ObjectFileELF: Use llvm::JamCRC to refactor CRC32 computation

[labath]

Thanks. I've been meaning to do this, but couldn't get around to it somehow...

lldb/trunk/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

 #include "lldb/Utility/Stream.h"
 #include "lldb/Utility/Timer.h"
 
 #include "llvm/ADT/IntervalMap.h"
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Object/Decompressor.h"
 #include "llvm/Support/ARMBuildAttributes.h"
+#include "llvm/Support/JamCRC.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/MipsABIFlags.h"
 
 #define CASE_AND_STREAM(s, def, width)                                         \
   case def:                                                                    \
     s->Printf("%-*s", width, #def);                                            \
     break;
bool ObjectFileELF::MagicBytesMatch(DataBufferSP &data_sp,
   if (data_sp &&
       data_sp->GetByteSize() > (llvm::ELF::EI_NIDENT + data_offset)) {
     const uint8_t *magic = data_sp->GetBytes() + data_offset;
     return ELFHeader::MagicBytesMatch(magic);
   }
   return false;
 }
 
-/*
- * crc function from http://svnweb.freebsd.org/base/head/sys/libkern/crc32.c
- *
- *   COPYRIGHT (C) 1986 Gary S. Brown. You may use this program, or
- *   code or tables extracted from it, as desired without restriction.
- */
-static uint32_t calc_crc32(uint32_t crc, const void *buf, size_t size) {
-  static const uint32_t g_crc32_tab[] = {
-      0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
-      0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
-      0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
-      0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
-      0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
-      0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
-      0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
-      0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
-      0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
-      0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
-      0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
-      0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
-      0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
-      0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
-      0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
-      0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
-      0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
-      0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
-      0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
-      0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
-      0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
-      0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
-      0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
-      0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
-      0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
-      0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
-      0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
-      0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
-      0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
-      0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
-      0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
-      0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
-      0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
-      0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
-      0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
-      0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
-      0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
-      0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
-      0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
-      0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
-      0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
-      0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
-      0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d};
-  const uint8_t *p = (const uint8_t *)buf;
-
-  crc = crc ^ ~0U;
-  while (size--)
-    crc = g_crc32_tab[(crc ^ *p++) & 0xFF] ^ (crc >> 8);
-  return crc ^ ~0U;
-}
-
-static uint32_t calc_gnu_debuglink_crc32(const void *buf, size_t size) {
-  return calc_crc32(0U, buf, size);
+static uint32_t calc_crc32(uint32_t init, const DataExtractor &data) {
+  llvm::JamCRC crc(~init);
+  crc.update(llvm::makeArrayRef(
+      reinterpret_cast<const char *>(data.GetDataStart()), data.GetByteSize()));
+  return ~crc.getCRC();
 }
 
 uint32_t ObjectFileELF::CalculateELFNotesSegmentsCRC32(
     const ProgramHeaderColl &program_headers, DataExtractor &object_data) {
 
   uint32_t core_notes_crc = 0;
 
   for (const ELFProgramHeader &H : program_headers) {
     if (H.p_type == llvm::ELF::PT_NOTE) {
       const elf_off ph_offset = H.p_offset;
       const size_t ph_size = H.p_filesz;
 
       DataExtractor segment_data;
       if (segment_data.SetData(object_data, ph_offset, ph_size) != ph_size) {
         // The ELF program header contained incorrect data, probably corefile
         // is incomplete or corrupted.
         break;
       }
 
-      core_notes_crc = calc_crc32(core_notes_crc, segment_data.GetDataStart(),
-                                  segment_data.GetByteSize());
+      core_notes_crc = calc_crc32(core_notes_crc, segment_data);
     }
   }
 
   return core_notes_crc;
 }
 
 static const char *OSABIAsCString(unsigned char osabi_byte) {
 #define _MAKE_OSABI_CASE(x)                                                    \
if (header.Parse(data, &header_offset)) {
               // to fallback to something simpler.
               if (header.e_type == llvm::ELF::ET_CORE) {
                 ProgramHeaderColl program_headers;
                 GetProgramHeaderInfo(program_headers, data, header);
 
                 core_notes_crc =
                     CalculateELFNotesSegmentsCRC32(program_headers, data);
               } else {
-                gnu_debuglink_crc = calc_gnu_debuglink_crc32(
-                    data.GetDataStart(), data.GetByteSize());
+                gnu_debuglink_crc = calc_crc32(0, data);
               }
             }
             using u32le = llvm::support::ulittle32_t;
             if (gnu_debuglink_crc) {
               // Use 4 bytes of crc from the .gnu_debuglink section.
               u32le data(gnu_debuglink_crc);
               uuid = UUID::fromData(&data, sizeof(data));
             } else if (core_notes_crc) {
if (GetType() == ObjectFile::eTypeCoreFile) {
         // Use 8 bytes - first 4 bytes for *magic* prefix, mainly to make it
         // look different form .gnu_debuglink crc - followed by 4 bytes of note
         // segments crc.
         u32le data[] = {u32le(g_core_uuid_magic), u32le(core_notes_crc)};
         m_uuid = UUID::fromData(data, sizeof(data));
       }
     } else {
       if (!m_gnu_debuglink_crc)
-        m_gnu_debuglink_crc = calc_gnu_debuglink_crc32(m_data.GetDataStart(),
-                                                       m_data.GetByteSize());
+        m_gnu_debuglink_crc = calc_crc32(0, m_data);
       if (m_gnu_debuglink_crc) {
         // Use 4 bytes of crc from the .gnu_debuglink section.
         u32le data(m_gnu_debuglink_crc);
         m_uuid = UUID::fromData(&data, sizeof(data));
       }
     }
   }