Use the same constants as zlib to represent compression level.

This change allows users pass compression level that was not listed
in the enum. Also, I think using different values than zlib's
compression levels was just confusing.

Differential Revision: https://reviews.llvm.org/D50196

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338939 91177308-0d34-0410-b5e6-96231b3b80d8

Author: rui314

include/llvm/Support/Compression.h

@@ -23,17 +23,15 @@ class StringRef;
 
 namespace zlib {
 
-enum CompressionLevel {
-  NoCompression,
-  DefaultCompression,
-  BestSpeedCompression,
-  BestSizeCompression
-};
+static constexpr int NoCompression = 0;
+static constexpr int BestSpeedCompression = 1;
+static constexpr int DefaultCompression = 6;
+static constexpr int BestSizeCompression = 9;
 
 bool isAvailable();
 
 Error compress(StringRef InputBuffer, SmallVectorImpl<char> &CompressedBuffer,
-               CompressionLevel Level = DefaultCompression);
+               int Level = DefaultCompression);
 
 Error uncompress(StringRef InputBuffer, char *UncompressedBuffer,
                  size_t &UncompressedSize);
@@ -49,4 +47,3 @@ uint32_t crc32(StringRef Buffer);
 } // End of namespace llvm
 
 #endif
-

lib/Support/Compression.cpp

@@ -29,16 +29,6 @@ static Error createError(StringRef Err) {
   return make_error<StringError>(Err, inconvertibleErrorCode());
 }
 
-static int encodeZlibCompressionLevel(zlib::CompressionLevel Level) {
-  switch (Level) {
-    case zlib::NoCompression: return 0;
-    case zlib::BestSpeedCompression: return 1;
-    case zlib::DefaultCompression: return Z_DEFAULT_COMPRESSION;
-    case zlib::BestSizeCompression: return 9;
-  }
-  llvm_unreachable("Invalid zlib::CompressionLevel!");
-}
-
 static StringRef convertZlibCodeToString(int Code) {
   switch (Code) {
   case Z_MEM_ERROR:
@@ -58,14 +48,12 @@ static StringRef convertZlibCodeToString(int Code) {
 bool zlib::isAvailable() { return true; }
 
 Error zlib::compress(StringRef InputBuffer,
-                     SmallVectorImpl<char> &CompressedBuffer,
-                     CompressionLevel Level) {
+                     SmallVectorImpl<char> &CompressedBuffer, int Level) {
   unsigned long CompressedSize = ::compressBound(InputBuffer.size());
   CompressedBuffer.reserve(CompressedSize);
-  int CLevel = encodeZlibCompressionLevel(Level);
-  int Res = ::compress2((Bytef *)CompressedBuffer.data(), &CompressedSize,
-                        (const Bytef *)InputBuffer.data(), InputBuffer.size(),
-                        CLevel);
+  int Res =
+      ::compress2((Bytef *)CompressedBuffer.data(), &CompressedSize,
+                  (const Bytef *)InputBuffer.data(), InputBuffer.size(), Level);
   // Tell MemorySanitizer that zlib output buffer is fully initialized.
   // This avoids a false report when running LLVM with uninstrumented ZLib.
   __msan_unpoison(CompressedBuffer.data(), CompressedSize);
@@ -118,4 +106,3 @@ uint32_t zlib::crc32(StringRef Buffer) {
   llvm_unreachable("zlib::crc32 is unavailable");
 }
 #endif
-

unittests/Support/CompressionTest.cpp

@@ -24,7 +24,7 @@ namespace {
 
 #if LLVM_ENABLE_ZLIB == 1 && HAVE_LIBZ
 
-void TestZlibCompression(StringRef Input, zlib::CompressionLevel Level) {
+void TestZlibCompression(StringRef Input, int Level) {
   SmallString<32> Compressed;
   SmallString<32> Uncompressed;