Fixed Pallas Mosaic GPU test following recent changes

PiperOrigin-RevId: 679504036

jax/_src/pallas/mosaic_gpu/lowering.py

@@ -357,6 +357,10 @@ def body(launch_ctx: mgpu.LaunchContext, *buffers: ir.Value):
  *aval.shape, dtype=mgpu_utils.dtype_to_ir_type(aval.dtype)
  )
  )
+ case gpu_core.AbstractMemoryRef() if isinstance(
+ aval.dtype, gpu_core.BarrierType
+ ):
+ pass
  case gpu_core.AbstractMemoryRef() if aval.memory_space == SMEM:
  scratch_buffers_template.append(next(smem_scratch_it))
  should_discharge.append(False)
@@ -397,7 +401,7 @@ def gmem_slice(
  step: ir.Value,
  block_mapping: pallas_core.BlockMapping,
  ) -> Sequence[mgpu.DynamicSlice]:
- assert len(sequential_axes) == 1
+ assert len(sequential_axes) <= 1
  program_ids = [step if i is None else i for i in program_ids_template]
  idxs = _eval_index_map(module_ctx, launch_ctx, program_ids, block_mapping)
  return tuple(
@@ -428,7 +432,7 @@ def store(
  idx: int, step: ir.Value, slot: ir.Value, prev_base_offset: ir.Value
  ) -> ir.Value:
  if not out_in_smem[idx]:
- return
+ return _as_index(-1)
 
  # We have to do some work to make sure that consecutive stores are not
  # going to be writing to the same location, or else we'll end up with