[cfe-commits] r61042 - in /cfe/trunk: include/clang/Lex/Preprocessor.h lib/Lex/PPDirectives.cpp lib/Lex/PPMacroExpansion.cpp lib/Lex/Preprocessor.cpp

[Chris Lattner]

On Dec 15, 2008, at 11:56 AM, Ted Kremenek wrote:

> Author: kremenek
> Date: Mon Dec 15 13:56:42 2008
> New Revision: 61042
>
> URL: http://llvm.org/viewvc/llvm-project?rev=61042&view=rev
> Log:
> Preprocessor: Allocate MacroInfo objects using a BumpPtrAllocator  
> instead using new/delete.  This speeds up -Eonly on Cocoa.h using  
> the regular lexer by 1.8% and the PTHLexer by 3%.

Very nice!  This also substantially sped us up on INPUTS/ 
macro_pounder_*.c.  We're now faster than GCC on _fn and within 2x of  
it on _obj:

(min of three runs for each):

$ time ~/llvm/Release-Asserts/bin/clang INPUTS/macro_pounder_fn.c -E  
 > /dev/null
1.834u 0.005s 0:01.84 99.4%	0+0k 0+0io 0pf+0w
$ time gcc -E INPUTS/macro_pounder_fn.c > /dev/null
2.043u 0.151s 0:02.19 100.0%	0+0k 0+0io 0pf+0w

$ time ~/llvm/Release-Asserts/bin/clang INPUTS/macro_pounder_obj.c -E  
 > /dev/null
0.415u 0.003s 0:00.42 97.6%	0+0k 0+0io 0pf+0w
$ time gcc -E INPUTS/macro_pounder_obj.c  > /dev/null
0.267u 0.040s 0:00.31 96.7%	0+0k 0+0io 0pf+0w

We used to be substantially slower at both of these, largely do to  
alloc/dealloc of macro info.

> +++ cfe/trunk/lib/Lex/Preprocessor.cpp Mon Dec 15 13:56:42 2008
> @@ -95,9 +95,9 @@
>   // Free any macro definitions.
>   for (llvm::DenseMap<IdentifierInfo*, MacroInfo*>::iterator I =
>        Macros.begin(), E = Macros.end(); I != E; ++I) {
> -    // Free the macro definition.
> -    delete I->second;
> -    I->second = 0;
> +    // We don't need to free the MacroInfo objects directly.  These
> +    // will be released when the BumpPtrAllocator 'BP' object gets
> +    // destroyed.
>     I->first->setHasMacroDefinition(false);
>   }

Please make sure that the code runs the MacroInfo destructor at the  
appropriate times.  The ReplacementTokens member has a dtor that must  
be run to avoid leaking memory.

Thanks Ted,

-Chris