[AArch64][PAC][NFC] Make checkAuthenticatedRegister() return void (#92507)

The return value is not used. This change simplifies the upcoming fix

Author: igorkudrin

llvm/lib/Target/AArch64/AArch64PointerAuth.cpp

@@ -231,7 +231,7 @@ MachineMemOperand *createCheckMemOperand(MachineFunction &MF,
 
 } // namespace
 
-MachineBasicBlock &llvm::AArch64PAuth::checkAuthenticatedRegister(
+void llvm::AArch64PAuth::checkAuthenticatedRegister(
     MachineBasicBlock::iterator MBBI, AuthCheckMethod Method,
     Register AuthenticatedReg, Register TmpReg, bool UseIKey, unsigned BrkImm) {
 
@@ -246,13 +246,13 @@ MachineBasicBlock &llvm::AArch64PAuth::checkAuthenticatedRegister(
   default:
     break;
   case AuthCheckMethod::None:
-    return MBB;
+    return;
   case AuthCheckMethod::DummyLoad:
     BuildMI(MBB, MBBI, DL, TII->get(AArch64::LDRWui), getWRegFromXReg(TmpReg))
         .addReg(AuthenticatedReg)
         .addImm(0)
         .addMemOperand(createCheckMemOperand(MF, Subtarget));
-    return MBB;
+    return;
   }
 
   // Control flow has to be changed, so arrange new MBBs.
@@ -287,7 +287,7 @@ MachineBasicBlock &llvm::AArch64PAuth::checkAuthenticatedRegister(
         .addReg(TmpReg)
         .addImm(62)
         .addMBB(BreakBlock);
-    return *SuccessBlock;
+    return;
   case AuthCheckMethod::XPACHint:
     assert(AuthenticatedReg == AArch64::LR &&
            "XPACHint mode is only compatible with checking the LR register");
@@ -304,7 +304,7 @@ MachineBasicBlock &llvm::AArch64PAuth::checkAuthenticatedRegister(
     BuildMI(CheckBlock, DL, TII->get(AArch64::Bcc))
         .addImm(AArch64CC::NE)
         .addMBB(BreakBlock);
-    return *SuccessBlock;
+    return;
   }
   llvm_unreachable("Unknown AuthCheckMethod enum");
 }

llvm/lib/Target/AArch64/AArch64PointerAuth.h

@@ -98,14 +98,10 @@ enum class AuthCheckMethod {
 /// using an I-key or D-key and which register can be used as temporary.
 /// If an explicit BRK instruction is used to generate an exception, BrkImm
 /// specifies its immediate operand.
-///
-/// \returns The machine basic block containing the code that is executed
-///          after the check succeeds.
-MachineBasicBlock &checkAuthenticatedRegister(MachineBasicBlock::iterator MBBI,
-                                              AuthCheckMethod Method,
-                                              Register AuthenticatedReg,
-                                              Register TmpReg, bool UseIKey,
-                                              unsigned BrkImm);
+void checkAuthenticatedRegister(MachineBasicBlock::iterator MBBI,
+                                AuthCheckMethod Method,
+                                Register AuthenticatedReg, Register TmpReg,
+                                bool UseIKey, unsigned BrkImm);
 
 /// Returns the number of bytes added by checkAuthenticatedRegister.
 unsigned getCheckerSizeInBytes(AuthCheckMethod Method);