[swiftinterface] Improve target overwrite for the swiftinterface

In certain cases (e.g. using arm64e interface to build arm64 target),
the target needs to be updated when building swiftinterface. Push the
target overwrite as early as possible to swiftinterface parsing by
providing a preferred target to relevant functions. In such cases, the
wrong target is never observed by other functions to avoid errors like
the sub-invocation was partially setup for the wrong target.

Author: cachemeifyoucan

include/swift/Frontend/ModuleInterfaceLoader.h

@@ -643,7 +643,6 @@ struct InterfaceSubContextDelegateImpl: InterfaceSubContextDelegate {
   llvm::StringSaver ArgSaver;
   std::vector<StringRef> GenericArgs;
   CompilerInvocation genericSubInvocation;
-  llvm::Triple ParentInvocationTarget;
 
   template<typename ...ArgTypes>
   InFlightDiagnostic diagnose(StringRef interfacePath,

include/swift/Serialization/SerializedModuleLoader.h

@@ -18,6 +18,7 @@
 #include "swift/AST/ModuleLoader.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/PrefixMapper.h"
+#include "llvm/TargetParser/Triple.h"
 
 namespace swift {
 class ModuleFile;
@@ -552,9 +553,10 @@ class SerializedASTFile final : public LoadedFile {
 };
 
 /// Extract compiler arguments from an interface file buffer.
-bool extractCompilerFlagsFromInterface(StringRef interfacePath,
-                                       StringRef buffer, llvm::StringSaver &ArgSaver,
-                                       SmallVectorImpl<const char *> &SubArgs);
+bool extractCompilerFlagsFromInterface(
+    StringRef interfacePath, StringRef buffer, llvm::StringSaver &ArgSaver,
+    SmallVectorImpl<const char *> &SubArgs,
+    std::optional<llvm::Triple> PreferredTarget = std::nullopt);
 
 /// Extract the user module version number from an interface file.
 llvm::VersionTuple extractUserModuleVersionFromInterface(StringRef moduleInterfacePath);

lib/Frontend/ModuleInterfaceLoader.cpp

@@ -1433,12 +1433,10 @@ bool ModuleInterfaceLoader::buildSwiftModuleFromSwiftInterface(
                                         SearchPathOpts.CandidateCompiledModules);
 }
 
-static bool readSwiftInterfaceVersionAndArgs(SourceManager &SM,
-                                             DiagnosticEngine &Diags,
-                                             llvm::StringSaver &ArgSaver,
-                                             SwiftInterfaceInfo &interfaceInfo,
-                                             StringRef interfacePath,
-                                             SourceLoc diagnosticLoc) {
+static bool readSwiftInterfaceVersionAndArgs(
+    SourceManager &SM, DiagnosticEngine &Diags, llvm::StringSaver &ArgSaver,
+    SwiftInterfaceInfo &interfaceInfo, StringRef interfacePath,
+    SourceLoc diagnosticLoc, llvm::Triple preferredTarget) {
   llvm::vfs::FileSystem &fs = *SM.getFileSystem();
   auto FileOrError = swift::vfs::getFileOrSTDIN(fs, interfacePath);
   if (!FileOrError) {
@@ -1461,7 +1459,8 @@ static bool readSwiftInterfaceVersionAndArgs(SourceManager &SM,
   }
 
   if (extractCompilerFlagsFromInterface(interfacePath, SB, ArgSaver,
-                                        interfaceInfo.Arguments)) {
+                                        interfaceInfo.Arguments,
+                                        preferredTarget)) {
     InterfaceSubContextDelegateImpl::diagnose(
         interfacePath, diagnosticLoc, SM, &Diags,
         diag::error_extracting_version_from_module_interface);
@@ -1543,9 +1542,10 @@ bool ModuleInterfaceLoader::buildExplicitSwiftModuleFromSwiftInterface(
   llvm::BumpPtrAllocator alloc;
   llvm::StringSaver ArgSaver(alloc);
   SwiftInterfaceInfo InterfaceInfo;
-  readSwiftInterfaceVersionAndArgs(Instance.getSourceMgr(), Instance.getDiags(),
-                                   ArgSaver, InterfaceInfo, interfacePath,
-                                   SourceLoc());
+  readSwiftInterfaceVersionAndArgs(
+      Instance.getSourceMgr(), Instance.getDiags(), ArgSaver, InterfaceInfo,
+      interfacePath, SourceLoc(),
+      Instance.getInvocation().getLangOptions().Target);
 
   auto Builder = ExplicitModuleInterfaceBuilder(
       Instance, &Instance.getDiags(), Instance.getSourceMgr(),
@@ -1707,7 +1707,8 @@ bool InterfaceSubContextDelegateImpl::extractSwiftInterfaceVersionAndArgs(
     CompilerInvocation &subInvocation, SwiftInterfaceInfo &interfaceInfo,
     StringRef interfacePath, SourceLoc diagnosticLoc) {
   if (readSwiftInterfaceVersionAndArgs(SM, *Diags, ArgSaver, interfaceInfo,
-                                       interfacePath, diagnosticLoc))
+                                       interfacePath, diagnosticLoc,
+                                       subInvocation.getLangOptions().Target))
     return true;
 
   // Prior to Swift 5.9, swiftinterfaces were always built (accidentally) with
@@ -1795,9 +1796,6 @@ InterfaceSubContextDelegateImpl::InterfaceSubContextDelegateImpl(
     GenericArgs.push_back("-application-extension");
   }
 
