optimize FIXABLE macro

Looking at the source code, FIXABLE tends to be just before LOING2FIX
to check applicability of that operation.  Why not try computing first
then check for overflow, which should be optimial.

I also tried the same thing for unsigned types but resulted in slower
execution.  It seems RB_POSFIXABLE() is fast enough on modern CPUs.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57789 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 12 insertions, 4 deletions

diff --git a/bignum.c b/bignum.c
index 8c723300f4..50700b4c4a 100644
--- a/bignum.c
+++ b/bignum.c
@@ -3184,15 +3184,13 @@ rb_int2big(SIGNED_VALUE n)
 VALUE
 rb_uint2inum(VALUE n)
 {
-    if (POSFIXABLE(n)) return LONG2FIX(n);
-    return rb_uint2big(n);
+    return ULONG2NUM(n);
 }
 
 VALUE
 rb_int2inum(SIGNED_VALUE n)
 {
-    if (FIXABLE(n)) return LONG2FIX(n);
-    return rb_int2big(n);
+    return LONG2NUM(n);
 }
 
 void
@@ -4438,8 +4436,18 @@ rb_ull2inum(unsigned LONG_LONG n)
 VALUE
 rb_ll2inum(LONG_LONG n)
 {
+#ifdef HAVE_BUILTIN___BUILTIN_MUL_OVERFLOW
+    SIGNED_VALUE v;
+    if (__builtin_mul_overflow(n, 2, &v)) {
+	return rb_ll2big(n);
+    }
+    else {
+	return ((VALUE)v) | RUBY_FIXNUM_FLAG;
+    }
+#else
     if (FIXABLE(n)) return LONG2FIX(n);
     return rb_ll2big(n);
+#endif
 }
 
 #endif  /* HAVE_LONG_LONG */