working/peft/tests/test_vera.py

# Copyright 2024-present the HuggingFace Inc. team.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# This test file is for tests specific to VeRA, since VeRA has some specific challenges due to the shared weights.

import os
import re

import pytest
import torch
from safetensors import safe_open
from torch import nn

from peft import PeftModel, VeraConfig, get_peft_model


class MLP(nn.Module):
    def __init__(self, bias=True):
        super().__init__()
        self.relu = nn.ReLU()
        self.lin0 = nn.Linear(10, 20, bias=bias)
        self.lin1 = nn.Linear(20, 20, bias=bias)  # lin1 and lin2 have same shape
        self.lin2 = nn.Linear(20, 20, bias=bias)
        self.lin3 = nn.Linear(20, 2, bias=bias)
        self.sm = nn.LogSoftmax(dim=-1)

    def forward(self, X):
        X = X.float()
        X = self.lin0(X)
        X = self.relu(X)
        X = self.lin1(X)
        X = self.relu(X)
        X = self.lin2(X)
        X = self.relu(X)
        X = self.lin3(X)
        X = self.sm(X)
        return X


class TestVera:
    @pytest.fixture
    def mlp(self):
        torch.manual_seed(0)
        model = MLP()
        return model

    @pytest.fixture
    def mlp_same_prng(self, mlp):
        torch.manual_seed(0)

        config = VeraConfig(target_modules=["lin1", "lin2"], init_weights=False)
        # creates a default VeRA adapter
        peft_model = get_peft_model(mlp, config)
        config2 = VeraConfig(target_modules=["lin1", "lin2"], init_weights=False)
        peft_model.add_adapter("other", config2)
        return peft_model

    def test_multiple_adapters_same_prng_weights(self, mlp_same_prng):
        # we can have multiple adapters with the same prng key, in which case the weights should be shared
        assert (
            mlp_same_prng.base_model.model.lin1.vera_A["default"]
            is mlp_same_prng.base_model.model.lin1.vera_A["other"]
        )
        assert (
            mlp_same_prng.base_model.model.lin1.vera_B["default"]
            is mlp_same_prng.base_model.model.lin1.vera_B["other"]
        )
        assert (
            mlp_same_prng.base_model.model.lin2.vera_A["default"]
            is mlp_same_prng.base_model.model.lin2.vera_A["other"]
        )
        assert (
            mlp_same_prng.base_model.model.lin2.vera_B["default"]
            is mlp_same_prng.base_model.model.lin2.vera_B["other"]
        )

        input = torch.randn(5, 10)
        mlp_same_prng.set_adapter("default")
        output_default = mlp_same_prng(input)
        mlp_same_prng.set_adapter("other")
        output_other = mlp_same_prng(input)
        assert not torch.allclose(output_default, output_other, atol=1e-3, rtol=1e-3)

    def test_multiple_adapters_different_prng_raises(self):
        # we cannot have multiple adapters with different prng keys
        model = MLP()
        config = VeraConfig(target_modules=["lin1", "lin2"], init_weights=False)
        # creates a default VeRA adapter
        peft_model = get_peft_model(model, config)
        config2 = VeraConfig(target_modules=["lin1", "lin2"], init_weights=False, projection_prng_key=123)

        msg = (
            r"Vera PRNG initialisation key must be the same for all adapters. Got config.projection_prng_key=123 but "
            r"previous config had 0"
        )
        with pytest.raises(ValueError, match=msg):
            peft_model.add_adapter("other", config2)

    def test_multiple_adapters_save_load_save_projection_true(self, mlp_same_prng, tmp_path):
        # check saving and loading works with multiple adapters and saved projection weights
        torch.manual_seed(0)
        input = torch.randn(5, 10)
        mlp_same_prng.set_adapter("default")
        output_default = mlp_same_prng(input)
        mlp_same_prng.set_adapter("other")
        output_other = mlp_same_prng(input)

