[X86] Add explicit alignment to __m128/__m128i/__m128d/etc. to allow matching of MSVC behavior with #pragma pack.

Summary:
With MSVC, #pragma pack is ignored when there is explicit alignment. This differs from gcc. Clang emulates this difference when compiling for Windows.

It appears that MSVC and its headers consider the __m128/__m128i/__m128d/etc. types to be explicitly aligned and ignores #pragma pack for them. Since we don't have explicit alignment on them in our headers, we don't match the MSVC behavior here.

This patch adds explicit alignment to match this behavior. I'm hoping this won't cause any problems when we're not emulating MSVC. But if someone knows of something that would be different we can swith to conditionally adding the alignment based on _MSC_VER.

I had to add explicitly unaligned types as well so we could use them in the loadu/storeu intrinsics which use __attribute__(__packed__). Using the now explicitly aligned types wouldn't produce align 1 accesses when targeting Windows.

Reviewers: rnk, erichkeane, spatel, RKSimon

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D57961

llvm-svn: 353555

1 files changed, 227 insertions, 0 deletions

diff --git a/clang/test/CodeGen/x86-vec-struct-packing.c b/clang/test/CodeGen/x86-vec-struct-packing.c
new file mode 100644
index 00000000000..01458d131ed
--- /dev/null
+++ b/clang/test/CodeGen/x86-vec-struct-packing.c
@@ -0,0 +1,227 @@
+// RUN: %clang_cc1 -ffreestanding -emit-llvm-only  -triple x86_64-windows-coff -fdump-record-layouts %s | FileCheck %s --check-prefix=CHECK-MS
+// RUN: %clang_cc1 -ffreestanding -emit-llvm-only  -triple x86_64-apple-darwin -fdump-record-layouts %s | FileCheck %s --check-prefix=CHECK-NOTMS
+#include <x86intrin.h>
+
+#pragma pack(1)
+
+struct s_m64 {
+  int a;
+  __m64 b;
+};
+typedef struct s_m64 m64;
+
+#if defined(_WIN32)
+static int a1[(sizeof(m64) == 16) - 1];
+#else
+static int a1[(sizeof(m64) == 12) - 1];
+#endif
+
+struct s_m128 {
+  int a;
+  __m128 b;
+};
+typedef struct s_m128 m128;
+
+#if defined(_WIN32)
+static int a1[(sizeof(m128) == 32) - 1];
+#else
+static int a1[(sizeof(m128) == 20) - 1];
+#endif
+
+struct s_m128i {
+  int a;
+  __m128i b;
+};
+typedef struct s_m128i m128i;
+
+#if defined(_WIN32)
+static int a1[(sizeof(m128i) == 32) - 1];
+#else
+static int a1[(sizeof(m128i) == 20) - 1];
+#endif
+
+struct s_m128d {
+  int a;
+  __m128d b;
+};
+typedef struct s_m128d m128d;
+
+#if defined(_WIN32)
+static int a1[(sizeof(m128d) == 32) - 1];
+#else
+static int a1[(sizeof(m128d) == 20) - 1];
+#endif
+
+struct s_m256 {
+  int a;
+  __m256 b;
+};
+typedef struct s_m256 m256;
+
+#if defined(_WIN32)
+static int a1[(sizeof(m256) == 64) - 1];
+#else
+static int a1[(sizeof(m256) == 36) - 1];
+#endif
+
+struct s_m256i {
+  int a;
+  __m256i b;
+};
+typedef struct s_m256i m256i;
+
+#if defined(_WIN32)
+static int a1[(sizeof(m256i) == 64) - 1];
+#else
+static int a1[(sizeof(m256i) == 36) - 1];
+#endif
+
+struct s_m256d {
+  int a;
+  __m256d b;
+};
+typedef struct s_m256d m256d;
+
+#if defined(_WIN32)
+static int a1[(sizeof(m256d) == 64) - 1];
+#else
+static int a1[(sizeof(m256d) == 36) - 1];
+#endif
+
+struct s_m512 {
+  int a;
+  __m512 b;
+};
+typedef struct s_m512 m512;
+
+#if defined(_WIN32)
+static int a1[(sizeof(m512) == 128) - 1];
+#else
+static int a1[(sizeof(m512) == 68) - 1];
+#endif
+
+struct s_m512i {
+  int a;
+  __m512i b;
+};
+typedef struct s_m512i m512i;
+
+#if defined(_WIN32)
+static int a1[(sizeof(m512i) == 128) - 1];
+#else
+static int a1[(sizeof(m512i) == 68) - 1];
+#endif
+
+struct s_m512d {
+  int a;
+  __m512d b;
+};
+typedef struct s_m512d m512d;
+
+#if defined(_WIN32)
+static int a1[(sizeof(m512d) == 128) - 1];
+#else
+static int a1[(sizeof(m512d) == 68) - 1];
+#endif
+
+// CHECK-MS: *** Dumping AST Record Layout
+// CHECK-MS:          0 | struct s_m64
+// CHECK-MS:          0 |   int a
+// CHECK-MS:          8 |   __m64 b
+// CHECK-MS:            | [sizeof=16, align=8]
+// CHECK-MS: *** Dumping AST Record Layout
+// CHECK-MS:          0 | struct s_m128
