COMPMID-1271: New system for GEMM heuristics

This patch implements a system for separating the "validity" from
"preferred" aspect of the current heuristics in gemm_*.cpp.

Now, each gemm_*.cpp defines a list of candidate implementations,
each of which supplies an is_valid() function (to check for
validity), an is_preferred() function (the "heuristic" part), and an
instantiate() function which actually produces the GemmCommon object
pointer.

The actual gemm() function is now templated and uses this list to
select an implementation.  This patch also implements a mechanism to
identify the preferred implementation, and override it via the
GemmConfig structure.

Change-Id: Id49ab7af8bf2e3e9fd951a9698883ade234d40e1
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/139120
Reviewed-by: Anthony Barbier <anthony.barbier@arm.com>
Tested-by: Jenkins <bsgcomp@arm.com>

1 files changed, 131 insertions, 0 deletions

diff --git a/src/core/NEON/kernels/arm_gemm/gemm_implementation.hpp b/src/core/NEON/kernels/arm_gemm/gemm_implementation.hpp
new file mode 100644
index 0000000000..6734e3cce0
--- /dev/null
+++ b/src/core/NEON/kernels/arm_gemm/gemm_implementation.hpp
@@ -0,0 +1,131 @@
+/*
+ * Copyright (c) 2018 ARM Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "gemv_batched.hpp"
+
+namespace arm_gemm {
+
+template<typename Top, typename Tret>
+class GemmImplementation {
+public:
+    /* Is this implementation compatible with the args as provided? */
+    virtual bool is_supported(const GemmArgs<Tret> &args)   { return true; }
+    /* Is this implementation "recommended" for these args (heuristic)? */
+    virtual bool is_recommended(const GemmArgs<Tret> &args) { return true; }
+    /* Instantiate this method please. */
+    virtual UniqueGemmCommon<Top, Tret> instantiate(const GemmArgs<Tret> &args) = 0;
+
+    /* Indicate the "GemmMethod" for use as a selector */
+    const GemmMethod method;
+
+    virtual ~GemmImplementation() { }
+
+    GemmImplementation(GemmMethod method) : method(method) { }
+};
+
+/* "gemv_batched" implementation is type-agnostic, so template it here. */
+template<typename Top, typename Tret>
+class GemmImpl_gemv_batched : public GemmImplementation<Top, Tret> {
+public:
+    bool is_supported(const GemmArgs<Tret> &args) override {
+        return (args._Msize==1 && args._nbatches > 1);
+    }
+
+    UniqueGemmCommon<Top, Tret> instantiate(const GemmArgs<Tret> &args) override {
+        return UniqueGemmCommon<Top, Tret> (new GemvBatched<Top, Tret>(args));
+    }
+
+    GemmImpl_gemv_batched() : GemmImplementation<Top, Tret>(GemmMethod::GEMV_BATCHED) { }
+};
+
+/* "Master" function implemented for each valid combination of types.
+ * Returns a list of GEMM implementation descriptors for processing by the
+ * other functions.  */
+template<typename Top, typename Tret>
+std::vector<GemmImplementation<Top, Tret> *> &gemm_implementation_list();
+
+template<typename Top, typename Tret>
+GemmImplementation<Top, Tret> *find_implementation(GemmArgs<Tret> &args, GemmConfig *cfg) {
+    auto gemms = gemm_implementation_list<Top, Tret>();
+
+    for(auto &&i : gemms) {
+        /* Skip if this implementation doesn't support these args. */
+        if (!i->is_supported(args)) {
+            continue;
+        }
+
+        /* Skip if a specific method is requested and this is a different one. */
+        if (cfg && cfg->method != GemmMethod::DEFAULT && i->method != cfg->method) {
+            continue;
+        }
+
+        /* If no specific method is requested, check that this method recommends itself. */
+        if ((!cfg || cfg->method == GemmMethod::DEFAULT) && !i->is_recommended(args)) {
+            continue;
+        }
+
+        return i;
+    }
+
+    return nullptr;
+}
+
+template<typename Top, typename Tret>
+UniqueGemmCommon<Top, Tret> gemm(GemmArgs<Tret> &args, GemmConfig *cfg) {
+    auto impl = find_implementation<Top, Tret>(args, cfg);
+
+    if (impl) {
+        return impl->instantiate(args);
+    }
+
+    return UniqueGemmCommon<Top, Tret>(nullptr);
+}
+
+template<typename Top, typename Tret>
+GemmMethod get_gemm_method(GemmArgs<Tret> &args) {
+    auto impl = find_implementation<Top, Tret>(args, nullptr);
+
+    if (impl) {
+        return impl->method;
+    }
+
+    /* This shouldn't happen - there should always be at least one valid implementation. */
+    return GemmMethod::DEFAULT;
+}
+
+template<typename Top, typename Tret>
+bool method_is_compatible(GemmMethod method, GemmArgs<Tret> &args) {
+    /* Determine if the method is valid by attempting to obtain an implementation specifying this method. */
+    GemmConfig cfg(method);
+
+    auto impl = find_implementation<Top, Tret>(args, &cfg);
+
+    if (impl) {
+        return true;
+    }
+
+    return false;
+}
+
+} // namespace arm_gemm