[PATCH] gas: Add --with-optimization=OPTION

Jan Beulich JBeulich@suse.com
Tue Feb 27 12:54:00 GMT 2018


>>> On 27.02.18 at 12:55, <hjl.tools@gmail.com> wrote:
> On Tue, Feb 27, 2018 at 12:13 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>>> On 26.02.18 at 19:41, <hjl.tools@gmail.com> wrote:
>>> On Mon, Feb 26, 2018 at 10:33 AM, Joseph Myers <joseph@codesourcery.com> wrote:
>>>> On Mon, 26 Feb 2018, H.J. Lu wrote:
>>>>
>>>>> 1. Add --with-optimization=OPTION configure option for x86 gas.  This
>>>>> allows the default optimization type to be adjusted at configure time.
>>>>
>>>> I don't think such a configure option is appropriate.  It's far outside
>>>> the standard definition of either --enable or --with options.
>>>> Command-line options and assembler directives should be fully sufficient
>>>> without any such configure option, especially given that the assembler is
>>>
>>> So it is OK to enable encoding optimization by default.  But it is inappropriate
>>> to control it at configure time.
>>>
>>>> mainly used for assembling compiler output.
>>>>
>>>
>>> x86 assembler optimizes, immediate. displacement as well as VEX vs EVEX.
>>> I am intending to enable this by default.   --with-optimization=OPTION provides
>>> a way to test it for a while.
>>
>> I don't think optimizations should be enabled by default - that's
>> simply incompatible with prior versions of gas, and may break
>> existing code.
> 
> If this is true, we shouldn't do it at all.

So maybe I misunderstood: Did you mean the assembler to
default to optimizing, or just the configure process to default
to _allow_ optimizing to be enabled via command line option?

Jan



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