[patch] More thorough checking in reg_fits_class_p

[Jim MacArthur]

On 02/05/12 14:55, Richard Sandiford wrote:
> Richard Earnshaw<rearnsha@arm.com>  writes:
>> On 02/05/12 14:00, Richard Sandiford wrote:
>>> Jim MacArthur<jim.macarthur@arm.com>  writes:
>>>> New Changelog text:
>>>>
>>>> 2012-05-02 Jim MacArthur<jim.macarthur@arm.com>
>>>> * recog.c (reg_fits_class_p): Check both regno and regno + offset are
>>>> hard registers.
>>> Thanks.  I still think the final:
>>>
>>>> +	&&  HARD_REGISTER_NUM_P (end_hard_regno (regno + offset, mode))
>>> check belongs in in_hard_reg_set_p, since most callers don't (and IMO
>>> shouldn't need to) check this.  The idea behind adding these functions
>>> was to commonise various bits of code that were doing the same checks
>>> in slightly different ways.  Requiring each caller to check the end
>>> register would go against that to some extent.
>>>
>> If you're going to do that (which is fine, BTW), I think
>> in_hard_reg_set_p should gcc_assert() that regno is a valid hard reg.
> Sounds good.
>
> Richard
>

Sorry for the delay in responding to this, I had a few problems with 
end_hard_regno. Here's a new version of the patch, which adds to 
in_hard_reg_set_p the assert and a check for the hardness of end_regno.  
end_hard_regno is the exclusive upper bound of the range, so not 
actually a meaningful reg no. HARD_REGNO_NREGS is required to return a 
positive value, so (end_regno - 1) is always safe, as I understand it.

I've tested this with an x86 bootstrap which shows no errors, and with 
our own AArch64 back end.

Jim

New ChangeLog text:

2012-05-17  Jim MacArthur<jim.macarthur@arm.com>
       * recog.c (reg_fits_class_p): Check both regno and regno + offset are  
hard registers.
       * regs.h (in_hard_reg_set_p): Assert that regno is a hard register and
check end_regno - 1 is a hard register.

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