[embedded] Explicitly disable PerfDiags from SourceKit instead of always disabling when WMO is off

Author: kubamracek

include/swift/AST/SILOptions.h

@@ -150,6 +150,10 @@ class SILOptions {
   /// Enables SIL-level diagnostics for NonescapableTypes.
   bool EnableLifetimeDependenceDiagnostics = true;
 
+  /// Enables SIL-level performance diagnostics (for @noLocks, @noAllocation
+  /// annotations and for Embedded Swift).
+  bool EnablePerformanceDiagnostics = true;
+
   /// Controls whether or not paranoid verification checks are run.
   bool VerifyAll = false;
 

lib/SILOptimizer/Mandatory/PerformanceDiagnostics.cpp

@@ -805,9 +805,10 @@ class PerformanceDiagnosticsPass : public SILModuleTransform {
   void run() override {
     SILModule *module = getModule();
 
-    // Skip all performance/embedded diagnostics if not in WMO mode. Building in
-    // non-WMO mode currently results in false positives.
-    if (!module->isWholeModule()) return;
+    // Skip all performance/embedded diagnostics if asked. This is used from
+    // SourceKit to avoid reporting false positives when WMO is turned off for
+    // indexing purposes.
+    if (!module->getOptions().EnablePerformanceDiagnostics) return;
 
     PerformanceDiagnostics diagnoser(*module, getAnalysis<BasicCalleeAnalysis>());
 

tools/SourceKit/lib/SwiftLang/SwiftASTManager.cpp

@@ -1219,6 +1219,11 @@ ASTUnitRef ASTBuildOperation::buildASTUnit(std::string &Error) {
       // flag and might thus fail, which SILGen cannot handle.
       llvm::SaveAndRestore<std::shared_ptr<std::atomic<bool>>> DisableCancellationDuringSILGen(CompIns.getASTContext().CancellationFlag, nullptr);
       SILOptions SILOpts = Invocation.getSILOptions();
+
+      // Disable PerformanceDiagnostics SIL pass, which in some cases requires
+      // WMO (e.g. for Embedded Swift diags) but SourceKit compiles without WMO.
+      SILOpts.EnablePerformanceDiagnostics = false;
+
       auto &TC = CompIns.getSILTypes();
       std::unique_ptr<SILModule> SILMod = performASTLowering(*SF, TC, SILOpts);
       if (CancellationFlag->load(std::memory_order_relaxed)) {