Clang: Add patch improving reparse performance on windows

Patch provides faster preamble loading by improving the handling of
diagnostics.

Change-Id: I61a79160e0272335d6d4e76478a7a35760cdf9ef
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

2 files changed, 51 insertions, 25 deletions

diff --git a/dist/clang/patches/D29755_Cache-FileID-when-translating-diagnostics-in-PCH-files.patch b/dist/clang/patches/D29755_Cache-FileID-when-translating-diagnostics-in-PCH-files.patch
deleted file mode 100644
index 41e7c1d2c3..0000000000
--- a/dist/clang/patches/D29755_Cache-FileID-when-translating-diagnostics-in-PCH-files.patch
+++ /dev/null
@@ -1,25 +0,0 @@
-diff --git a/tools/clang/lib/Frontend/ASTUnit.cpp b/tools/clang/lib/Frontend/ASTUnit.cpp
-index d892996..5148a8b 100644
---- a/tools/clang/lib/Frontend/ASTUnit.cpp
-+++ b/tools/clang/lib/Frontend/ASTUnit.cpp
-@@ -2534,6 +2534,8 @@ void ASTUnit::TranslateStoredDiagnostics(
- 
-   SmallVector<StoredDiagnostic, 4> Result;
-   Result.reserve(Diags.size());
-+  const FileEntry *PreviousFE = nullptr;
-+  FileID FID;
-   for (const StandaloneDiagnostic &SD : Diags) {
-     // Rebuild the StoredDiagnostic.
-     if (SD.Filename.empty())
-@@ -2541,7 +2543,10 @@ void ASTUnit::TranslateStoredDiagnostics(
-     const FileEntry *FE = FileMgr.getFile(SD.Filename);
-     if (!FE)
-       continue;
--    FileID FID = SrcMgr.translateFile(FE);
-+    if (FE != PreviousFE) {
-+      FID = SrcMgr.translateFile(FE);
-+      PreviousFE = FE;
-+    }
-     SourceLocation FileLoc = SrcMgr.getLocForStartOfFile(FID);
-     if (FileLoc.isInvalid())
-       continue;
diff --git a/dist/clang/patches/D33493_Cache-source-locations-on-PCH-loading.patch b/dist/clang/patches/D33493_Cache-source-locations-on-PCH-loading.patch
new file mode 100644
index 0000000000..7a781ece28
--- /dev/null
+++ b/dist/clang/patches/D33493_Cache-source-locations-on-PCH-loading.patch
@@ -0,0 +1,51 @@
+diff --git a/tools/clang/include/clang/Frontend/ASTUnit.h b/tools/clang/include/clang/Frontend/ASTUnit.h
+index 04e6dce511..3eaf054139 100644
+--- a/tools/clang/include/clang/Frontend/ASTUnit.h
++++ b/tools/clang/include/clang/Frontend/ASTUnit.h
+@@ -184,6 +184,14 @@ private:
+   /// some number of calls.
+   unsigned PreambleRebuildCounter;
+ 
++  /// \brief Cache pairs "filename - source location"
++  ///
++  /// Cache contains only source locations from preamble so it is
++  /// guaranteed that they stay valid when the SourceManager is recreated.
++  /// This cache is used when loading preambule to increase performance
++  /// of that loading. It must be cleared when preamble is recreated.
++  llvm::StringMap<SourceLocation> PreambleSrcLocCache;
++
+ public:
+   class PreambleData {
+     const FileEntry *File;
+diff --git a/tools/clang/lib/Frontend/ASTUnit.cpp b/tools/clang/lib/Frontend/ASTUnit.cpp
+index 76fd00a132..c1c2680dcd 100644
+--- a/tools/clang/lib/Frontend/ASTUnit.cpp
++++ b/tools/clang/lib/Frontend/ASTUnit.cpp
+@@ -1142,6 +1142,8 @@ bool ASTUnit::Parse(std::shared_ptr<PCHContainerOperations> PCHContainerOps,
+   if (SavedMainFileBuffer)
+     TranslateStoredDiagnostics(getFileManager(), getSourceManager(),
+                                PreambleDiagnostics, StoredDiagnostics);
++  else
++    PreambleSrcLocCache.clear();
+ 
+   if (!Act->Execute())
+     goto error;
+@@ -2544,8 +2546,16 @@ void ASTUnit::TranslateStoredDiagnostics(
+     const FileEntry *FE = FileMgr.getFile(SD.Filename);
+     if (!FE)
+       continue;
+-    FileID FID = SrcMgr.translateFile(FE);
+-    SourceLocation FileLoc = SrcMgr.getLocForStartOfFile(FID);
++    SourceLocation FileLoc;
++    auto ItFileID = PreambleSrcLocCache.find(SD.Filename);
++    if (ItFileID == PreambleSrcLocCache.end()) {
++      FileID FID = SrcMgr.translateFile(FE);
++      FileLoc = SrcMgr.getLocForStartOfFile(FID);
++      PreambleSrcLocCache[SD.Filename] = FileLoc;
++    } else {
++      FileLoc = ItFileID->getValue();
++    }
++
+     if (FileLoc.isInvalid())
+       continue;
+     SourceLocation L = FileLoc.getLocWithOffset(SD.LocOffset);