Add e2e tests for mhlo.bitcast_convert (#6846)

The op now exists in standard and we have a lowering to it from MHLO.
Lowering of std.bitcast to spirv is not yet done, but that's further
down the pipeline.

Fixes https://github.com/google/iree/issues/6106

iree/test/e2e/xla_ops/BUILD

diff --git a/iree/test/e2e/xla_ops/BUILD b/iree/test/e2e/xla_ops/BUILD
index 14aeb8b..54c70b7 100644
--- a/iree/test/e2e/xla_ops/BUILD
+++ b/iree/test/e2e/xla_ops/BUILD
@@ -27,6 +27,7 @@
             "abs.mlir",
             "add.mlir",
             "batch_norm_inference.mlir",
+            "bitcast_convert.mlir",
             "broadcast.mlir",
             "broadcast_add.mlir",
             "broadcast_in_dim.mlir",
@@ -171,6 +172,7 @@
             "abs.mlir",
             "add.mlir",
             "batch_norm_inference.mlir",
+            "bitcast_convert.mlir",
             "broadcast.mlir",
             "broadcast_add.mlir",
             "broadcast_in_dim.mlir",
@@ -237,6 +239,7 @@
             "abs.mlir",
             "add.mlir",
             "batch_norm_inference.mlir",
+            "bitcast_convert.mlir",
             "broadcast.mlir",
             "broadcast_add.mlir",
             "broadcast_in_dim.mlir",
@@ -350,6 +353,7 @@
         ],
         include = ["*.mlir"],
         exclude = [
+            "bitcast_convert.mlir",
             "round.mlir",
             "scatter.mlir",  # TODO(GH-6388): Enable the test.
             "scatter_dynamic.mlir",  # TODO(GH-6388): Enable the test.

iree/test/e2e/xla_ops/CMakeLists.txt

diff --git a/iree/test/e2e/xla_ops/CMakeLists.txt b/iree/test/e2e/xla_ops/CMakeLists.txt
index d6894f2..08d15b6 100644
--- a/iree/test/e2e/xla_ops/CMakeLists.txt
+++ b/iree/test/e2e/xla_ops/CMakeLists.txt
@@ -17,6 +17,7 @@
     "abs.mlir"
     "add.mlir"
     "batch_norm_inference.mlir"
+    "bitcast_convert.mlir"
     "broadcast.mlir"
     "broadcast_add.mlir"
     "broadcast_in_dim.mlir"
@@ -84,6 +85,7 @@
     "abs.mlir"
     "add.mlir"
     "batch_norm_inference.mlir"
+    "bitcast_convert.mlir"
     "broadcast.mlir"
     "broadcast_add.mlir"
     "broadcast_in_dim.mlir"
@@ -146,6 +148,7 @@
     "abs.mlir"
     "add.mlir"
     "batch_norm_inference.mlir"
+    "bitcast_convert.mlir"
     "broadcast.mlir"
     "broadcast_add.mlir"
     "broadcast_in_dim.mlir"

iree/test/e2e/xla_ops/bitcast_convert.mlir

diff --git a/iree/test/e2e/xla_ops/bitcast_convert.mlir b/iree/test/e2e/xla_ops/bitcast_convert.mlir
new file mode 100644
index 0000000..72dd2c5
--- /dev/null
+++ b/iree/test/e2e/xla_ops/bitcast_convert.mlir
@@ -0,0 +1,6 @@
+func @bitcast() {
+  %input = util.unfoldable_constant dense<0> : tensor<4xi32>
+  %result = "mhlo.bitcast_convert"(%input) : (tensor<4xi32>) -> tensor<4xf32>
+  check.expect_eq_const(%result, dense<0.0> : tensor<4xf32>) : tensor<4xf32>
+  return
+}