Use AvailabilityContext to check for concurrency availability

(cherry picked from commit 4d7854f)

Author: aschwaighofer

lib/IRGen/IRGenModule.cpp

@@ -1744,36 +1744,14 @@ const TypeLayoutEntry &IRGenModule::getTypeLayoutEntry(SILType T) {
   return Types.getTypeLayoutEntry(T);
 }
 
-/// Return whether FrameLowering should always set the "extended frame
-/// present" bit in FP, or set it based on a symbol in the runtime.
-static bool isSwiftAsyncContextIsDynamicallySet(llvm::Triple TT) {
-  // Older OS versions (particularly system unwinders) are confused by the
-  // Swift extended frame, so when building code that might be run on them we
-  // must dynamically query the concurrency library to determine whether
-  // extended frames should be flagged as present.
-  unsigned Major, Minor, Micro;
-  TT.getOSVersion(Major, Minor, Micro);
-  switch(TT.getOS()) {
-  default:
-    return false;
-  case llvm::Triple::IOS:
-  case llvm::Triple::TvOS:
-    return Major < 15;
-  case llvm::Triple::WatchOS:
-    return Major < 8;
-  case llvm::Triple::MacOSX:
-  case llvm::Triple::Darwin:
-    return Major < 12;
-  }
-}
 
 void IRGenModule::emitSwiftAsyncExtendedFrameInfoWeakRef() {
   if (!hasSwiftAsyncFunctionDef || extendedFramePointerFlagsWeakRef)
     return;
   if (IRGen.Opts.SwiftAsyncFramePointer !=
       SwiftAsyncFramePointerKind::Auto)
     return;
-  if (!isSwiftAsyncContextIsDynamicallySet(Triple))
+  if (isConcurrencyAvailable())
     return;
 
   // Emit a weak reference to the `swift_async_extendedFramePointerFlags` symbol
@@ -1785,3 +1763,10 @@ void IRGenModule::emitSwiftAsyncExtendedFrameInfoWeakRef() {
                                          llvm::GlobalValue::ExternalWeakLinkage, nullptr,
                                          symbolName);
 }
+
+bool IRGenModule::isConcurrencyAvailable() {
+  auto &ctx = getSwiftModule()->getASTContext();
+  auto deploymentAvailability =
+    AvailabilityContext::forDeploymentTarget(ctx);
+  return deploymentAvailability.isContainedIn(ctx.getConcurrencyAvailability());
+}

lib/IRGen/IRGenModule.h

@@ -1698,6 +1698,7 @@ private:                            \
   /// symbol needed by Swift async functions.
   void emitSwiftAsyncExtendedFrameInfoWeakRef();
 public:
+  bool isConcurrencyAvailable();
   void noteSwiftAsyncFunctionDef() {
     hasSwiftAsyncFunctionDef = true;
   }

lib/IRGen/MetadataRequest.cpp

@@ -1230,13 +1230,6 @@ static MetadataResponse emitTupleTypeMetadataRef(IRGenFunction &IGF,
   }
 }
 
-/// Determine whether concurrency support is available in the runtime.
-static bool isConcurrencyAvailable(ASTContext &ctx) {
-  auto deploymentAvailability =
-    AvailabilityContext::forDeploymentTarget(ctx);
-  return deploymentAvailability.isContainedIn(ctx.getConcurrencyAvailability());
-}
-
 namespace {
   /// A visitor class for emitting a reference to a metatype object.
   /// This implements a "raw" access, useful for implementing cache
@@ -1598,7 +1591,7 @@ namespace {
         }
 
         auto *getMetadataFn = type->getGlobalActor()
-            ? (isConcurrencyAvailable(IGF.getSwiftModule()->getASTContext())
+            ? (IGF.IGM.isConcurrencyAvailable()
                ? IGF.IGM.getGetFunctionMetadataGlobalActorFn()
                : IGF.IGM.getGetFunctionMetadataGlobalActorBackDeployFn())
             : type->isDifferentiable()