[mlir][GPU] Add builders to allow passing in integer upper_bounds

These are convendience builders to allow user code that knows (or optionally
knows) the upper_bound on, say, a `gpu.thread_id` to specify that bound
without needing to manually construct an IndexAttr.

Author: krzysz00

mlir/include/mlir/Dialect/GPU/IR/GPUOps.td

@@ -74,7 +74,20 @@ class GPU_IndexOp<string mnemonic, list<Trait> traits = []> :
     }]>,
     OpBuilder<(ins "::mlir::Type":$resultType, "::mlir::gpu::Dimension":$dimension), [{
       build($_builder, $_state, resultType, dimension, /*upperBound=*/nullptr);
+    }]>,
+    OpBuilder<(ins "::mlir::gpu::Dimension":$dimension, "std::optional<int64_t>":$upperBound), [{
+      ::mlir::IntegerAttr upperBoundAttr = nullptr;
+      if (upperBound.has_value())
+        upperBoundAttr = $_builder.getIndexAttr(*upperBound);
+      build($_builder, $_state, dimension, upperBoundAttr);
+    }]>,
+    OpBuilder<(ins "::mlir::Type":$resultType, "::mlir::gpu::Dimension":$dimension, "std::optional<int64_t>":$upperBound), [{
+      ::mlir::IntegerAttr upperBoundAttr = nullptr;
+      if (upperBound.has_value())
+        upperBoundAttr = $_builder.getIndexAttr(*upperBound);
+      build($_builder, $_state, resultType, dimension, upperBoundAttr);
     }]>
+
   ];
 }