[SourceKit] Disable expensive SIL options (#17306)

Disable the sanitizers and code coverage when building a swift
invocation for the purpose of collecting diagnostics.

This should speed up diagnostic generation and reduce exposure to
compiler bugs.

rdar://40955900

Author: vedantk

tools/SourceKit/lib/SwiftLang/SwiftASTManager.cpp

@@ -464,6 +464,9 @@ bool SwiftASTManager::initCompilerInvocation(CompilerInvocation &Invocation,
   // We don't care about LLVMArgs
   FrontendOpts.LLVMArgs.clear();
 
+  // Disable expensive SIL options to reduce time spent in SILGen.
+  disableExpensiveSILOptions(Invocation.getSILOptions());
+
   return false;
 }
 

tools/SourceKit/lib/SwiftLang/SwiftLangSupport.cpp

@@ -18,6 +18,7 @@
 
 #include "swift/AST/ASTVisitor.h"
 #include "swift/AST/ClangModuleLoader.h"
+#include "swift/AST/SILOptions.h"
 #include "swift/AST/USRGeneration.h"
 #include "swift/Config.h"
 #include "swift/IDE/CodeCompletion.h"
@@ -777,3 +778,13 @@ CloseClangModuleFiles::~CloseClangModuleFiles() {
       M->getASTFile()->closeFile();
   }
 }
+
+void SourceKit::disableExpensiveSILOptions(SILOptions &Opts) {
+  // Disable the sanitizers.
+  Opts.Sanitizers = {};
+
+  // Disable PGO and code coverage.
+  Opts.GenerateProfile = false;
+  Opts.EmitProfileCoverageMapping = false;
+  Opts.UseProfile = "";
+}

tools/SourceKit/lib/SwiftLang/SwiftLangSupport.h

@@ -39,6 +39,7 @@ namespace swift {
   class Type;
   class AbstractStorageDecl;
   class SourceFile;
+  class SILOptions;
   class ValueDecl;
   enum class AccessorKind;
 
@@ -532,6 +533,10 @@ class CloseClangModuleFiles {
   ~CloseClangModuleFiles();
 };
 
+
+/// Disable expensive SIL options which do not affect indexing or diagnostics.
+void disableExpensiveSILOptions(swift::SILOptions &Opts);
+
 } // namespace SourceKit
 
 #endif