Re: Sparse-LLVM issue compiling NULL pointers

From: Dibyendu Majumdar <mobile@majumdar.org.uk>
To: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Linux-Sparse <linux-sparse@vger.kernel.org>
Subject: Re: Sparse-LLVM issue compiling NULL pointers
Date: Thu, 2 Mar 2017 17:18:16 +0000	[thread overview]
Message-ID: <CACXZuxdaYwKm2pJV3zbusUbUdKx2M-nVjSJBfV6G4QwTY1vJ-A@mail.gmail.com> (raw)
In-Reply-To: <CACXZuxeayh3PUdypas6Ww_1mT23ZOuJiZZA_NWDkSQbfes9Xzw@mail.gmail.com>

Hi Luc,

I was looking at whether I can use the standard LLVM GEP api to access
struct and array members in sparse-llvm. I noticed that the output
from sparse has byte offsets of each member - but not the member's
ordinal position. To use the native LLVM methods we would have to
allow LLVM to work out byte offsets, and just use the struct or array
definition. This would I think make the code more robust and also lead
to better optimisation.

Unfortunately LLVM does not support unions so for unions a bit of what
is being done now is probably needed, but even here it is better to
cast a union to its member struct type and then use LLVM GEP api to
access its members.

What do you think?

I think adding the ordinal position to sparse symbols is a trivial
enhancement - do you agree?

Regards
Dibyendu