[LLVMdev] Fix crash in llvm_gcda_emit_arcs()

Nick Lewycky nicholas at mxc.ca
Thu Sep 5 01:37:42 PDT 2013

Bill, could you take a look at this? I don't have a checkout of 
compiler-rt that builds.

It seems obviously-correct to me, but I wish it did a compare against 
cur_buffer_size to make sure it's in range.


Joseph Kain wrote:
> Hi,
> I've been seeing a crash in llvm_gcda_emit_arcs() on x86_64.  The crash
> occurs executing a movdqa instruction with an unaligned src address.
>   The attached patch to the compiler-rt project fixes the problem by
> using memcpy() to read data from the write_buffer[] in GCDAProfiling.c.
> This is my first patch submission to llvm so please let me know if I've
> missed any steps.  I'm not on the mailing list so please include me on
> any replies.
> I haven't run the tests on this change but would be happy to do so if
> someone could point me to documentation on how to do so.  I couldn't
> find testing instructions linked from
> http://llvm.org/docs/DeveloperPolicy.html.  I have built the change and
> run it with the programs I was testing originally.  With this change the
> crash no longer occurs.
> Thanks,
> Joseph Kain
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