[PATCH] D128465: [llvm] add zstd to `llvm::compression` namespace

[Fangrui Song via Phabricator via cfe-commits]

MaskRay added inline comments.


================
Comment at: llvm/include/llvm/Support/Compression.h:48
+
+constexpr int NoCompression = -5;
+constexpr int BestSpeedCompression = 1;
----------------
MaskRay wrote:
> I missed the values here. Why is -5 picked for NoCompression? What does it mean?
> 
> zstd.h says ZSTD_maxCLevel() is currently 22. The CLI program mentions 19. Why is BestSizeCompression 12?
> 
> ZSTD_CLEVEL_DEFAULT/the CLI CLI uses 3 for the default level. Why is DefaultCompression 5?
Ping @ckissane about the choice.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D128465/new/

https://reviews.llvm.org/D128465