[arm64] Use static_cast instead of reinterpret_cast in CFI code

In a couple of places we cast between uintptr_t and uint64_t with a
reinterpret_cast. While this is correct when these types are aliased
to the same type, if they are defined to be different integral types
(while still of the same size), reinterpet_cast won't work.

Change-Id: I6e935c6c263d8df16f88659ac285faeb5e073add
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2614678Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Georgia Kouveli <georgia.kouveli@arm.com>
Cr-Commit-Position: refs/heads/master@{#71988}

src/execution/arm64/pointer-authentication-arm64.h

@@ -24,7 +24,7 @@ namespace internal {
 V8_INLINE Address PointerAuthentication::AuthenticatePC(
     Address* pc_address, unsigned offset_from_sp) {
   uint64_t sp = reinterpret_cast<uint64_t>(pc_address) + offset_from_sp;
-  uint64_t pc = reinterpret_cast<uint64_t>(*pc_address);
+  uint64_t pc = static_cast<uint64_t>(*pc_address);
 #ifdef USE_SIMULATOR
   pc = Simulator::AuthPAC(pc, sp, Simulator::kPACKeyIB,
                           Simulator::kInstructionPointer);
@@ -67,7 +67,7 @@ V8_INLINE void PointerAuthentication::ReplacePC(Address* pc_address,
                                                 Address new_pc,
                                                 int offset_from_sp) {
   uint64_t sp = reinterpret_cast<uint64_t>(pc_address) + offset_from_sp;
-  uint64_t old_pc = reinterpret_cast<uint64_t>(*pc_address);
+  uint64_t old_pc = static_cast<uint64_t>(*pc_address);
 #ifdef USE_SIMULATOR
   uint64_t auth_old_pc = Simulator::AuthPAC(old_pc, sp, Simulator::kPACKeyIB,
                                             Simulator::kInstructionPointer);