AST: On iOS, use _stdlib_isOSVersionAtLeast_AEIC() for availability checks.

Resolves rdar://134793410.

Author: tshortli

include/swift/AST/ASTContext.h

@@ -734,6 +734,9 @@ class ASTContext final {
   // Retrieve the declaration of Swift._stdlib_isOSVersionAtLeast.
   FuncDecl *getIsOSVersionAtLeastDecl() const;
 
+  // Retrieve the declaration of Swift._stdlib_isOSVersionAtLeast_AEIC.
+  FuncDecl *getIsOSVersionAtLeastAEICDecl() const;
+
   // Retrieve the declaration of Swift._stdlib_isVariantOSVersionAtLeast.
   FuncDecl *getIsVariantOSVersionAtLeastDecl() const;
 

lib/AST/ASTContext.cpp

@@ -390,6 +390,13 @@ struct ASTContext::Implementation {
   ///    -> Builtin.Int1
   FuncDecl *IsOSVersionAtLeastDecl = nullptr;
 
+  /// func _stdlib_isOSVersionAtLeast_AEIC(
+  ///   Builtin.Word,
+  ///   Builtin.Word,
+  ///   Builtin.word)
+  ///  -> Builtin.Int1
+  FuncDecl *IsOSVersionAtLeastAEICDecl = nullptr;
+
   /// func _stdlib_isVariantOSVersionAtLeast(
   ///   Builtin.Word,
   ///   Builtin.Word,
@@ -1828,6 +1835,18 @@ ConstructorDecl *ASTContext::getMakeUTF8StringDecl() const {
 }
 
 FuncDecl *ASTContext::getIsOSVersionAtLeastDecl() const {
+  // On iOS, the compiler should emit calls to the @_alwaysEmitIntoClient
+  // variant of _stdlib_isOSVersionAtLeast because availability checks must
+  // have the correct platform ID embedded in them in order for the binary to
+  // be able to run correctly on other platforms (e.g. macOS).
+  //
+  // FIXME: This exception should be temporary. The @_alwaysEmitIntoClient
+  //        variant should be used consistently on all platforms in the future.
+  if (LangOpts.Target.getOS() == llvm::Triple::IOS) {
+    if (auto decl = getIsOSVersionAtLeastAEICDecl())
+      return decl;
+  }
+
   if (getImpl().IsOSVersionAtLeastDecl)
     return getImpl().IsOSVersionAtLeastDecl;
 
@@ -1861,6 +1880,18 @@ FuncDecl *ASTContext::getIsOSVersionAtLeastDecl() const {
   return decl;
 }
 
+FuncDecl *ASTContext::getIsOSVersionAtLeastAEICDecl() const {
+  if (getImpl().IsOSVersionAtLeastAEICDecl)
+    return getImpl().IsOSVersionAtLeastAEICDecl;
+
+  auto decl = findLibraryIntrinsic(*this, "_stdlib_isOSVersionAtLeast_AEIC");
+  if (!decl)
+    return nullptr;
+
+  getImpl().IsOSVersionAtLeastAEICDecl = decl;
+  return decl;
+}
+
 FuncDecl *ASTContext::getIsVariantOSVersionAtLeastDecl() const {
   if (getImpl().IsVariantOSVersionAtLeastDecl)
     return getImpl().IsVariantOSVersionAtLeastDecl;

test/SILGen/availability_query_maccatalyst_zippered.swift

@@ -51,7 +51,7 @@ if #available(tvOS 9.0, *) {
 // CHECK: [[MACOS_MAJOR:%.*]] = integer_literal $Builtin.Word, 10
 // CHECK: [[MACOS_MINOR:%.*]] = integer_literal $Builtin.Word, 54
 // CHECK: [[MACOS_PATCH:%.*]] = integer_literal $Builtin.Word, 3
-// CHECK: [[QUERY_FUNC:%.*]] = function_ref @$ss26_stdlib_isOSVersionAtLeastyBi1_Bw_BwBwtF : $@convention(thin) (Builtin.Word, Builtin.Word, Builtin.Word) -> Builtin.Int1
+// CHECK: [[QUERY_FUNC:%.*]] = function_ref @${{ss26_stdlib_isOSVersionAtLeasty|ss31_stdlib_isOSVersionAtLeast_AEICy}}Bi1_Bw_BwBwtF : $@convention(thin) (Builtin.Word, Builtin.Word, Builtin.Word) -> Builtin.Int1
 // CHECK: [[QUERY_RESULT:%.*]] = apply [[QUERY_FUNC]]([[MACOS_MAJOR]], [[MACOS_MINOR]], [[MACOS_PATCH]]) : $@convention(thin) (Builtin.Word, Builtin.Word, Builtin.Word) -> Builtin.Int1
 // The '*' matches for iOS, so we only need to check to check the
 // macOS version and thus use the primary target version check