[llvm] [CSSPGO] Error out if the checksum mismatch is high (PR #84097)

[via llvm-commits]

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@@ -234,6 +234,21 @@ static cl::opt<unsigned> ProfileICPRelativeHotnessSkip(
     cl::desc(
         "Skip relative hotness check for ICP up to given number of targets."));
 
+static cl::opt<unsigned> HotFuncCutoffForStalenessError(
+    "hot-func-cutoff-for-staleness-error", cl::Hidden, cl::init(999000),
+    cl::desc("Hot function cutoff for staleness error. It's percentile value "
+             "(multiplied by 10000), e.g. 995000 for 99.5 percentile."));
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WenleiHe wrote:

nit, rephrase the description to be consistent with the ones in `ProfileSummaryBuilder.cpp`.

`A function is considered hot for staleness error check if its total sample count is above the specified percentile.`

https://github.com/llvm/llvm-project/pull/84097