pkg/highway

src/terminal/simdvt/example.cpp

@@ -0,0 +1,61 @@
+// Generates code for every target that this compiler can support.
+#undef HWY_TARGET_INCLUDE
+#define HWY_TARGET_INCLUDE "example.cpp"  // this file
+#include <hwy/foreach_target.h>  // must come before highway.h
+#include <hwy/highway.h>
+
+namespace project {
+namespace HWY_NAMESPACE {  // required: unique per target
+
+// Can skip hn:: prefixes if already inside hwy::HWY_NAMESPACE.
+namespace hn = hwy::HWY_NAMESPACE;
+
+using T = float;
+
+// Alternative to per-function HWY_ATTR: see HWY_BEFORE_NAMESPACE
+HWY_ATTR void MulAddLoop(const T* HWY_RESTRICT mul_array,
+                const T* HWY_RESTRICT add_array,
+                const size_t size, T* HWY_RESTRICT x_array) {
+  const hn::ScalableTag<T> d;
+  for (size_t i = 0; i < size; i += hn::Lanes(d)) {
+    const auto mul = hn::Load(d, mul_array + i);
+    const auto add = hn::Load(d, add_array + i);
+    auto x = hn::Load(d, x_array + i);
+    x = hn::MulAdd(mul, x, add);
+    hn::Store(x, d, x_array + i);
+  }
+}
+
+}  // namespace HWY_NAMESPACE
+}  // namespace project
+
+// The table of pointers to the various implementations in HWY_NAMESPACE must
+// be compiled only once (foreach_target #includes this file multiple times).
+// HWY_ONCE is true for only one of these 'compilation passes'.
+#if HWY_ONCE
+
+namespace project {
+
+// This macro declares a static array used for dynamic dispatch.
+HWY_EXPORT(MulAddLoop);
+
+void CallMulAddLoop(const float* HWY_RESTRICT mul_array,
+                const float* HWY_RESTRICT add_array,
+                const size_t size, float* HWY_RESTRICT x_array) {
+  // This must reside outside of HWY_NAMESPACE because it references (calls the
+  // appropriate one from) the per-target implementations there.
+  // For static dispatch, use HWY_STATIC_DISPATCH.
+  return HWY_DYNAMIC_DISPATCH(MulAddLoop)(mul_array, add_array, size, x_array);
+}
+
+}  // namespace project
+
+extern "C" float example() {
+    float mul_array[] {1, 2, 3, 4, 5};
+    float add_array[] {2, 3, 4, 5, 6};
+    float x_array[] {0, 0, 0, 0, 0};
+    project::CallMulAddLoop(mul_array, add_array, 5, x_array);
+    return x_array[0];
+}
+
+#endif  // HWY_ONCE