Add refinement test for if/case (#2675)

cc @bartchr808 for pointing out this test gap

stablehlo/tests/transforms/stablehlo_refine_shapes.mlir

@@ -1199,6 +1199,60 @@ func.func @refine_while(%arg0: tensor<4xf32>) -> tensor<?xf32> {
 
 // -----
 
+// Unlike WhileOp which requires separate patterns for propagating information
+// to block arguments, If/Case don't have region arguments, so relies on all
+// free variables and body variables to be refined before the case op is refined
+
+// CHECK-LABEL: func @refine_case
+// CHECK-SAME: tensor<2x3x224x224xf32>
+func.func @refine_case() -> tensor<?x3x224x224xf32> {
+  %c = stablehlo.constant dense<1> : tensor<i32>
+  %0 = "stablehlo.case"(%c) ({
+    %cst = stablehlo.constant dense<1.000000e+00> : tensor<f32>
+    %c_0 = stablehlo.constant dense<[2, 3, 224, 224]> : tensor<4xi32>
+    %1 = stablehlo.dynamic_broadcast_in_dim %cst, %c_0, dims = [] : (tensor<f32>, tensor<4xi32>) -> tensor<?x3x224x224xf32>
+    // CHECK: return {{.*}} : tensor<2x3x224x224xf32>
+    stablehlo.return %1 : tensor<?x3x224x224xf32>
+  }, {
+    %cst = stablehlo.constant dense<0.000000e+00> : tensor<f32>
+    %c_0 = stablehlo.constant dense<[2, 3, 224, 224]> : tensor<4xi32>
+    %1 = stablehlo.dynamic_broadcast_in_dim %cst, %c_0, dims = [] : (tensor<f32>, tensor<4xi32>) -> tensor<?x3x224x224xf32>
+    // CHECK: return {{.*}} : tensor<2x3x224x224xf32>
+    stablehlo.return %1 : tensor<?x3x224x224xf32>
+  }) : (tensor<i32>) -> tensor<?x3x224x224xf32>
+  // CHECK: return {{.*}} : tensor<2x3x224x224xf32>
+  return %0 : tensor<?x3x224x224xf32>
+}
+
+// -----
+
+// Unlike WhileOp which requires separate patterns for propagating information
+// to block arguments, If/Case don't have region arguments, so relies on all
+// free variables and body variables to be refined before the case op is refined
+
+// CHECK-LABEL: func @refine_if
+// CHECK-SAME: tensor<2x3x224x224xf32>
+func.func @refine_if() -> tensor<?x3x224x224xf32> {
+  %c = stablehlo.constant dense<true> : tensor<i1>
+  %0 = "stablehlo.if"(%c) ({
+    %cst = stablehlo.constant dense<1.000000e+00> : tensor<f32>
+    %c_0 = stablehlo.constant dense<[2, 3, 224, 224]> : tensor<4xi32>
+    %1 = stablehlo.dynamic_broadcast_in_dim %cst, %c_0, dims = [] : (tensor<f32>, tensor<4xi32>) -> tensor<?x3x224x224xf32>
+    // CHECK: return {{.*}} : tensor<2x3x224x224xf32>
+    stablehlo.return %1 : tensor<?x3x224x224xf32>
+  }, {
+    %cst = stablehlo.constant dense<0.000000e+00> : tensor<f32>
+    %c_0 = stablehlo.constant dense<[2, 3, 224, 224]> : tensor<4xi32>
+    %1 = stablehlo.dynamic_broadcast_in_dim %cst, %c_0, dims = [] : (tensor<f32>, tensor<4xi32>) -> tensor<?x3x224x224xf32>
+    // CHECK: return {{.*}} : tensor<2x3x224x224xf32>
+    stablehlo.return %1 : tensor<?x3x224x224xf32>
+  }) : (tensor<i1>) -> tensor<?x3x224x224xf32>
+  // CHECK: return {{.*}} : tensor<2x3x224x224xf32>
+  return %0 : tensor<?x3x224x224xf32>
+}
+
+// -----
+
 // TODO: Implement support for these ops.
 // * dynamic_conv (#867).
 // * dynamic_fft (#1366).