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Re: Porting libsanitizer to aarch64
- From: Richard Henderson <rth at redhat dot com>
- To: Richard Earnshaw <rearnsha at arm dot com>
- Cc: Jakub Jelinek <jakub at redhat dot com>, Konstantin Serebryany <konstantin dot s dot serebryany at gmail dot com>, Christophe Lyon <christophe dot lyon at linaro dot org>, GCC Development <gcc at gcc dot gnu dot org>
- Date: Thu, 23 May 2013 10:17:52 -0700
- Subject: Re: Porting libsanitizer to aarch64
- References: <CAKdteOa-UDeo5zDwCeYSydu0K-WqmTjPgj3sYUpKrc0YPoncCg at mail dot gmail dot com> <20130521154426 dot GA1377 at tucnak dot redhat dot com> <CAGQ9bdyXCWDt0FF4+F5_4LbW7XcZACczKfHhr28nnwk96rf5Mw at mail dot gmail dot com> <20130522074341 dot GC1377 at tucnak dot redhat dot com> <519D2839 dot 5070602 at redhat dot com> <519E43AD dot 60002 at arm dot com> <20130523163613 dot GB1377 at tucnak dot redhat dot com> <519E4726 dot 8030609 at arm dot com>
On 05/23/2013 09:43 AM, Richard Earnshaw wrote:
> So you're saying the documentation is wrong, or at the very least
> misleading... What about dealing with address validation for soft accesses?
> Surely we get better code if the SFP ~= HFP since we end up with fewer cases
> where we fall back to sub-optimal sequences.
It's not wrong, exactly. It's exactly correct that the frame pointer in
question is the soft frame pointer at the beginning of rtl generation.
SFP != HFP can be tricky to do well, I agree. For Alpha I was able to get good
results by allowing any signed 32-bit offset to SFP and then using
LEGITIMIZE_RELOAD_ADDRESS to split the adjusted offset optimally.
r~