Optimize three-valued comparison between integers.

(a > b ? 1 : a < b ? -1 : 0) is the same as (a > b) - (a < b).

* m4/gnulib-common.m4 (gl_COMMON): Define _GL_CMP.
* lib/c-strcasecmp.c (c_strcasecmp): Use _GL_CMP.
* lib/c-strncasecmp.c (c_strncasecmp): Likewise.
* lib/dfa.c (compare): Likewise.
* lib/fts.c (fts_compare_ino): Likewise.
* lib/mbmemcasecmp.c (mbmemcasecmp): Likewise.
* lib/mbscasecmp.c (mbscasecmp): Likewise.
* lib/mbsncasecmp.c (mbsncasecmp): Likewise.
* lib/memcasecmp.c (memcasecmp): Likewise.
* lib/memcmp2.c (memcmp2): Likewise.
* lib/savedir.c (direntry_cmp_inode): Likewise.
* lib/strcasecmp.c (strcasecmp): Likewise.
* lib/strncasecmp.c (strncasecmp): Likewise.
* lib/unistr/u-cmp2.h (FUNC): Likewise.

13 files changed, 14 insertions, 26 deletions

diff --git a/lib/c-strcasecmp.c b/lib/c-strcasecmp.c
index 3ac650f87c..1de04b7066 100644
--- a/lib/c-strcasecmp.c
+++ b/lib/c-strcasecmp.c
@@ -52,5 +52,5 @@ c_strcasecmp (const char *s1, const char *s2)
     /* On machines where 'char' and 'int' are types of the same size, the
        difference of two 'unsigned char' values - including the sign bit -
        doesn't fit in an 'int'.  */
-    return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
+    return _GL_CMP (c1, c2);
 }
diff --git a/lib/c-strncasecmp.c b/lib/c-strncasecmp.c
index a4e67d1655..1782e54ad1 100644
--- a/lib/c-strncasecmp.c
+++ b/lib/c-strncasecmp.c
@@ -52,5 +52,5 @@ c_strncasecmp (const char *s1, const char *s2, size_t n)
     /* On machines where 'char' and 'int' are types of the same size, the
        difference of two 'unsigned char' values - including the sign bit -
        doesn't fit in an 'int'.  */
-    return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
+    return _GL_CMP (c1, c2);
 }
diff --git a/lib/dfa.c b/lib/dfa.c
index dee7be8617..1d2d404574 100644
--- a/lib/dfa.c
+++ b/lib/dfa.c
@@ -2466,7 +2466,7 @@ static int
 compare (const void *a, const void *b)
 {
   position const *p = a, *q = b;
-  return p->index < q->index ? -1 : p->index > q->index;
+  return _GL_CMP (p->index, q->index);
 }
 
 static void
diff --git a/lib/fts.c b/lib/fts.c
index 5e357bee59..a34092ca25 100644
--- a/lib/fts.c
+++ b/lib/fts.c
@@ -1190,8 +1190,7 @@ fts_children (register FTS *sp, int instr)
 static int
 fts_compare_ino (struct _ftsent const **a, struct _ftsent const **b)
 {
-  return (a[0]->fts_statp->st_ino < b[0]->fts_statp->st_ino ? -1
-          : b[0]->fts_statp->st_ino < a[0]->fts_statp->st_ino ? 1 : 0);
+  return _GL_CMP (a[0]->fts_statp->st_ino, b[0]->fts_statp->st_ino);
 }
 
 /* Map the dirent.d_type value, DTYPE, to the corresponding stat.st_mode
diff --git a/lib/mbmemcasecmp.c b/lib/mbmemcasecmp.c
index 57039d2950..d0eea69d4b 100644
--- a/lib/mbmemcasecmp.c
+++ b/lib/mbmemcasecmp.c
@@ -33,7 +33,7 @@ int
 mbmemcasecmp (const char *s1, size_t n1, const char *s2, size_t n2)
 {
   if (s1 == s2)
-    return (n1 < n2 ? -1 : n1 > n2 ? 1 : 0);
+    return _GL_CMP (n1, n2);
 
