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Re: [PATCH] PR/Target 47998
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On 03/17/11 09:31, Yoshinori Sato wrote:
> At Wed, 16 Mar 2011 10:22:20 -0600,
> Jeff Law wrote:
>>
> On 03/16/11 09:32, Yoshinori Sato wrote:
>>>> Hi All,
>>>>
>>>> This problem optimize rule missing.
>>>> gen_lowpart got invalid operand.
>>>>
>>>> I attached fix patch.
>>>>
>>>> diff --git a/gcc/ChangeLog b/gcc/ChangeLog
>>>> index ca9398c..9982644 100644
>>>> --- a/gcc/ChangeLog
>>>> +++ b/gcc/ChangeLog
>>>> @@ -1,3 +1,9 @@
>>>> +2011-03-16 Yoshinori Sato <ysato@users.sourceforge.jp>
>>>> +
>>>> + PR/target 47998
>>>> + * config/h8300/h8300.md
>>>> + (peephole): Add rule.
>
> It appears that you're restricting operands1 to be a REG/SUBREG, if
> that's what your intention is, then changing the operand predicate seems
> to be a better solution.
>
> Furthermore, you'd need to explain why restricting operand1 to be a
> REG/SUBREG is the right thing to do.
>
>> This rtl machied it.
>> (const:SI (plus:SI (symbol_ref:SI ("buf") <var_decl 0x7ffff7f93000 buf>)
>> (const_int 31 [0x1f])))
>
>> But gen_lowpart_general not supported this operand.
>> So assert test failed.
>> I think this rule is inapposite.
OK. That's helpful. It seems to me that your change will cause poorer
code generation when operand1 is a MEM.
I think you can address this problem by changing the "general_operand"
predicate to "general_operand_dst". While the name
"general_operand_dst" is unfortunate given the proposed usage in the
peephole, I think it's the proper predicate. Using that should fix your
bug without causing poorer code generation.
I think you should fix the other closely related peepholes (there are 3
or 4 which do similar things and appear to all have the same underlying
problem allowing (const (plus ...)) then passing that operand to
gen_lowpart.
Jeff
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