[clang] d59b4ac - [analyzer][ctu] Reland "Avoid parsing invocation list again and again..

[Balazs Benics via cfe-commits]

Author: Ella Ma
Date: 2021-05-25T09:44:13+02:00
New Revision: d59b4acf80d59c461decd41400988febaf0af8ca

URL: https://github.com/llvm/llvm-project/commit/d59b4acf80d59c461decd41400988febaf0af8ca
DIFF: https://github.com/llvm/llvm-project/commit/d59b4acf80d59c461decd41400988febaf0af8ca.diff

LOG: [analyzer][ctu] Reland "Avoid parsing invocation list again and again..

..during on-demand parsing of CTU"

During CTU, the *on-demand parsing* will read and parse the invocation
list to know how to compile the file being imported. However, it seems
that the invocation list will be parsed again if a previous parsing
has failed.
Then, parse again and fail again. This patch tries to overcome the
problem by storing the error code during the first parsing, and
re-create the stored error during the later parsings.

Reland without test.

Reviewed By: steakhal

Patch By: OikawaKirie!

Differential Revision: https://reviews.llvm.org/D101763

Added: 
    

Modified: 
    clang/include/clang/CrossTU/CrossTranslationUnit.h
    clang/lib/CrossTU/CrossTranslationUnit.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/CrossTU/CrossTranslationUnit.h b/clang/include/clang/CrossTU/CrossTranslationUnit.h
index b419b9be67cb9..d9f9c51fccd9c 100644
--- a/clang/include/clang/CrossTU/CrossTranslationUnit.h
+++ b/clang/include/clang/CrossTU/CrossTranslationUnit.h
@@ -38,6 +38,7 @@ class TranslationUnitDecl;
 namespace cross_tu {
 
 enum class index_error_code {
+  success = 0,
   unspecified = 1,
   missing_index_file,
   invalid_index_format,
@@ -253,6 +254,7 @@ class CrossTranslationUnitContext {
     /// In case of on-demand parsing, the invocations for parsing the source
     /// files is stored.
     llvm::Optional<InvocationListTy> InvocationList;
+    index_error_code PreviousParsingResult = index_error_code::success;
   };
 
   /// Maintain number of AST loads and check for reaching the load limit.

diff  --git a/clang/lib/CrossTU/CrossTranslationUnit.cpp b/clang/lib/CrossTU/CrossTranslationUnit.cpp
index 640538cae3bbc..adee55304c871 100644
--- a/clang/lib/CrossTU/CrossTranslationUnit.cpp
+++ b/clang/lib/CrossTU/CrossTranslationUnit.cpp
@@ -92,6 +92,10 @@ class IndexErrorCategory : public std::error_category {
 
   std::string message(int Condition) const override {
     switch (static_cast<index_error_code>(Condition)) {
+    case index_error_code::success:
+      // There should not be a success error. Jump to unreachable directly.
+      // Add this case to make the compiler stop complaining.
+      break;
     case index_error_code::unspecified:
       return "An unknown error has occurred.";
     case index_error_code::missing_index_file:
@@ -667,12 +671,15 @@ llvm::Error CrossTranslationUnitContext::ASTLoader::lazyInitInvocationList() {
   /// Lazily initialize the invocation list member used for on-demand parsing.
   if (InvocationList)
     return llvm::Error::success();
+  if (index_error_code::success != PreviousParsingResult)
+    return llvm::make_error<IndexError>(PreviousParsingResult);
 
   llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> FileContent =
       llvm::MemoryBuffer::getFile(InvocationListFilePath);
-  if (!FileContent)
-    return llvm::make_error<IndexError>(
-        index_error_code::invocation_list_file_not_found);
+  if (!FileContent) {
+    PreviousParsingResult = index_error_code::invocation_list_file_not_found;
+    return llvm::make_error<IndexError>(PreviousParsingResult);
+  }
   std::unique_ptr<llvm::MemoryBuffer> ContentBuffer = std::move(*FileContent);
   assert(ContentBuffer && "If no error was produced after loading, the pointer "
                           "should not be nullptr.");
@@ -680,8 +687,13 @@ llvm::Error CrossTranslationUnitContext::ASTLoader::lazyInitInvocationList() {
   llvm::Expected<InvocationListTy> ExpectedInvocationList =
       parseInvocationList(ContentBuffer->getBuffer(), PathStyle);
 
-  if (!ExpectedInvocationList)
-    return ExpectedInvocationList.takeError();
+  // Handle the error to store the code for next call to this function.
+  if (!ExpectedInvocationList) {
+    llvm::handleAllErrors(
+        ExpectedInvocationList.takeError(),
+        [&](const IndexError &E) { PreviousParsingResult = E.getCode(); });
+    return llvm::make_error<IndexError>(PreviousParsingResult);
+  }
 
   InvocationList = *ExpectedInvocationList;