Failure in GPU pass pipeline

With the following MLIR in `out.mlir`:
```mlir
#map = affine_map<(d0, d1) -> (d0, d1)>
#map1 = affine_map<(d0) -> (d0)>
module {
func.func private @printMemrefI64(tensor<*xi64>)
func.func private @printMemrefF64(tensor<*xf64>)
func.func @main() {
%cst = arith.constant dense<6> : tensor<2xindex>
%cst_0 = arith.constant 0.000000e+00 : f64
%c5_i64 = arith.constant 5 : i64
%c0 = arith.constant 0 : index
%c1 = arith.constant 1 : index
%0 = tensor.empty() : tensor<1x5xi64>
%1 = linalg.generic {indexing_maps = [#map], iterator_types = ["parallel", "parallel"]} outs(%0 : tensor<1x5xi64>) {
^bb0(%out: i64):
linalg.yield %c5_i64 : i64
} -> tensor<1x5xi64>
%2 = tensor.empty() : tensor<36xi64>
%3 = linalg.generic {indexing_maps = [#map1], iterator_types = ["parallel"]} outs(%2 : tensor<36xi64>) {
^bb0(%out: i64):
%9 = linalg.index 0 : index
%10 = arith.index_cast %9 : index to i64
%11 = arith.sitofp %10 : i64 to f64
%12 = arith.addf %11, %cst_0 : f64
%13 = arith.fptosi %12 : f64 to i64
linalg.yield %13 : i64
} -> tensor<36xi64>
%cast = tensor.cast %3 : tensor<36xi64> to tensor
%reshape = tensor.reshape %cast(%cst) : (tensor, tensor<2xindex>) -> tensor
%dim = tensor.dim %reshape, %c0 : tensor
%dim_1 = tensor.dim %reshape, %c1 : tensor
%4 = tensor.empty(%dim, %dim_1) : tensor
%5 = bufferization.to_memref %4 : memref
%6 = bufferization.to_memref %reshape : memref>
memref.copy %6, %5 : memref> to memref
%7 = bufferization.to_memref %1 : memref<1x5xi64>
%8 = bufferization.to_memref %reshape : memref>
%subview = memref.subview %8[1, 1] [1, 5] [5, 1] : memref> to memref<1x5xi64, strided<[?, ?], offset: ?>>
linalg.generic {indexing_maps = [#map, #map], iterator_types = ["parallel", "parallel"]} ins(%7 : memref<1x5xi64>) outs(%subview : memref<1x5xi64, strided<[?, ?], offset: ?>>) {
^bb0(%in: i64, %out: i64):
linalg.yield %in : i64
}
%cast_2 = tensor.cast %reshape : tensor to tensor<*xi64>
call @printMemrefI64(%cast_2) : (tensor<*xi64>) -> ()
return
}
}
```
the command `python bin/imex-runner.py -f ./ptensor-gpu.pp -i ./out.mlir` fails with the following message:
```
./out.mlir:39:5: error: failed to legalize operation 'gpu.func'
linalg.generic {indexing_maps = [#map, #map], iterator_types = ["parallel", "parallel"]} ins(%7 : memref<1x5xi64>) outs(%subview : memref<1x5xi64, strided<[?, ?], offset: ?>>) {
^
./out.mlir:39:5: note: see current operation:
"gpu.func"() ({
^bb0(%arg0: memref<1x5xi64, #spirv.storage_class>, %arg1: index, %arg2: memref<1x5xi64, strided<[?, 1], offset: ?>, #spirv.storage_class>):
%0 = "gpu.block_id"() {dimension = #gpu} : () -> index
%1 = "memref.load"(%arg0, %arg1, %0) {nontemporal = false} : (memref<1x5xi64, #spirv.storage_class>, index, index) -> i64
"memref.store"(%1, %arg2, %arg1, %0) {nontemporal = false} : (i64, memref<1x5xi64, strided<[?, 1], offset: ?>, #spirv.storage_class>, index, index) -> ()
"gpu.return"() : () -> ()
}) {function_type = (memref<1x5xi64, #spirv.storage_class>, index, memref<1x5xi64, strided<[?, 1], offset: ?>, #spirv.storage_class>) -> (), gpu.kernel, gpu.known_block_size = array, gpu.known_grid_size = array, spirv.entry_point_abi = #spirv.entry_point_abi<>, sym_name = "main_kernel", workgroup_attributions = 0 : i64} : () -> ()
```

Here's the content of `ptensor-gpu.pp`:
```
builtin.module(
convert-tensor-to-linalg
arith-bufferize
func.func(empty-tensor-to-alloc-tensor
//eliminate-empty-tensors
scf-bufferize
shape-bufferize
linalg-bufferize
bufferization-bufferize
tensor-bufferize)
func-bufferize
func.func(finalizing-bufferize
convert-linalg-to-parallel-loops
imex-add-outer-parallel-loop
gpu-map-parallel-loops
convert-parallel-loops-to-gpu)
// insert-gpu-allocs pass can have client-api = opencl or vulkan args
func.func(insert-gpu-allocs{client-api=opencl})
canonicalize
normalize-memrefs
// Unstride memrefs does not seem to be needed.
// func.func(unstride-memrefs)
func.func(lower-affine)
gpu-kernel-outlining
canonicalize
cse
// The following set-spirv-* passes can have client-api = opencl or vulkan args
set-spirv-capabilities{client-api=opencl}
gpu.module(set-spirv-abi-attrs{client-api=opencl})
canonicalize
fold-memref-alias-ops
imex-convert-gpu-to-spirv
spirv.module(spirv-lower-abi-attrs
spirv-update-vce)
func.func(llvm-request-c-wrappers)
serialize-spirv
convert-gpu-to-gpux
convert-func-to-llvm
convert-math-to-llvm
convert-gpux-to-llvm
expand-strided-metadata
lower-affine
finalize-memref-to-llvm
reconcile-unrealized-casts)
```