[PtrAuth] Adopt AsyncContextResume schema.

Author: nate-chandler

include/swift/AST/IRGenOptions.h

@@ -140,6 +140,9 @@ struct PointerAuthOptions : clang::PointerAuthOptions {
 
   /// The parent async context stored within a child async context.
   PointerAuthSchema AsyncContextParent;
+
+  /// The function to call to resume running in the parent context.
+  PointerAuthSchema AsyncContextResume;
 };
 
 enum class JITDebugArtifact : unsigned {

lib/IRGen/GenCall.cpp

@@ -2374,8 +2374,7 @@ class AsyncCallEmission final : public CallEmission {
           llvm::Intrinsic::coro_async_resume, {});
       auto fnVal = currentResumeFn;
       // Sign the pointer.
-      // TODO: use a distinct schema.
-      if (auto schema = IGF.IGM.getOptions().PointerAuth.AsyncContextParent) {
+      if (auto schema = IGF.IGM.getOptions().PointerAuth.AsyncContextResume) {
         Address fieldAddr =
             fieldLayout.project(IGF, this->context, /*offsets*/ llvm::None);
         auto authInfo = PointerAuthInfo::emit(
@@ -4577,8 +4576,7 @@ void irgen::emitAsyncReturn(IRGenFunction &IGF, AsyncContextLayout &asyncLayout,
       .loadAsCopy(IGF, returnToCallerAddr, fn);
   llvm::Value *fnVal = fn.claimNext();
 
-  // TODO: use distinct schema
-  if (auto schema = IGF.IGM.getOptions().PointerAuth.AsyncContextParent) {
+  if (auto schema = IGF.IGM.getOptions().PointerAuth.AsyncContextResume) {
     Address fieldAddr =
         returnToCallerLayout.project(IGF, contextAddr, /*offsets*/ llvm::None);
     auto authInfo = PointerAuthInfo::emit(IGF, schema, fieldAddr.getAddress(),

lib/IRGen/IRGen.cpp

@@ -692,6 +692,10 @@ static void setPointerAuthOptions(PointerAuthOptions &opts,
   opts.AsyncContextParent =
       PointerAuthSchema(codeKey, /*address*/ true, Discrimination::Constant,
                         SpecialPointerAuthDiscriminators::AsyncContextParent);
+
+  opts.AsyncContextResume =
+      PointerAuthSchema(codeKey, /*address*/ true, Discrimination::Constant,
+                        SpecialPointerAuthDiscriminators::AsyncContextResume);
 }
 
 std::unique_ptr<llvm::TargetMachine>