+// CHECK-MS:          0 |   int a
+// CHECK-MS:         16 |   __m128 b
+// CHECK-MS:            | [sizeof=32, align=16]
+// CHECK-MS: *** Dumping AST Record Layout
+// CHECK-MS:          0 | struct s_m128i
+// CHECK-MS:          0 |   int a
+// CHECK-MS:         16 |   __m128i b
+// CHECK-MS:            | [sizeof=32, align=16]
+// CHECK-MS: *** Dumping AST Record Layout
+// CHECK-MS:          0 | struct s_m128d
+// CHECK-MS:          0 |   int a
+// CHECK-MS:         16 |   __m128d b
+// CHECK-MS:            | [sizeof=32, align=16]
+// CHECK-MS: *** Dumping AST Record Layout
+// CHECK-MS:          0 | struct s_m256
+// CHECK-MS:          0 |   int a
+// CHECK-MS:         32 |   __m256 b
+// CHECK-MS:            | [sizeof=64, align=32]
+// CHECK-MS: *** Dumping AST Record Layout
+// CHECK-MS:          0 | struct s_m256i
+// CHECK-MS:          0 |   int a
+// CHECK-MS:         32 |   __m256i b
+// CHECK-MS:            | [sizeof=64, align=32]
+// CHECK-MS: *** Dumping AST Record Layout
+// CHECK-MS:          0 | struct s_m256d
+// CHECK-MS:          0 |   int a
+// CHECK-MS:         32 |   __m256d b
+// CHECK-MS:            | [sizeof=64, align=32]
+// CHECK-MS: *** Dumping AST Record Layout
+// CHECK-MS:          0 | struct s_m512
+// CHECK-MS:          0 |   int a
+// CHECK-MS:         64 |   __m512 b
+// CHECK-MS:            | [sizeof=128, align=64]
+// CHECK-MS: *** Dumping AST Record Layout
+// CHECK-MS:          0 | struct s_m512i
+// CHECK-MS:          0 |   int a
+// CHECK-MS:         64 |   __m512i b
+// CHECK-MS:            | [sizeof=128, align=64]
+// CHECK-MS: *** Dumping AST Record Layout
+// CHECK-MS:          0 | struct s_m512d
+// CHECK-MS:          0 |   int a
+// CHECK-MS:         64 |   __m512d b
+// CHECK-MS:            | [sizeof=128, align=64]
+
+// CHECK-NOTMS: *** Dumping AST Record Layout
+// CHECK-NOTMS:          0 | struct s_m64
+// CHECK-NOTMS:          0 |   int a
+// CHECK-NOTMS:          4 |   __m64 b
+// CHECK-NOTMS:            | [sizeof=12, align=1]
+// CHECK-NOTMS: *** Dumping AST Record Layout
+// CHECK-NOTMS:          0 | struct s_m128
+// CHECK-NOTMS:          0 |   int a
+// CHECK-NOTMS:          4 |   __m128 b
+// CHECK-NOTMS:            | [sizeof=20, align=1]
+// CHECK-NOTMS: *** Dumping AST Record Layout
+// CHECK-NOTMS:          0 | struct s_m128i
+// CHECK-NOTMS:          0 |   int a
+// CHECK-NOTMS:          4 |   __m128i b
+// CHECK-NOTMS:            | [sizeof=20, align=1]
+// CHECK-NOTMS: *** Dumping AST Record Layout
+// CHECK-NOTMS:          0 | struct s_m128d
+// CHECK-NOTMS:          0 |   int a
+// CHECK-NOTMS:          4 |   __m128d b
+// CHECK-NOTMS:            | [sizeof=20, align=1]
+// CHECK-NOTMS: *** Dumping AST Record Layout
+// CHECK-NOTMS:          0 | struct s_m256
+// CHECK-NOTMS:          0 |   int a
+// CHECK-NOTMS:          4 |   __m256 b
+// CHECK-NOTMS:            | [sizeof=36, align=1]
+// CHECK-NOTMS: *** Dumping AST Record Layout
+// CHECK-NOTMS:          0 | struct s_m256i
+// CHECK-NOTMS:          0 |   int a
+// CHECK-NOTMS:          4 |   __m256i b
+// CHECK-NOTMS:            | [sizeof=36, align=1]
+// CHECK-NOTMS: *** Dumping AST Record Layout
+// CHECK-NOTMS:          0 | struct s_m256d
+// CHECK-NOTMS:          0 |   int a
+// CHECK-NOTMS:          4 |   __m256d b
+// CHECK-NOTMS:            | [sizeof=36, align=1]
+// CHECK-NOTMS: *** Dumping AST Record Layout
+// CHECK-NOTMS:          0 | struct s_m512
+// CHECK-NOTMS:          0 |   int a
+// CHECK-NOTMS:          4 |   __m512 b
+// CHECK-NOTMS:            | [sizeof=68, align=1]
+// CHECK-NOTMS: *** Dumping AST Record Layout
+// CHECK-NOTMS:          0 | struct s_m512i
+// CHECK-NOTMS:          0 |   int a
+// CHECK-NOTMS:          4 |   __m512i b
+// CHECK-NOTMS:            | [sizeof=68, align=1]
+// CHECK-NOTMS: *** Dumping AST Record Layout
+// CHECK-NOTMS:          0 | struct s_m512d
+// CHECK-NOTMS:          0 |   int a
+// CHECK-NOTMS:          4 |   __m512d b
+// CHECK-NOTMS:            | [sizeof=68, align=1]