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

[Pavel Labath via llvm-commits]

================
@@ -0,0 +1,167 @@
+//===-- llvm/BinaryFormat/SFrame.h ---SFrame Data Structures ----*- C++ -*-===//
+//
+// 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
+///
+/// Naming conventions follow the spec document. #defines converted to constants
+/// and enums for better C++ compatibility.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_BINARYFORMAT_SFRAME_H
+#define LLVM_BINARYFORMAT_SFRAME_H
+
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/DataTypes.h"
+
+namespace llvm {
+
+namespace sframe {
+
+//===----------------------------------------------------------------------===//
+
+constexpr uint16_t SFRAME_MAGIC = 0xDEE2;
+
+enum : uint8_t {
+  SFRAME_VERSION_1 = 1,
+  SFRAME_VERSION_2 = 2,
+};
+
+/// sframe_preable.sfp_flags flags.
+enum : uint8_t {
+  SFRAME_F_FDE_SORTED = 0x1,
+  SFRAME_F_FRAME_POINTER = 0x2,
+};
+
+/// Possible values for sframe_header.sfh_abi_arch.
+enum : uint8_t {
+  SFRAME_ABI_AARCH64_ENDIAN_BIG = 1,
+  SFRAME_ABI_AARCH64_ENDIAN_LITTLE = 2,
+  SFRAME_ABI_AMD64_ENDIAN_LITTLE = 3
+};
+
+/// SFrame FRE Types. Bits 0-3 of sframe_func_desc_entry.sfde_func_info.
+enum : uint8_t {
+  SFRAME_FRE_TYPE_ADDR1 = 0,
+  SFRAME_FRE_TYPE_ADDR2 = 1,
+  SFRAME_FRE_TYPE_ADDR4 = 2,
+};
+
+/// SFrame FDE Types. Bit 4 of sframe_func_desc_entry.sfde_func_info.
+enum : uint8_t {
+  SFRAME_FDE_TYPE_PCINC = 0,
+  SFRAME_FDE_TYPE_PCMASK = 1,
+};
+
+/// Speficies key used for signing return addresses. Bit 5 of
+/// sframe_func_desc_entry.sfde_func_info.
+enum : uint8_t {
+  SFRAME_AARCH64_PAUTH_KEY_A = 0,
+  SFRAME_AARCH64_PAUTH_KEY_B = 1,
+};
+
+/// Size of stack offsets. Bits 5-6 of sframe_fre_info.fre_info.
+enum : uint8_t {
+  SFRAME_FRE_OFFSET_1B = 0,
+  SFRAME_FRE_OFFSET_2B = 1,
+  SFRAME_FRE_OFFSET_4B = 2,
+};
+
+/// Stack frame base register. Bit 0 of sframe_fre_info.fre_info.
+enum : uint8_t { SFRAME_BASE_REG_FP = 0, SFRAME_BASE_REG_SP = 1 };
+
+LLVM_PACKED_START
+
+struct sframe_preamble {
+  uint16_t sfp_magic;
+  uint8_t sfp_version;
+  uint8_t sfp_flags;
+};
+
+struct sframe_header {
+  sframe_preamble sfh_preamble;
+  uint8_t sfh_abi_arch;
+  int8_t sfh_cfa_fixed_fp_offset;
+  int8_t sfh_cfa_fixed_ra_offset;
+  uint8_t sfh_auxhdr_len;
+  uint32_t sfh_num_fdes;
+  uint32_t sfh_num_fres;
+  uint32_t sfh_fre_len;
+  uint32_t sfh_fdeoff;
+  uint32_t sfh_freoff;
+};
+
+struct sframe_func_desc_entry {
+  int32_t sfde_func_start_address;
+  uint32_t sfde_func_size;
+  uint32_t sfde_func_start_fre_off;
+  uint32_t sfde_func_num_fres;
+  uint8_t sfde_func_info;
+  uint8_t sfde_func_rep_size;
+  uint16_t sfde_func_padding2;
+
+  uint8_t getPAuthKey() const { return (sfde_func_info >> 5) & 1; }
+  uint8_t getFDEType() const { return (sfde_func_info >> 4) & 1; }
+  uint8_t getFREType() const { return sfde_func_info & 0xf; }
+  void setPAuthKey(uint8_t P) { setFuncInfo(P, getFDEType(), getFREType()); }
+  void setFDEType(uint8_t D) { setFuncInfo(getPAuthKey(), D, getFREType()); }
+  void setFREType(uint8_t R) { setFuncInfo(getPAuthKey(), getFDEType(), R); }
+  void setFuncInfo(uint8_t PAuthKey, uint8_t FDEType, uint8_t FREType) {
+    sfde_func_info =
+        ((PAuthKey & 1) << 5) | ((FDEType & 1) << 4) | (FREType & 0xf);
+  }
----------------
labath wrote:

This part was inspired by `Elf32_Sym::setBindingAndType` and friends.

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