TBDGen: when previous install name map is specified, emit $ld$previous linker directives.

include/swift/AST/Attr.h

@@ -1607,6 +1607,7 @@ class OriginallyDefinedInAttr: public DeclAttribute {
   const llvm::VersionTuple MovedVersion;
 
   struct ActiveVersion {
+    StringRef ModuleName;
     PlatformKind Platform;
     bool IsSimulator;
     llvm::VersionTuple Version;

include/swift/AST/Decl.h

@@ -753,6 +753,11 @@ class alignas(1 << DeclAlignInBits) Decl {
     return Attrs;
   }
 
+  /// Returns the introduced OS version in the given platform kind specified
+  /// by @available attribute.
+  /// This function won't consider the parent context to get the information.
+  Optional<llvm::VersionTuple> getIntroducedOSVersion(PlatformKind Kind) const;
+
   /// Returns the starting location of the entire declaration.
   SourceLoc getStartLoc() const { return getSourceRange().Start; }
 

include/swift/AST/DiagnosticsFrontend.def

@@ -282,6 +282,9 @@ REMARK(platform_previous_install_name, none,
 ERROR(unknown_platform_name, none,
       "unkown platform name %0", (StringRef))
 
+ERROR(cannot_find_install_name, none,
+      "cannot find previous install name for module %0 in %1", (StringRef, StringRef))
+
 ERROR(symbol_in_tbd_not_in_ir,none,
       "symbol '%0' (%1) is in TBD file, but not in generated IR",
       (StringRef, StringRef))

lib/AST/Attr.cpp

@@ -1291,6 +1291,7 @@ OriginallyDefinedInAttr::isActivePlatform(const ASTContext &ctx) const {
   OriginallyDefinedInAttr::ActiveVersion Result;
   Result.Platform = Platform;
   Result.Version = MovedVersion;
+  Result.ModuleName = OriginalModuleName;
   if (isPlatformActive(Platform, ctx.LangOpts)) {
     Result.IsSimulator = ctx.LangOpts.Target.isSimulatorEnvironment();
     return Result;

lib/AST/Decl.cpp

@@ -331,6 +331,18 @@ StringRef Decl::getDescriptiveKindName(DescriptiveDeclKind K) {
   llvm_unreachable("bad DescriptiveDeclKind");
 }
 
+Optional<llvm::VersionTuple>
+Decl::getIntroducedOSVersion(PlatformKind Kind) const {
+  for (auto *attr: getAttrs()) {
+    if (auto *ava = dyn_cast<AvailableAttr>(attr)) {
+      if (ava->Platform == Kind && ava->Introduced) {
+        return ava->Introduced;
+      }
+    }
+  }
+  return None;
+}
+
 llvm::raw_ostream &swift::operator<<(llvm::raw_ostream &OS,
                                      StaticSpellingKind SSK) {
   switch (SSK) {

lib/TBDGen/TBDGen.cpp

@@ -86,18 +86,6 @@ getAllMovedPlatformVersions(Decl *D) {
   return Results;
 }
 
-static Optional<llvm::VersionTuple>
-getIntroducedOSVersion(Decl *D, PlatformKind Kind) {
-  for (auto *attr: D->getAttrs()) {
-    if (auto *ava = dyn_cast<AvailableAttr>(attr)) {
-      if (ava->Platform == Kind && ava->Introduced) {
-        return ava->Introduced;
-      }
-    }
-  }
-  return None;
-}
-
 static StringRef getLinkerPlatformName(uint8_t Id) {
   switch (Id) {
 #define LD_PLATFORM(Name, Id) case Id: return #Name;
@@ -245,8 +233,85 @@ TBDGenVisitor::parsePreviousModuleInstallNameMap() {
   return pResult;
 }
 
