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authorSiddhesh Poyarekar <siddhesh@redhat.com>2013-01-02 11:44:13 +0530
committerSiddhesh Poyarekar <siddhesh@redhat.com>2013-01-02 11:44:13 +0530
commit44e0d4c20ce5bf3825897e5d4b7caae94016214d (patch)
tree2bab235b70c634cd73cfa936c4f0fbfa82d91e8e /sysdeps/ieee754
parent4d55b4e596d63705b86200d15d905b2549dd25df (diff)
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Split mantissa calculation loop and add branch prediction
Diffstat (limited to 'sysdeps/ieee754')
-rw-r--r--sysdeps/ieee754/dbl-64/mpa.c67
1 files changed, 43 insertions, 24 deletions
diff --git a/sysdeps/ieee754/dbl-64/mpa.c b/sysdeps/ieee754/dbl-64/mpa.c
index 499dbd309d..266c971c18 100644
--- a/sysdeps/ieee754/dbl-64/mpa.c
+++ b/sysdeps/ieee754/dbl-64/mpa.c
@@ -447,33 +447,52 @@ void
SECTION
__mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
- int i, i1, i2, j, k, k2;
+ int i, j, k, k2;
double u;
- /* Is z=0? */
- if (X[0]*Y[0]==ZERO)
- { Z[0]=ZERO; return; }
-
- /* Multiply, add and carry */
- k2 = (p<3) ? p+p : p+3;
- Z[k2]=ZERO;
- for (k=k2; k>1; ) {
- if (k > p) {i1=k-p; i2=p+1; }
- else {i1=1; i2=k; }
- for (i=i1,j=i2-1; i<i2; i++,j--) Z[k] += X[i]*Y[j];
-
- u = (Z[k] + CUTTER)-CUTTER;
- if (u > Z[k]) u -= RADIX;
- Z[k] -= u;
- Z[--k] = u*RADIXI;
- }
+ /* Is z=0? */
+ if (__glibc_unlikely (X[0] * Y[0] == ZERO))
+ {
+ Z[0]=ZERO;
+ return;
+ }
- /* Is there a carry beyond the most significant digit? */
- if (Z[1] == ZERO) {
- for (i=1; i<=p; i++) Z[i]=Z[i+1];
- EZ = EX + EY - 1; }
- else
- EZ = EX + EY;
+ /* Multiply, add and carry */
+ k2 = (__glibc_unlikely (p < 3)) ? p + p : p + 3;
+ Z[k2] = ZERO;
+
+ for (k = k2; k > p; )
+ {
+ for (i = k - p, j = p; i < p + 1; i++, j--)
+ Z[k] += X[i] * Y[j];
+
+ u = (Z[k] + CUTTER) - CUTTER;
+ if (u > Z[k])
+ u -= RADIX;
+ Z[k] -= u;
+ Z[--k] = u * RADIXI;
+ }
+
+ while (k > 1)
+ {
+ for (i = 1,j = k - 1; i < k; i++, j--)
+ Z[k] += X[i] * Y[j];
+
+ u = (Z[k] + CUTTER) - CUTTER;
+ if (u > Z[k])
+ u -= RADIX;
+ Z[k] -= u;
+ Z[--k] = u * RADIXI;
+ }
+
+ EZ = EX + EY;
+ /* Is there a carry beyond the most significant digit? */
+ if (__glibc_unlikely (Z[1] == ZERO))
+ {
+ for (i = 1; i <= p; i++)
+ Z[i] = Z[i+1];
+ EZ--;
+ }
Z[0] = X[0] * Y[0];
}