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| 1 | +// Copyright (c) Kyutai, all rights reserved. |
| 2 | +// This source code is licensed under the license found in the |
| 3 | +// LICENSE file in the root directory of this source tree. |
| 4 | + |
| 5 | +import MLX |
| 6 | +import MLXFast |
| 7 | +import MLXNN |
| 8 | + |
| 9 | +public struct QwenConfig: Codable { |
| 10 | + public var bosTokenId: Int |
| 11 | + public var eosTokenId: Int |
| 12 | + public var hiddenSize: Int |
| 13 | + public var intermediateSize: Int |
| 14 | + public var maxPositionEmbeddings: Int |
| 15 | + public var maxWindowLayers: Int |
| 16 | + public var numAttentionHeads: Int |
| 17 | + public var numHiddenLayers: Int |
| 18 | + public var numKeyValueHeads: Int |
| 19 | + public var rmsNormEps: Float |
| 20 | + public var ropeTheta: Float |
| 21 | + public var tieWordEmbeddings: Bool |
| 22 | + public var useSlidingWindow: Bool |
| 23 | + public var vocabSize: Int |
| 24 | + |
| 25 | + public func headDim() -> Int { |
| 26 | + self.hiddenSize / self.numAttentionHeads |
| 27 | + } |
| 28 | +} |
| 29 | + |
| 30 | +private class Mlp: Module, UnaryLayer { |
| 31 | + @ModuleInfo(key: "gate_proj") var gateProj: Linear |
| 32 | + @ModuleInfo(key: "down_proj") var downProj: Linear |
| 33 | + @ModuleInfo(key: "up_proj") var upProj: Linear |
| 34 | + |
| 35 | + init(_ cfg: QwenConfig) { |
| 36 | + self._gateProj.wrappedValue = Linear(cfg.hiddenSize, cfg.intermediateSize, bias: false) |
| 37 | + self._upProj.wrappedValue = Linear(cfg.hiddenSize, cfg.intermediateSize, bias: false) |
| 38 | + self._downProj.wrappedValue = Linear(cfg.intermediateSize, cfg.hiddenSize, bias: false) |
| 39 | + } |
| 40 | + |
| 41 | + func callAsFunction(_ x: MLXArray) -> MLXArray { |
| 42 | + return downProj(silu(gateProj(x)) * upProj(x)) |
| 43 | + } |
| 44 | +} |
| 45 | + |
| 46 | +private class Attention: Module { |
| 47 | + let cfg: QwenConfig |
| 48 | + let scale: Float |
| 49 | + let rope: RoPE |
| 50 | + |
| 51 | + @ModuleInfo(key: "q_proj") var qProj: Linear |
| 52 | + @ModuleInfo(key: "k_proj") var kProj: Linear |
| 53 | + @ModuleInfo(key: "v_proj") var vProj: Linear |
| 54 | + @ModuleInfo(key: "o_proj") var oProj: Linear |
| 55 | + |
| 56 | + init(_ cfg: QwenConfig) { |
| 57 | + self.cfg = cfg |
| 58 | + self.scale = 1.0 / sqrt(Float(cfg.headDim())) |
| 59 | + let headDim = cfg.headDim() |
| 60 | + self._qProj.wrappedValue = Linear( |
| 61 | + cfg.hiddenSize, cfg.numAttentionHeads * headDim, bias: true) |
| 62 | + self._kProj.wrappedValue = Linear( |
| 63 | + cfg.hiddenSize, cfg.numKeyValueHeads * headDim, bias: true) |
| 64 | + self._vProj.wrappedValue = Linear( |
| 65 | + cfg.hiddenSize, cfg.numKeyValueHeads * headDim, bias: true) |
| 66 | + self._oProj.wrappedValue = Linear( |
| 67 | + cfg.numAttentionHeads * headDim, cfg.hiddenSize, bias: false) |
| 68 | + self.rope = |
| 69 | + RoPE(dimensions: cfg.headDim(), traditional: false, base: Float(cfg.ropeTheta)) |
| 70 | + } |
| 71 | + |
| 72 | + func callAsFunction(_ x: MLXArray, mask: MLXArray?, cache: KVCache?) -> MLXArray { |
| 73 | + let (B, T, H) = (x.dim(0), x.dim(1), x.dim(2)) |
| 74 | + let headDim = cfg.headDim() |
| 75 | + var queryStates = qProj(x).reshaped(B, T, -1, headDim).transposed(0, 2, 1, 3) |
| 76 | + var keyStates = kProj(x).reshaped(B, T, -1, headDim).transposed(0, 2, 1, 3) |