-void TBDGenVisitor::addLinkerDirectiveSymbols(StringRef name,
-                                              llvm::MachO::SymbolKind kind) {
+static LinkerPlatformId
+getLinkerPlatformId(OriginallyDefinedInAttr::ActiveVersion Ver) {
+  switch(Ver.Platform) {
+  case swift::PlatformKind::none:
+    llvm_unreachable("cannot find platform kind");
+  case swift::PlatformKind::iOS:
+  case swift::PlatformKind::iOSApplicationExtension:
+    return Ver.IsSimulator ? LinkerPlatformId::iOS_sim:
+                             LinkerPlatformId::iOS;
+  case swift::PlatformKind::tvOS:
+  case swift::PlatformKind::tvOSApplicationExtension:
+    return Ver.IsSimulator ? LinkerPlatformId::tvOS_sim:
+                             LinkerPlatformId::tvOS;
+  case swift::PlatformKind::watchOS:
+  case swift::PlatformKind::watchOSApplicationExtension:
+    return Ver.IsSimulator ? LinkerPlatformId::watchOS_sim:
+                             LinkerPlatformId::watchOS;
+  case swift::PlatformKind::OSX:
+  case swift::PlatformKind::OSXApplicationExtension:
+    return LinkerPlatformId::macOS;
+  }
+}
+
+static StringRef
+getLinkerPlatformName(OriginallyDefinedInAttr::ActiveVersion Ver) {
+  return getLinkerPlatformName((uint8_t)getLinkerPlatformId(Ver));
+}
+
+void TBDGenVisitor::addLinkerDirectiveSymbolsLdPrevious(StringRef name,
+                                                llvm::MachO::SymbolKind kind) {
+  if (kind != llvm::MachO::SymbolKind::GlobalSymbol)
+    return;
+  if (!TopLevelDecl)
+    return;
+  auto MovedVers = getAllMovedPlatformVersions(TopLevelDecl);
+  if (MovedVers.empty())
+    return;
+  assert(!MovedVers.empty());
+  assert(previousInstallNameMap);
+  auto &Ctx = TopLevelDecl->getASTContext();
+  for (auto &Ver: MovedVers) {
+    auto IntroVer = TopLevelDecl->getIntroducedOSVersion(Ver.Platform);
+    assert(IntroVer && "cannot find OS intro version");
+    if (!IntroVer.hasValue())
+      continue;
+    auto PlatformNumber = getLinkerPlatformId(Ver);
+    auto It = previousInstallNameMap->find(Ver.ModuleName);
+    if (It == previousInstallNameMap->end()) {
+      Ctx.Diags.diagnose(SourceLoc(), diag::cannot_find_install_name,
+                         Ver.ModuleName, getLinkerPlatformName(Ver));
+      continue;
+    }
+    auto InstallName = It->second.getInstallName(PlatformNumber);
+    if (InstallName.empty()) {
+      Ctx.Diags.diagnose(SourceLoc(), diag::cannot_find_install_name,
+                         Ver.ModuleName, getLinkerPlatformName(Ver));
+      continue;
+    }
+    llvm::SmallString<64> Buffer;
+    llvm::raw_svector_ostream OS(Buffer);
+    // Empty compatible version indicates using the current compatible version.
+    StringRef ComptibleVersion = "";
+    OS << "$ld$previous$";
+    OS << InstallName << "$";
+    OS << ComptibleVersion << "$";
+    OS << std::to_string((uint8_t)PlatformNumber) << "$";
+    static auto getMinor = [](Optional<unsigned> Minor) {
+      return Minor.hasValue() ? *Minor : 0;
+    };
+    OS << IntroVer->getMajor() << "." << getMinor(IntroVer->getMinor()) << "$";
+    OS << Ver.Version.getMajor() << "." << getMinor(Ver.Version.getMinor()) << "$";
+    OS << name << "$";
+    addSymbolInternal(OS.str(), llvm::MachO::SymbolKind::GlobalSymbol,
+                      /*LinkerDirective*/true);
+  }
+}
+
+void TBDGenVisitor::addLinkerDirectiveSymbolsLdHide(StringRef name,
+                                                    llvm::MachO::SymbolKind kind) {
   if (kind != llvm::MachO::SymbolKind::GlobalSymbol)
     return;
   if (!TopLevelDecl)
@@ -265,7 +330,7 @@ void TBDGenVisitor::addLinkerDirectiveSymbols(StringRef name,
   unsigned Minor[2];
   Major[1] = MovedVer.getMajor();
   Minor[1] = MovedVer.getMinor().hasValue() ? *MovedVer.getMinor(): 0;
-  auto IntroVer = getIntroducedOSVersion(TopLevelDecl, Platform);
+  auto IntroVer = TopLevelDecl->getIntroducedOSVersion(Platform);
   assert(IntroVer && "cannot find the start point of availability");
   if (!IntroVer.hasValue())
     return;
@@ -296,7 +361,11 @@ void TBDGenVisitor::addSymbol(StringRef name, SymbolKind kind) {
   SmallString<32> mangled;
   llvm::Mangler::getNameWithPrefix(mangled, name, DataLayout);
   addSymbolInternal(mangled, kind);
-  addLinkerDirectiveSymbols(mangled, kind);
+  if (previousInstallNameMap) {
+    addLinkerDirectiveSymbolsLdPrevious(mangled, kind);
+  } else {
+    addLinkerDirectiveSymbolsLdHide(mangled, kind);
+  }
 }
 
