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Re: help for arm avr bfin cris frv h8300 m68k mcore mmix pdp11 rs6000 sh vax
Ian Lance Taylor wrote:
> Paolo Bonzini <bonzini@gnu.org> writes:
>
>> This in turn means that the description given by SHIFT_COUNT_TRUNCATED
>> must be exact. Right now !SHIFT_COUNT_TRUNCATED means "I don't know",
>> I want it to mean "it is never truncated".
>
> You need to do more work to make that happen, as SHIFT_COUNT_TRUNCATED
> applies to both the shift instructions and the bitfield instructions.
> On some processors one or the other is truncated; SHIFT_COUNT_TRUNCATED
> may currently only be set to 1 if both are truncated. (E.g., I believe
> that m68k truncates shifts but not bitfield instructions.)
Yes, I've also split TARGET_SHIFT_TRUNCATION_MASK and
TARGET_EXTRACT_TRUNCATION_MASK, but for the latter a conservative
default can be used since it's used only in one optimization in combine.
[trimmed CC list]
Paolo