Unify the two CRC implementations

David added the JamCRC implementation in r246590. More recently, Eugene
added a CRC-32 implementation in r357901, which falls back to zlib's
crc32 function if present.

These checksums are essentially the same, so having multiple
implementations seems unnecessary. This replaces the CRC-32
implementation with the simpler one from JamCRC, and implements the
JamCRC interface in terms of CRC-32 since this means it can use zlib's
implementation when available, saving a few bytes and potentially making
it faster.

JamCRC took an ArrayRef<char> argument, and CRC-32 took a StringRef.
This patch changes it to ArrayRef<uint8_t> which I think is the best
choice, and simplifies a few of the callers nicely.

Differential revision: https://reviews.llvm.org/D68570

llvm-svn: 374148

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

@@ -36,7 +36,7 @@
 #include "llvm/BinaryFormat/ELF.h"
 #include "llvm/Object/Decompressor.h"
 #include "llvm/Support/ARMBuildAttributes.h"
-#include "llvm/Support/JamCRC.h"
+#include "llvm/Support/CRC.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/MipsABIFlags.h"
@@ -398,10 +398,8 @@ bool ObjectFileELF::MagicBytesMatch(DataBufferSP &data_sp,
 }
 
 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();
+  return llvm::crc32(
+      init, llvm::makeArrayRef(data.GetDataStart(), data.GetByteSize()));
 }
 
 uint32_t ObjectFileELF::CalculateELFNotesSegmentsCRC32(