optimized sgemv_t_4 kernel for very small sizes

diff --git a/kernel/x86_64/sgemv_t_4.c b/kernel/x86_64/sgemv_t_4.c
index e4476080a96501a3107ade75baa4ae02b834f688..692dd536d3ab1259bd2b64709a894ebe0d1cc9d3 100644 (file)
--- a/kernel/x86_64/sgemv_t_4.c
+++ b/kernel/x86_64/sgemv_t_4.c
@@ -423,14 +423,37 @@ int CNAME(BLASLONG m, BLASLONG n, BLASLONG dummy1, FLOAT alpha, FLOAT *a, BLASLO
 
                FLOAT *aj = a_ptr;
                y_ptr = y;
-               for ( j=0; j<n; j++ )
+
+               if ( lda == 3 && inc_y == 1 )
+               {
+
+                       for ( j=0; j< ( n & -4) ; j+=4 )
+                       {
+
+                               y_ptr[j]   += aj[0] * xtemp0 + aj[1]  * xtemp1 + aj[2]  * xtemp2;
+                               y_ptr[j+1] += aj[3] * xtemp0 + aj[4]  * xtemp1 + aj[5]  * xtemp2;
+                               y_ptr[j+2] += aj[6] * xtemp0 + aj[7]  * xtemp1 + aj[8]  * xtemp2;
+                               y_ptr[j+3] += aj[9] * xtemp0 + aj[10] * xtemp1 + aj[11] * xtemp2;
+                               aj        += 12;
+                       }
+
+                       for ( ; j<n; j++ )
+                       {
+                               y_ptr[j]  += aj[0] * xtemp0 + aj[1] * xtemp1 + aj[2] * xtemp2;
+                               aj        += 3;
+                       }
+
+               }
+               else
                {
-                       *y_ptr += *aj * xtemp0 + *(aj+1) * xtemp1 + *(aj+2) *xtemp2;
-                        y_ptr += inc_y;
-                        aj    += lda;
+                       for ( j=0; j<n; j++ )
+                       {
+                               *y_ptr += *aj * xtemp0 + *(aj+1) * xtemp1 + *(aj+2) * xtemp2;
+                               y_ptr += inc_y;
+                               aj    += lda;
+                       }
                }
                return(0);
-
        }
 
        if ( m3 == 2 )
@@ -441,11 +464,38 @@ int CNAME(BLASLONG m, BLASLONG n, BLASLONG dummy1, FLOAT alpha, FLOAT *a, BLASLO
 
                FLOAT *aj = a_ptr;
                y_ptr = y;
-               for ( j=0; j<n; j++ )
+
+               if ( lda == 2 && inc_y == 1 )
+               {
+
+                       for ( j=0; j< ( n & -4) ; j+=4 )
+                       {
+                               y_ptr[j]   += aj[0] * xtemp0 + aj[1] * xtemp1 ;
+                               y_ptr[j+1] += aj[2] * xtemp0 + aj[3] * xtemp1 ;
+                               y_ptr[j+2] += aj[4] * xtemp0 + aj[5] * xtemp1 ;
+                               y_ptr[j+3] += aj[6] * xtemp0 + aj[7] * xtemp1 ;
+                               aj         += 8;
+
+                       }
+
+                       for ( ; j<n; j++ )
+                       {
+                               y_ptr[j] += aj[0] * xtemp0 + aj[1] * xtemp1 ;
+                               aj       += 2;
+                       }
+
+               }
+               else
                {
-                       *y_ptr += *aj * xtemp0 + *(aj+1) * xtemp1 ;
-                        y_ptr += inc_y;
-                        aj    += lda;
+
+                       for ( j=0; j<n; j++ )
+                       {
+                               *y_ptr += *aj * xtemp0 + *(aj+1) * xtemp1 ;
+                               y_ptr += inc_y;
+                               aj    += lda;
+                       }
+
+
                }
                return(0);
 
@@ -454,13 +504,33 @@ int CNAME(BLASLONG m, BLASLONG n, BLASLONG dummy1, FLOAT alpha, FLOAT *a, BLASLO
        FLOAT xtemp = *x_ptr * alpha;
        FLOAT *aj = a_ptr;
        y_ptr = y;
-       for ( j=0; j<n; j++ )
+       if ( lda == 1 && inc_y == 1 )
+       {
+               for ( j=0; j< ( n & -4) ; j+=4 )
+               {
+                       y_ptr[j]   += aj[j]   * xtemp;
+                       y_ptr[j+1] += aj[j+1] * xtemp;
+                       y_ptr[j+2] += aj[j+2] * xtemp;
+                       y_ptr[j+3] += aj[j+3] * xtemp;
+               }
+               for ( ; j<n   ; j++ )
+               {
+                       y_ptr[j] += aj[j] * xtemp;
+               }
+
+
+
+       }
+       else
        {
-               *y_ptr += *aj * xtemp;
-                y_ptr += inc_y;
-                aj    += lda;
+               for ( j=0; j<n; j++ )
+               {
+                       *y_ptr += *aj * xtemp;
+                       y_ptr += inc_y;
+                       aj    += lda;
+               }
        }
-       
+
        return(0);
 }