[llvm] [LFI][AArch64] Add rewrites for control flow (PR #192602)

[Nick Desaulniers via llvm-commits]

================
@@ -51,3 +51,14 @@ bool MCLFIRewriter::mayModifyRegister(const MCInst &Inst,
                                       MCRegister Reg) const {
   return InstInfo->get(Inst.getOpcode()).hasDefOfPhysReg(Inst, Reg, *RegInfo);
 }
+
+bool MCLFIRewriter::explicitlyModifiesRegister(const MCInst &Inst,
+                                               MCRegister Reg) const {
+  const MCInstrDesc &Desc = InstInfo->get(Inst.getOpcode());
+  for (unsigned I = 0, E = Desc.getNumDefs(); I != E; ++I) {
+    if (Desc.operands()[I].OperandType == MCOI::OPERAND_REGISTER &&
+        RegInfo->isSubRegisterEq(Reg, Inst.getOperand(I).getReg()))
+      return true;
+  }
----------------
nickdesaulniers wrote:

Also, do we need to worry about that second loop?

https://github.com/llvm/llvm-project/pull/192602