SIMD: Rename NPY_SIMDX to NPY_HWY

Rename Highway wrapper macros for clarity: - NPY_SIMDX → NPY_HWY - NPY_SIMDX_F16 → NPY_HWY_F16 - NPY_SIMDX_F64 → NPY_HWY_F64 - NPY_SIMDX_FMA → NPY_HWY_FMA To avoids confusion with legacy SIMD macros.
numpy · Mousius · Jun 5, 2025 · Apr 1, 2025 · Apr 12, 2025 · Apr 17, 2025
commit 6519b288d66dcc7ed27cfeb664a1eb2d279d8492
diff --git a/numpy/_core/src/common/simd/README.md b/numpy/_core/src/common/simd/README.md
@@ -45,19 +45,19 @@ StoreU(v128, data);
 #include "simd/simd.hpp"
 
 // Check if SIMD is enabled
-#if NPY_SIMDX
+#if NPY_HWY
     // SIMD code
 #else
     // Scalar fallback code
 #endif
 
 // Check for float64 support
-#if NPY_SIMDX_F64
+#if NPY_HWY_F64
     // Use float64 SIMD operations
 #endif
 
 // Check for FMA support
-#if NPY_SIMDX_FMA
+#if NPY_HWY_FMA
     // Use FMA operations
 #endif
 ```
@@ -70,9 +70,9 @@ The wrapper provides type constraints to help with SFINAE (Substitution Failure
   ```cpp
   // Base template - always defined, even when SIMD is not enabled (for SFINAE)
   template <typename TLane>
-  constexpr bool kSupportLane = NPY_SIMDX != 0;
+  constexpr bool kSupportLane = NPY_HWY != 0;
   template <>
-  constexpr bool kSupportLane<double> = NPY_SIMDX_F64 != 0;
+  constexpr bool kSupportLane<double> = NPY_HWY_F64 != 0;
   ```
 
 - `kMaxLanes<TLane>`: Maximum number of lanes supported by the SIMD extension for the specified lane type.
@@ -175,15 +175,15 @@ The SIMD wrapper automatically disables SIMD operations when optimizations are d
 
 2. **Legacy Universal Intrinsics**
    - The older universal intrinsics C interface (in `simd.h` and accessible via `NPY_SIMD` macros) is deprecated
-   - All new SIMD code should use this Highway-based wrapper (accessible via `NPY_SIMDX` macros) 
+   - All new SIMD code should use this Highway-based wrapper (accessible via `NPY_HWY` macros) 
    - The legacy code is maintained for compatibility but will eventually be removed
 
 3. **Feature Detection Constants vs. Highway Constants**
-   - NumPy-specific constants (`NPY_SIMDX_F16`, `NPY_SIMDX_F64`, `NPY_SIMDX_FMA`) provide additional safety beyond raw Highway constants
+   - NumPy-specific constants (`NPY_HWY_F16`, `NPY_HWY_F64`, `NPY_HWY_FMA`) provide additional safety beyond raw Highway constants
    - Highway constants (e.g., `HWY_HAVE_FLOAT16`) only check platform capabilities but don't consider NumPy's build configuration
    - Our constants combine both checks:
      ```cpp
-     #define NPY_SIMDX_F16 (NPY_SIMDX && HWY_HAVE_FLOAT16)
+     #define NPY_HWY_F16 (NPY_HWY && HWY_HAVE_FLOAT16)
      ```
    - This ensures SIMD features won't be used when:
      - Platform supports it but NumPy optimization is disabled via meson option:

diff --git a/numpy/_core/src/common/simd/simd.hpp b/numpy/_core/src/common/simd/simd.hpp
@@ -10,7 +10,7 @@
  */
 /**
  * Since `NPY_SIMD` is only limited to NumPy C universal intrinsics,
- * `NPY_SIMDX` is defined to indicate the SIMD availability for Google's Highway
+ * `NPY_HWY` is defined to indicate the SIMD availability for Google's Highway
  * C++ code.
  *
  * Highway SIMD is only available when optimization is enabled.
@@ -29,31 +29,31 @@
  *
  * Therefore, we only enable SIMD when the Highway target is not scalar.
  */
-#define NPY_SIMDX (HWY_TARGET != HWY_SCALAR)
+#define NPY_HWY (HWY_TARGET != HWY_SCALAR)
 
 // Indicates if the SIMD operations are available for float16.
-#define NPY_SIMDX_F16 (NPY_SIMDX && HWY_HAVE_FLOAT16)
+#define NPY_HWY_F16 (NPY_HWY && HWY_HAVE_FLOAT16)
 // Note: Highway requires SIMD extentions with native float32 support, so we don't need
 // to check for it.
 
 // Indicates if the SIMD operations are available for float64.
-#define NPY_SIMDX_F64 (NPY_SIMDX && HWY_HAVE_FLOAT64)
+#define NPY_HWY_F64 (NPY_HWY && HWY_HAVE_FLOAT64)
 
 // Indicates if the SIMD floating operations are natively supports fma.
-#define NPY_SIMDX_FMA (NPY_SIMDX && HWY_NATIVE_FMA)
+#define NPY_HWY_FMA (NPY_HWY && HWY_NATIVE_FMA)
 
 #else
-#define NPY_SIMDX 0
-#define NPY_SIMDX_F16 0
-#define NPY_SIMDX_F64 0
-#define NPY_SIMDX_FMA 0
+#define NPY_HWY 0
+#define NPY_HWY_F16 0
+#define NPY_HWY_F64 0
+#define NPY_HWY_FMA 0
 #endif
 
 namespace np {
 
 /// Represents the max SIMD width supported by the platform.
 namespace simd {
-#if NPY_SIMDX
+#if NPY_HWY
 /// The highway namespace alias.
 /// We can not import all the symbols from the HWY_NAMESPACE because it will
 /// conflict with the existing symbols in the numpy namespace.
@@ -67,7 +67,7 @@ using _Tag = hn::ScalableTag<TLane>;
 
 /// Represents the 128-bit SIMD width.
 namespace simd128 {
-#if NPY_SIMDX
+#if NPY_HWY
 namespace hn = hwy::HWY_NAMESPACE;
 template <typename TLane>
 using _Tag = hn::Full128<TLane>;

diff --git a/numpy/_core/src/common/simd/simd.inc.hpp b/numpy/_core/src/common/simd/simd.inc.hpp
@@ -1,6 +1,6 @@
-#ifndef NPY_SIMDX
+#ifndef NPY_HWY
 #error "This is not a standalone header. Include simd.hpp instead."
-#define NPY_SIMDX 1 // Prevent editors from graying out the happy branch
+#define NPY_HWY 1  // Prevent editors from graying out the happy branch
 #endif
 
 // Using anonymous namespace instead of inline to ensure each translation unit
@@ -17,9 +17,9 @@ namespace {
  * @tparam TLane The lane type to check for support.
  */
 template <typename TLane>
-constexpr bool kSupportLane = NPY_SIMDX != 0;
+constexpr bool kSupportLane = NPY_HWY != 0;
 
-#if NPY_SIMDX
+#if NPY_HWY
 // Define lane type support based on Highway capabilities
 template <>
 constexpr bool kSupportLane<hwy::float16_t> = HWY_HAVE_FLOAT16 != 0;
@@ -127,6 +127,6 @@ using hn::Sqrt;
 using hn::Sub;
 using hn::Xor;
 
-#endif  // NPY_SIMDX
+#endif  // NPY_HWY
 
-} // namespace anonymous
+}  // namespace