[Support] Check zstd decompress result before msan unpoison

[yingcong-wu]

We should check the zstd decompress result before doing the msan unpoison. If the res is abnormal, then it would be a huge number, which will cause undesired msan unpoison behavior and will run for a long time.

[llvmbot]

@llvm/pr-subscribers-llvm-support

Author: Wu Yingcong (yingcong-wu)

Changes

We should check the zstd decompress result before doing the msan unpoison. If the res is abnormal, then it would be a huge number, which will cause undesired msan unpoison behavior and will run for a long time.

---

Full diff: https://github.com/llvm/llvm-project/pull/117276.diff

1 Files Affected:

• (modified) llvm/lib/Support/Compression.cpp (+4-3)

diff --git a/llvm/lib/Support/Compression.cpp b/llvm/lib/Support/Compression.cpp
index badaf68ab59cd0..3979ca6acaf74e 100644
--- a/llvm/lib/Support/Compression.cpp
+++ b/llvm/lib/Support/Compression.cpp
@@ -206,12 +206,13 @@ Error zstd::decompress(ArrayRef<uint8_t> Input, uint8_t *Output,
   const size_t Res = ::ZSTD_decompress(
       Output, UncompressedSize, (const uint8_t *)Input.data(), Input.size());
   UncompressedSize = Res;
+  if (ZSTD_isError(Res))
+    return make_error<StringError>(ZSTD_getErrorName(Res),
+                                   inconvertibleErrorCode());
   // Tell MemorySanitizer that zstd output buffer is fully initialized.
   // This avoids a false report when running LLVM with uninstrumented ZLib.
   __msan_unpoison(Output, UncompressedSize);
-  return ZSTD_isError(Res) ? make_error<StringError>(ZSTD_getErrorName(Res),
-                                                     inconvertibleErrorCode())
-                           : Error::success();
+  return Error::success();
 }
 
 Error zstd::decompress(ArrayRef<uint8_t> Input,

[yingcong-wu]

For the CI failure, I think the test result looks good, the problem seems to be with

python3 /var/lib/buildkite-agent/builds/linux-56-59b8f5d88-mqg5l-1/llvm-project/github-pull-requests/.ci/generate_test_report.py

Does it count as an infrastructure problem?