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

[Farzon Lotfi via cfe-commits]

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@@ -160,6 +160,24 @@ static Value *handleHlslSplitdouble(const CallExpr *E, CodeGenFunction *CGF) {
   return LastInst;
 }
 
+static Value *handleHlslWaveActiveBallot(const CallExpr *E,
+                                         CodeGenFunction *CGF) {
+  Value *Cond = CGF->EmitScalarExpr(E->getArg(0));
+  llvm::Type *I32 = CGF->Int32Ty;
+
+  if (CGF->CGM.getTarget().getTriple().isDXIL()) {
+    return CGF->EmitRuntimeCall(
+        CGF->CGM.getIntrinsic(Intrinsic::dx_wave_ballot, {I32}), Cond);
+  }
+
+  if (CGF->CGM.getTarget().getTriple().isSPIRV())
+    return CGF->EmitRuntimeCall(
+        CGF->CGM.getIntrinsic(Intrinsic::spv_wave_ballot), Cond);
----------------
farzonl wrote:

I have some concerns with these intrinsics being the same name and having different return types. 

Further I'm pretty sure this is going to break in the HLSL header when we call the `WaveActiveBallot` api because the return types are different but we are doing nothing in codegen to uniform them.

I think we should rename `spv_wave_ballot` to `spirv_subgroup_ballot`. Wave is not a concept in spirv and now that the intrinsics in DirectX and SPIRV no longer match we don't have to force a standard naming convention since we aren't using the intrinsic toggling helpers.


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