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

2 files changed, 5 insertions, 18 deletions

diff --git a/llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp b/llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
index 60f70d71349..2a8d816e6f3 100644
--- a/llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
+++ b/llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
@@ -16,8 +16,8 @@
 
 #include "llvm/Object/Binary.h"
 #include "llvm/Object/COFF.h"
+#include "llvm/Support/CRC.h"
 #include "llvm/Support/Errc.h"
-#include "llvm/Support/JamCRC.h"
 #include "llvm/Support/Path.h"
 #include <cassert>
 
@@ -40,22 +40,13 @@ static uint64_t getNextRVA(const Object &Obj) {
                  Obj.IsPE ? Obj.PeHeader.SectionAlignment : 1);
 }
 
-static uint32_t getCRC32(StringRef Data) {
-  JamCRC CRC;
-  CRC.update(ArrayRef<char>(Data.data(), Data.size()));
-  // The CRC32 value needs to be complemented because the JamCRC dosn't
-  // finalize the CRC32 value. It also dosn't negate the initial CRC32 value
-  // but it starts by default at 0xFFFFFFFF which is the complement of zero.
-  return ~CRC.getCRC();
-}
-
 static std::vector<uint8_t> createGnuDebugLinkSectionContents(StringRef File) {
   ErrorOr<std::unique_ptr<MemoryBuffer>> LinkTargetOrErr =
       MemoryBuffer::getFile(File);
   if (!LinkTargetOrErr)
     error("'" + File + "': " + LinkTargetOrErr.getError().message());
   auto LinkTarget = std::move(*LinkTargetOrErr);
-  uint32_t CRC32 = getCRC32(LinkTarget->getBuffer());
+  uint32_t CRC32 = llvm::crc32(arrayRefFromStringRef(LinkTarget->getBuffer()));
 
   StringRef FileName = sys::path::filename(File);
   size_t CRCPos = alignTo(FileName.size() + 1, 4);
diff --git a/llvm/tools/llvm-objcopy/CopyConfig.cpp b/llvm/tools/llvm-objcopy/CopyConfig.cpp
index 9b51b745d50..952b3a71796 100644
--- a/llvm/tools/llvm-objcopy/CopyConfig.cpp
+++ b/llvm/tools/llvm-objcopy/CopyConfig.cpp
@@ -14,10 +14,10 @@
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
+#include "llvm/Support/CRC.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Compression.h"
 #include "llvm/Support/Errc.h"
-#include "llvm/Support/JamCRC.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/StringSaver.h"
 #include <memory>
@@ -461,12 +461,8 @@ Expected<DriverConfig> parseObjcopyOptions(ArrayRef<const char *> ArgsArr) {
     if (!DebugOrErr)
       return createFileError(Config.AddGnuDebugLink, DebugOrErr.getError());
     auto Debug = std::move(*DebugOrErr);
-    JamCRC CRC;
-    CRC.update(
-        ArrayRef<char>(Debug->getBuffer().data(), Debug->getBuffer().size()));
-    // The CRC32 value needs to be complemented because the JamCRC doesn't
-    // finalize the CRC32 value.
-    Config.GnuDebugLinkCRC32 = ~CRC.getCRC();
+    Config.GnuDebugLinkCRC32 =
+        llvm::crc32(arrayRefFromStringRef(Debug->getBuffer()));
   }
   Config.BuildIdLinkDir = InputArgs.getLastArgValue(OBJCOPY_build_id_link_dir);
   if (InputArgs.hasArg(OBJCOPY_build_id_link_input))