[src/{add,sub}.c] Consider UBF numbers as special cases so that

mpfr_sub1sp and mpfr_add1sp, which do not support UBF, are never
called on UBF numbers. This should also (very slightly) speed up
the normal cases.

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/branches/ubf@10416 280ebfd0-de03-0410-8827-d642c229c3f4

2 files changed, 44 insertions, 14 deletions

diff --git a/src/add.c b/src/add.c
index 43a4507d1..969a64d0a 100644
--- a/src/add.c
+++ b/src/add.c
@@ -31,7 +31,7 @@ mpfr_add (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode)
       mpfr_get_prec (c), mpfr_log_prec, c, rnd_mode),
      ("a[%Pu]=%.*Rg", mpfr_get_prec (a), mpfr_log_prec, a));
 
-  if (MPFR_ARE_SINGULAR(b,c))
+  if (MPFR_ARE_SINGULAR_OR_UBF (b, c))
     {
       if (MPFR_IS_NAN(b) || MPFR_IS_NAN(c))
         {
@@ -59,7 +59,7 @@ mpfr_add (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode)
             MPFR_SET_SAME_SIGN(a, c);
             MPFR_RET(0); /* exact */
           }
-      /* now either b or c is zero */
+      /* now both b and c are finite numbers */
       else if (MPFR_IS_ZERO(b))
         {
           if (MPFR_IS_ZERO(c))
@@ -78,15 +78,27 @@ mpfr_add (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode)
             }
           return mpfr_set (a, c, rnd_mode);
         }
-      else
+      else if (MPFR_IS_ZERO(c))
         {
-          MPFR_ASSERTD(MPFR_IS_ZERO(c));
           return mpfr_set (a, b, rnd_mode);
         }
+      else
+        {
+          MPFR_ASSERTD (MPFR_IS_PURE_UBF (b));
+          MPFR_ASSERTD (MPFR_IS_PURE_UBF (c));
+          /* mpfr_sub1sp and mpfr_add1sp are not intended to support UBF,
+             for which optimization is less important. */
+          if (MPFR_SIGN(b) != MPFR_SIGN(c))
+            return mpfr_sub1 (a, b, c, rnd_mode);
+          else if (MPFR_EXP_LESS_P (b, c))
+            return mpfr_add1 (a, c, b, rnd_mode);
+          else
+            return mpfr_add1 (a, b, c, rnd_mode);
+        }
     }
 
-  MPFR_ASSERTD (MPFR_IS_PURE_UBF (b));
-  MPFR_ASSERTD (MPFR_IS_PURE_UBF (c));
+  MPFR_ASSERTD (MPFR_IS_PURE_FP (b));
+  MPFR_ASSERTD (MPFR_IS_PURE_FP (c));
 
   if (MPFR_UNLIKELY(MPFR_SIGN(b) != MPFR_SIGN(c)))
     { /* signs differ, it is a subtraction */
@@ -100,12 +112,12 @@ mpfr_add (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode)
     { /* signs are equal, it's an addition */
       if (MPFR_LIKELY(MPFR_PREC(a) == MPFR_PREC(b)
                       && MPFR_PREC(b) == MPFR_PREC(c)))
-        if (MPFR_EXP_LESS_P (b, c))
+        if (MPFR_GET_EXP(b) < MPFR_GET_EXP(c))
           return mpfr_add1sp(a, c, b, rnd_mode);
         else
           return mpfr_add1sp(a, b, c, rnd_mode);
       else
-        if (MPFR_EXP_LESS_P (b, c))
+        if (MPFR_GET_EXP(b) < MPFR_GET_EXP(c))
           return mpfr_add1(a, c, b, rnd_mode);
         else
           return mpfr_add1(a, b, c, rnd_mode);
diff --git a/src/sub.c b/src/sub.c
index f6a4e16d5..c95cfdb0a 100644
--- a/src/sub.c
+++ b/src/sub.c
@@ -31,7 +31,7 @@ mpfr_sub (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode)
       mpfr_get_prec (c), mpfr_log_prec, c, rnd_mode),
      ("a[%Pu]=%.*Rg", mpfr_get_prec (a), mpfr_log_prec, a));
 
-  if (MPFR_ARE_SINGULAR (b,c))
+  if (MPFR_ARE_SINGULAR_OR_UBF (b,c))
     {
       if (MPFR_IS_NAN (b) || MPFR_IS_NAN (c))
         {
@@ -72,15 +72,33 @@ mpfr_sub (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode)
           else
             return mpfr_neg (a, c, rnd_mode);
         }
-      else
+      else if (MPFR_IS_ZERO (c))
         {
-          MPFR_ASSERTD (MPFR_IS_ZERO (c));
           return mpfr_set (a, b, rnd_mode);
         }
+      else
+        {
+          MPFR_ASSERTD (MPFR_IS_PURE_UBF (b));
+          MPFR_ASSERTD (MPFR_IS_PURE_UBF (c));
+          /* mpfr_sub1sp and mpfr_add1sp are not intended to support UBF,
+             for which optimization is less important. */
+          if (MPFR_SIGN(b) == MPFR_SIGN(c))
+            return mpfr_sub1 (a, b, c, rnd_mode);
+          else if (MPFR_EXP_LESS_P (b, c))
+            {
+              int inexact;
+              rnd_mode = MPFR_INVERT_RND (rnd_mode);
+              inexact = mpfr_add1 (a, c, b, rnd_mode);
+              MPFR_CHANGE_SIGN (a);
+              return -inexact;
+            }
+          else
+            return mpfr_add1 (a, b, c, rnd_mode);
+        }
     }
 
-  MPFR_ASSERTD (MPFR_IS_PURE_UBF (b));
-  MPFR_ASSERTD (MPFR_IS_PURE_UBF (c));
+  MPFR_ASSERTD (MPFR_IS_PURE_FP (b));
+  MPFR_ASSERTD (MPFR_IS_PURE_FP (c));
 
   if (MPFR_LIKELY (MPFR_SIGN (b) == MPFR_SIGN (c)))
     { /* signs are equal, it's a real subtraction */
@@ -92,7 +110,7 @@ mpfr_sub (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode)
     }
   else
     { /* signs differ, it's an addition */
-      if (MPFR_EXP_LESS_P (b, c))
+      if (MPFR_GET_EXP (b) < MPFR_GET_EXP (c))
          { /* exchange rounding modes toward +/- infinity */
           int inexact;
           rnd_mode = MPFR_INVERT_RND (rnd_mode);