[llvm-commits] [PATCH] Incorrect VFP version supporting ARM Cortex-M4

[Jiangning Liu]

Hi Jim,

No, Cortex-M4 doesn't support full VFPv4, so you are right fpv4-sp-d16 is different from full VFPv4.
 
1) 'V' here implies vector instructions, while Cortex-M4 doesn't have.
2) sp means SIngle Precision
3) d16 means only 16-bit data operation only.

This is why other attributes are specified for Cortex-M4 as well. I think FeatureVFPOnlySP is being used to make this difference.

At least we can't say Cortex-M4 is VFPv2.

Thanks,
-Jiangning

在 2012-7-14，上午1:09，Jim Grosbach <grosbach at apple.com> 写道：

> VFP4 means something very different from VFP2. Does the M4 really have a full VFP4 implementation available?
> 
> -Jim
> 
> On Jul 13, 2012, at 1:17 AM, Jiangning Liu <jiangning.liu at arm.com> wrote:
> 
>> Hi,
>> 
>> The full name of FP version of ARM Cortex-M4 is fpv4-sp-d16, so the FP
>> version should be vfp4 rather than vfp2. This patch changes FeatureVFP2 to
>> FeatureVFP4 for Cortex-M4.
>> 
>> Thanks,
>> -Jiangning
>> 
>> diff --git a/lib/Target/ARM/ARM.td b/lib/Target/ARM/ARM.td
>> index cd3c0e0..69e2346 100644
>> --- a/lib/Target/ARM/ARM.td
>> +++ b/lib/Target/ARM/ARM.td
>> @@ -224,7 +224,7 @@ def : ProcNoItin<"cortex-m3",       [HasV7Ops,
>> def : ProcNoItin<"cortex-m4",       [HasV7Ops,
>>                                     FeatureThumb2, FeatureNoARM,
>> FeatureDB,
>>                                     FeatureHWDiv, FeatureDSPThumb2,
>> -                                     FeatureT2XtPk, FeatureVFP2,
>> +                                     FeatureT2XtPk, FeatureVFP4,
>>                                     FeatureVFPOnlySP, FeatureMClass]>;
>> 
>> 
>> //===----------------------------------------------------------------------=
>> ==//<cortex_m4_fpv4.patch>_______________________________________________
>> llvm-commits mailing list
>> llvm-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> 
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