[AArch64] Add ptrauth + BTI support.

Author: ahmedbougacha

clang/include/clang/Driver/Options.td

@@ -3889,6 +3889,8 @@ let Group = f_Group in {
       HelpText<"Enable type discrimination of vtable pointers">;
     def fptrauth_soft : Flag<["-"], "fptrauth-soft">,
       HelpText<"Enable software lowering of pointer authentication">;
+    def fbranch_target_identification : Flag<["-"], "fbranch-target-identification">,
+      HelpText<"Emit branch target identification instructions for indirect branch destinations">;
     def fptrauth_block_descriptor_pointers : Flag<["-"], "fptrauth-block-descriptor-pointers">,
       HelpText<"enable signing block descriptors">;
     def fptrauth_function_pointer_type_discrimination : Flag<["-"], "fptrauth-function-pointer-type-discrimination">,
@@ -3910,6 +3912,7 @@ let Group = f_Group in {
   def fno_ptrauth_objc_isa : Flag<["-"], "fno-ptrauth-objc-isa">;
   def fno_ptrauth_block_descriptor_pointers : Flag<["-"], "fno-ptrauth-block-descriptor-pointers">;
   def fno_ptrauth_function_pointer_type_discrimination : Flag<["-"], "fno-ptrauth-function-pointer-type-discrimination">;
+  def fno_branch_target_identification : Flag<["-"], "fno-branch-target-identification">;
 }
 
 let Group = f_Group in {

clang/lib/Driver/ToolChains/Clang.cpp

@@ -7023,6 +7023,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
           options::OPT_fno_ptrauth_function_pointer_type_discrimination, false))
     CmdArgs.push_back("-fptrauth-function-pointer-type-discrimination");
 
+  if (Args.hasArg(options::OPT_fbranch_target_identification,
+                  options::OPT_fno_branch_target_identification, false))
+    CmdArgs.push_back("-mbranch-target-enforce");
+
 
   // -fsigned-bitfields is default, and clang doesn't yet support
   // -funsigned-bitfields.

clang/test/CodeGen/ptrauth-function-attributes.c

@@ -12,11 +12,15 @@
 // RUN: %clang_cc1 -triple arm64e-apple-ios -fptrauth-auth-traps -emit-llvm %s -o - | FileCheck %s --check-prefixes=ALL,TRAPS
 // RUN: %clang_cc1 -triple arm64e-apple-ios                      -emit-llvm %s -o - | FileCheck %s --check-prefixes=ALL,OFF
 
+// RUN: %clang_cc1 -triple arm64e-apple-ios  -mbranch-target-enforce -emit-llvm %s -o - | FileCheck %s --check-prefixes=ALL,BTI
+
 // ALL-LABEL: define void @test() #0
 void test() {
 }
 
 // RETS: attributes #0 = {{{.*}} "ptrauth-returns" {{.*}}}
 // CALLS: attributes #0 = {{{.*}} "ptrauth-calls" {{.*}}}
 // TRAPS: attributes #0 = {{{.*}} "ptrauth-auth-traps" {{.*}}}
+// BTI: !1 = !{i32 8, !"branch-target-enforcement", i32 1}
 // OFF-NOT: attributes {{.*}} "ptrauth-
+// OFF-NOT: !"branch-target-enforcement"

clang/test/Driver/arch-arm64e.c

@@ -7,6 +7,7 @@
 // NONE-NOT: "-fptrauth-returns"
 // NONE-NOT: "-fptrauth-auth-traps"
 // NONE-NOT: "-fptrauth-soft"
+// NONE-NOT: "-mbranch-target-enforce"
 
 // RUN: %clang -target arm64-apple-ios -fptrauth-calls -c %s -### 2>&1 | FileCheck %s --check-prefix CALL
 // CALL: "-cc1"{{.*}} {{.*}} "-fptrauth-calls"
@@ -23,6 +24,9 @@
 // RUN: %clang -target arm64-apple-ios -fptrauth-soft -c %s -### 2>&1 | FileCheck %s --check-prefix SOFT
 // SOFT: "-cc1"{{.*}} {{.*}} "-fptrauth-soft"
 
+// RUN: %clang -target arm64-apple-ios -fbranch-target-identification -c %s -### 2>&1 | FileCheck %s --check-prefix BTI
+// BTI: "-cc1"{{.*}} {{.*}} "-mbranch-target-enforce"
+
 
 // Check the arm64e defaults.
 // isa signing is configurable at cmake time, so it's not useful to check the default.