[clang] [llvm] [HLSL] Handle WaveActiveBallot struct return type appropriately (PR #175105)

[Finn Plummer via cfe-commits]

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@@ -1,10 +1,22 @@
 ; RUN: opt -S -dxil-op-lower -mtriple=dxil-pc-shadermodel6.3-compute %s | FileCheck %s
 
-define noundef <4 x i32> @wave_ballot_simple(i1 noundef %p1) {
+%dx.types.fouri32 = type { i32, i32, i32, i32 }
+
+define <4 x i32> @wave_ballot_simple(i1 noundef %p1) {
 entry:
-; CHECK: call <4 x i32> @dx.op.waveBallot.void(i32 118, i1 %p1)
-  %ret = call <4 x i32> @llvm.dx.wave.ballot(i1 %p1)
-  ret <4 x i32> %ret
+; CHECK: call %dx.types.fouri32 @dx.op.waveActiveBallot(i32 116, i1 %p1)
+; CHECK-NOT: ret %dx.types.fouri32
+; CHECK: ret <4 x i32>
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inbelic wrote:

Maybe this is just a confusion on my part but. I would not have expected us to return a vector in the final dxil output? IIUC that is the point of the custom struct type.

Ah wait, the insertelements will go away when we run the scalarizer.

Can we add a test that runs with the scalarizer to ensure we get the expected output in that case?

edit: Although I see in the `dxil-dis` we still have a vector around, why is that?

https://github.com/llvm/llvm-project/pull/175105