[cfe-dev] [Patch] Make ParseAST() take ASTContext and TU params

[Alexei Svitkine]

Ah, thanks for the clarification.

Here's an updated patch that passes the correct parameters to the
ASTContext() constructor under each case. I didn't rename the
parameter in ASTContext however - since it actually does not call
Deallocate when FreeMemory is false.

-Alexei

On Tue, Jan 27, 2009 at 6:59 PM, Ted Kremenek <kremenek at apple.com> wrote:
> On Jan 27, 2009, at 3:51 PM, Alexei Svitkine wrote:
>
> Oops - it looks like there was a change to ParseAST() earlier that I
> wasn't up to date with. This one:
>
> http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20090126/011412.html
>
> That change involves propagating the FreeMemory param to the
> ASTContext constructor... which is problematic with my change which
> gets rid of that param entirely. I'm not sure how to handle this.
>
> The "FreeMemory" argument to ASTContext is a little of a misnomer.  It's
> more a selector of which Allocator that ASTContext uses to allocate ASTs
> (i.e., MallocAllocator or BumpPtrAllocator).  Calling ~ASTContext() will
> *always* release memory.  Feel free to rename that parameter to something
> more appropriate.
> Much of your patch is orthogonal to these changes.  Your patch is about
> creating a new interface for ParseAST that allows clients to hold on the
> TranslationUnit/ASTContext after ParseAST has completed.
>
> What is the purpose of -disable-free in the context of the
> command-line clang tool?
>
> Our timings show that a significant amount of time is spent in clang freeing
> ASTs.
> When invoking 'clang' for compilation from the command-line, freeing ASTs is
> a waste of time since the OS will automatically reclaim that memory.
>  Providing -disable-free from the command line allows us to experiment with
> the performance of just having the OS free memory versus freeing the memory
> directly.
> Moreover, having it as a command-line option (rather than hard-coded) allows
> us to free memory ASTs manually for debugging (to make sure all the
> ownership issues are correct) but still have the --disable-free option for
> production releases.
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