-  // Save the parent invocation's Target Triple
-  ParentInvocationTarget = langOpts.Target;
-
   // Pass down -explicit-swift-module-map-file
   StringRef explicitSwiftModuleMap = searchPathOpts.ExplicitSwiftModuleMap;
   genericSubInvocation.getSearchPathOptions().ExplicitSwiftModuleMap =
@@ -2060,31 +2058,6 @@ InterfaceSubContextDelegateImpl::runInSubCompilerInstance(StringRef moduleName,
   BuildArgs.insert(BuildArgs.end(), interfaceInfo.Arguments.begin(),
                    interfaceInfo.Arguments.end());
 
-  // If the target triple parsed from the Swift interface file differs
-  // only in subarchitecture from the original target triple, then
-  // we have loaded a Swift interface from a different-but-compatible
-  // architecture slice. Use the original subarchitecture.
-  llvm::Triple parsedTargetTriple(subInvocation.getTargetTriple());
-  if (parsedTargetTriple.getSubArch() != originalTargetTriple.getSubArch() &&
-      parsedTargetTriple.getArch() == originalTargetTriple.getArch() &&
-      parsedTargetTriple.getVendor() == originalTargetTriple.getVendor() &&
-      parsedTargetTriple.getOS() == originalTargetTriple.getOS() &&
-      parsedTargetTriple.getEnvironment()
-      == originalTargetTriple.getEnvironment()) {
-    parsedTargetTriple.setArchName(originalTargetTriple.getArchName());
-    subInvocation.setTargetTriple(parsedTargetTriple.str());
-  }
-
-  // Find and overload all "-target" to be parsedTargetTriple. This make sure
-  // the build command for the interface is the same no matter what the parent
-  // triple is so there is no need to spawn identical jobs.
-  assert(llvm::find(BuildArgs, "-target") != BuildArgs.end() &&
-         "missing target option");
-  for (unsigned idx = 0, end = BuildArgs.size(); idx < end; ++idx) {
-    if (BuildArgs[idx] == "-target" && ++idx < end)
-      BuildArgs[idx] = parsedTargetTriple.str();
-  }
-
   // restore `StrictImplicitModuleContext`
   subInvocation.getFrontendOptions().StrictImplicitModuleContext =
       StrictImplicitModuleContext;

lib/Serialization/SerializedModuleLoader.cpp

@@ -1265,37 +1265,34 @@ void swift::serialization::diagnoseSerializedASTLoadFailureTransitive(
   }
 }
 
-bool swift::extractCompilerFlagsFromInterface(StringRef interfacePath,
-                                              StringRef buffer,
-                                              llvm::StringSaver &ArgSaver,
-                                              SmallVectorImpl<const char *> &SubArgs) {
+bool swift::extractCompilerFlagsFromInterface(
+    StringRef interfacePath, StringRef buffer, llvm::StringSaver &ArgSaver,
+    SmallVectorImpl<const char *> &SubArgs,
+    std::optional<llvm::Triple> PreferredTarget) {
   SmallVector<StringRef, 1> FlagMatches;
   auto FlagRe = llvm::Regex("^// swift-module-flags:(.*)$", llvm::Regex::Newline);
   if (!FlagRe.match(buffer, &FlagMatches))
     return true;
   assert(FlagMatches.size() == 2);
   llvm::cl::TokenizeGNUCommandLine(FlagMatches[1], ArgSaver, SubArgs);
 
-  auto intFileName = llvm::sys::path::filename(interfacePath);
-
-  // Sanitize arch if the file name and the encoded flags disagree.
-  // It's a known issue that we are using arm64e interfaces contents for the arm64 target,
-  // meaning the encoded module flags are using -target arm64e-x-x. Fortunately,
-  // we can tell the target arch from the interface file name, so we could sanitize
-  // the target to use by inferring target from the file name.
-  StringRef arm64 = "arm64";
-  StringRef arm64e = "arm64e";
-  if (intFileName.contains(arm64) && !intFileName.contains(arm64e)) {
-    for (unsigned I = 1; I < SubArgs.size(); ++I) {
-      if (strcmp(SubArgs[I - 1], "-target") != 0) {
-        continue;
-      }
-      StringRef triple(SubArgs[I]);
-      if (triple.startswith(arm64e)) {
-        SubArgs[I] = ArgSaver.save((llvm::Twine(arm64) +
-          triple.substr(arm64e.size())).str()).data();
-      }
+  // If the target triple parsed from the Swift interface file differs
+  // only in subarchitecture from the compatible target triple, then
+  // we have loaded a Swift interface from a different-but-compatible
+  // architecture slice. Use the compatible subarchitecture.
+  for (unsigned I = 1; I < SubArgs.size(); ++I) {
+    if (strcmp(SubArgs[I - 1], "-target") != 0) {
+      continue;
     }
+    llvm::Triple target(SubArgs[I]);
+    if (PreferredTarget &&
+        target.getSubArch() != PreferredTarget->getSubArch() &&
+        target.getArch() == PreferredTarget->getArch() &&
+        target.getVendor() == PreferredTarget->getVendor() &&
+        target.getOS() == PreferredTarget->getOS() &&
+        target.getEnvironment() == PreferredTarget->getEnvironment())
+      target.setArch(PreferredTarget->getArch(), PreferredTarget->getSubArch());
+    SubArgs[I] = ArgSaver.save(target.str()).data();
   }
 
   SmallVector<StringRef, 1> IgnFlagMatches;