| 77 | + var valueStates = vProj(x).reshaped(B, T, -1, headDim).transposed(0, 2, 1, 3) |
| 78 | + let offset = cache?.offset ?? 0 |
| 79 | + queryStates = rope(queryStates, offset: offset) |
| 80 | + keyStates = rope(keyStates, offset: offset) |
| 81 | + if let cache { |
| 82 | + (keyStates, valueStates) = cache.update(keys: keyStates, values: valueStates) |
| 83 | + } |
| 84 | + // sliding window is not supported here |
| 85 | + var mask = mask |
| 86 | + if let m = mask { |
| 87 | + let maskLen = m.dim(-1) |
| 88 | + if keyStates.dim(2) < maskLen { |
| 89 | + let offset = maskLen - keyStates.dim(2) |
| 90 | + mask = m[0..., offset...] |
| 91 | + } |
| 92 | + } |
| 93 | + let x = MLXFast.scaledDotProductAttention( |
| 94 | + queries: queryStates, keys: keyStates, values: valueStates, scale: self.scale, |
| 95 | + mask: mask |
| 96 | + ).transposed(0, 2, 1, 3).reshaped(B, T, H) |
| 97 | + return oProj(x) |
| 98 | + } |
| 99 | +} |
| 100 | + |
| 101 | +private class Layer: Module { |
| 102 | + @ModuleInfo(key: "mlp") var mlp: Mlp |
| 103 | + @ModuleInfo(key: "input_layernorm") var inputNorm: RMSNorm |
| 104 | + @ModuleInfo(key: "post_attention_layernorm") var postAttnNorm: RMSNorm |
| 105 | + @ModuleInfo(key: "self_attn") var selfAttn: Attention |
| 106 | + |
| 107 | + init(_ cfg: QwenConfig) { |
| 108 | + self._mlp.wrappedValue = Mlp(cfg) |
| 109 | + self._inputNorm.wrappedValue = RMSNorm(dimensions: cfg.hiddenSize, eps: cfg.rmsNormEps) |
| 110 | + self._postAttnNorm.wrappedValue = RMSNorm(dimensions: cfg.hiddenSize, eps: cfg.rmsNormEps) |
| 111 | + self._selfAttn.wrappedValue = Attention(cfg) |
| 112 | + } |
| 113 | + |
| 114 | + func callAsFunction(_ x: MLXArray, mask: MLXArray?, cache: KVCache) -> MLXArray { |
| 115 | + var residual = x |
| 116 | + var x = x |
| 117 | + x = selfAttn(inputNorm(x), mask: mask, cache: cache) |
| 118 | + x = residual + x |
| 119 | + residual = x |
| 120 | + x = mlp(postAttnNorm(x)) |
| 121 | + return residual + x |
| 122 | + } |
| 123 | +} |
| 124 | + |
| 125 | +public class QwenModel: Module { |
| 126 | + let cfg: QwenConfig |
| 127 | + private let norm: RMSNorm |
| 128 | + private let layers: [Layer] |
| 129 | + @ModuleInfo(key: "embed_tokens") var embedTokens: Embedding |
| 130 | + |
| 131 | + public init(_ cfg: QwenConfig) { |
| 132 | + self.cfg = cfg |
| 133 | + self.layers = (0..<cfg.numHiddenLayers).map { _ in Layer(cfg) } |
| 134 | + self.norm = RMSNorm(dimensions: cfg.hiddenSize, eps: cfg.rmsNormEps) |
| 135 | + self._embedTokens.wrappedValue = Embedding( |
| 136 | + embeddingCount: cfg.vocabSize, dimensions: cfg.hiddenSize) |
| 137 | + } |
| 138 | + |
| 139 | + public func callAsFunction(_ x: MLXArray, cache: [KVCache]) -> MLXArray { |
| 140 | + var x = embedTokens(x) |
| 141 | + let mask = cache.first?.createAttentionMask(h: x) |
| 142 | + for (layer, c) in zip(self.layers, cache) { |
| 143 | + x = layer(x, mask: mask, cache: c) |
| 144 | + } |
| 145 | + return embedTokens.asLinear(norm(x)) |
| 146 | + } |
| 147 | + |
| 148 | + public func makeCache(bSize: Int) -> [KVCache] { |
| 149 | + let kvHeads = cfg.numKeyValueHeads |
| 150 | + let cache = (0..<cfg.numHiddenLayers).map { _ in |
| 151 | + KVCacheSimple(headDim: .init(cfg.headDim()), kvHeads: kvHeads) |
| 152 | + } |
| 153 | + return cache |
| 154 | + } |
| 155 | +} |
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