        # sanity check
        assert not torch.allclose(output_default, output_other, atol=1e-3, rtol=1e-3)

        save_path = tmp_path / "vera"
        mlp_same_prng.save_pretrained(save_path)
        assert os.path.exists(save_path / "adapter_config.json")
        assert os.path.exists(save_path / "other" / "adapter_config.json")

        torch.manual_seed(0)
        mlp = MLP()
        peft_model = PeftModel.from_pretrained(mlp, save_path)
        peft_model.load_adapter(save_path / "other", "other")

        peft_model.set_adapter("default")
        output_default_loaded = peft_model(input)
        peft_model.set_adapter("other")
        output_other_loaded = peft_model(input)

        assert torch.allclose(output_default, output_default_loaded, atol=1e-3, rtol=1e-3)
        assert torch.allclose(output_other, output_other_loaded, atol=1e-3, rtol=1e-3)

    def test_multiple_adapters_save_load_save_projection_false(self, mlp, tmp_path):
        # check saving and loading works with multiple adapters without saved projection weights
        torch.manual_seed(1)
        config = VeraConfig(target_modules=["lin1", "lin2"], init_weights=False, save_projection=False)
        # creates a default VeRA adapter
        peft_model = get_peft_model(mlp, config, adapter_name="first")
        config2 = VeraConfig(target_modules=["lin1", "lin2"], init_weights=False, save_projection=False)
        peft_model.add_adapter("second", config2)

        input = torch.randn(5, 10)
        peft_model.set_adapter("first")
        output_first = peft_model(input)
        peft_model.set_adapter("second")
        output_second = peft_model(input)

        # sanity check
        assert not torch.allclose(output_first, output_second, atol=1e-3, rtol=1e-3)

        save_path = tmp_path / "vera"
        peft_model.save_pretrained(save_path)
        assert os.path.exists(save_path / "first" / "adapter_config.json")
        assert os.path.exists(save_path / "second" / "adapter_config.json")

        torch.manual_seed(0)
        mlp = MLP()
        peft_model = PeftModel.from_pretrained(mlp, save_path / "first", adapter_name="first")
        peft_model.load_adapter(save_path / "second", "second")

        peft_model.set_adapter("first")
        output_first_loaded = peft_model(input)
        peft_model.set_adapter("second")
        output_second_loaded = peft_model(input)

        assert torch.allclose(output_first, output_first_loaded, atol=1e-3, rtol=1e-3)
        assert torch.allclose(output_second, output_second_loaded, atol=1e-3, rtol=1e-3)

    def test_multiple_adapters_save_projection_true_contains_vera_A_vera_B(self, mlp_same_prng, tmp_path):
        # check that the state_dicts don't contain the projection weights
        save_path = tmp_path / "vera"
        mlp_same_prng.save_pretrained(save_path)

        sd_default = {}
        with safe_open(save_path / "adapter_model.safetensors", framework="pt", device="cpu") as f:
            for key in f.keys():
                sd_default[key] = f.get_tensor(key)

        assert any("vera_A" in key for key in sd_default)
        assert any("vera_B" in key for key in sd_default)
        # default rank for VeRA is 256
        assert sd_default["base_model.vera_A"].shape == (256, 20)
        assert sd_default["base_model.vera_B"].shape == (20, 256)

        sd_other = {}
        with safe_open(save_path / "other" / "adapter_model.safetensors", framework="pt", device="cpu") as f:
            for key in f.keys():
                sd_other[key] = f.get_tensor(key)

        assert any("vera_A" in key for key in sd_other)
        assert any("vera_B" in key for key in sd_other)
        assert sd_other["base_model.vera_A"].shape == (256, 20)
        assert sd_other["base_model.vera_B"].shape == (20, 256)