   if (MB_CUR_MAX > 1)
     {
@@ -80,7 +80,7 @@ mbmemcasecmp (const char *s1, size_t n1, const char *s2, size_t n2)
                 /* On machines where 'char' and 'int' are types of the same
                    size, the difference of two 'unsigned char' values
                    - including the sign bit - doesn't fit in an 'int'.  */
-                return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
+                return _GL_CMP (c1, c2);
             }
           ++p1;
           ++p2;
diff --git a/lib/mbscasecmp.c b/lib/mbscasecmp.c
index 9a1ea4bb35..976e94a070 100644
--- a/lib/mbscasecmp.c
+++ b/lib/mbscasecmp.c
@@ -93,6 +93,6 @@ mbscasecmp (const char *s1, const char *s2)
         /* On machines where 'char' and 'int' are types of the same size, the
            difference of two 'unsigned char' values - including the sign bit -
            doesn't fit in an 'int'.  */
-        return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
+        return _GL_CMP (c1, c2);
     }
 }
diff --git a/lib/mbsncasecmp.c b/lib/mbsncasecmp.c
index a414a6986f..da43d5cb8c 100644
--- a/lib/mbsncasecmp.c
+++ b/lib/mbsncasecmp.c
@@ -94,6 +94,6 @@ mbsncasecmp (const char *s1, const char *s2, size_t n)
         /* On machines where 'char' and 'int' are types of the same size, the
            difference of two 'unsigned char' values - including the sign bit -
            doesn't fit in an 'int'.  */
-        return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
+        return _GL_CMP (c1, c2);
     }
 }
diff --git a/lib/memcasecmp.c b/lib/memcasecmp.c
index a44379373c..6720b8cdb8 100644
--- a/lib/memcasecmp.c
+++ b/lib/memcasecmp.c
@@ -40,8 +40,7 @@ memcasecmp (const void *vs1, const void *vs2, size_t n)
       unsigned char u2 = s2[i];
       int U1 = toupper (u1);
       int U2 = toupper (u2);
-      int diff = (UCHAR_MAX <= INT_MAX ? U1 - U2
-                  : U1 < U2 ? -1 : U2 < U1);
+      int diff = (UCHAR_MAX <= INT_MAX ? U1 - U2 : _GL_CMP (U1, U2));
       if (diff)
         return diff;
     }
diff --git a/lib/memcmp2.c b/lib/memcmp2.c
index c9c3316870..bbfbb0294d 100644
--- a/lib/memcmp2.c
+++ b/lib/memcmp2.c
@@ -26,11 +26,6 @@ memcmp2 (const char *s1, size_t n1, const char *s2, size_t n2)
 {
   int cmp = memcmp (s1, s2, n1 <= n2 ? n1 : n2);
   if (cmp == 0)
-    {
-      if (n1 < n2)
-        cmp = -1;
-      else if (n1 > n2)
-        cmp = 1;
-    }
+    cmp = _GL_CMP (n1, n2);
   return cmp;
 }
diff --git a/lib/savedir.c b/lib/savedir.c
index 5d7151ea81..c93b81a0b9 100644
--- a/lib/savedir.c
+++ b/lib/savedir.c
@@ -65,7 +65,7 @@ direntry_cmp_inode (void const *a, void const *b)
   direntry_t const *dea = a;
   direntry_t const *deb = b;
 
-  return dea->ino < deb->ino ? -1 : dea->ino > deb->ino;
+  return _GL_CMP (dea->ino, deb->ino);
 }
 #endif
 
diff --git a/lib/strcasecmp.c b/lib/strcasecmp.c
index c0b610e5e8..bcb9adb185 100644
--- a/lib/strcasecmp.c
+++ b/lib/strcasecmp.c
@@ -58,5 +58,5 @@ strcasecmp (const char *s1, const char *s2)
     /* On machines where 'char' and 'int' are types of the same size, the
        difference of two 'unsigned char' values - including the sign bit -
        doesn't fit in an 'int'.  */
-    return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
+    return _GL_CMP (c1, c2);
 }
diff --git a/lib/strncasecmp.c b/lib/strncasecmp.c
index 4c1b5b52c9..396d1caaa2 100644
--- a/lib/strncasecmp.c
+++ b/lib/strncasecmp.c
@@ -58,5 +58,5 @@ strncasecmp (const char *s1, const char *s2, size_t n)
     /* On machines where 'char' and 'int' are types of the same size, the
        difference of two 'unsigned char' values - including the sign bit -
        doesn't fit in an 'int'.  */
-    return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
+    return _GL_CMP (c1, c2);
 }
diff --git a/lib/unistr/u-cmp2.h b/lib/unistr/u-cmp2.h
index 85a5db80c5..1e0ea72802 100644
--- a/lib/unistr/u-cmp2.h
+++ b/lib/unistr/u-cmp2.h
@@ -21,12 +21,7 @@ FUNC (const UNIT *s1, size_t n1, const UNIT *s2, size_t n2)
   int cmp = U_CMP (s1, s2, MIN (n1, n2));
 
   if (cmp == 0)
-    {
-      if (n1 < n2)
-        cmp = -1;
-      else if (n1 > n2)
-        cmp = 1;
-    }
+    cmp = _GL_CMP (n1, n2);
 
   return cmp;
 }