Fix quant. gemv kernel driver by adding set_quantized_bias()

arm_gemm fuses the actual bias addition with the output stage in quantized gemm.

The output stage, in its very basic form, is:
	A_offset * B_offset - sum(A_row_i) * B_offset - sum(B_col_j) * A_offset

Matrix B is usually constant (e.g. weight matrix in convolutions). Therefore, except the middle term above, the expression is constant across the same output row because the column sums of matrix B are pre-calculated.

The bias is also usually constant. When it is, it makes sense to add the bias vector to the above sum and just perform a single addition on top of the output tensor.

For this to happen, the column sum computation of B tensor must account for the bias. This is ensured by set_quantized_bias() method in the interface. This function passes the bias pointer and strides to arm_gemm.

Gemv_pretransposed does not implement set_quantized_bias() and uses the parent function, which does nothing. Therefore, the bias is not added to the output. This causes tests to fail.

Resolves: COMPMID-6928
Change-Id: Iba24fabc65fdc47edb12db6abff2fb47784c0743
Signed-off-by: Gunes Bayir <gunes.bayir@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/11310
Benchmark: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Jakub Sujak <jakub.sujak@arm.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/core/NEON/kernels/arm_gemm/gemv_pretransposed.hpp b/src/core/NEON/kernels/arm_gemm/gemv_pretransposed.hpp
index f70fc98572..92c884ce18 100644
--- a/src/core/NEON/kernels/arm_gemm/gemv_pretransposed.hpp
+++ b/src/core/NEON/kernels/arm_gemm/gemv_pretransposed.hpp
@@ -215,6 +215,15 @@ public:
         }
     }
 
+    void set_quantized_bias(const int32_t *bias, size_t bias_multi_stride) override {
+        if (std::is_same<OutputStage, Requantize32>::value) {
+            Requantize32 *qp = reinterpret_cast<Requantize32 *>(&_os);
+
+            qp->bias = bias;
+            qp->bias_multi_stride = bias_multi_stride;
+        }
+    }
+
     void pretranspose_B_array(void *buffer, const To *B, const int ldb, const int B_multi_stride, bool transposed) override {
         assert(!transposed);