[Test] Add reproducer for strided universal_copy in convert-fly-to-rocdl

Freezes current (buggy) lowering: a non-unit-stride !fly.memref on one
side of fly.copy_atom_call is lowered to a single contiguous llvm.load
/ llvm.store against the memory-side pointer, silently ignoring the
stride. Next commit will fix emitAtomCallSSA and update these CHECKs.

Author: kefan203

tests/mlir/Transforms/convert_fly_to_rocdl_universal_copy_strided.mlir

@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright (c) 2025 FlyDSL Project Contributors
+// RUN: %fly-opt %s --fly-convert-atom-call-to-ssa-form --convert-fly-to-rocdl | FileCheck %s
+
+gpu.module @bug_strided_universal_copy {
+
+// CHECK-LABEL: gpu.func @load_strided_global_into_register(
+// CHECK-SAME:     %[[ARG0:.*]]: !llvm.ptr<1>
+// CHECK:      %[[REG:.*]] = llvm.alloca %{{.*}} x f16 : (i64) -> !llvm.ptr<5>
+// CHECK:      %[[V:.*]] = llvm.load %[[ARG0]] : !llvm.ptr<1> -> vector<4xf16>
+// CHECK-NEXT: llvm.store %[[V]], %[[REG]] : vector<4xf16>, !llvm.ptr<5>
+  gpu.func @load_strided_global_into_register(%src: !fly.ptr<f16,  global>) kernel {
+    %shape4  = fly.make_int_tuple() : () -> !fly.int_tuple<4>
+    %stride1 = fly.make_int_tuple() : () -> !fly.int_tuple<1>
+    %stride8 = fly.make_int_tuple() : () -> !fly.int_tuple<8>
+
+    %src_layout = fly.make_layout(%shape4, %stride8)
+        : (!fly.int_tuple<4>, !fly.int_tuple<8>) -> !fly.layout<4:8>
+    %reg_layout = fly.make_layout(%shape4, %stride1)
+        : (!fly.int_tuple<4>, !fly.int_tuple<1>) -> !fly.layout<4:1>
+
+    %src_view = fly.make_view(%src, %src_layout)
+        : (!fly.ptr<f16,  global>, !fly.layout<4:8>) -> !fly.memref<f16,  global, 4:8>
+
+    %copy = fly.make_copy_atom {valBits = 16 : i32}
+        : !fly.copy_atom<!fly.universal_copy<64>, 16>
+
+    %reg_ptr  = fly.make_ptr() {dictAttrs = {allocaSize = 4 : i64}}
+        : () -> !fly.ptr<f16,  register>
+    %reg_view = fly.make_view(%reg_ptr, %reg_layout)
+        : (!fly.ptr<f16,  register>, !fly.layout<4:1>) -> !fly.memref<f16,  register, 4:1>
+
+    fly.copy_atom_call(%copy, %src_view, %reg_view)
+        : (!fly.copy_atom<!fly.universal_copy<64>, 16>,
+           !fly.memref<f16,  global, 4:8>,
+           !fly.memref<f16,  register, 4:1>) -> ()
+    gpu.return
+  }
+
+// CHECK-LABEL: gpu.func @store_register_into_strided_global(
+// CHECK-SAME:     %[[ARG0:.*]]: !llvm.ptr<1>
+// CHECK:      %[[REG:.*]] = llvm.alloca %{{.*}} x f16 : (i64) -> !llvm.ptr<5>
+// CHECK:      %[[V:.*]] = llvm.load %[[REG]] : !llvm.ptr<5> -> vector<4xf16>
+// CHECK-NEXT: llvm.store %[[V]], %[[ARG0]] : vector<4xf16>, !llvm.ptr<1>
+  gpu.func @store_register_into_strided_global(%dst: !fly.ptr<f16,  global>) kernel {
+    %shape4  = fly.make_int_tuple() : () -> !fly.int_tuple<4>
+    %stride1 = fly.make_int_tuple() : () -> !fly.int_tuple<1>
+    %stride8 = fly.make_int_tuple() : () -> !fly.int_tuple<8>
+
+    %dst_layout = fly.make_layout(%shape4, %stride8)
+        : (!fly.int_tuple<4>, !fly.int_tuple<8>) -> !fly.layout<4:8>
+    %reg_layout = fly.make_layout(%shape4, %stride1)
+        : (!fly.int_tuple<4>, !fly.int_tuple<1>) -> !fly.layout<4:1>
+
+    %dst_view = fly.make_view(%dst, %dst_layout)
+        : (!fly.ptr<f16,  global>, !fly.layout<4:8>) -> !fly.memref<f16,  global, 4:8>
+
+    %copy = fly.make_copy_atom {valBits = 16 : i32}
+        : !fly.copy_atom<!fly.universal_copy<64>, 16>
+
+    %reg_ptr  = fly.make_ptr() {dictAttrs = {allocaSize = 4 : i64}}
+        : () -> !fly.ptr<f16,  register>
+    %reg_view = fly.make_view(%reg_ptr, %reg_layout)
+        : (!fly.ptr<f16,  register>, !fly.layout<4:1>) -> !fly.memref<f16,  register, 4:1>
+
+    fly.copy_atom_call(%copy, %reg_view, %dst_view)
+        : (!fly.copy_atom<!fly.universal_copy<64>, 16>,
+           !fly.memref<f16,  register, 4:1>,
+           !fly.memref<f16,  global, 4:8>) -> ()
+    gpu.return
+  }
+}