[AArch64][PAC] Support ptrauth builtins and -fptrauth-intrinsics. (#65996)

This defines the basic set of pointer authentication clang builtins
(provided in a new header, ptrauth.h), with diagnostics and IRGen
support.  The availability of the builtins is gated on a new flag,
`-fptrauth-intrinsics`.

Note that this only includes the basic intrinsics, and notably excludes
`ptrauth_sign_constant`, `ptrauth_type_discriminator`, and
`ptrauth_string_discriminator`, which need extra logic to be fully
supported.

This also introduces clang/docs/PointerAuthentication.rst, which
describes the ptrauth model in general, in addition to these builtins.

Co-Authored-By: Akira Hatanaka <ahatanaka@apple.com>
Co-Authored-By: John McCall <rjmccall@apple.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 2d3cbb9..2a21a9d 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -3293,6 +3293,17 @@ static void ParseAPINotesArgs(APINotesOptions &Opts, ArgList &Args,
     Opts.ModuleSearchPaths.push_back(A->getValue());
 }
 
+static void GeneratePointerAuthArgs(const LangOptions &Opts,
+                                    ArgumentConsumer Consumer) {
+  if (Opts.PointerAuthIntrinsics)
+    GenerateArg(Consumer, OPT_fptrauth_intrinsics);
+}
+
+static void ParsePointerAuthArgs(LangOptions &Opts, ArgList &Args,
+                                 DiagnosticsEngine &Diags) {
+  Opts.PointerAuthIntrinsics = Args.hasArg(OPT_fptrauth_intrinsics);
+}
+
 /// Check if input file kind and language standard are compatible.
 static bool IsInputCompatibleWithStandard(InputKind IK,
                                           const LangStandard &S) {
@@ -4613,6 +4624,8 @@ bool CompilerInvocation::CreateFromArgsImpl(
                         Res.getFileSystemOpts().WorkingDir);
   ParseAPINotesArgs(Res.getAPINotesOpts(), Args, Diags);
 
+  ParsePointerAuthArgs(LangOpts, Args, Diags);
+
   ParseLangArgs(LangOpts, Args, DashX, T, Res.getPreprocessorOpts().Includes,
                 Diags);
   if (Res.getFrontendOpts().ProgramAction == frontend::RewriteObjC)
@@ -4843,6 +4856,7 @@ void CompilerInvocationBase::generateCC1CommandLine(
   GenerateTargetArgs(getTargetOpts(), Consumer);
   GenerateHeaderSearchArgs(getHeaderSearchOpts(), Consumer);
   GenerateAPINotesArgs(getAPINotesOpts(), Consumer);
+  GeneratePointerAuthArgs(getLangOpts(), Consumer);
   GenerateLangArgs(getLangOpts(), Consumer, T, getFrontendOpts().DashX);
   GenerateCodeGenArgs(getCodeGenOpts(), Consumer, T,
                       getFrontendOpts().OutputFile, &getLangOpts());