[llvm] [BinaryFormat] Add "SFrame" structures and constants (PR #147264)

[Pavel Labath via llvm-commits]

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@@ -0,0 +1,163 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file
+/// This file contains data-structure definitions and constants to support
+/// unwinding based on .sframe sections.  This only supports SFRAME_VERSION_2
+/// as described at https://sourceware.org/binutils/docs/sframe-spec.html
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_BINARYFORMAT_SFRAME_H
+#define LLVM_BINARYFORMAT_SFRAME_H
+
+#include "llvm/ADT/BitmaskEnum.h"
+#include "llvm/Support/DataTypes.h"
+#include "llvm/Support/Endian.h"
+
+namespace llvm::sframe {
+
+LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();
+
+constexpr uint16_t Magic = 0xdee2;
+
+enum class Version : uint8_t {
+  V1 = 1,
+  V2 = 2,
+};
+
+enum class Flags : uint8_t {
+  FDESorted = 0x01,
+  FramePointer = 0x02,
+  LLVM_MARK_AS_BITMASK_ENUM(/*LargestValue=*/0xff),
+};
+
+enum class ABI : uint8_t {
+  AArch64EndianBig = 1,
+  AArch64EndianLittle = 2,
+  AMD64EndianLittle = 3,
+};
+
+/// SFrame FRE Types. Bits 0-3 of FuncDescEntry.Info.
+enum class FREType : uint8_t {
+  Addr1 = 0,
+  Addr2 = 1,
+  Addr4 = 2,
+};
+
+/// SFrame FDE Types. Bit 4 of FuncDescEntry.Info.
+enum class FDEType : uint8_t {
+  PCInc = 0,
+  PCMask = 1,
+};
+
+/// Speficies key used for signing return addresses. Bit 5 of
+/// FuncDescEntry.Info.
+enum class AArch64PAuthKey : uint8_t {
+  A = 0,
+  B = 1,
+};
+
+/// Size of stack offsets. Bits 5-6 of FREInfo.Info.
+enum class FREOffset : uint8_t {
+  B1 = 0,
+  B2 = 1,
+  B4 = 2,
+};
+
+/// Stack frame base register. Bit 0 of FREInfo.Info.
+enum class BaseReg : uint8_t {
+  FP = 0,
+  SP = 1,
+};
+
+namespace detail {
+template <typename T, endianness E>
+using packed =
+    support::detail::packed_endian_specific_integral<T, E, support::unaligned>;
+}
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labath wrote:

I'm tempted to add something like `packed_endian_t` to `Support/Endian.h`

https://github.com/llvm/llvm-project/pull/147264