[clang] [llvm] [HLSL] Implement the `reflect` HLSL function (PR #122992)

[Finn Plummer via llvm-commits]

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@@ -51,6 +51,38 @@ bool SemaSPIRV::CheckSPIRVBuiltinFunctionCall(unsigned BuiltinID,
     TheCall->setType(RetTy);
     break;
   }
+  case SPIRV::BI__builtin_spirv_reflect: {
+    if (SemaRef.checkArgCount(TheCall, 2))
+      return true;
+
+    ExprResult A = TheCall->getArg(0);
+    QualType ArgTyA = A.get()->getType();
+    auto *VTyA = ArgTyA->getAs<VectorType>();
+    if (VTyA == nullptr) {
+      SemaRef.Diag(A.get()->getBeginLoc(),
+                   diag::err_typecheck_convert_incompatible)
+          << ArgTyA
+          << SemaRef.Context.getVectorType(ArgTyA, 2, VectorKind::Generic) << 1
+          << 0 << 0;
+      return true;
+    }
+
+    ExprResult B = TheCall->getArg(1);
+    QualType ArgTyB = B.get()->getType();
+    auto *VTyB = ArgTyB->getAs<VectorType>();
+    if (VTyB == nullptr) {
+      SemaRef.Diag(A.get()->getBeginLoc(),
+                   diag::err_typecheck_convert_incompatible)
+          << ArgTyB
+          << SemaRef.Context.getVectorType(ArgTyB, 2, VectorKind::Generic) << 1
+          << 0 << 0;
+      return true;
+    }
+
+    QualType RetTy = ArgTyA;
+    TheCall->setType(RetTy);
----------------
inbelic wrote:

FYI: this is the reason that it will fail to compile without having the diagnostics. Since the intrinsic types are being overloaded, you have to set it specifically here.

https://github.com/llvm/llvm-project/pull/122992