[Support/Compression] - Change zlib API to return Error instead of custom status.

[grimar]

Summary

Previously API returned custom enum values.
Patch changes it to return Error with string description.
That should help users to report errors in universal way.

[grimar]

• Addressed review comments.

include/llvm/Support/Compression.h

 
 #ifndef LLVM_SUPPORT_COMPRESSION_H
 #define LLVM_SUPPORT_COMPRESSION_H
 
 #include "llvm/Support/DataTypes.h"
 
 namespace llvm {
 template <typename T> class SmallVectorImpl;
+class Error;
 class StringRef;
 
 namespace zlib {
 
 enum CompressionLevel {
   NoCompression,
   DefaultCompression,
   BestSpeedCompression,
   BestSizeCompression
 };
 
-enum Status {
-  StatusOK,
-  StatusUnsupported,    // zlib is unavailable
-  StatusOutOfMemory,    // there was not enough memory
-  StatusBufferTooShort, // there was not enough room in the output buffer
-  StatusInvalidArg,     // invalid input parameter
-  StatusInvalidData     // data was corrupted or incomplete
-};
-
 bool isAvailable();
 
-Status compress(StringRef InputBuffer, SmallVectorImpl<char> &CompressedBuffer,
-                CompressionLevel Level = DefaultCompression);
+Error compress(StringRef InputBuffer, SmallVectorImpl<char> &CompressedBuffer,
 
-Status uncompress(StringRef InputBuffer, char *UncompressedBuffer,
-                  size_t &UncompressedSize);
+Error uncompress(StringRef InputBuffer, char *UncompressedBuffer,
 
-Status uncompress(StringRef InputBuffer,
-                  SmallVectorImpl<char> &UncompressedBuffer,
-                  size_t UncompressedSize);
+Error uncompress(StringRef InputBuffer,
 
 uint32_t crc32(StringRef Buffer);
 
 }  // End of namespace zlib
 
 } // End of namespace llvm
 
 #endif
 

lib/MC/ELFObjectWriter.cpp

 #include "llvm/MC/MCSectionELF.h"
 #include "llvm/MC/MCSymbolELF.h"
 #include "llvm/MC/MCValue.h"
 #include "llvm/MC/StringTableBuilder.h"
 #include "llvm/Support/Compression.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ELF.h"
 #include "llvm/Support/Endian.h"
+#include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/StringSaver.h"
 #include <vector>
 
 using namespace llvm;
 
 #undef  DEBUG_TYPE
 #define DEBUG_TYPE "reloc-info"
void ELFObjectWriter::writeSectionData(const MCAssembler &Asm, MCSection &Sec,
   SmallVector<char, 128> UncompressedData;
   raw_svector_ostream VecOS(UncompressedData);
   raw_pwrite_stream &OldStream = getStream();
   setStream(VecOS);
   Asm.writeSectionData(&Section, Layout);
   setStream(OldStream);
 
   SmallVector<char, 128> CompressedContents;
-  zlib::Status Success = zlib::compress(
+  if (Error E = zlib::compress(
           StringRef(UncompressedData.data(), UncompressedData.size()),
-      CompressedContents);
-  if (Success != zlib::StatusOK) {
+          CompressedContents)) {
     getStream() << UncompressedData;
     return;
   }
 
   bool ZlibStyle = Asm.getContext().getAsmInfo()->compressDebugSections() ==
                    DebugCompressionType::DCT_Zlib;
   if (!maybeWriteCompression(UncompressedData.size(), CompressedContents,
                              ZlibStyle, Sec.getAlignment())) {

lib/Object/Decompressor.cpp

 
 Error Decompressor::decompress(SmallString<32> &Out) {
   Out.resize(DecompressedSize);
   return decompress({Out.data(), (size_t)DecompressedSize});
 }
 
 Error Decompressor::decompress(MutableArrayRef<char> Buffer) {
   size_t Size = Buffer.size();
-  zlib::Status Status = zlib::uncompress(SectionData, Buffer.data(), Size);
-  if (Status != zlib::StatusOK)
-    return createError("decompression failed");
-  return Error::success();
+  return zlib::uncompress(SectionData, Buffer.data(), Size);
 }

lib/ProfileData/InstrProf.cpp

auto WriteStringToResult = [&](size_t CompressedLen, StringRef InputStr) {
     return Error::success();
   };
 
   if (!doCompression) {
     return WriteStringToResult(0, UncompressedNameStrings);
   }
 
