Re: RFA: patch for PR59535

[Richard Earnshaw <rearnsha at arm dot com>]

On 07/02/14 22:06, Jeff Law wrote:
> On 02/07/14 11:20, Vladimir Makarov wrote:
>>    The following patch improves code size for ARM.  Before the patch
>> CSiBE size generated by GCC configured --with-arch=armv7-a
>> --with-fpu=vfpv3-d16 --with-float=hard (with -mthumb) was
>>
>> 2414926
>>
>> After the patch the size is
>>
>> 2396798
>>
>> For comparison, when the reload pass is used the size is
>>
>> 2400154
>>
>> The change in arm.h is to prevent reloading sp as an address by LRA.
>> Reload has no such problem as it uses legitimate address hook and LRA
>> mostly relies on base_reg_class.
>>
>> Richard, is this part ok to commit to the trunk?
> I think so.  It's fixing a P1 regression, that makes it "in scope" as 
> far as I'm concerned.
> 

While this is a useful fix for Thumb2 (which had regressed slightly),
the PR is for Thumb1.  I tried this patch when compiling CSiBE with
-mthumb -mcpu=arm7tdmi -Os.  Sadly it made no difference at all to the
numbers there.

So this does not resolve PR59535.

R.

> 
>>
>> The change in lra-constraints.c is for correct alternative choice in
>> move patterns when pseudo is of class of general reg and one alternative
>> contains lo regs and another one contains hi regs.
>>
>> The patch was bootstrapped on x86/x86-64 and arm.
>>
>> 2014-02-07  Vladimir Makarov  <vmakarov@redhat.com>
>>
>>          PR rtl-optimization/59535
>>          * lra-constraints.c (process_alt_operands): Encourage alternative
>>          when unassigned pseudo class is superset of the alternative class.
>>          * config/arm/arm.h (MODE_BASE_REG_CLASS): Return CORE_REGS for
>>          Thumb2 for LRA.
> Just one nit in the comment in lra-constraints.c
> s/stil/still/
> Jeff
> 
> 
>