[llvm] [BOLT] Support runtime library hook via DT_INIT_ARRAY (PR #167467)

[Maksim Panchenko via llvm-commits]

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@@ -294,6 +295,28 @@ cl::bits<GadgetScannerKind> GadgetScannersToRun(
         clEnumValN(GS_ALL, "all", "All implemented scanners")),
     cl::ZeroOrMore, cl::CommaSeparated, cl::cat(BinaryAnalysisCategory));
 
+// Primary targets for hooking runtime library initialization hooking
+// with fallback to next item in case if current item is not available
+// in the input binary.
+enum RuntimeLibInitHookTarget : char {
+  RLIH_ENTRY_POINT = 0, /// Use ELF Header Entry Point
+  RLIH_INIT = 1,        /// Use ELF DT_INIT entry
+  RLIH_INIT_ARRAY = 2,  /// Use ELF 1st entry of .init_array
+};
+
+cl::opt<RuntimeLibInitHookTarget> RuntimeLibInitHook(
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maksfb wrote:

Do you consider this an "expert" option, i.e. only used by < 1% of the users? If so, let's make it `cl::Hidden`.

https://github.com/llvm/llvm-project/pull/167467