[clang] [OpenACC][CIR] Implement beginning of 'copy' lowering for compute con… (PR #140304)

[Erich Keane via cfe-commits]

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@@ -250,14 +420,26 @@ class OpenACCClauseCIREmitter final
   }
 
   void VisitAsyncClause(const OpenACCAsyncClause &clause) {
+    hasAsyncClause = true;
     if constexpr (isOneOfTypes<OpTy, mlir::acc::ParallelOp, mlir::acc::SerialOp,
                                mlir::acc::KernelsOp, mlir::acc::DataOp>) {
       if (!clause.hasIntExpr())
         operation.addAsyncOnly(builder.getContext(), lastDeviceTypeValues);
-      else
-        operation.addAsyncOperand(builder.getContext(),
-                                  createIntExpr(clause.getIntExpr()),
+      else {
+
+        mlir::Value intExpr;
+        {
+          // Async int exprs can be referenced by the data operands, which means
+          // that the int-exprs have to appear before them.  IF there is a data
+          // operand already, set the insertion point to 'before' it.
+          mlir::OpBuilder::InsertionGuard guardCase(builder);
+          if (!dataOperands.empty())
+            builder.setInsertionPoint(dataOperands.front());
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erichkeane wrote:

I considered putting these at the beginning of the 'block', but that ends up moving them very far away, which made for less readable IR.  Instead, I just make sure they are before the first data operation.

https://github.com/llvm/llvm-project/pull/140304