Weaken an assertion in memcpyization to account for

unnamed bitfields.

Unnamed bitfields won't have an explicit copy operation
in the AST, which breaks the strong form of the invariant.

rdar://13816940

llvm-svn: 181289

2 files changed, 47 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index 3fd075701d0..e4180a0d72d 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -859,8 +859,12 @@ namespace {
       }
 
     void addNextField(FieldDecl *F) {
-      assert(F->getFieldIndex() == LastAddedFieldIndex + 1 &&
-             "Cannot aggregate non-contiguous fields.");
+      // For the most part, the following invariant will hold:
+      //   F->getFieldIndex() == LastAddedFieldIndex + 1
+      // The one exception is that Sema won't add a copy-initializer for an
+      // unnamed bitfield, which will show up here as a gap in the sequence.
+      assert(F->getFieldIndex() >= LastAddedFieldIndex + 1 &&
+             "Cannot aggregate fields out of order.");
       LastAddedFieldIndex = F->getFieldIndex();
 
       // The 'first' and 'last' fields are chosen by offset, rather than field
diff --git a/clang/test/CodeGenCXX/copy-constructor-synthesis.cpp b/clang/test/CodeGenCXX/copy-constructor-synthesis.cpp
index 68f680574b7..f6c38219517 100644
--- a/clang/test/CodeGenCXX/copy-constructor-synthesis.cpp
+++ b/clang/test/CodeGenCXX/copy-constructor-synthesis.cpp
@@ -136,6 +136,32 @@ void f(B b1) {
   B b2 = b1;
 }
 
+// CHECK:    define linkonce_odr [[A:%.*]]* @_ZN12rdar138169401AaSERKS0_(
+// CHECK:      [[THIS:%.*]] = load [[A]]**
+// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[A]]* [[THIS]], i32 0, i32 1
+// CHECK-NEXT: [[T1:%.*]] = bitcast [2 x i8]* [[T0]] to i16*
+// CHECK-NEXT: [[OTHER:%.*]] = load [[A]]**
+// CHECK-NEXT: [[T2:%.*]] = getelementptr inbounds [[A]]* [[OTHER]], i32 0, i32 1
+// CHECK-NEXT: [[T3:%.*]] = bitcast [2 x i8]* [[T2]] to i16*
+// CHECK-NEXT: [[T4:%.*]] = bitcast i16* [[T1]] to i8*
+// CHECK-NEXT: [[T5:%.*]] = bitcast i16* [[T3]] to i8*
+// CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* [[T4]], i8* [[T5]], i64 8, i32 8, i1 false)
+// CHECK-NEXT: ret [[A]]* [[THIS]]
+
+// CHECK:    define linkonce_odr void @_ZN12rdar138169401AC2ERKS0_(
+// CHECK:      [[THIS:%.*]] = load [[A]]**
+// CHECK-NEXT: [[T0:%.*]] = bitcast [[A]]* [[THIS]] to i8***
+// CHECK-NEXT: store i8** getelementptr inbounds ([4 x i8*]* @_ZTVN12rdar138169401AE, i64 0, i64 2), i8*** [[T0]]
+// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[A]]* [[THIS]], i32 0, i32 1
+// CHECK-NEXT: [[T1:%.*]] = bitcast [2 x i8]* [[T0]] to i16*
+// CHECK-NEXT: [[OTHER:%.*]] = load [[A]]**
+// CHECK-NEXT: [[T2:%.*]] = getelementptr inbounds [[A]]* [[OTHER]], i32 0, i32 1
+// CHECK-NEXT: [[T3:%.*]] = bitcast [2 x i8]* [[T2]] to i16*
+// CHECK-NEXT: [[T4:%.*]] = bitcast i16* [[T1]] to i8*
+// CHECK-NEXT: [[T5:%.*]] = bitcast i16* [[T3]] to i8*
+// CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* [[T4]], i8* [[T5]], i64 8, i32 8, i1 false)
+// CHECK-NEXT: ret void
+
 // CHECK: define linkonce_odr void @_ZN6PR66281BC2ERKS0_(%"struct.PR6628::B"* %this, %"struct.PR6628::B"*) unnamed_addr
 // CHECK: call void @_ZN6PR66281TC1Ev
 // CHECK: call void @_ZN6PR66281TC1Ev
@@ -154,3 +180,18 @@ void f(B b1) {
 // CHECK: call void @_ZN6PR66281TD1Ev
 }
 
+// rdar://13816940
+// Test above because things get weirdly re-ordered.
+namespace rdar13816940 {
+  struct A {
+    virtual ~A();
+    unsigned short a : 1;
+    unsigned short : 15;
+    unsigned other;
+  };
+
+  void test(A &a) {
+    A x = a; // force copy constructor into existence
+    x = a; // also force the copy assignment operator
+  }
+}