[PAC][ELF][AArch64] Support signed personality function pointer (#119361)

Re-apply #113148 after revert in #119331

If function pointer signing is enabled, sign personality function
pointer stored in `.DW.ref.__gxx_personality_v0` section with IA key,
0x7EAD = `ptrauth_string_discriminator("personality")` constant
discriminator and address diversity enabled.

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MachineModuleInfoImpls.cpp b/llvm/lib/CodeGen/MachineModuleInfoImpls.cpp
index 9563175..5c5f4b6 100644
--- a/llvm/lib/CodeGen/MachineModuleInfoImpls.cpp
+++ b/llvm/lib/CodeGen/MachineModuleInfoImpls.cpp
@@ -14,6 +14,8 @@
 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Module.h"
 #include "llvm/MC/MCSymbol.h"
 
 using namespace llvm;
@@ -59,3 +61,10 @@ MachineModuleInfoImpl::ExprStubListTy MachineModuleInfoImpl::getSortedExprStubs(
   ExprStubs.clear();
   return List;
 }
+
+MachineModuleInfoELF::MachineModuleInfoELF(const MachineModuleInfo &MMI) {
+  const Module *M = MMI.getModule();
+  const auto *Flag = mdconst::extract_or_null<ConstantInt>(
+      M->getModuleFlag("ptrauth-sign-personality"));
+  HasSignedPersonality = Flag && Flag->getZExtValue() == 1;
+}