Displaying 5 results from an estimated 5 matches for "nvbit".
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2009 Dec 04
2
[LLVMdev] Possible bug in ExpandShiftWithUnknownAmountBit
Hi Duncan,
I don't know if the optimization would help us much. Our architecture
performs integer shifts and subtractions at the same speed. I think the
optimization is limited to the case where NVBits is a power of two. That is
the case for all current value types but there's a separate thread where
someone is proposing adding i20 as a native type.
In your previous email you mentioned some comments added to check-in 90564.
In our architecture shifting by 0 doesn't cause any problems bu...
2009 Dec 05
0
[LLVMdev] Possible bug in ExpandShiftWithUnknownAmountBit
Hi Javier,
> I don't know if the optimization would help us much. Our architecture
> performs integer shifts and subtractions at the same speed. I think the
> optimization is limited to the case where NVBits is a power of two.
it is irrelevant whether it is a power of two or not. Anyway, since you
are the only user, and this is not helpful for you, I guess we can forget
it :)
> In your previous email you mentioned some comments added to check-in 90564.
> In our architecture shifting by 0 does...
2009 Dec 05
1
[LLVMdev] Possible bug in ExpandShiftWithUnknownAmountBit
...8:30:59 +0100, Duncan Sands <baldrick at free.fr> wrote:
> Hi Javier,
>
>> I don't know if the optimization would help us much. Our architecture
>> performs integer shifts and subtractions at the same speed. I think the
>> optimization is limited to the case where NVBits is a power of two.
>
> it is irrelevant whether it is a power of two or not. Anyway, since you
> are the only user, and this is not helpful for you, I guess we can forget
> it :)
>
>> In your previous email you mentioned some comments added to check-in
>> 90564.
>&...
2009 Dec 04
0
[LLVMdev] Possible bug in ExpandShiftWithUnknownAmountBit
PS: For a small optimization, in the case where Amt is bigger than 32
(or whatever NVTBits is) you might want to use an "and" to mask off
the top bits of Amt rather than subtracting 32 (if Amt is 64 or greater
then the result of the shift was undefined anyway, so it is ok to mask
off all the upper bits).
2009 Dec 04
4
[LLVMdev] Possible bug in ExpandShiftWithUnknownAmountBit
Duncan,
Thanks for committing a fix. I see that you fixed a bug in my patch with
the HiL in the case of an SRA.
The issue with a test case is that it will depend on the target to expose
it. Like you noted in the check-in comment x86 doesn't expose the bug. The
target I'm working on isn't public. Short of writing a new one for the
purpose of a test case I don't know what else to