message: [XLA GPU] Do not special case index type to int64 in reduction emitter
diff: @@ -3174,6 +3174,14 @@ Status IrEmitterUnnested::EmitReductionFromOrToContiguousDimensions(
  ReductionCodegenInfo reduction_info =
  ComputeReductionCodegenInfo(unnested_hlo, first_reduce);
  + const KernelMappingScheme& mapping_scheme =
  + reduction_info.GetKernelMappingScheme();
  + LaunchDimensions launch_dimensions(mapping_scheme.GetNumberOfBlocks(),
  + mapping_scheme.GetThreadsPerBlock());
  + llvm::Type* index_ty = GetIndexTypeForKernel(
  + unnested_hlo, launch_dimensions.launch_bound(), &b_);
  + EmitPrologueForReduction(unnested_hlo, &reduction_info, reduce_instructions,
  + index_ty);
  EmitElementFunction emit_reduction_tile =
  [&](const llvm_ir::IrArray::Index& index, llvm::Value* y_loc,
  llvm::Value* x_loc, int64 x_iter_num) {
  @@ -3182,16 +3190,6 @@ Status IrEmitterUnnested::EmitReductionFromOrToContiguousDimensions(
  reducers, x_iter_num);
  };
  - const auto& mapping_scheme = reduction_info.GetKernelMappingScheme();
  - LaunchDimensions launch_dimensions(mapping_scheme.GetNumberOfBlocks(),
  - mapping_scheme.GetThreadsPerBlock());
  - llvm::Type* index_ty =
  - reduction_info.IsRowReduction()
  - ? GetIndexTypeForKernel(unnested_hlo,
  - launch_dimensions.launch_bound(), &b_)
  - : b_.getInt64Ty();
  - EmitPrologueForReduction(unnested_hlo, &reduction_info, reduce_instructions,
  - index_ty);
  llvm::Value* lane_id = EmitTilingKernel(
  mapping_scheme, index_ty,
  /*tile_element_generator=*/
  