Merge pull request #66908 from bnbarham/cherry-reuse-cursor-ast

[5.9][CursorInfo] Re-use already built ASTs when possible

Author: bnbarham

test/SourceKit/CursorInfo/cursor_reuses_ast.swift

@@ -0,0 +1,23 @@
+// RUN: %empty-directory(%t)
+// RUN: touch %t/empty.swift %t/func.swift
+
+// Check that cursor info re-uses the underlying AST if it's able to based
+// off edit snapshots.
+
+// RUN: %sourcekitd-test \
+// RUN:   -shell -- echo '## State 1' == \
+// RUN:   -req=open -text-input %t/empty.swift %t/func.swift -- %t/func.swift == \
+// RUN:   -req=edit -offset=0 -length=0 -replace="func foo() {}" -req-opts=enablesyntaxmap=0,enablesubstructure=0,enablediagnostics=0,syntactic_only=1 %t/func.swift -- %t/func.swift == \
+// RUN:   -req=cursor -offset=5 %t/func.swift -- %t/func.swift == \
+// RUN:   -shell -- echo '## State 2' == \
+// RUN:   -req=edit -offset=0 -length=0 -replace="/* some comment */ " -req-opts=enablesyntaxmap=0,enablesubstructure=0,enablediagnostics=0,syntactic_only=1 %t/func.swift -- %t/func.swift == \
+// RUN:   -req=cursor -offset=24 %t/func.swift -- %t/func.swift | %FileCheck %s
+
+// CHECK: ## State 1
+// CHECK: source.lang.swift.decl.function.free
+// CHECK: foo()
+// CHECK: DID REUSE AST CONTEXT: 0
+// CHECK: ## State 2
+// CHECK: source.lang.swift.decl.function.free
+// CHECK: foo()
+// CHECK: DID REUSE AST CONTEXT: 1

tools/SourceKit/include/SourceKit/Core/LangSupport.h

@@ -1086,7 +1086,8 @@ class LangSupport {
                      Receiver) = 0;
 
   virtual void
-  getNameInfo(StringRef Filename, unsigned Offset, NameTranslatingInfo &Input,
+  getNameInfo(StringRef PrimaryFilePath, StringRef InputBufferName,
+              unsigned Offset, NameTranslatingInfo &Input,
               ArrayRef<const char *> Args,
               SourceKitCancellationToken CancellationToken,
               std::function<void(const RequestResult<NameTranslatingInfo> &)>

tools/SourceKit/lib/SwiftLang/SwiftASTManager.cpp

@@ -1240,30 +1240,61 @@ bool ASTBuildOperation::addConsumer(SwiftASTConsumerRef Consumer) {
   return true;
 }
 
+/// Returns a build operation that `Consumer` can use, in order of the
+/// following:
+///   1. The latest finished build operation that either exactly matches, or
+///      can be used with snapshots
+///   2. If none, the latest in-progress build operation with the same
+///      conditions
+///   3. `nullptr` otherwise
 ASTBuildOperationRef ASTProducer::getBuildOperationForConsumer(
     SwiftASTConsumerRef Consumer,
     IntrusiveRefCntPtr<llvm::vfs::FileSystem> FileSystem,
     SwiftASTManagerRef Mgr) {
+  ASTBuildOperationRef LatestUsableOp;
+  Statistic *StatCount = nullptr;
   for (auto &BuildOp : llvm::reverse(BuildOperations)) {
-    if (BuildOp->isCancelled()) {
+    if (BuildOp->isCancelled())
+      continue;
+
+    // No point checking for a match, we already have one - we're just looking
+    // for a finished operation that can be used with the file contents of
+    // `BuildOp` at this point (which we will prefer over an incomplete
+    // operation, whether that exactly matches or not).
+    if (LatestUsableOp && !BuildOp->isFinished())
+      continue;
+
+    // Check for an exact match
+    if (BuildOp->matchesSourceState(FileSystem)) {
+      LatestUsableOp = BuildOp;
+      StatCount = &Mgr->Impl.Stats->numASTCacheHits;
+      if (BuildOp->isFinished())
+        break;
       continue;
     }
+
+    // Check for whether the operation can be used taking into account
+    // snapshots
     std::vector<ImmutableTextSnapshotRef> Snapshots;
     Snapshots.reserve(BuildOp->getFileContents().size());
     for (auto &FileContent : BuildOp->getFileContents()) {
       if (FileContent.Snapshot) {
         Snapshots.push_back(FileContent.Snapshot);
       }
     }
-    if (BuildOp->matchesSourceState(FileSystem)) {
-      ++Mgr->Impl.Stats->numASTCacheHits;
-      return BuildOp;
-    } else if (Consumer->canUseASTWithSnapshots(Snapshots)) {
-      ++Mgr->Impl.Stats->numASTsUsedWithSnapshots;
-      return BuildOp;
+
+    if (Consumer->canUseASTWithSnapshots(Snapshots)) {
+      LatestUsableOp = BuildOp;
+      StatCount = &Mgr->Impl.Stats->numASTsUsedWithSnapshots;
+      if (BuildOp->isFinished())
+        break;
     }
   }
-  return nullptr;
+
+  if (StatCount) {
+    ++(*StatCount);
+  }
+  return LatestUsableOp;
 }
 
 void ASTProducer::enqueueConsumer(

tools/SourceKit/lib/SwiftLang/SwiftLangSupport.h

@@ -660,8 +660,9 @@ class SwiftLangSupport : public LangSupport {
                      Receiver) override;
 
   void getNameInfo(
-      StringRef Filename, unsigned Offset, NameTranslatingInfo &Input,
-      ArrayRef<const char *> Args, SourceKitCancellationToken CancellationToken,
+      StringRef PrimaryFilePath, StringRef InputBufferName, unsigned Offset,
+      NameTranslatingInfo &Input, ArrayRef<const char *> Args,
+      SourceKitCancellationToken CancellationToken,
       std::function<void(const RequestResult<NameTranslatingInfo> &)> Receiver)
       override;