[llvm] [BOLT] Gadget scanner: detect non-protected indirect calls (PR #131899)

[Jacob Bramley via llvm-commits]

================
@@ -277,6 +277,33 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
     }
   }
 
+  MCPhysReg
+  getRegUsedAsCallDest(const MCInst &Inst,
+                       bool &IsAuthenticatedInternally) const override {
+    assert(isCall(Inst) || isBranch(Inst));
+    IsAuthenticatedInternally = false;
+
+    switch (Inst.getOpcode()) {
+    case AArch64::BR:
+    case AArch64::BLR:
+      return Inst.getOperand(0).getReg();
+    case AArch64::BRAA:
+    case AArch64::BRAB:
+    case AArch64::BRAAZ:
+    case AArch64::BRABZ:
+    case AArch64::BLRAA:
+    case AArch64::BLRAB:
+    case AArch64::BLRAAZ:
+    case AArch64::BLRABZ:
+      IsAuthenticatedInternally = true;
+      return Inst.getOperand(0).getReg();
+    default:
+      if (isIndirectCall(Inst) || isIndirectBranch(Inst))
----------------
jacobbramley wrote:

As noted on another thread, I think `isIndirectCall()` needs updating, but then it'll work as an assertion (and a gate before this is called).

https://github.com/llvm/llvm-project/pull/131899