[llvm] Fix compress/decompress in LLVM Offloading API (PR #150064)

[James Henderson via llvm-commits]

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@@ -260,11 +299,233 @@ static std::string formatWithCommas(unsigned long long Value) {
 }
 
 llvm::Expected<std::unique_ptr<llvm::MemoryBuffer>>
-CompressedOffloadBundle::decompress(llvm::MemoryBufferRef &Input,
+CompressedOffloadBundle::compress(llvm::compression::Params P,
+                                  const llvm::MemoryBuffer &Input,
+                                  uint16_t Version, bool Verbose) {
+  if (!llvm::compression::zstd::isAvailable() &&
+      !llvm::compression::zlib::isAvailable())
+    return createStringError(llvm::inconvertibleErrorCode(),
+                             "Compression not supported");
+  llvm::Timer HashTimer("Hash Calculation Timer", "Hash calculation time",
+                        OffloadBundlerTimerGroup);
+  if (Verbose)
+    HashTimer.startTimer();
+  llvm::MD5 Hash;
+  llvm::MD5::MD5Result Result;
+  Hash.update(Input.getBuffer());
+  Hash.final(Result);
+  uint64_t TruncatedHash = Result.low();
+  if (Verbose)
+    HashTimer.stopTimer();
+
+  SmallVector<uint8_t, 0> CompressedBuffer;
+  auto BufferUint8 = llvm::ArrayRef<uint8_t>(
+      reinterpret_cast<const uint8_t *>(Input.getBuffer().data()),
+      Input.getBuffer().size());
+  llvm::Timer CompressTimer("Compression Timer", "Compression time",
+                            OffloadBundlerTimerGroup);
+  if (Verbose)
+    CompressTimer.startTimer();
+  llvm::compression::compress(P, BufferUint8, CompressedBuffer);
+  if (Verbose)
+    CompressTimer.stopTimer();
+
+  uint16_t CompressionMethod = static_cast<uint16_t>(P.format);
+
+  // Store sizes in 64-bit variables first
+  uint64_t UncompressedSize64 = Input.getBuffer().size();
+  uint64_t TotalFileSize64;
+
+  // Calculate total file size based on version
+  if (Version == 2) {
+    // For V2, ensure the sizes don't exceed 32-bit limit
+    if (UncompressedSize64 > std::numeric_limits<uint32_t>::max())
+      return createStringError(llvm::inconvertibleErrorCode(),
+                               "Uncompressed size exceeds version 2 limit");
+    if ((MagicNumber.size() + sizeof(uint32_t) + sizeof(Version) +
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jh7370 wrote:

Do we need to worry about overflows too?

https://github.com/llvm/llvm-project/pull/150064