Add ARM32 kernel implementation

larq_compute_engine/core/BUILD

@@ -108,6 +108,7 @@ cc_library(
     name = "bgemm_kernels_arm",
     hdrs = [
         "bgemm_kernels_arm.h",
+        "bgemm_kernels_arm32.h",
         "bgemm_kernels_arm64.h",
     ],
     deps = [

larq_compute_engine/core/bgemm_impl_ruy.h

@@ -77,8 +77,9 @@ struct BGemmImplUsingRuy {
     if (bgemm_runtime_path == ruy::Path::kNeonDotprod)
       bgemm_runtime_path = ruy::Path::kNeon;
 #if RUY_PLATFORM_NEON_32
-    // 32-bit NEON optimized code is not available yet
-    bgemm_runtime_path = ruy::Path::kStandardCpp;
+    if (!std::is_same<LhsScalar, std::uint32_t>::value) {
+      bgemm_runtime_path = ruy::Path::kStandardCpp;
+    }
 #endif
     // Currently we only have 32-bit and 64-bit optimized kernels.
     // For 8-bit, fall back to the standard cpp kernel.

larq_compute_engine/core/bgemm_kernels_arm.h

@@ -50,6 +50,31 @@ struct BgemmKernel<ruy::Path::kNeonDotprod, LhsScalar, RhsScalar, DstScalar,
   }
 };
 
+#if RUY_PLATFORM_NEON && RUY_OPT(ASM) && RUY_PLATFORM_NEON_32
+// A BGEMM kernel for ARM32 Neon.
+#include "bgemm_kernels_arm32.h"
+template <>
+struct BgemmKernel<ruy::Path::kNeon, std::uint32_t, std::uint32_t, float,
+                   BinaryMulParams<std::int32_t, float>> {
+  Tuning tuning = Tuning::kAuto;
+  using LhsLayout = FixedKernelLayout<Order::kColMajor, 4, 4>;
+  using RhsLayout = FixedKernelLayout<Order::kColMajor, 4, 4>;
+  explicit BgemmKernel(Tuning tuning_) : tuning(tuning_) {}
+  void Run(const ruy::PMat<std::uint32_t>& lhs,
+           const ruy::PMat<std::uint32_t>& rhs,
+           const BinaryMulParams<std::int32_t /* accum. scalar */, float>&
+               mul_params,
+           int start_row, int start_col, int end_row, int end_col,
+           ruy::Mat<float>* dst) const {
+    BinaryKernelParams<LhsLayout::kCols, RhsLayout::kCols, std::uint32_t>
+        params;
+    MakeBinaryKernelParams(lhs, rhs, mul_params, start_row, start_col, end_row,
+                           end_col, dst, &params);
+    BinaryKernelNeonOutOfOrder32BP4x4(params);
+  }
+};
+#endif
+
 #if RUY_PLATFORM_NEON && RUY_OPT(ASM) && RUY_PLATFORM_NEON_64
 // A BGEMM kernel for ARM64 Neon.
 #include "bgemm_kernels_arm64.h"