[llvm] [SampleProfile] Fix bug where remapper returns empty string and crashing Sample Profile loader (PR #71479)

[Mingming Liu via llvm-commits]

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@@ -1630,7 +1630,7 @@ void SampleProfileLoader::promoteMergeNotInlinedContextSamples(
         // separate map so that it does not rehash the original profile.
         if (!OutlineFS)
           OutlineFS = &OutlineFunctionSamples[
-              FunctionSamples::getCanonicalFnName(Callee->getName())];
+              FunctionId(FunctionSamples::getCanonicalFnName(Callee->getName()))];
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minglotus-6 wrote:

pretty much a drive-by comment

It seems to me `SampleContext` could take either a StringRef or a FunctionId in its constructor, and the former asserts names are not empty (https://github.com/llvm/llvm-project/blob/5f295552f1eb9b00efe0d83c5f8e6c9b948cb238/llvm/include/llvm/ProfileData/SampleProf.h#L529) while the latter doesn't (`FunctionId` ctor doesn't require names are not empty either); and this PR wants to fix a crash for the former constructor.

If I understand correctly, is this `FunctionId` needed here and below?

https://github.com/llvm/llvm-project/pull/71479