 void TBDGenVisitor::addSymbol(SILDeclRef declRef) {

lib/TBDGen/TBDGenVisitor.h

@@ -78,7 +78,8 @@ class TBDGenVisitor : public ASTVisitor<TBDGenVisitor> {
     parsePreviousModuleInstallNameMap();
   void addSymbolInternal(StringRef name, llvm::MachO::SymbolKind kind,
                          bool isLinkerDirective = false);
-  void addLinkerDirectiveSymbols(StringRef name, llvm::MachO::SymbolKind kind);
+  void addLinkerDirectiveSymbolsLdHide(StringRef name, llvm::MachO::SymbolKind kind);
+  void addLinkerDirectiveSymbolsLdPrevious(StringRef name, llvm::MachO::SymbolKind kind);
   void addSymbol(StringRef name, llvm::MachO::SymbolKind kind =
                                      llvm::MachO::SymbolKind::GlobalSymbol);
 

test/TBD/Inputs/install-name-map-toasterkit.json

@@ -0,0 +1,12 @@
+[
+  {
+    "module": "ToasterKit",
+    "install_name": "/System/Previous/macOS/ToasterKit.dylib",
+    "platforms": ["macOS"]
+  },
+  {
+    "module": "ToasterKit",
+    "install_name": "/System/Previous/iOS/ToasterKit.dylib",
+    "platforms": ["iOS"]
+  }
+]

test/TBD/Inputs/linker-directive.swift

@@ -0,0 +1,9 @@
+@available(OSX 10.8, iOS 10.2, *)
+@_originallyDefinedIn(module: "ToasterKit", macOS 10.15, iOS 13)
+public func toast() {}
+
+@available(OSX 10.8, iOS 10.2, *)
+@_originallyDefinedIn(module: "ToasterKit", macOS 10.15, iOS 13)
+public struct Vehicle {
+  public func move() {}
+}

test/TBD/linker-directives-ld-previous-ios.swift

@@ -0,0 +1,14 @@
+// REQUIRES: OS=ios
+
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend -typecheck %S/Inputs/linker-directive.swift -tbd-is-installapi -emit-tbd -emit-tbd-path %t/linker_directives.tbd -previous-module-installname-map-file %S/Inputs/install-name-map-toasterkit.json
+// RUN: %FileCheck %s < %t/linker_directives.tbd
+// RUN: %target-swift-frontend -typecheck %S/Inputs/linker-directive.swift -emit-tbd -emit-tbd-path %t/linker_directives.tbd -previous-module-installname-map-file %S/Inputs/install-name-map-toasterkit.json
+// RUN: %FileCheck %s < %t/linker_directives.tbd
+
+// CHECK: $ld$previous$/System/Previous/iOS/ToasterKit.dylib$$2$10.2$13.0$_$s10ToasterKit5toastyyF$
+// CHECK: $ld$previous$/System/Previous/iOS/ToasterKit.dylib$$2$10.2$13.0$_$s10ToasterKit7VehicleV4moveyyF$
+// CHECK: $ld$previous$/System/Previous/iOS/ToasterKit.dylib$$2$10.2$13.0$_$s10ToasterKit7VehicleVMa$
+// CHECK: $ld$previous$/System/Previous/iOS/ToasterKit.dylib$$2$10.2$13.0$_$s10ToasterKit7VehicleVMn$
+// CHECK: $ld$previous$/System/Previous/iOS/ToasterKit.dylib$$2$10.2$13.0$_$s10ToasterKit7VehicleVN$

test/TBD/linker-directives-ld-previous-macos.swift

@@ -0,0 +1,14 @@
+// REQUIRES: OS=macosx
+
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend -typecheck %S/Inputs/linker-directive.swift -tbd-is-installapi -emit-tbd -emit-tbd-path %t/linker_directives.tbd -previous-module-installname-map-file %S/Inputs/install-name-map-toasterkit.json
+// RUN: %FileCheck %s < %t/linker_directives.tbd
+// RUN: %target-swift-frontend -typecheck %S/Inputs/linker-directive.swift -emit-tbd -emit-tbd-path %t/linker_directives.tbd -previous-module-installname-map-file %S/Inputs/install-name-map-toasterkit.json
+// RUN: %FileCheck %s < %t/linker_directives.tbd
+
+// CHECK: $ld$previous$/System/Previous/macOS/ToasterKit.dylib$$1$10.8$10.15$_$s10ToasterKit5toastyyF$
+// CHECK: $ld$previous$/System/Previous/macOS/ToasterKit.dylib$$1$10.8$10.15$_$s10ToasterKit7VehicleV4moveyyF$
+// CHECK: $ld$previous$/System/Previous/macOS/ToasterKit.dylib$$1$10.8$10.15$_$s10ToasterKit7VehicleVMa$
+// CHECK: $ld$previous$/System/Previous/macOS/ToasterKit.dylib$$1$10.8$10.15$_$s10ToasterKit7VehicleVMn$
+// CHECK: $ld$previous$/System/Previous/macOS/ToasterKit.dylib$$1$10.8$10.15$_$s10ToasterKit7VehicleVN$