   SmallString<128> CompressedNameStrings;
-  zlib::Status Success =
-      zlib::compress(StringRef(UncompressedNameStrings), CompressedNameStrings,
-                     zlib::BestSizeCompression);
-
-  if (Success != zlib::StatusOK)
+  Error E = zlib::compress(StringRef(UncompressedNameStrings),
+                           CompressedNameStrings, zlib::BestSizeCompression);
+  if (E)
     return make_error<InstrProfError>(instrprof_error::compress_failed);
 
   return WriteStringToResult(CompressedNameStrings.size(),
                              CompressedNameStrings);
 }
 
 StringRef getPGOFuncNameVarInitializer(GlobalVariable *NameVar) {
   auto *Arr = cast<ConstantDataArray>(NameVar->getInitializer());
while (P < EndP) {
     uint64_t CompressedSize = decodeULEB128(P, &N);
     P += N;
     bool isCompressed = (CompressedSize != 0);
     SmallString<128> UncompressedNameStrings;
     StringRef NameStrings;
     if (isCompressed) {
       StringRef CompressedNameStrings(reinterpret_cast<const char *>(P),
                                       CompressedSize);
-      if (zlib::uncompress(CompressedNameStrings, UncompressedNameStrings,
-                           UncompressedSize) != zlib::StatusOK)
+      if (Error E = zlib::uncompress(CompressedNameStrings,
+                                     UncompressedNameStrings, UncompressedSize))
         return make_error<InstrProfError>(instrprof_error::uncompress_failed);
       P += CompressedSize;
       NameStrings = StringRef(UncompressedNameStrings.data(),
                               UncompressedNameStrings.size());
     } else {
       NameStrings =
           StringRef(reinterpret_cast<const char *>(P), UncompressedSize);
       P += UncompressedSize;

lib/Support/Compression.cpp

 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/Compression.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Config/config.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
 #if LLVM_ENABLE_ZLIB == 1 && HAVE_ZLIB_H
 #include <zlib.h>
 #endif
 
 using namespace llvm;
 
 #if LLVM_ENABLE_ZLIB == 1 && HAVE_LIBZ
+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 zlib::Status encodeZlibReturnValue(int ReturnValue) {
-  switch (ReturnValue) {
-    case Z_OK: return zlib::StatusOK;
-    case Z_MEM_ERROR: return zlib::StatusOutOfMemory;
-    case Z_BUF_ERROR: return zlib::StatusBufferTooShort;
-    case Z_STREAM_ERROR: return zlib::StatusInvalidArg;
-    case Z_DATA_ERROR: return zlib::StatusInvalidData;
-    default: llvm_unreachable("unknown zlib return status!");
+static StringRef ZlibCodeToString(int Code) {
+  switch (Code) {
+  case Z_MEM_ERROR:
+    return "zlib error: Z_MEM_ERROR";
+  case Z_BUF_ERROR:
+    return "zlib error: Z_BUF_ERROR";
+  case Z_STREAM_ERROR:
+    return "zlib error: Z_STREAM_ERROR";
+  case Z_DATA_ERROR:
+    return "zlib error: Z_DATA_ERROR";
+  case Z_OK:
+  default:
+    llvm_unreachable("unknown or unexpected zlib status code");
   }
 }
 
 bool zlib::isAvailable() { return true; }
-zlib::Status zlib::compress(StringRef InputBuffer,
-                            SmallVectorImpl<char> &CompressedBuffer,
-                            CompressionLevel Level) {
+
+Error zlib::compress(StringRef InputBuffer,
   unsigned long CompressedSize = ::compressBound(InputBuffer.size());
   CompressedBuffer.resize(CompressedSize);
   int CLevel = encodeZlibCompressionLevel(Level);
-  Status Res = encodeZlibReturnValue(::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(),
+                        CLevel);
   // 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);
   CompressedBuffer.resize(CompressedSize);
-  return Res;
+  return Res ? createError(ZlibCodeToString(Res)) : Error::success();
 }
 
