Re: [arm][patch] fix arm_neon_ok check on !arm_arch7

[Kyrill Tkachov <kyrylo.tkachov@arm.com>]

On 23/09/14 09:27, James Greenhalgh wrote:
> On Mon, Sep 15, 2014 at 11:56:03AM +0100, Andrew Stubbs wrote:
>> On 15/09/14 10:46, Richard Earnshaw wrote:
>>> Hmm, I wonder if arm_override_options should reject neon + (arch < 7).
>> Is this more to your taste?
> Is this really such a good idea? It causes carnage throughout the
> testsuite if you have configured with support for Neon and the testcase
> is written with dg-options for a pre-armv7-a -march value.
>
> For example in:
>    testsuite/gcc.target/arm/di-longlong64-sync-withhelpers.c
>
> Which forces -march=armv5.
>
> Perhaps you just have to fix the effective-target-ok tests - but then
> we lose swathes of test coverage.

This also causes subtle Linux kernel compile failures.
Over there they use make rules where they check if the compiler supports 
-march=armv5te and if not use -march=armv4t.
With this patch if the compiler is configured with something like 
--with-fpu=neon the test will fail with your error message,
even though the compiler supports -march=armv5te.

Kyrill


>
> Thanks,
> James
>
>> Andrew
>>
>> P.S. arm_override_options was renamed in 2010.
>> 2014-09-15  Andrew Stubbs  <ams@codesourcery.com>
>>
>> 	* gcc/config/arm/arm.c (arm_option_override): Reject -mfpu=neon
>> 	when architecture is older than ARMv7.
>>
>> Index: gcc/config/arm/arm.c
>> ===================================================================
>> --- gcc/config/arm/arm.c	(revision 215228)
>> +++ gcc/config/arm/arm.c	(working copy)
>> @@ -2845,6 +2845,9 @@
>>   
>>     arm_fpu_desc = &all_fpus[arm_fpu_index];
>>   
>> +  if (TARGET_NEON && !arm_arch7)
>> +    error ("target CPU does not support NEON");
>> +
>>     switch (arm_fpu_desc->model)
>>       {
>>       case ARM_FP_MODEL_VFP: