ENH, SIMD: add new universal intrinsics for trunc

Author: howjmay

numpy/core/src/_simd/_simd.dispatch.c.src

@@ -381,7 +381,7 @@ SIMD_IMPL_INTRIN_1(sumup_@sfx@, @esfx@, v@sfx@)
  ***************************/
 #if @fp_only@
 /**begin repeat1
- * #intrin = sqrt, recip, abs, square, ceil#
+ * #intrin = sqrt, recip, abs, square, ceil, trunc#
  */
 SIMD_IMPL_INTRIN_1(@intrin@_@sfx@, v@sfx@, v@sfx@)
 /**end repeat1**/
@@ -615,7 +615,7 @@ SIMD_INTRIN_DEF(sumup_@sfx@)
  ***************************/
 #if @fp_only@
 /**begin repeat1
- * #intrin = sqrt, recip, abs, square, ceil#
+ * #intrin = sqrt, recip, abs, square, ceil, trunc#
  */
 SIMD_INTRIN_DEF(@intrin@_@sfx@)
 /**end repeat1**/

numpy/core/src/common/simd/avx2/math.h

@@ -109,4 +109,8 @@ NPY_FINLINE npyv_s64 npyv_min_s64(npyv_s64 a, npyv_s64 b)
 #define npyv_ceil_f32 _mm256_ceil_ps
 #define npyv_ceil_f64 _mm256_ceil_pd
 
+// trunc
+#define npyv_trunc_f32(A) _mm256_round_ps(A, _MM_FROUND_TO_ZERO)
+#define npyv_trunc_f64(A) _mm256_round_pd(A, _MM_FROUND_TO_ZERO)
+
 #endif // _NPY_SIMD_AVX2_MATH_H

numpy/core/src/common/simd/avx512/math.h

@@ -116,4 +116,8 @@ NPY_FINLINE npyv_f64 npyv_minp_f64(npyv_f64 a, npyv_f64 b)
 #define npyv_ceil_f32(A) _mm512_roundscale_ps(A, _MM_FROUND_TO_POS_INF)
 #define npyv_ceil_f64(A) _mm512_roundscale_pd(A, _MM_FROUND_TO_POS_INF)
 
+// trunc
+#define npyv_trunc_f32(A) _mm512_roundscale_ps(A, _MM_FROUND_TO_ZERO)
+#define npyv_trunc_f64(A) _mm512_roundscale_pd(A, _MM_FROUND_TO_ZERO)
+
 #endif // _NPY_SIMD_AVX512_MATH_H

numpy/core/src/common/simd/neon/math.h

@@ -190,4 +190,37 @@ NPY_FINLINE npyv_s64 npyv_min_s64(npyv_s64 a, npyv_s64 b)
     #define npyv_ceil_f64 vrndpq_f64
 #endif // NPY_SIMD_F64
 
+// trunc
+#ifdef NPY_HAVE_ASIMD
+    #define npyv_trunc_f32 vrndq_f32
+#else
+   NPY_FINLINE npyv_f32 npyv_trunc_f32(npyv_f32 a)
+   {
+        const npyv_s32 szero = vreinterpretq_s32_f32(vdupq_n_f32(-0.0f));
+        const npyv_s32 max_int = vdupq_n_s32(0x7fffffff);
+        /**
+         * On armv7, vcvtq.f32 handles special cases as follows:
+         *  NaN return 0
+         * +inf or +outrange return 0x80000000(-0.0f)
+         * -inf or -outrange return 0x7fffffff(nan)
+         */
+        npyv_s32 roundi = vcvtq_s32_f32(a);
+        npyv_f32 round = vcvtq_f32_s32(roundi);
+        // respect signed zero, e.g. -0.5 -> -0.0
+        npyv_f32 rzero = vreinterpretq_f32_s32(vorrq_s32(
+            vreinterpretq_s32_f32(round),
+            vandq_s32(vreinterpretq_s32_f32(a), szero)
+        ));
+        // if nan or overflow return a
+        npyv_u32 nnan = npyv_notnan_f32(a);
+        npyv_u32 overflow = vorrq_u32(
+            vceqq_s32(roundi, szero), vceqq_s32(roundi, max_int)
+        );
+        return vbslq_f32(vbicq_u32(nnan, overflow), rzero, a);
+   }
+#endif
+#if NPY_SIMD_F64
+    #define npyv_trunc_f64 vrndq_f64
+#endif // NPY_SIMD_F64
+
 #endif // _NPY_SIMD_NEON_MATH_H

numpy/core/src/common/simd/sse/math.h

@@ -174,4 +174,32 @@ NPY_FINLINE npyv_s64 npyv_min_s64(npyv_s64 a, npyv_s64 b)
     }
 #endif
 
