[llvm] [llvm-profdata] Enabled functionality to write split-layout profile (PR #101795)

[William Junda Huang via llvm-commits]

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+RUN: llvm-profdata merge --sample --extbinary --split_layout %p/Inputs/sample-profile.proftext -o %t-output
+RUN: diff %t-output %p/Inputs/split-layout.profdata
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huangjd wrote:

And there's no point to represent that in text mode, because the point of split layout is to allow sample profile reader to skip reading an entire section when used by ThinLTO since samples without inline callsites provide no info to advise inlining. In text mode the profile is read sequentially anyways so you can't skip anything 

https://github.com/llvm/llvm-project/pull/101795