Add a stop gap to Sema::CorrectTypo() to correct only up to 20 typos.
This is to address a serious performance problem observed when running
'clang -fsyntax-only' on really broken source files. In one case,
repeatedly calling CorrectTypo() caused one source file to be rejected
after 2 minutes instead of 1 second.
This patch causes typo correction to take neglible time on that file
while still providing correction results for the first 20 cases. I
felt this was a reasonable number for moderately broken source files.
I don't claim this is the best solution. Comments welcome. It is
necessary for us to address this issue because it is a serious
performance problem.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@95049 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/Sema.cpp b/lib/Sema/Sema.cpp
index c0e7572..903b987 100644
--- a/lib/Sema/Sema.cpp
+++ b/lib/Sema/Sema.cpp
@@ -364,7 +364,7 @@
GlobalNewDeleteDeclared(false),
CompleteTranslationUnit(CompleteTranslationUnit),
NumSFINAEErrors(0), NonInstantiationEntries(0),
- CurrentInstantiationScope(0)
+ CurrentInstantiationScope(0), TyposCorrected(0)
{
TUScope = 0;
if (getLangOptions().CPlusPlus)
diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index 1595941..9e28b51 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -3305,6 +3305,9 @@
/// variables.
LocalInstantiationScope *CurrentInstantiationScope;
+ /// \brief The number of typos corrected by CorrectTypo.
+ unsigned TyposCorrected;
+
/// \brief An entity for which implicit template instantiation is required.
///
/// The source location associated with the declaration is the first place in
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index 95f0d31..d1a3794 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -2348,9 +2348,16 @@
bool Sema::CorrectTypo(LookupResult &Res, Scope *S, const CXXScopeSpec *SS,
DeclContext *MemberContext, bool EnteringContext,
const ObjCObjectPointerType *OPT) {
-
if (Diags.hasFatalErrorOccurred())
return false;
+
+ // Provide a stop gap for files that are just seriously broken. Trying
+ // to correct all typos can turn into a HUGE performance penalty, causing
+ // some files to take minutes to get rejected by the parser.
+ // FIXME: Is this the right solution?
+ if (TyposCorrected == 20)
+ return false;
+ ++TyposCorrected;
// We only attempt to correct typos for identifiers.
IdentifierInfo *Typo = Res.getLookupName().getAsIdentifierInfo();