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

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 */

compile.c

@@ -3190,7 +3190,7 @@ case_when_optimizable_literal(NODE *node)
 	double ival;
 	if (RB_TYPE_P(v, T_FLOAT) &&
 	    modf(RFLOAT_VALUE(v), &ival) == 0.0) {
-	    return FIXABLE(ival) ? LONG2FIX((long)ival) : rb_dbl2big(ival);
+	    return rb_dbl2ival(ival);
 	}
 	if (SYMBOL_P(v) || rb_obj_is_kind_of(v, rb_cNumeric)) {
 	    return v;

include/ruby/ruby.h

@@ -1504,6 +1504,29 @@ rb_integer_type_p(VALUE obj)
 }
 #endif
 
+static inline int
+rb_long2fix_overflow(long l, VALUE *ptr)
+{
+#ifdef HAVE_BUILTIN___BUILTIN_MUL_OVERFLOW
+    SIGNED_VALUE v;
+    if (__builtin_mul_overflow(l, 2, &v)) {
+	return 1;
+    }
+    else {
+	*ptr = ((VALUE)v) | RUBY_FIXNUM_FLAG;
+	return 0;
+    }
+#else
+    if (RB_FIXABLE(l)) {
+	*ptr = RB_LONG2FIX(l);
+	return 0;
+    }
+    else {
+	return 1;
+    }
+#endif
+}
+
 #if SIZEOF_INT < SIZEOF_LONG
 # define RB_INT2NUM(v) RB_INT2FIX((int)(v))
 # define RB_UINT2NUM(v) RB_LONG2FIX((unsigned int)(v))
@@ -1511,10 +1534,11 @@ rb_integer_type_p(VALUE obj)
 static inline VALUE
 rb_int2num_inline(int v)
 {
-    if (RB_FIXABLE(v))
-	return RB_INT2FIX(v);
-    else
+    VALUE ret;
+    if (rb_long2fix_overflow(v, &ret))
 	return rb_int2big(v);
+    else
+	return ret;
 }
 #define RB_INT2NUM(x) rb_int2num_inline(x)
 
@@ -1534,10 +1558,11 @@ rb_uint2num_inline(unsigned int v)
 static inline VALUE
 rb_long2num_inline(long v)
 {
-    if (RB_FIXABLE(v))
-	return RB_LONG2FIX(v);
-    else
+    VALUE ret;
+    if (rb_long2fix_overflow(v, &ret))
 	return rb_int2big(v);
+    else
+	return ret;
 }
 #define RB_LONG2NUM(x) rb_long2num_inline(x)
 

insns.def

@@ -1345,7 +1345,7 @@ opt_case_dispatch
 	    if (RB_FLOAT_TYPE_P(key)) {
 		double kval = RFLOAT_VALUE(key);
 		if (!isinf(kval) && modf(kval, &kval) == 0.0) {
-		    key = FIXABLE(kval) ? LONG2FIX((long)kval) : rb_dbl2big(kval);
+		    key = rb_dbl2ival(kval);
 		}
 	    }
 	    if (st_lookup(RHASH_TBL_RAW(hash), key, &val)) {

internal.h

@@ -1383,6 +1383,18 @@ rb_float_new_inline(double d)
 #define rb_float_value(v) rb_float_value_inline(v)
 #define rb_float_new(d)   rb_float_new_inline(d)
 
+static inline VALUE
+rb_dbl2ival(double d)
+{
+    VALUE val;
+    if (rb_long2fix_overflow(d, &val)) {
+	return rb_dbl2big(d);
+    }
+    else {
+	return val;
+    }
+}
+
 /* object.c */
 void rb_obj_copy_ivar(VALUE dest, VALUE obj);
 CONSTFUNC(VALUE rb_obj_equal(VALUE obj1, VALUE obj2));

numeric.c

@@ -1279,10 +1279,7 @@ flo_mod(VALUE x, VALUE y)
 static VALUE
 dbl2ival(double d)
 {
-    if (FIXABLE(d)) {
-	return LONG2FIX((long)d);
-    }
-    return rb_dbl2big(d);
+    return rb_dbl2ival(d);
 }
 
 /*
@@ -1967,7 +1964,6 @@ static VALUE
 flo_floor(int argc, VALUE *argv, VALUE num)
 {
     double number, f;
-    long val;
     int ndigits = 0;
 
     if (rb_check_arity(argc, 0, 1)) {
@@ -1984,11 +1980,7 @@ flo_floor(int argc, VALUE *argv, VALUE num)
 	return DBL2NUM(f);
     }
     f = floor(number);
-    if (!FIXABLE(f)) {
-	return rb_dbl2big(f);
-    }
-    val = (long)f;
-    return LONG2FIX(val);
+    return dbl2ival(f);
 }
 
 /*
@@ -2327,16 +2319,11 @@ static VALUE
 flo_to_i(VALUE num)
 {
     double f = RFLOAT_VALUE(num);
-    long val;
 
     if (f > 0.0) f = floor(f);
     if (f < 0.0) f = ceil(f);
 
-    if (!FIXABLE(f)) {
-	return rb_dbl2big(f);
-    }
-    val = (long)f;
-    return LONG2FIX(val);
+    return dbl2ival(f);
 }
 
 /*
@@ -3020,13 +3007,17 @@ VALUE
 rb_num2fix(VALUE val)
 {
     long v;
+    VALUE w;
 
-    if (FIXNUM_P(val)) return val;
-
-    v = rb_num2long(val);
-    if (!FIXABLE(v))
+    if (FIXNUM_P(val)) {
+	return val;
+    }
+    else if (rb_long2fix_overflow((v = rb_num2long(val)), &w)) {
 	rb_raise(rb_eRangeError, "integer %ld out of range of fixnum", v);
-    return LONG2FIX(v);
+    }
+    else {
+	return w;
+    }
 }
 
 #if HAVE_LONG_LONG

object.c

@@ -2747,11 +2747,8 @@ rb_convert_to_integer(VALUE val, int base)
     VALUE tmp;
 
     if (RB_FLOAT_TYPE_P(val)) {
-	double f;
 	if (base != 0) goto arg_error;
-	f = RFLOAT_VALUE(val);
-	if (FIXABLE(f)) return LONG2FIX((long)f);
-	return rb_dbl2big(f);
+	return rb_dbl2ival(RFLOAT_VALUE(val));
     }
     else if (RB_INTEGER_TYPE_P(val)) {
 	if (base != 0) goto arg_error;

sprintf.c

@@ -832,11 +832,7 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
 	      bin_retry:
 		switch (TYPE(val)) {
 		  case T_FLOAT:
-		    if (FIXABLE(RFLOAT_VALUE(val))) {
-			val = LONG2FIX((long)RFLOAT_VALUE(val));
-			goto bin_retry;
-		    }
-		    val = rb_dbl2big(RFLOAT_VALUE(val));
+		    val = rb_dbl2ival(RFLOAT_VALUE(val));
 		    if (FIXNUM_P(val)) goto bin_retry;
 		    bignum = 1;
 		    break;