Clang: Add patch against very slow reparsing of large files

Task-number: QTCREATORBUG-17397
Change-Id: I3734b77341ca2c7fd87b0f8e5d1502b859de7692
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

1 files changed, 25 insertions, 0 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
new file mode 100644
index 0000000000..41e7c1d2c3
--- /dev/null
+++ b/dist/clang/patches/D29755_Cache-FileID-when-translating-diagnostics-in-PCH-files.patch
@@ -0,0 +1,25 @@
+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;