[llvm] [llvm-profgen] Improve sample profile density (PR #92144)

[via llvm-commits]

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@@ -768,9 +748,89 @@ void ProfileGenerator::populateBoundarySamplesForAllFunctions(
   }
 }
 
+// Note taht ideally the size should be the number of function's instruction.
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WenleiHe wrote:

type taht -> that

https://github.com/llvm/llvm-project/pull/92144