[PATCH] D57071: GlobalISel: Handle more cases for widenScalar for G_STORE

[Matt Arsenault via Phabricator via llvm-commits]

arsenm marked an inline comment as done.
arsenm added inline comments.


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Comment at: lib/CodeGen/GlobalISel/LegalizerHelper.cpp:946
+    unsigned ExtType = Ty.getScalarSizeInBits() == 1 ?
+      TargetOpcode::G_ZEXT : TargetOpcode::G_ANYEXT;
+    widenScalarSrc(MI, WideTy, 0, ExtType);
----------------
aemerson wrote:
> arsenm wrote:
> > aemerson wrote:
> > > SelectionDAG does zext for the same IR for all types, so I think we should be consistent there.
> > I don't think that's true? 
> > 
> > In this test case for example, in PromoteIntOp_STORE/PromoteIntRes_LOAD it decided to use the morally equivalent ISD::EXTLOAD extload type.
> > 
> > define void @foo(i8 addrspace(1)* %in, i8 addrspace(1)* %out) {
> >   %val = load i8, i8 addrspace(1)* %in
> >   store i8 %val, i8 addrspace(1)* %out
> >   ret void
> > }
> > 
> > The high bits also won't matter for a truncating store
> So I was using a test case like this to check:
> 
> ```
> define void @test(i12 %v, i12 *%ptr) {
>   store i12 %v, i12* %ptr
>   ret void
> }
> ```
> 
> I get your point that in theory it should be semantically correct to do anyext. However I'd rather not we change the way i1s are handled.
This is preserving how i1 is handled. It's using zext for i1, and anyext for anything else. I don't think any other non-byte sizes are special cased though


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  https://reviews.llvm.org/D57071/new/

https://reviews.llvm.org/D57071