llvm dev - Sep 2010 - [LLVMdev] Patch to allow llvm.gcroot to work with non-pointer allocas.

I'm moving this thread to llvm-dev in the hopes of reaching a wider
audience.

This patch relaxes the restriction on llvm.gcroot so that it can work with
non-pointer allocas. The only changes are to Verifier.cpp - it appears from
my testing that llvm.gcroot always worked fine with non-pointer allocas,
except that the verifier wouldn't allow it. I've used this patch to
build an
efficient stack crawler (an alternative to shadow-stack that uses only
static constant data structures.)

Here's a deal: If you accept this patch, I'll write up an extensive
tutorial
on how to write a stack crawler like mine. (Actually, it's already written,
however without this patch the tutorial doesn't make any sense.)

-- 
-- Talin
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...crickets...

On Wed, Sep 22, 2010 at 8:52 AM, Talin <viridia at gmail.com> wrote:
> I'm moving this thread to llvm-dev in the hopes of reaching a wider
> audience.
>
> This patch relaxes the restriction on llvm.gcroot so that it can work with
> non-pointer allocas. The only changes are to Verifier.cpp - it appears from
> my testing that llvm.gcroot always worked fine with non-pointer allocas,
> except that the verifier wouldn't allow it. I've used this patch to
build an
> efficient stack crawler (an alternative to shadow-stack that uses only
> static constant data structures.)
>
> Here's a deal: If you accept this patch, I'll write up an extensive
> tutorial on how to write a stack crawler like mine. (Actually, it's
already
> written, however without this patch the tutorial doesn't make any
sense.)
>
> --
> -- Talin
>


-- 
-- Talin
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On Sep 22, 2010, at 8:52 AM, Talin wrote:
> I'm moving this thread to llvm-dev in the hopes of reaching a wider
audience.
> 
> This patch relaxes the restriction on llvm.gcroot so that it can work with
non-pointer allocas. The only changes are to Verifier.cpp - it appears from my
testing that llvm.gcroot always worked fine with non-pointer allocas, except
that the verifier wouldn't allow it. I've used this patch to build an
efficient stack crawler (an alternative to shadow-stack that uses only static
constant data structures.)
> 
> Here's a deal: If you accept this patch, I'll write up an extensive
tutorial on how to write a stack crawler like mine. (Actually, it's already
written, however without this patch the tutorial doesn't make any sense.)
Hi Talin,

I don't think anyone is really using the GC support, other than Nicolas in
VMKit.  If he's ok with the change, I am too.  Please make sure the dox stay
up to date though.

-Chris

Thanks for the heads up Chris.

Talin, how is your GC dealing with non-pointers (be it allocas or not)? What
is the use-case (either in C or LLVM)?

Nicolas

On Fri, Sep 24, 2010 at 7:00 PM, Chris Lattner <clattner at apple.com>
wrote:
> On Sep 22, 2010, at 8:52 AM, Talin wrote:
> > I'm moving this thread to llvm-dev in the hopes of reaching a
wider
> audience.
> >
> > This patch relaxes the restriction on llvm.gcroot so that it can work
> with non-pointer allocas. The only changes are to Verifier.cpp - it appears
> from my testing that llvm.gcroot always worked fine with non-pointer
> allocas, except that the verifier wouldn't allow it. I've used this
patch to
> build an efficient stack crawler (an alternative to shadow-stack that uses
> only static constant data structures.)
> >
> > Here's a deal: If you accept this patch, I'll write up an
extensive
> tutorial on how to write a stack crawler like mine. (Actually, it's
already
> written, however without this patch the tutorial doesn't make any
sense.)
>
> Hi Talin,
>
> I don't think anyone is really using the GC support, other than Nicolas
in
> VMKit.  If he's ok with the change, I am too.  Please make sure the dox
stay
> up to date though.
>
> -Chris
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
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