[GitHub] [orc] guiyanakuang commented on a change in pull request #958: ORC-1041: Fix the implementation of copy data blocks during LZO decompression

[GitBox <gi...@apache.org>]

guiyanakuang commented on a change in pull request #958:
URL: https://github.com/apache/orc/pull/958#discussion_r742480546



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File path: c++/src/LzoDecompressor.cc
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@@ -312,13 +312,11 @@ namespace orc {
               output += SIZE_OF_INT;
               matchAddress += increment32;
 
-              *reinterpret_cast<int32_t*>(output) =
-                *reinterpret_cast<int32_t*>(matchAddress);
+              memcpy(output, matchAddress, SIZE_OF_INT);

Review comment:
       > The combination of `reinterpret_cast` + `assignment` looks cheaper than `memcpy` function invocation. I'm wondering if we need to pay some performance penalty here.
   
   I'll do some performance tests later, `repeat_cast` + `assignment` makes direct use of registers, `memcpy` is usually used for larger copies of data, I'm not sure if it's lossy yet
   




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