Avoid erts_cmp jump in atom, int and float comparisons

Given the function definition below:

    check(X) when X >= 0, X <= 20 -> true.

@nox has originally noticed that perfoming lt and ge
guard tests were performing slower than they should be.

Further investigation revealed that most of the cost
was in jumping to the erts_cmp function. This patch
brings the operations already inlined in erts_cmp
into the emulator, removing the jump cost.

After applying these changes, invoking the check/1
function defined above 30000 times with different
values from 0 to 20 has fallen from 367us to 213us
(measured as average of 3 runs). This is a
considerably improvement over Erlang 18 which takes
556us on average.

Floats have also dropped their time from 1126us
(on Erlang 18) to 613us.

1 files changed, 9 insertions, 9 deletions

diff --git a/erts/emulator/beam/utils.c b/erts/emulator/beam/utils.c
index ef851d840d..6aad1ff778 100644
--- a/erts/emulator/beam/utils.c
+++ b/erts/emulator/beam/utils.c
@@ -2991,7 +2991,7 @@ static int cmpbytes(byte *s1, int l1, byte *s2, int l2)
 
 #define float_comp(x,y)    (((x)<(y)) ? -1 : (((x)==(y)) ? 0 : 1))
 
-static int cmp_atoms(Eterm a, Eterm b)
+int erts_cmp_atoms(Eterm a, Eterm b)
 {
     Atom *aa = atom_tab(atom_val(a));
     Atom *bb = atom_tab(atom_val(b));
@@ -3010,12 +3010,12 @@ Sint cmp(Eterm a, Eterm b)
     return erts_cmp(a, b, 0, 0);
 }
 
-static Sint erts_cmp_compound(Eterm a, Eterm b, int exact, int eq_only);
+Sint erts_cmp_compound(Eterm a, Eterm b, int exact, int eq_only);
 
 Sint erts_cmp(Eterm a, Eterm b, int exact, int eq_only)
 {
     if (is_atom(a) && is_atom(b)) {
-        return cmp_atoms(a, b);
+        return erts_cmp_atoms(a, b);
     } else if (is_both_small(a, b)) {
         return (signed_val(a) - signed_val(b));
     } else if (is_float(a) && is_float(b)) {
@@ -3032,7 +3032,7 @@ Sint erts_cmp(Eterm a, Eterm b, int exact, int eq_only)
  * exact = 1 -> term-based compare
  * exact = 0 -> arith-based compare
  */
-static Sint erts_cmp_compound(Eterm a, Eterm b, int exact, int eq_only)
+Sint erts_cmp_compound(Eterm a, Eterm b, int exact, int eq_only)
 {
 #define PSTACK_TYPE struct erts_cmp_hashmap_state
     struct erts_cmp_hashmap_state {
@@ -3089,7 +3089,7 @@ static Sint erts_cmp_compound(Eterm a, Eterm b, int exact, int eq_only)
     do {								\
 	if((AN) != (BN)) {						\
             if((AN)->sysname != (BN)->sysname)				\
-                RETURN_NEQ(cmp_atoms((AN)->sysname, (BN)->sysname));	\
+                RETURN_NEQ(erts_cmp_atoms((AN)->sysname, (BN)->sysname));	\
 	    ASSERT((AN)->creation != (BN)->creation);			\
 	    RETURN_NEQ(((AN)->creation < (BN)->creation) ? -1 : 1);	\
 	}								\
@@ -3107,7 +3107,7 @@ tailrecur_ne:
     /* deal with majority (?) cases by brute-force */
     if (is_atom(a)) {
 	if (is_atom(b)) {
-	    ON_CMP_GOTO(cmp_atoms(a, b));
+	    ON_CMP_GOTO(erts_cmp_atoms(a, b));
 	}
     } else if (is_both_small(a, b)) {
 	ON_CMP_GOTO(signed_val(a) - signed_val(b));
@@ -3341,10 +3341,10 @@ tailrecur_ne:
 		    Export* a_exp = *((Export **) (export_val(a) + 1));
 		    Export* b_exp = *((Export **) (export_val(b) + 1));
 
-		    if ((j = cmp_atoms(a_exp->code[0], b_exp->code[0])) != 0) {
+		    if ((j = erts_cmp_atoms(a_exp->code[0], b_exp->code[0])) != 0) {
 			RETURN_NEQ(j);
 		    }
-		    if ((j = cmp_atoms(a_exp->code[1], b_exp->code[1])) != 0) {
+		    if ((j = erts_cmp_atoms(a_exp->code[1], b_exp->code[1])) != 0) {
 			RETURN_NEQ(j);
 		    }
 		    ON_CMP_GOTO((Sint) a_exp->code[2] - (Sint) b_exp->code[2]);
@@ -3659,7 +3659,7 @@ term_array: /* arrays in 'aa' and 'bb', length in 'i' */
 	b = *bb++;
 	if (!is_same(a, b)) {
 	    if (is_atom(a) && is_atom(b)) {
-		if ((j = cmp_atoms(a, b)) != 0) {
+		if ((j = erts_cmp_atoms(a, b)) != 0) {
 		    goto not_equal;
 		}
 	    } else if (is_both_small(a, b)) {