    def test_multiple_adapters_save_projection_false_contains_no_vera_A_vera_B(self, mlp, tmp_path):
        torch.manual_seed(1)
        config = VeraConfig(target_modules=["lin1", "lin2"], init_weights=False, save_projection=False)
        # creates a default VeRA adapter
        peft_model = get_peft_model(mlp, config, adapter_name="first")
        config2 = VeraConfig(target_modules=["lin1", "lin2"], init_weights=False, save_projection=False)
        peft_model.add_adapter("second", config2)

        save_path = tmp_path / "vera"
        peft_model.save_pretrained(save_path)

        sd_default = {}
        with safe_open(save_path / "first" / "adapter_model.safetensors", framework="pt", device="cpu") as f:
            for key in f.keys():
                sd_default[key] = f.get_tensor(key)

        assert not any("vera_A" in key for key in sd_default)
        assert not any("vera_B" in key for key in sd_default)

        sd_other = {}
        with safe_open(save_path / "second" / "adapter_model.safetensors", framework="pt", device="cpu") as f:
            for key in f.keys():
                sd_other[key] = f.get_tensor(key)

        assert not any("vera_A" in key for key in sd_other)
        assert not any("vera_B" in key for key in sd_other)

    def test_vera_A_vera_B_share_memory(self, mlp_same_prng):
        vera_A = mlp_same_prng.vera_A["default"]
        vera_B = mlp_same_prng.vera_B["default"]

        # these tensors should share the same data
        assert vera_A.data_ptr() == mlp_same_prng.base_model.model.lin1.vera_A["default"].data_ptr()
        assert vera_B.data_ptr() == mlp_same_prng.base_model.model.lin1.vera_B["default"].data_ptr()
        assert vera_A.data_ptr() == mlp_same_prng.base_model.model.lin2.vera_A["default"].data_ptr()
        assert vera_B.data_ptr() == mlp_same_prng.base_model.model.lin2.vera_B["default"].data_ptr()
        # sanity check: these tensors shouldn't share the same data
        assert vera_A.data_ptr() != vera_B.data_ptr()

    def test_vera_lambda_dont_share_memory(self, mlp_same_prng):
        # sanity check: these tensors shouldn't share the same data
        assert (
            mlp_same_prng.base_model.model.lin1.vera_lambda_b["default"].data_ptr()
            != mlp_same_prng.base_model.model.lin1.vera_lambda_b["other"].data_ptr()
        )
        assert (
            mlp_same_prng.base_model.model.lin1.vera_lambda_b["default"].data_ptr()
            != mlp_same_prng.base_model.model.lin2.vera_lambda_b["default"].data_ptr()
        )
        assert (
            mlp_same_prng.base_model.model.lin1.vera_lambda_b["other"].data_ptr()
            != mlp_same_prng.base_model.model.lin2.vera_lambda_b["other"].data_ptr()
        )
        assert (
            mlp_same_prng.base_model.model.lin1.vera_lambda_d["default"].data_ptr()
            != mlp_same_prng.base_model.model.lin1.vera_lambda_d["other"].data_ptr()
        )
        assert (
            mlp_same_prng.base_model.model.lin1.vera_lambda_d["default"].data_ptr()
            != mlp_same_prng.base_model.model.lin2.vera_lambda_d["default"].data_ptr()
        )
        assert (
            mlp_same_prng.base_model.model.lin1.vera_lambda_d["other"].data_ptr()
            != mlp_same_prng.base_model.model.lin2.vera_lambda_d["other"].data_ptr()
        )

    def test_vera_different_shapes_raises(self, mlp):
        # It is not possible (currently) to have vera_A and vera_B for different shapes, as they cannot be shared if
        # their shapes are not identical. lin0 and lin1 have different shapes.
        config = VeraConfig(target_modules=["lin0", "lin1"], init_weights=False)
        msg = re.escape(
            "Multiple target layers with different dimensions were specified. VeRA only supports a single dimension "
            "size. Expected shape (20, 10), got (20, 20)."
        )
        with pytest.raises(ValueError, match=msg):
            get_peft_model(mlp, config)