diff --git a/BUILD.bazel b/BUILD.bazel index 885bb665..aca15c86 100644 --- a/BUILD.bazel +++ b/BUILD.bazel @@ -626,6 +626,7 @@ cc_library( "//compression:compress", "//compression:types", "@highway//:hwy", + "@highway//:math", "@highway//:profiler", ], ) diff --git a/gemma/flash_attention.cc b/gemma/flash_attention.cc index ebe8ee18..a63e4dac 100644 --- a/gemma/flash_attention.cc +++ b/gemma/flash_attention.cc @@ -53,6 +53,7 @@ #include "gemma/attention.h" #include "ops/matmul-inl.h" #include "ops/ops-inl.h" +#include "hwy/contrib/math/fast_math-inl.h" HWY_BEFORE_NAMESPACE(); namespace gcpp { @@ -523,25 +524,22 @@ static HWY_INLINE void FlashAttentionTileStepAndApplySoftCap4( new_max = hn::Max(new_max, old_max_vf); auto changed_max = hn::Gt(new_max, hn::Set(df4, kNegInf)); hn::StoreU(new_max, df4, old_max); + auto apply_exp = [&](int i, VF& x_p0, VF& x_p1) HWY_ATTR { + const VF new_max_i = hn::Set(df, old_max[i]); + x_p0 = hn::FastExp(df, hn::Sub(x_p0, new_max_i)); + x_p1 = hn::FastExp(df, hn::Sub(x_p1, new_max_i)); + }; if constexpr (kNumQueries >= 1) { - const VF new_max_0 = hn::Set(df, old_max[0]); - x_0_p0 = hn::CallExp(df, hn::Sub(x_0_p0, new_max_0)); - x_0_p1 = hn::CallExp(df, hn::Sub(x_0_p1, new_max_0)); + apply_exp(0, x_0_p0, x_0_p1); } if constexpr (kNumQueries >= 2) { - const VF new_max_0 = hn::Set(df, old_max[1]); - x_1_p0 = hn::CallExp(df, hn::Sub(x_1_p0, new_max_0)); - x_1_p1 = hn::CallExp(df, hn::Sub(x_1_p1, new_max_0)); + apply_exp(1, x_1_p0, x_1_p1); } if constexpr (kNumQueries >= 3) { - const VF new_max_0 = hn::Set(df, old_max[2]); - x_2_p0 = hn::CallExp(df, hn::Sub(x_2_p0, new_max_0)); - x_2_p1 = hn::CallExp(df, hn::Sub(x_2_p1, new_max_0)); + apply_exp(2, x_2_p0, x_2_p1); } if constexpr (kNumQueries >= 4) { - const VF new_max_0 = hn::Set(df, old_max[3]); - x_3_p0 = hn::CallExp(df, hn::Sub(x_3_p0, new_max_0)); - x_3_p1 = hn::CallExp(df, hn::Sub(x_3_p1, new_max_0)); + apply_exp(3, x_3_p0, x_3_p1); } VF4 old_d_vf = hn::Set(df4, 0.0f); old_d_vf = hn::LoadU(df4, old_d); @@ -592,10 +590,6 @@ static HWY_INLINE void FlashAttentionTileStepAndApplySoftCap4( } } -template > -HWY_NOINLINE VF CallExp(DF df, VF x_p0) { - return hn::Exp(df, x_p0); -} template > static HWY_INLINE void FlashAttentionTileStepAndApplySoftCap8( DF df, float att_cap, float one_over_att_cap, VF& x_0_p0, VF& x_0_p1, @@ -649,45 +643,36 @@ static HWY_INLINE void FlashAttentionTileStepAndApplySoftCap8( new_max = hn::Max(new_max, old_max_vf); auto changed_max = hn::Gt(new_max, hn::Set(df8, kNegInf)); hn::StoreU(new_max, df8, old_max); + + auto apply_exp = [&](int i, VF& x_p0, VF& x_p1) HWY_ATTR { + const VF new_max_i = hn::Set(df, old_max[i]); + x_p0 = hn::Exp(df, hn::Sub(x_p0, new_max_i)); + x_p1 = hn::Exp(df, hn::Sub(x_p1, new_max_i)); + }; + if constexpr (kNumQueries >= 1) { - const VF new_max_0 = hn::Set(df, old_max[0]); - x_0_p0 = hn::CallExp(df, hn::Sub(x_0_p0, new_max_0)); - x_0_p1 = hn::CallExp(df, hn::Sub(x_0_p1, new_max_0)); + apply_exp(0, x_0_p0, x_0_p1); } if