[PATCH, i386] PR 57927: -march=core-avx2 different than -march=native on INTEL Haswell (i7-4700K)

[Uros Bizjak]

Hello!

>> >>> As reported in [1] the host processor detection has not yet been updated
>> >>> to recognize Intel Ivy Bridge and Haswell processors.
>> >>> This small patch adds the detection of these processors and assumes
>> >>> core-avx2 as march for unknown processors of the PENTIUMPRO family that
>> >>> support AVX2.
>> >>
>> >> I have committed slightly improved (attached) patch that uses
>> >> core-avx-i for IvyBridge and adds another IvyBridge model number.
>> >> While there, I also reordered a bunch  of statements.
>> >>
>> > Page C-3 in ntel optimization guide shows:
>> >
>> > 06_3CH, 06_45H, 06_46H Intel microarchitecture Haswell
>> > 06_3AH, 06_3EH Intel microarchitecture Ivy Bridge
>> > 06_2AH, 06_2DH Intel microarchitecture Sandy Bridge
>> > 06_25H, 06_2CH, 06_2FH Intel microarchitecture Westmere
>> > 06_1AH, 06_1EH, 06_1FH, Intel microarchitecture Nehalem
>> > 06_2EH
>> > 06_17H, 06_1DH Enhanced Intel Core microarchitecture
>> > 06_0FH Intel Core microarchitecture
>> >
>> > At least, we should add 0x45 and 0x46 to Haswell.
>>
>> OK, the patch is pre-approved.
>
> Can these changes be backported to 4.8 and the Ivy Bridge parts to 4.7 as
> well? We've had a couple reports of bad -march=native results for Haswell on
> 4.7.  I can file PRs if you're interested.

I have backported all relevant patches to release branches (4.7, 4.8).

Uros.