Optimize instructions for comparing a register with a literal

We can avoid calling eq() from the is_eq_exact_literal/3
and is_ne_exact_literal/3 instructions if the source operand is
an immediate (since a literal is either a boxed or a list, never
an immediate).

1 files changed, 4 insertions, 2 deletions

diff --git a/erts/emulator/beam/instrs.tab b/erts/emulator/beam/instrs.tab
index 20d356a81d..c17d1a8f69 100644
--- a/erts/emulator/beam/instrs.tab
+++ b/erts/emulator/beam/instrs.tab
@@ -788,7 +788,8 @@ is_eq_exact(Fail, X, Y) {
 }
 
 i_is_eq_exact_literal(Fail, Src, Literal) {
-    if (!eq($Src, $Literal)) {
+    Eterm src = $Src;
+    if (is_immed(src) || !eq(src, $Literal)) {
         $FAIL($Fail);
     }
 }
@@ -800,7 +801,8 @@ is_ne_exact(Fail, X, Y) {
 }
 
 i_is_ne_exact_literal(Fail, Src, Literal) {
-    if (eq($Src, $Literal)) {
+    Eterm src = $Src;
+    if (!is_immed(src) && eq(src, $Literal)) {
         $FAIL($Fail);
     }
 }