[PATCH] D115724: [InstCombine] Fold for masked scatters to a uniform address

[Caroline via Phabricator via llvm-commits]

CarolineConcatto marked an inline comment as done and an inline comment as not done.
CarolineConcatto added inline comments.


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Comment at: llvm/test/Transforms/InstCombine/vscale_masked_intrinsics.ll:16
+  %broadcast.splatvalue = shufflevector <vscale x 4 x i16> %broadcast.value, <vscale x 4 x i16> poison, <vscale x 4 x i32> zeroinitializer
+  call void @llvm.masked.scatter.nxv4i16.nxv4p0i16(<vscale x 4 x i16> %broadcast.splatvalue, <vscale x 4 x i16*> %broadcast.splat, i32 2, <vscale x 4 x i1> shufflevector (<vscale x 4 x i1> insertelement (<vscale x 4 x i1> poison, i1 true, i32 1), <vscale x 4 x i1> poison, <vscale x 4 x i32> zeroinitializer))
+  ret void
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sdesmalen wrote:
> CarolineConcatto wrote:
> > sdesmalen wrote:
> > > instead of passing an all true mask, you could simply insert 1 `i1 1` element into a zeroinitializer
> > I have updated the all zero mask to be:
> > <vscale x 4 x i1> zeroinitializer, 
> > I don't know if I follow what you want here.
> The comment says:
>   ;; Value splat and  mask is not not all active/one
> 
> Yet in the test it uses an all-poison mask:
> 
>   <vscale x 4 x i1> shufflevector (<vscale x 4 x i1> insertelement (<vscale x 4 x i1> poison, i1 true, i32 1), <vscale x 4 x i1> poison, <vscale x 4 x i32> zeroinitializer
> 
> this inserts `i1 1` into element 1 (not zero) of a poison vector, so you get:
>   <poison, 1, poison, poison, ... >
> 
> and then does a splat of element 0, leading to
>   <poison, poison, poison, poison, ...>
> 
> If you want to pass a mask that is not all active *and* not all ones *and* not all `poison`, I think you want something like this:
> 
>   <vscale x 4 x i1> insertelement (<vscale x 4 x i1> zeroinitializer, i1 true, i32 1)
>   <=>
>   <0, 1, 0, 0, ...>
I have done something different, suggested by David.  
Mask is an input, so we don't know if it is all active or inactive.


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  https://reviews.llvm.org/D115724/new/

https://reviews.llvm.org/D115724