Rewrite record layout for ms_struct structs.

The old implementation of ms_struct in RecordLayoutBuilder was a
complete mess: it depended on complicated conditionals which didn't
really reflect the underlying logic, and placed a burden on users of
the resulting RecordLayout. This commit rips out almost all of the
old code, and replaces it with simple checks in
RecordLayoutBuilder::LayoutBitField.

This commit also fixes <rdar://problem/14252115>, a bug where class
inheritance would cause us to lay out bitfields incorrectly.

llvm-svn: 185018

3 files changed, 21 insertions, 2 deletions

diff --git a/clang/test/CodeGen/tbaa-struct.cpp b/clang/test/CodeGen/tbaa-struct.cpp
index 6d593a3c1b2..9320a8375cb 100644
--- a/clang/test/CodeGen/tbaa-struct.cpp
+++ b/clang/test/CodeGen/tbaa-struct.cpp
@@ -70,5 +70,5 @@ void copy5(struct six *a, struct six *b) {
 // CHECK: [[TS2]] = metadata !{i64 0, i64 1, metadata !{{.*}}, i64 4, i64 2, metadata !{{.*}}, i64 8, i64 4, metadata !{{.*}}, i64 12, i64 1, metadata !{{.*}}, i64 16, i64 4, metadata {{.*}}, i64 20, i64 4, metadata {{.*}}}
 // (offset, size) = (0,8) char; (0,2) char; (4,8) char
 // CHECK: [[TS3]] = metadata !{i64 0, i64 8, metadata !{{.*}}, i64 0, i64 2, metadata !{{.*}}, i64 4, i64 8, metadata !{{.*}}}
-// CHECK: [[TS4]] = metadata !{i64 0, i64 1, metadata [[CHAR]], i64 1, i64 1, metadata [[CHAR]], i64 2, i64 1, metadata [[CHAR]]}
+// CHECK: [[TS4]] = metadata !{i64 0, i64 1, metadata [[CHAR]], i64 1, i64 4, metadata [[INT]], i64 1, i64 1, metadata [[CHAR]], i64 2, i64 1, metadata [[CHAR]]}
 // CHECK: [[TS5]] = metadata !{i64 0, i64 1, metadata [[CHAR]], i64 4, i64 4, metadata [[INT]], i64 4, i64 1, metadata [[CHAR]], i64 5, i64 1, metadata [[CHAR]]}
diff --git a/clang/test/CodeGen/tbaa.cpp b/clang/test/CodeGen/tbaa.cpp
index afb8893d3e6..77133e473a4 100644
--- a/clang/test/CodeGen/tbaa.cpp
+++ b/clang/test/CodeGen/tbaa.cpp
@@ -250,6 +250,6 @@ char g14(struct six *a, struct six *b) {
 // PATH: [[TAG_D_b_a_f32]] = metadata !{metadata [[TYPE_D:!.*]], metadata [[TYPE_INT]], i64 12}
 // PATH: [[TYPE_D]] = metadata !{metadata !"_ZTS7StructD", metadata [[TYPE_SHORT]], i64 0, metadata [[TYPE_B]], i64 4, metadata [[TYPE_INT]], i64 28, metadata [[TYPE_CHAR]], i64 32}
 // PATH: [[TAG_five_b]] = metadata !{metadata [[TYPE_five:!.*]], metadata [[TYPE_CHAR]], i64 1}
-// PATH: [[TYPE_five]] = metadata !{metadata !"_ZTS4five", metadata [[TYPE_CHAR]], i64 0, metadata [[TYPE_CHAR]], i64 1, metadata [[TYPE_CHAR]], i64 2}
+// PATH: [[TYPE_five]] = metadata !{metadata !"_ZTS4five", metadata [[TYPE_CHAR]], i64 0, metadata [[TYPE_INT]], i64 1, metadata [[TYPE_CHAR]], i64 1, metadata [[TYPE_CHAR]], i64 2}
 // PATH: [[TAG_six_b]] = metadata !{metadata [[TYPE_six:!.*]], metadata [[TYPE_CHAR]], i64 4}
 // PATH: [[TYPE_six]] = metadata !{metadata !"_ZTS3six", metadata [[TYPE_CHAR]], i64 0, metadata [[TYPE_INT]], i64 4, metadata [[TYPE_CHAR]], i64 4, metadata [[TYPE_CHAR]], i64 5}
diff --git a/clang/test/SemaCXX/ms_struct.cpp b/clang/test/SemaCXX/ms_struct.cpp
new file mode 100644
index 00000000000..fd1ed904fa8
--- /dev/null
+++ b/clang/test/SemaCXX/ms_struct.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -triple i686-apple-darwin9 -std=c++11 %s
+// expected-no-diagnostics
+
+#pragma ms_struct on
+
+struct A {
+  unsigned long a:4;
+  unsigned char b;
+  A();
+};
+
+struct B : public A {
+  unsigned long c:16;
+	int d;
+  B();
+};
+
+static_assert(__builtin_offsetof(B, d) == 12,
+  "We can't allocate the bitfield into the padding under ms_struct");
\ No newline at end of file