Re: [PATCH 04/13] arm: Add GENERAL_AND_VPR_REGS regclass

[Christophe LYON <christophe.lyon@foss.st.com>]

On 07/09/2021 15:35, Richard Earnshaw wrote:
>
>
> On 07/09/2021 13:05, Christophe LYON wrote:
>>
>> On 07/09/2021 11:42, Richard Earnshaw wrote:
>>>
>>>
>>> On 07/09/2021 10:15, Christophe Lyon via Gcc-patches wrote:
>>>> At some point during the development of this patch series, it appeared
>>>> that in some cases the register allocator wants “VPR or general”
>>>> rather than “VPR or general or FP” (which is the same thing as
>>>> ALL_REGS).  The series does not seem to require this anymore, but it
>>>> seems to be a good thing to do anyway, to give the register allocator
>>>> more freedom.
>>>>
>>>> 2021-09-01  Christophe Lyon <christophe.lyon@foss.st.com>
>>>>
>>>>     gcc/
>>>>     * config/arm/arm.h (reg_class): Add GENERAL_AND_VPR_REGS.
>>>>     (REG_CLASS_NAMES): Likewise.
>>>>     (REG_CLASS_CONTENTS): Likewise. Add VPR_REG to ALL_REGS.
>>>>
>>>> diff --git a/gcc/config/arm/arm.h b/gcc/config/arm/arm.h
>>>> index 015299c1534..fab39d05916 100644
>>>> --- a/gcc/config/arm/arm.h
>>>> +++ b/gcc/config/arm/arm.h
>>>> @@ -1286,6 +1286,7 @@ enum reg_class
>>>>     SFP_REG,
>>>>     AFP_REG,
>>>>     VPR_REG,
>>>> +  GENERAL_AND_VPR_REGS,
>>>>     ALL_REGS,
>>>>     LIM_REG_CLASSES
>>>>   };
>>>> @@ -1315,6 +1316,7 @@ enum reg_class
>>>>     "SFP_REG",        \
>>>>     "AFP_REG",        \
>>>>     "VPR_REG",        \
>>>> +  "GENERAL_AND_VPR_REGS", \
>>>>     "ALL_REGS"        \
>>>>   }
>>>>   @@ -1343,7 +1345,8 @@ enum reg_class
>>>>     { 0x00000000, 0x00000000, 0x00000000, 0x00000040 }, /* SFP_REG 
>>>> */    \
>>>>     { 0x00000000, 0x00000000, 0x00000000, 0x00000080 }, /* AFP_REG 
>>>> */    \
>>>>     { 0x00000000, 0x00000000, 0x00000000, 0x00000400 }, /* VPR_REG. 
>>>> */    \
>>>> -  { 0xFFFF7FFF, 0xFFFFFFFF, 0xFFFFFFFF, 0x0000000F }  /* ALL_REGS. 
>>>> */    \
>>>> +  { 0x00005FFF, 0x00000000, 0x00000000, 0x00000400 }, /* 
>>>> GENERAL_AND_VPR_REGS.  */ \
>>>> +  { 0xFFFF7FFF, 0xFFFFFFFF, 0xFFFFFFFF, 0x0000040F }  /* ALL_REGS. 
>>>> */    \
>>>>   }
>>>
>>> You've changed the definition of ALL_REGS here (to include VPR_REG), 
>>> but not really explained why.  Is that the source of the underlying 
>>> issue with the 'appeared' you mention?
>>
>>
>> I first added VPR_REG to ALL_REGS, but Richard Sandiford suggested I 
>> create a new GENERAL_AND_VPR_REGS that would be more restrictive. I 
>> did not remove VPR_REG from ALL_REGS because I thought it was an 
>> omission: shouldn't ALL_REGS contain all registers?
>
> Surely that should be a separate patch then.

OK, I can remove that line from this patch and make a separate one-liner 
for ALL_REGS.

Thanks,

Christophe


>
> R.
>
>>
>>
>>>
>>> R.
>>>
>>>
>>>>     #define FP_SYSREGS \
>>>>