On 12/12/14 04:07, Alan Hayward wrote:
[Cleaning this thread up to submit patch again, with better explanation]
This patch causes subreg_get_info() to exit early in the simple cases
where we are extracting a whole register from a multi register.
In aarch64 for Big Endian we were producing a subreg of a OImode (256bits)
from a CImode (384bits) This would hit the following assert in
subreg_get_info:
gcc_assert ((GET_MODE_SIZE (xmode) % GET_MODE_SIZE (ymode)) == 0);
This is a rule we should be able to relax a little - if the subreg we want
fits into a whole register then this is a valid result and can be easily
detected earlier in the function.
This has the bonus that we should be slightly reducing the execution time
for more common cases, for example a subreg of 64bits from 256bits.
This patch is required for the second part of the patch, which is aarch64
specific, and fixes up aarch64 Big Endian movoi/ci/xi. This second part
has already been approved.
This patch will apply cleanly by itself and no regressions were seen when
testing aarch64 and x86_64 on make check.
Cheers,
Alan
Changelog:
2014-11-14 Alan Hayward <alan.hayw...@arm.com>
* rtlanal.c
(subreg_get_info): Exit early for simple and common cases
ChangeLog nit. Should be:
* rtlanal.c (subreg_get_info): Exit early for simple and common
cases.
With ChangeLog fixed, this patch is OK for the trunk.
If you have a testcase, please submit it as well.
Thanks for your patience,
Jeff
