Refactor common into cpu specific and truly common (#1817)

* refactor

* fix extension example

* fix no-cpu

mlx/backend/cpu/binary_ops.h

@@ -0,0 +1,98 @@
+// Copyright © 2023-2024 Apple Inc.
+
+#pragma once
+
+#include "mlx/backend/cpu/simd/simd.h"
+
+namespace mlx::core::detail {
+
+using namespace mlx::core::simd;
+
+#define BINARY_SINGLE()                                 \
+  template <typename T>                                 \
+  T operator()(T x, T y) {                              \
+    return (*this)(Simd<T, 1>(x), Simd<T, 1>(y)).value; \
+  }
+
+#define DEFAULT_BINARY_OP(Op, op)                       \
+  struct Op {                                           \
+    template <int N, typename T>                        \
+    Simd<T, N> operator()(Simd<T, N> x, Simd<T, N> y) { \
+      return op(x, y);                                  \
+    }                                                   \
+    BINARY_SINGLE()                                     \
+  };
+
+DEFAULT_BINARY_OP(Add, operator+)
+DEFAULT_BINARY_OP(ArcTan2, atan2)
+DEFAULT_BINARY_OP(Divide, operator/)
+DEFAULT_BINARY_OP(Multiply, operator*)
+DEFAULT_BINARY_OP(Subtract, operator-)
+DEFAULT_BINARY_OP(LogicalAnd, operator&&)
+DEFAULT_BINARY_OP(LogicalOr, operator||)
+DEFAULT_BINARY_OP(BitwiseAnd, operator&)
+DEFAULT_BINARY_OP(BitwiseOr, operator|)
+DEFAULT_BINARY_OP(BitwiseXor, operator^)
+DEFAULT_BINARY_OP(LeftShift, operator<<)
+DEFAULT_BINARY_OP(RightShift, operator>>)
+DEFAULT_BINARY_OP(Remainder, remainder)
+DEFAULT_BINARY_OP(Maximum, maximum)
+DEFAULT_BINARY_OP(Minimum, minimum)
+DEFAULT_BINARY_OP(Power, pow)
+
+#define DEFAULT_BOOL_OP(Op, op)                            \
+  struct Op {                                              \
+    template <int N, typename T>                           \
+    Simd<bool, N> operator()(Simd<T, N> x, Simd<T, N> y) { \
+      return op(x, y);                                     \
+    }                                                      \
+    template <typename T>                                  \
+    bool operator()(T x, T y) {                            \
+      return (*this)(Simd<T, 1>(x), Simd<T, 1>(y)).value;  \
+    }                                                      \
+  };
+
+DEFAULT_BOOL_OP(Equal, operator==)
+DEFAULT_BOOL_OP(Greater, operator>)
+DEFAULT_BOOL_OP(GreaterEqual, operator>=)
+DEFAULT_BOOL_OP(Less, operator<)
+DEFAULT_BOOL_OP(LessEqual, operator<=)
+DEFAULT_BOOL_OP(NotEqual, operator!=)
+
+struct NaNEqual {
+  template <int N, typename T>
+  Simd<bool, N> operator()(Simd<T, N> x, Simd<T, N> y) {
+    return x == y || (isnan(x) && isnan(y));
+  }
+  template <typename T>
+  bool operator()(T x, T y) {
+    return (*this)(Simd<T, 1>(x), Simd<T, 1>(y)).value;
+  }
+};
+
+struct LogAddExp {
+  template <int N, typename T>
+  Simd<T, N> operator()(Simd<T, N> x, Simd<T, N> y) {
+    auto maxval = maximum(x, y);
+    auto minval = minimum(x, y);
+    auto mask = minval == -inf || maxval == inf;
+    auto out = maxval + log1p(exp(minval - maxval));
+    return select(mask, Simd<T, N>(maxval), Simd<T, N>(out));
+  }
+  BINARY_SINGLE()
+};
+
+struct Select {
+  template <typename T>
+  T operator()(bool condition, T x, T y) {
+    return (*this)(Simd<bool, 1>(condition), Simd<T, 1>(x), Simd<T, 1>(y))
+        .value;
+  }
+
+  template <int N, typename T>
+  Simd<T, N> operator()(Simd<bool, N> condition, Simd<T, N> x, Simd<T, N> y) {
+    return select(condition, x, y);
+  }
+};
+
+} // namespace mlx::core::detail