[clang] Improve documented sampling profiler steps to best known methods (PR #88438)

[Wei Xiao via cfe-commits]

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@@ -2443,27 +2443,29 @@ usual build cycle when using sample profilers for optimization:
    usual build flags that you always build your application with. The only
    requirement is that DWARF debug info including source line information is
    generated. This DWARF information is important for the profiler to be able
-   to map instructions back to source line locations.
+   to map instructions back to source line locations. The usefulness of this
+   DWARF information can be improved with the ``-fdebug-info-for-profiling``
+   and ``-funique-internal-linkage-names`` options.
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williamweixiao wrote:

do we also need  ``-fdebug-info-for-profiling`` and ``-funique-internal-linkage-names`` for step 4 ("-fprofile-sample-use=code.prof") ?

https://github.com/llvm/llvm-project/pull/88438