Should __attribute__((optimize("align-loops=32"))) work ? (for x86_64)

[Chris Hall]

On 28/01/18 12:46, Jonathan Wakely wrote:
> On 28 January 2018 at 11:25, Chris Hall wrote:
>> ...with v7.2.1, compiling for recent x86_64, the command line option
>> "-falign-loops=32" is accepted and has the desired effect.
>>
>> However I find that both:
>>
>>      _Pragma("GCC optimize(\"align-loops=32\")")
>>
>> and:
>>
>>      __attribute__((optimize("align-loops=32")))
>>
>> are rejected with a "warning: bad option '-falign-loops=32'" -- reported for
>> each and every affected function.
>>
>> Should I report this as a bug ?
> Yes, if you can't find an existing report for it.
OK: I have reported it.

FWIW: playing with "Compiler Explorer" suggests that this was broken by 
v7. Compiling with v6.3 does not generate the spurious warning, but the 
requested loop alignment is ignored. Going back to v5.4, I find the 
optimize("align-loops=32") actually works !

Thanks,

Chris