On Fri, May 20, 2016 at 7:49 PM, H.J. Lu <hjl.to...@gmail.com> wrote:
> On Fri, May 20, 2016 at 10:15 AM, Rainer Orth
> <r...@cebitec.uni-bielefeld.de> wrote:
>> "H.J. Lu" <hjl.to...@gmail.com> writes:
>>
>>> On Thu, May 12, 2016 at 10:54 AM, H.J. Lu <hjl.to...@gmail.com> wrote:
>>>>>> Here is a patch to add
>>>>>> -mgeneral-regs-only option to x86 backend. We can update
>>>>>> spec for interrupt handle to recommend compiling interrupt handler
>>>>>> with -mgeneral-regs-only option and add a note for compiler
>>>>>> implementers.
>>>>>>
>>>>>> OK for trunk if there is no regression?
>>>>>
>>>>>
>>>>> I can't comment on the code patch, but for the documentation part:
>>>>>
>>>>>> @@ -24242,6 +24242,12 @@ opcodes, to mitigate against certain forms of
>>>>>> attack. At the moment,
>>>>>> this option is limited in what it can do and should not be relied
>>>>>> on to provide serious protection.
>>>>>>
>>>>>> +@item -mgeneral-regs-only
>>>>>> +@opindex mgeneral-regs-only
>>>>>> +Generate code which uses only the general-purpose registers. This will
>>>>>
>>>>>
>>>>> s/which/that/
>>>>>
>>>>>> +prevent the compiler from using floating-point, vector, mask and bound
>>>>>
>>>>>
>>>>> s/will prevent/prevents/
>>>>>
>>>>>> +registers, but will not impose any restrictions on the assembler.
>>>>>
>>>>>
>>>>> Maybe you mean to say "does not restrict use of those registers in inline
>>>>> assembly code"? In any case, please get rid of the future tense here,
>>>>> too.
>>>>
>>>> I changed it to
>>>>
>>>> ---
>>>> @item -mgeneral-regs-only
>>>> @opindex mgeneral-regs-only
>>>> Generate code that uses only the general-purpose registers. This
>>>> prevents the compiler from using floating-point, vector, mask and bound
>>>> registers.
>>>> ---
>>>>
>>>
>>> Here is the updated patch. Tested on x86-64. OK for trunk?
>>
>> This patch broke {i386,x86_64}-apple-darwin15.5.0 bootstrap:
>>
>> In file included from ./tm.h:16:0,
>> from /vol/gcc/src/hg/trunk/local/gcc/genattrtab.c:108:
>> ./options.h:5443:2: error: #error too many target masks
>> #error too many target masks
>> ^
>> Makefile:2497: recipe for target 'build/genattrtab.o' failed
>> make[3]: *** [build/genattrtab.o] Error 1
>>
>> options.h has
>>
>> #define OPTION_MASK_ISA_XSAVES (HOST_WIDE_INT_1 << 62)
>> #error too many target masks
>>
>> The tree bootstraps just fine at the previous revision.
>>
>
> Tested on x86-64. OK for trunk?
No, this is a flag, not a variable. Let's figure out how to extend
target flags to more than 63 flags first.
Please revert the original patch in the mean time.
Thanks,
Uros.
