Add option to export FX Node metadata to StableHLO

[lsy323]

This fixes #7014

Example usage

ep = torch.export.export(M(), args)
export_options = StableHLOExportOptions()
export_options.export_node_metadata = True
shlo = exported_program_to_stablehlo(ep, options=export_options)

The fx.node.meta(Including stack_trace, nn_module_stack and source_fn_stack) will be serialized to JSON, stored in the NameLoc in StableHLO

Example output

module @IrToHlo.24 attributes {mhlo.cross_program_prefetches = [], mhlo.is_dynamic = false, mhlo.use_auto_spmd_partitioning = false} {
  func.func @main(%arg0: tensor<10xf32> [unknown], %arg1: tensor<10x16xf32> [unknown], %arg2: tensor<16xf32> [unknown], %arg3: tensor<16x4xf32> [unknown], %arg4: tensor<2x4xf32> [unknown]) -> tensor<2x10xf32> {
    %cst = stablehlo.constant dense<0.000000e+00> : tensor<2x10xf32> [unknown]
    %0 = stablehlo.transpose %arg3, dims = [1, 0] {result_layout = dense<[0, 1]> : tensor<2xindex>, xla_shape = "f32[4,16]{0,1}"} : (tensor<16x4xf32>) -> tensor<4x16xf32> "{\22stack_trace\22: \22  File \\\22/home/lsiyuan/work/pytorch/xla/test/stablehlo/test_exports.py\\\22, line 146, in forward\\n    x = self.fc1(x)\\n\22, \22nn_module_stack\22: \22L__self__,,__main__.ExportTest.test_export_node_metadata.<locals>.M;L__self___fc1,fc1,torch.nn.modules.linear.Linear\22, \22source_fn_stack\22: \22l__self___fc1,torch.nn.modules.linear.Linear\22, \22torch_fn\22: \22linear_1;builtin_function_or_method.linear\22}aten__permute"
    %1 = stablehlo.dot_general %arg4, %0, contracting_dims = [1] x [0], precision = [DEFAULT, DEFAULT] : (tensor<2x4xf32>, tensor<4x16xf32>) -> tensor<2x16xf32> "{\22stack_trace\22: \22  File \\\22/home/lsiyuan/work/pytorch/xla/test/stablehlo/test_exports.py\\\22, line 146, in forward\\n    x = self.fc1(x)\\n\22, \22nn_module_stack\22: \22L__self__,,__main__.ExportTest.test_export_node_metadata.<locals>.M;L__self___fc1,fc1,torch.nn.modules.linear.Linear\22, \22source_fn_stack\22: \22l__self___fc1,torch.nn.modules.linear.Linear\22, \22torch_fn\22: \22linear_1;builtin_function_or_method.linear\22}aten__addmm"
    %2 = stablehlo.broadcast_in_dim %arg2, dims = [1] : (tensor<16xf32>) -> tensor<2x16xf32> "{\22stack_trace\22: \22  File \\\22/home/lsiyuan/work/pytorch/xla/test/stablehlo/test_exports.py\\\22, line 146, in forward\\n    x = self.fc1(x)\\n\22, \22nn_module_stack\22: \22L__self__,,__main__.ExportTest.test_export_node_metadata.<locals>.M;L__self___fc1,fc1,torch.nn.modules.linear.Linear\22, \22source_fn_stack\22: \22l__self___fc1,torch.nn.modules.linear.Linear\22, \22torch_fn\22: \22linear_1;builtin_function_or_method.linear\22}aten__addmm"
    %3 = stablehlo.add %1, %2 : tensor<2x16xf32> "{\22stack_trace\22: \22  File \\\22/home/lsiyuan/work/pytorch/xla/test/stablehlo/test_exports.py\\\22, line 146, in forward\\n    x = self.fc1(x)\\n\22, \22nn_module_stack\22: \22L__self__,,__main__.ExportTest.test_export_node_metadata.<locals>.M;L__self___fc1,fc1,torch.nn.modules.linear.Linear\22, \22source_fn_stack\22: \22l__self___fc1,torch.nn.modules.linear.Linear\22, \22torch_fn\22: \22linear_1;builtin_function_or_method.linear\22}aten__addmm"
    %4 = stablehlo.transpose %arg1, dims = [1, 0] {result_layout = dense<[0, 1]> : tensor<2xindex>, xla_shape = "f32[16,10]{0,1}"} : (tensor<10x16xf32>) -> tensor<16x10xf32> "{\22stack_trace\22: \22  File \\\22/home/lsiyuan/work/pytorch/xla/test/stablehlo/test_exports.py\\\22, line 147, in forward\\n    x = self.fc2(x)\\n\22, \22nn_module_stack\22: \22L__self__,,__main__.ExportTest.test_export_node_metadata.<locals>.M;L__self___fc2,fc2,torch.nn.modules.linear.Linear\22, \22source_fn_stack\22: \22l__self___fc2,torch.nn.modules.linear.Linear\22, \22torch_fn\22: \22linear_2;builtin_function_or_method.linear\22}aten__permute"
    %5 = stablehlo.dot_general %3, %4, contracting_dims = [1] x [0], precision = [DEFAULT, DEFAULT] : (tensor<2x16xf32>, tensor<16x10xf32>) -> tensor<2x10xf32> "{\22stack_trace\22: \22  File \\\22/home/lsiyuan/work/pytorch/xla/test/stablehlo/test_exports.py\\\22, line 147, in forward\\n    x = self.fc2(x)\\n\22, \22nn_module_stack\22: \22L__self__,,__main__.ExportTest.test_export_node_metadata.<locals>.M;L__self___fc2,fc2,torch.nn.modules.linear.Linear\22, \22source_fn_stack\22: \22l__self___fc2,torch.nn.modules.linear.Linear\22, \22torch_fn\22: \22linear_2;builtin_function_or_method.linear\22}aten__addmm"
    %6 = stablehlo.broadcast_in_dim %arg0, dims = [1] : (tensor<10xf32>) -> tensor<2x10xf32> "{\22stack_trace\22: \22  File \\\22/home/lsiyuan/work/pytorch/xla/test/stablehlo/test_exports.py\\\22, line 147, in forward\\n    x = self.fc2(x)\\n\22, \22nn_module_stack\22: \22L__self__,,__main__.ExportTest.test_export_node_metadata.<locals>.M;L__self___fc2,fc2,torch.nn.modules.linear.Linear\22, \22source_fn_stack\22: \22l__self___fc2,torch.nn.modules.linear.Linear\22, \22torch_fn\22: \22linear_2;builtin_function_or_method.linear\22}aten__addmm"
    %7 = stablehlo.add %5, %6 : tensor<2x10xf32> "{\22stack_trace\22: \22  File \\\22/home/lsiyuan/work/pytorch/xla/test/stablehlo/test_exports.py\\\22, line 147, in forward\\n    x = self.fc2(x)\\n\22, \22nn_module_stack\22: \22L__self__,,__main__.ExportTest.test_export_node_metadata.<locals>.M;L__self___fc2,fc2,torch.nn.modules.linear.Linear\22, \22source_fn_stack\22: \22l__self___fc2,torch.nn.modules.linear.Linear\22, \22torch_fn\22: \22linear_2;builtin_function_or_method.linear\22}aten__addmm"
    %8 = stablehlo.maximum %7, %cst : tensor<2x10xf32> "{}aten__relu"
    return %8 : tensor<2x10xf32> [unknown]
  } [unknown]
} [unknown]