[cfe-commits] r121644 - in /cfe/trunk/lib/Sema: Sema.cpp SemaDeclCXX.cpp

[Nick Lewycky]

On 12 December 2010 13:36, Chandler Carruth <chandlerc at gmail.com> wrote:

> Author: chandlerc
> Date: Sun Dec 12 15:36:11 2010
> New Revision: 121644
>
> URL: http://llvm.org/viewvc/llvm-project?rev=121644&view=rev
> Log:
> Move the functionality to mark all vtables of key functions as used within
> a translation unit to the ActOnEndOfTranslationUnit function instead of
> doing
> it at the start of DefineUsedVTables. The latter is now called
> *recursively*
> during template instantiation, which causes an absolutely insane number of
> walks of every record decl in the translation unit.
>
> After this patch, an extremely template instantiation heavy test case's
> compile
> time drops by 10x, and we see between 15% and 20% improvement in average
> compile times across a project. This is just recovering a regression, it
> doesn't make anything faster than it was several weeks ago.
>

Ouch! Sorry about that, and thank you for the fix!!

Nick


> Modified:
>    cfe/trunk/lib/Sema/Sema.cpp
>    cfe/trunk/lib/Sema/SemaDeclCXX.cpp
>
> Modified: cfe/trunk/lib/Sema/Sema.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/Sema.cpp?rev=121644&r1=121643&r2=121644&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Sema/Sema.cpp (original)
> +++ cfe/trunk/lib/Sema/Sema.cpp Sun Dec 12 15:36:11 2010
> @@ -285,6 +285,18 @@
>   // At PCH writing, implicit instantiations and VTable handling info are
>   // stored and performed when the PCH is included.
>   if (CompleteTranslationUnit) {
> +    // If any dynamic classes have their key function defined within
> +    // this translation unit, then those vtables are considered "used" and
> must
> +    // be emitted.
> +    for (unsigned I = 0, N = DynamicClasses.size(); I != N; ++I) {
> +      if (const CXXMethodDecl *KeyFunction
> +          = Context.getKeyFunction(DynamicClasses[I])) {
> +        const FunctionDecl *Definition = 0;
> +        if (KeyFunction->hasBody(Definition))
> +          MarkVTableUsed(Definition->getLocation(), DynamicClasses[I],
> true);
> +      }
> +    }
> +
>     // If DefinedUsedVTables ends up marking any virtual member functions
> it
>     // might lead to more pending template instantiations, which we then
> need
>     // to instantiate.
>
> Modified: cfe/trunk/lib/Sema/SemaDeclCXX.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclCXX.cpp?rev=121644&r1=121643&r2=121644&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaDeclCXX.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaDeclCXX.cpp Sun Dec 12 15:36:11 2010
> @@ -6895,21 +6895,9 @@
>  }
>
>  bool Sema::DefineUsedVTables() {
> -  // If any dynamic classes have their key function defined within
> -  // this translation unit, then those vtables are considered "used" and
> must
> -  // be emitted.
> -  for (unsigned I = 0, N = DynamicClasses.size(); I != N; ++I) {
> -    if (const CXXMethodDecl *KeyFunction
> -                             = Context.getKeyFunction(DynamicClasses[I]))
> {
> -      const FunctionDecl *Definition = 0;
> -      if (KeyFunction->hasBody(Definition))
> -        MarkVTableUsed(Definition->getLocation(), DynamicClasses[I],
> true);
> -    }
> -  }
> -
>   if (VTableUses.empty())
>     return false;
> -
> +
>   // Note: The VTableUses vector could grow as a result of marking
>   // the members of a class as "used", so we check the size each
>   // time through the loop and prefer indices (with are stable) to
>
>
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