+// trunc
+#ifdef NPY_HAVE_SSE41
+    #define npyv_trunc_f32(A) _mm_round_ps(A, _MM_FROUND_TO_ZERO)
+    #define npyv_trunc_f64(A) _mm_round_pd(A, _MM_FROUND_TO_ZERO)
+#else
+    NPY_FINLINE npyv_f32 npyv_trunc_f32(npyv_f32 a)
+    {
+        const npyv_f32 szero = _mm_set1_ps(-0.0f);
+        npyv_s32 roundi = _mm_cvttps_epi32(a);
+        npyv_f32 trunc = _mm_cvtepi32_ps(roundi);
+        // respect signed zero, e.g. -0.5 -> -0.0
+        npyv_f32 rzero = _mm_or_ps(trunc, _mm_and_ps(a, szero));
+        // if overflow return a
+        return npyv_select_f32(_mm_cmpeq_epi32(roundi, _mm_castps_si128(szero)), a, rzero);
+    }
+    NPY_FINLINE npyv_f64 npyv_trunc_f64(npyv_f64 a)
+    {
+        const npyv_f64 szero = _mm_set1_pd(-0.0);
+        const npyv_f64 one = _mm_set1_pd(1.0);
+        const npyv_f64 two_power_52 = _mm_set1_pd(0x10000000000000);
+        npyv_f64 abs_a = npyv_abs_f64(a);
+        // round by add magic number 2^52
+        npyv_f64 abs_round = _mm_sub_pd(_mm_add_pd(abs_a, two_power_52), two_power_52);
+        npyv_f64 subtrahend = _mm_and_pd(_mm_cmpgt_pd(abs_round, abs_a), one);
+        return _mm_or_pd(_mm_sub_pd(abs_round, subtrahend), _mm_and_pd(a, szero));
+    }
+#endif
+
 #endif // _NPY_SIMD_SSE_MATH_H

numpy/core/src/common/simd/vsx/math.h

@@ -73,4 +73,8 @@ NPY_FINLINE npyv_f64 npyv_square_f64(npyv_f64 a)
 #define npyv_ceil_f32 vec_ceil
 #define npyv_ceil_f64 vec_ceil
 
+// trunc
+#define npyv_trunc_f32 vec_trunc
+#define npyv_trunc_f64 vec_trunc
+
 #endif // _NPY_SIMD_VSX_MATH_H

numpy/core/tests/test_simd.py

@@ -330,12 +330,15 @@ def test_square(self):
         square = self.square(vdata)
         assert square == data_square
 
-    @pytest.mark.parametrize("intrin, func", [("self.ceil", math.ceil)])
+    @pytest.mark.parametrize("intrin, func", [("self.ceil", math.ceil),
+    ("self.trunc", math.trunc)])
     def test_rounding(self, intrin, func):
         """
         Test intrinsics:
             npyv_ceil_##SFX
+            npyv_trunc_##SFX
         """
+        intrin_name = intrin
         intrin = eval(intrin)
         pinf, ninf, nan = self._pinfinity(), self._ninfinity(), self._nan()
         # special cases
@@ -352,11 +355,12 @@ def test_rounding(self, intrin, func):
                 _round = intrin(vdata)
                 assert _round == data_round
         # signed zero
-        for w in (-0.25, -0.30, -0.45):
-            _round = self._to_unsigned(intrin(self.setall(w)))
-            data_round = self._to_unsigned(self.setall(-0.0))
-            assert _round == data_round
-
+        if "ceil" in intrin_name or "trunc" in intrin_name:
+            for w in (-0.25, -0.30, -0.45):
+                _round = self._to_unsigned(intrin(self.setall(w)))
+                data_round = self._to_unsigned(self.setall(-0.0))
+                assert _round == data_round
+    
     def test_max(self):
         """
         Test intrinsics: