[cfe-commits] r95049 - in /cfe/trunk/lib/Sema: Sema.cpp Sema.h SemaLookup.cpp

[Douglas Gregor]

This looks good. Thanks!

Sent from my iPhone

On Feb 1, 2010, at 6:07 PM, Ted Kremenek <kremenek at apple.com> wrote:

> Author: kremenek
> Date: Mon Feb  1 20:07:01 2010
> New Revision: 95049
>
> URL: http://llvm.org/viewvc/llvm-project?rev=95049&view=rev
> Log:
> 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.
>
> Modified:
>    cfe/trunk/lib/Sema/Sema.cpp
>    cfe/trunk/lib/Sema/Sema.h
>    cfe/trunk/lib/Sema/SemaLookup.cpp
>
> Modified: cfe/trunk/lib/Sema/Sema.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/Sema.cpp?rev=95049&r1=95048&r2=95049&view=diff
>
> ===
> ===
> ===
> =====================================================================
> --- cfe/trunk/lib/Sema/Sema.cpp (original)
> +++ cfe/trunk/lib/Sema/Sema.cpp Mon Feb  1 20:07:01 2010
> @@ -364,7 +364,7 @@
>     GlobalNewDeleteDeclared(false),
>     CompleteTranslationUnit(CompleteTranslationUnit),
>     NumSFINAEErrors(0), NonInstantiationEntries(0),
> -    CurrentInstantiationScope(0)
> +    CurrentInstantiationScope(0), TyposCorrected(0)
> {
>   TUScope = 0;
>   if (getLangOptions().CPlusPlus)
>
> Modified: cfe/trunk/lib/Sema/Sema.h
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/Sema.h?rev=95049&r1=95048&r2=95049&view=diff
>
> ===
> ===
> ===
> =====================================================================
> --- cfe/trunk/lib/Sema/Sema.h (original)
> +++ cfe/trunk/lib/Sema/Sema.h Mon Feb  1 20:07:01 2010
> @@ -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
>
> Modified: cfe/trunk/lib/Sema/SemaLookup.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaLookup.cpp?rev=95049&r1=95048&r2=95049&view=diff
>
> === 
> === 
> === 
> =====================================================================
> --- cfe/trunk/lib/Sema/SemaLookup.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaLookup.cpp Mon Feb  1 20:07:01 2010
> @@ -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();
>
>
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