Displaying 4 results from an estimated 4 matches for "j6mo3t".
2019 Sep 27
2
Shift-by-signext - sext is bad for analysis - ignore it's use count?
In https://reviews.llvm.org/D68103 the InstCombine learned that shift-by-sext
is simply a shift-by-zext. But the transform is limited to single-use sext.
We can quite trivially get a case where there are two shifts by the same sext:
https://godbolt.org/z/j6mO3t <- We should handle those cases.
In https://reviews.llvm.org/D68103#1686130 Sanjay Patel notes that this
sext is intrusive for analysis, that we will gain far better analysis with zext,
so we should just ignore forego of the one-use check,
and simply replace all shift-by-sext with shift-by-zex...
2019 Oct 01
2
Shift-by-signext - sext is bad for analysis - ignore it's use count?
...tunities by not exploiting knowledge of
> the a known negative shift amount?
Anything specific you are thinking of?
> > But the transform is limited to single-use sext.
> > We can quite trivially get a case where there are two shifts by the same sext:
> > https://godbolt.org/z/j6mO3t <- We should handle those cases.
> >
> > In https://reviews.llvm.org/D68103#1686130 Sanjay Patel notes that this
> > sext is intrusive for analysis, that we will gain far better analysis with zext,
> > so we should just ignore forego of the one-use check,
> > and s...
2019 Oct 01
2
Shift-by-signext - sext is bad for analysis - ignore it's use count?
...the a known negative shift amount?
>> Anything specific you are thinking of?
>>
>> > > But the transform is limited to single-use sext.
>> > > We can quite trivially get a case where there are two shifts by the same sext:
>> > > https://godbolt.org/z/j6mO3t <- We should handle those cases.
>> > >
>> > > In https://reviews.llvm.org/D68103#1686130 Sanjay Patel notes that this
>> > > sext is intrusive for analysis, that we will gain far better analysis with zext,
>> > > so we should just ignore forego o...
2019 Oct 07
2
Shift-by-signext - sext is bad for analysis - ignore it's use count?
...thought would be CVP and LVI, but i did not look yet..
Roman
> > >> > > But the transform is limited to single-use sext.
> > >> > > We can quite trivially get a case where there are two shifts by the same sext:
> > >> > > https://godbolt.org/z/j6mO3t <- We should handle those cases.
> > >> > >
> > >> > > In https://reviews.llvm.org/D68103#1686130 Sanjay Patel notes that this
> > >> > > sext is intrusive for analysis, that we will gain far better analysis with zext,
> > >> >...