constexpr (kNumQueries >= 2) { - const VF new_max_0 = hn::Set(df, old_max[1]); - x_1_p0 = hn::CallExp(df, hn::Sub(x_1_p0, new_max_0)); - x_1_p1 = hn::CallExp(df, hn::Sub(x_1_p1, new_max_0)); + apply_exp(1, x_1_p0, x_1_p1); } if constexpr (kNumQueries >= 3) { - const VF new_max_0 = hn::Set(df, old_max[2]); - x_2_p0 = hn::CallExp(df, hn::Sub(x_2_p0, new_max_0)); - x_2_p1 = hn::CallExp(df, hn::Sub(x_2_p1, new_max_0)); + apply_exp(2, x_2_p0, x_2_p1); } if constexpr (kNumQueries >= 4) { - const VF new_max_0 = hn::Set(df, old_max[3]); - x_3_p0 = hn::CallExp(df, hn::Sub(x_3_p0, new_max_0)); - x_3_p1 = hn::CallExp(df, hn::Sub(x_3_p1, new_max_0)); + apply_exp(3, x_3_p0, x_3_p1); } if constexpr (kNumQueries >= 5) { - const VF new_max_0 = hn::Set(df, old_max[4]); - x_4_p0 = hn::CallExp(df, hn::Sub(x_4_p0, new_max_0)); - x_4_p1 = hn::CallExp(df, hn::Sub(x_4_p1, new_max_0)); + apply_exp(4, x_4_p0, x_4_p1); } if constexpr (kNumQueries >= 6) { - const VF new_max_0 = hn::Set(df, old_max[5]); - x_5_p0 = hn::CallExp(df, hn::Sub(x_5_p0, new_max_0)); - x_5_p1 = hn::CallExp(df, hn::Sub(x_5_p1, new_max_0)); + apply_exp(5, x_5_p0, x_5_p1); } if constexpr (kNumQueries >= 7) { - const VF new_max_0 = hn::Set(df, old_max[6]); - x_6_p0 = hn::CallExp(df, hn::Sub(x_6_p0, new_max_0)); - x_6_p1 = hn::CallExp(df, hn::Sub(x_6_p1, new_max_0)); + apply_exp(6, x_6_p0, x_6_p1); } if constexpr (kNumQueries >= 8) { - const VF new_max_0 = hn::Set(df, old_max[7]); - x_7_p0 = hn::CallExp(df, hn::Sub(x_7_p0, new_max_0)); - x_7_p1 = hn::CallExp(df, hn::Sub(x_7_p1, new_max_0)); + apply_exp(7, x_7_p0, x_7_p1); } VF8 old_d_vf = hn::Set(df8, 0.0f); old_d_vf = hn::LoadU(df8, old_d); diff --git a/gemma/flash_attention_test.cc b/gemma/flash_attention_test.cc index bbb63f5a..740addc3 100644 --- a/gemma/flash_attention_test.cc +++ b/gemma/flash_attention_test.cc @@ -349,11 +349,11 @@ void TestTiledFlashAttention() { for (int i = 0; i < num_queries; ++i) { std::cerr << "exp_d: " << exp_denominator_sums[i] << " max_logit: " << max_logits[i] << std::endl; - EXPECT_NEAR(exp_denominator_sums[i], exp_denominator_sums_gold[i], 1e-4f) + EXPECT_NEAR(exp_denominator_sums[i], exp_denominator_sums_gold[i], 4e-2f) << "i=" << i; EXPECT_NEAR(max_logits[i], max_logits_gold[i], 1e-6f) << "i=" << i; for (int j = 0; j < qkv_dim; ++j) { - EXPECT_NEAR(att_out.Row(i)[j], att_out_gold[i * qkv_dim + j], 1e-6f); + EXPECT_NEAR(att_out.Row(i)[j], att_out_gold[i * qkv_dim + j], 1e-4f); } } } @@ -464,7 +464,7 @@ void TestTiledFlashAttentionBF16() { for (int i = 0; i < num_queries; ++i) { std::cerr << "exp_d: " << exp_denominator_sums[i] << " max_logit: " << max_logits[i] << std::endl; - EXPECT_NEAR(exp_denominator_sums[i], exp_denominator_sums_gold[i], 2e-2f) + EXPECT_NEAR(exp_denominator_sums[i], exp_denominator_sums_gold[i], 4e-2f) << "i=" << i; EXPECT_NEAR(max_logits[i], max_logits_gold[i], 1e-3f) << "i=" << i; for (int j = 0; j < qkv_dim; ++j) {