHECK-NEXT:   %vbase_offs = load i32* %4, align 4
+// CHECK-NEXT:   %5 = getelementptr inbounds i8* %1, i32 %vbase_offs
+// CHECK-NEXT:   %6 = tail call i8* @__RTCastToVoid(i8* %5) #2
+// CHECK-NEXT:   br label %dynamic_cast.call
+// CHECK: dynamic_cast.call:                                ; preds = %dynamic_cast.valid, %entry
+// CHECK-NEXT:   %7 = phi i8* [ %6, %dynamic_cast.valid ], [ null, %entry ]
+// CHECK-NEXT:   ret i8* %7
+// CHECK-NEXT: }
+
+void* test9(B* x) { return dynamic_cast<void*>(x); }
+// CHECK: define i8* @"\01?test9@@YAPAXPAUB@@@Z"(%struct.B* %x) #1 {
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   %0 = icmp eq %struct.B* %x, null
+// CHECK-NEXT:   br i1 %0, label %dynamic_cast.call, label %dynamic_cast.valid
+// CHECK: dynamic_cast.valid:                               ; preds = %entry
+// CHECK-NEXT:   %1 = getelementptr inbounds %struct.B* %x, i32 0, i32 0, i32 0
+// CHECK-NEXT:   %vbptr = getelementptr inbounds i8* %1, i32 4
+// CHECK-NEXT:   %2 = bitcast i8* %vbptr to i8**
+// CHECK-NEXT:   %vbtable = load i8** %2, align 4
+// CHECK-NEXT:   %3 = getelementptr inbounds i8* %vbtable, i32 4
+// CHECK-NEXT:   %4 = bitcast i8* %3 to i32*
+// CHECK-NEXT:   %vbase_offs = load i32* %4, align 4
+// CHECK-NEXT:   %5 = add nsw i32 %vbase_offs, 4
+// CHECK-NEXT:   %6 = getelementptr inbounds i8* %1, i32 %5
+// CHECK-NEXT:   %7 = tail call i8* @__RTCastToVoid(i8* %6) #2
+// CHECK-NEXT:   br label %dynamic_cast.call
+// CHECK: dynamic_cast.call:                                ; preds = %dynamic_cast.valid, %entry
+// CHECK-NEXT:   %8 = phi i8* [ %7, %dynamic_cast.valid ], [ null, %entry ]
+// CHECK-NEXT:   ret i8* %8
+// CHECK-NEXT: }