-zlib::Status zlib::uncompress(StringRef InputBuffer, char *UncompressedBuffer,
-                              size_t &UncompressedSize) {
-  Status Res = encodeZlibReturnValue(
+Error zlib::uncompress(StringRef InputBuffer, char *UncompressedBuffer,
+  int Res =
       ::uncompress((Bytef *)UncompressedBuffer, (uLongf *)&UncompressedSize,
-                   (const Bytef *)InputBuffer.data(), InputBuffer.size()));
+                   (const Bytef *)InputBuffer.data(), InputBuffer.size());
   // Tell MemorySanitizer that zlib output buffer is fully initialized.
   // This avoids a false report when running LLVM with uninstrumented ZLib.
   __msan_unpoison(UncompressedBuffer, UncompressedSize);
-  return Res;
+  return Res ? createError(ZlibCodeToString(Res)) : Error::success();
 }
 
-zlib::Status zlib::uncompress(StringRef InputBuffer,
-                              SmallVectorImpl<char> &UncompressedBuffer,
-                              size_t UncompressedSize) {
+Error zlib::uncompress(StringRef InputBuffer,
   UncompressedBuffer.resize(UncompressedSize);
-  Status Res =
+  Error E =
       uncompress(InputBuffer, UncompressedBuffer.data(), UncompressedSize);
   UncompressedBuffer.resize(UncompressedSize);
-  return Res;
+  return E;
 }
 
 uint32_t zlib::crc32(StringRef Buffer) {
   return ::crc32(0, (const Bytef *)Buffer.data(), Buffer.size());
 }
 
 #else
 bool zlib::isAvailable() { return false; }
-zlib::Status zlib::compress(StringRef InputBuffer,
-                            SmallVectorImpl<char> &CompressedBuffer,
-                            CompressionLevel Level) {
-  return zlib::StatusUnsupported;
+Error zlib::compress(StringRef InputBuffer,
+  llvm_unreachable("zlib::compress is unavailable");
 }
-zlib::Status zlib::uncompress(StringRef InputBuffer, char *UncompressedBuffer,
-                              size_t &UncompressedSize) {
-  return zlib::StatusUnsupported;
+Error zlib::uncompress(StringRef InputBuffer, char *UncompressedBuffer,
+  llvm_unreachable("zlib::uncompress is unavailable");
 }
-zlib::Status zlib::uncompress(StringRef InputBuffer,
-                              SmallVectorImpl<char> &UncompressedBuffer,
-                              size_t UncompressedSize) {
-  return zlib::StatusUnsupported;
+Error zlib::uncompress(StringRef InputBuffer,
+  llvm_unreachable("zlib::uncompress is unavailable");
 }
 uint32_t zlib::crc32(StringRef Buffer) {
   llvm_unreachable("zlib::crc32 is unavailable");
 }
 #endif
 

unittests/Support/CompressionTest.cpp

 //===- llvm/unittest/Support/CompressionTest.cpp - Compression tests ------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements unit tests for the Compression functions.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/Compression.h"
+#include "llvm/Support/Error.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Config/config.h"
 #include "gtest/gtest.h"
 
 using namespace llvm;
 
 namespace {
 
 #if LLVM_ENABLE_ZLIB == 1 && HAVE_LIBZ
 
 void TestZlibCompression(StringRef Input, zlib::CompressionLevel Level) {
   SmallString<32> Compressed;
   SmallString<32> Uncompressed;
-  EXPECT_EQ(zlib::StatusOK, zlib::compress(Input, Compressed, Level));
+  Error E = zlib::compress(Input, Compressed, Level);
+  EXPECT_FALSE(E);
   // Check that uncompressed buffer is the same as original.
-  EXPECT_EQ(zlib::StatusOK,
-            zlib::uncompress(Compressed, Uncompressed, Input.size()));
+  E = zlib::uncompress(Compressed, Uncompressed, Input.size());
+  EXPECT_FALSE(E);
   EXPECT_EQ(Input, Uncompressed);
   if (Input.size() > 0) {
     // Uncompression fails if expected length is too short.
-    EXPECT_EQ(zlib::StatusBufferTooShort,
-              zlib::uncompress(Compressed, Uncompressed, Input.size() - 1));
+    E = zlib::uncompress(Compressed, Uncompressed, Input.size() - 1);
+    EXPECT_EQ("zlib error: Z_BUF_ERROR", llvm::toString(std::move(E)));
   }
 }
 
 TEST(CompressionTest, Zlib) {
   TestZlibCompression("", zlib::DefaultCompression);
 
   TestZlibCompression("hello, world!", zlib::NoCompression);
   TestZlibCompression("hello, world!", zlib::BestSizeCompression);