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core: vectorize dotProd_32s

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Use 4x FMA chains to sum on SIMD 128 FP64 targets. On
x86 this showed about 1.4x improvement.

For PPC, do a full multiply (32x32->64b), convert to DP
then accumulate. This may be slightly less precise for
some inputs. But is 1.5x faster than the above which
is about 1.5x than the FMA above for ~2.5x speedup.
This commit is contained in:
Paul E. Murphy 2019-08-20 11:26:38 -05:00
parent 7295983964
commit 33fb253a66
2 changed files with 38 additions and 0 deletions
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9
modules/core/include/opencv2/core/hal/intrin_vsx.hpp
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@ -1051,6 +1051,15 @@ inline v_float64x2 v_cvt_f64(const v_float32x4& a)
inline v_float64x2 v_cvt_f64_high(const v_float32x4& a)
{ return v_float64x2(vec_cvfo(vec_mergel(a.val, a.val))); }
// The altivec intrinsic is missing for this 2.06 insn
inline v_float64x2 v_cvt_f64(const v_int64x2& a)
{
vec_double2 out;
__asm__ ("xvcvsxddp %x0,%x1" : "=wa"(out) : "wa"(a.val));
return v_float64x2(out);
}
////////////// Lookup table access ////////////////////
inline v_int8x16 v_lut(const schar* tab, const int* idx)

29
modules/core/src/matmul.simd.hpp
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@ -2493,7 +2493,36 @@ double dotProd_16s(const short* src1, const short* src2, int len)
double dotProd_32s(const int* src1, const int* src2, int len)
{
#if CV_SIMD128_64F
double r = 0.0;
int i = 0;
int lenAligned = len & -v_int32x4::nlanes;
v_float64x2 a(0.0, 0.0);
v_float64x2 b(0.0, 0.0);
for( i = 0; i < lenAligned; i += v_int32x4::nlanes )
{
v_int32x4 s1 = v_load(src1);
v_int32x4 s2 = v_load(src2);
#if CV_VSX
// Do 32x32->64 multiplies, convert/round to double, accumulate
// Potentially less precise than FMA, but 1.5x faster than fma below.
a += v_cvt_f64(v_int64(vec_mule(s1.val, s2.val)));
b += v_cvt_f64(v_int64(vec_mulo(s1.val, s2.val)));
#else
a = v_fma(v_cvt_f64(s1), v_cvt_f64(s2), a);
b = v_fma(v_cvt_f64_high(s1), v_cvt_f64_high(s2), b);
#endif
src1 += v_int32x4::nlanes;
src2 += v_int32x4::nlanes;
}
a += b;
r = v_reduce_sum(a);
return r + dotProd_(src1, src2, len - i);
#else
return dotProd_(src1, src2, len);
#endif
}
double dotProd_32f(const float* src1, const float* src2, int len)