[AArch64] Enable return address signing for static ctors

[olista01]

Summary

Functions generated by clang and included in the .init_array section (such as static constructors) do not follow the usual code path for adding target-specific function attributes, so we have to add the return address signing attribute here too, as is currently done for the sanitisers.

[LukeCheeseman]

LGTM

lib/CodeGen/CGDeclCXX.cpp

llvm::Function *CodeGenModule::CreateGlobalInitOrDestructFunction(
   if (getLangOpts().Sanitize.has(SanitizerKind::SafeStack) &&
       !isInSanitizerBlacklist(SanitizerKind::SafeStack, Fn, Loc))
     Fn->addFnAttr(llvm::Attribute::SafeStack);
 
   if (getLangOpts().Sanitize.has(SanitizerKind::ShadowCallStack) &&
       !isInSanitizerBlacklist(SanitizerKind::ShadowCallStack, Fn, Loc))
     Fn->addFnAttr(llvm::Attribute::ShadowCallStack);
 
+  auto RASignKind = getCodeGenOpts().getSignReturnAddress();
+  if (RASignKind != CodeGenOptions::SignReturnAddressScope::None)
+    Fn->addFnAttr("sign-return-address",
+                  RASignKind == CodeGenOptions::SignReturnAddressScope::All
+                      ? "all"
+                      : "non-leaf");
   return Fn;
 }
 
 /// Create a global pointer to a function that will initialize a global
 /// variable.  The user has requested that this pointer be emitted in a specific
 /// section.
 void CodeGenModule::EmitPointerToInitFunc(const VarDecl *D,
                                           llvm::GlobalVariable *GV,

test/CodeGenCXX/aarch64-sign-return-address-static-ctor.cpp

+// RUN: %clang -target aarch64-arm-none-eabi -S -emit-llvm -o - -msign-return-address=none  %s | \
+// RUN: FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-NONE
+// RUN: %clang -target aarch64-arm-none-eabi -S -emit-llvm -o - -msign-return-address=non-leaf %s | \
+// RUN: FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-PARTIAL
+// RUN: %clang -target aarch64-arm-none-eabi -S -emit-llvm -o - -msign-return-address=all %s | \
+// RUN: FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-ALL
+
+struct Foo {
+  Foo() {}
+  ~Foo() {}
+};
+
+Foo f;
+
+// CHECK: @llvm.global_ctors {{.*}}i32 65535, void ()* @[[CTOR_FN:.*]], i8* null
+
+// CHECK: @[[CTOR_FN]]() #[[ATTR:[0-9]*]]
+
+// CHECK-NONE-NOT: attributes #[[ATTR]] = { {{.*}} "sign-return-address"={{.*}} }}
+// CHECK-PARTIAL: attributes #[[ATTR]] = { {{.*}} "sign-return-address"="non-leaf" {{.*}}}
+// CHECK-ALL: attributes #[[ATTR]] = { {{.*}} "sign-return-address"="all" {{.*}} }