[clang] [HLSL] Implement output parameter (PR #101083)

[Chris B via cfe-commits]

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@@ -4148,6 +4151,30 @@ static void emitWriteback(CodeGenFunction &CGF,
   assert(!isProvablyNull(srcAddr.getBasePointer()) &&
          "shouldn't have writeback for provably null argument");
 
+  if (CGF.getLangOpts().HLSL) {
+    if (writeback.CastExpr) {
+      RValue TmpVal = CGF.EmitAnyExprToTemp(writeback.CastExpr);
+      if (TmpVal.isScalar())
+        CGF.EmitStoreThroughLValue(TmpVal, srcLV);
+      else
+        CGF.EmitAggregateStore(srcLV.getPointer(CGF),
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llvm-beanz wrote:

I think there's a codegen bug (and missing test coverage related to this. I'm debugging right now and will fix and post additional tests once I have it resolved.

https://github.com/llvm/llvm-project/pull/101083