[llvm] [BOLT][binary-analysis] Add initial pac-ret gadget scanner (PR #122304)

[Anatoly Trosinenko via llvm-commits]

================
@@ -3490,7 +3498,24 @@ void RewriteInstance::runOptimizationPasses() {
   BC->logBOLTErrorsAndQuitOnFatal(BinaryFunctionPassManager::runAllPasses(*BC));
 }
 
-void RewriteInstance::runBinaryAnalyses() {}
+void RewriteInstance::runBinaryAnalyses() {
+  NamedRegionTimer T("runBinaryAnalyses", "run binary analysis passes",
+                     TimerGroupName, TimerGroupDesc, opts::TimeRewrite);
+  BinaryFunctionPassManager Manager(*BC);
+  // FIXME: add a pass that warns about which functions do not have CFG,
+  // and therefore, analysis is most likely to be less accurate.
+  using GSK = opts::GadgetScannerKind;
+  // if no command line option was given, act as if "all" was specified.
+  if (opts::GadgetScannersToRun.size() == 0)
----------------
atrosinenko wrote:

```suggestion
  if (opts::GadgetScannersToRun.empty())
```

https://github.com/llvm/llvm-project/pull/122304