Eliminate use of GetArg1() in the select_val instruction

Instead of having one i_select_val_sfI instruction that uses
the GetArg1() macro to fetch the controlling expression, use
three separate instructions for each of the register types.
That will save one word when selecting on the {x,0} register.
It should also be slightly faster since a conditional branch
is eliminated.

Although it seems that the BEAM compiler will never generate
a constant controlling expression (even with optimizations
turned off), we still make sure that they will work by
evaluating the select_val instruction at load time.

Handle the select_tuple_arity instruction in the same way.

2 files changed, 84 insertions, 3 deletions

diff --git a/erts/emulator/test/beam_literals_SUITE.erl b/erts/emulator/test/beam_literals_SUITE.erl
index 2238e89748..f56d7ac1c5 100644
--- a/erts/emulator/test/beam_literals_SUITE.erl
+++ b/erts/emulator/test/beam_literals_SUITE.erl
@@ -406,10 +406,15 @@ fconv_2(F) when is_float(F) ->
 literal_case_expression(Config) when is_list(Config) ->
     ?line DataDir = ?config(data_dir, Config),
     ?line Src = filename:join(DataDir, "literal_case_expression"),
-    ?line {ok,literal_case_expression=Mod,Code} = compile:file(Src, [from_asm,binary]),
+    ?line {ok,literal_case_expression=Mod,Code} =
+	compile:file(Src, [from_asm,binary]),
     ?line {module,Mod} = code:load_binary(Mod, Src, Code),
     ?line ok = Mod:x(),
     ?line ok = Mod:y(),
+    ?line ok = Mod:zi1(),
+    ?line ok = Mod:zi2(),
+    ?line ok = Mod:za1(),
+    ?line ok = Mod:za2(),
     ?line true = code:delete(Mod),
     ?line code:purge(Mod),
     ok.
diff --git a/erts/emulator/test/beam_literals_SUITE_data/literal_case_expression.S b/erts/emulator/test/beam_literals_SUITE_data/literal_case_expression.S
index c0ffe9ab53..bfdfc079dc 100644
--- a/erts/emulator/test/beam_literals_SUITE_data/literal_case_expression.S
+++ b/erts/emulator/test/beam_literals_SUITE_data/literal_case_expression.S
@@ -1,10 +1,11 @@
 {module, literal_case_expression}.  %% version = 0
 
-{exports, [{module_info,0},{module_info,1},{x,0},{y,0}]}.
+{exports, [{module_info,0},{module_info,1},{x,0},{y,0},
+	   {zi1,0},{zi2,0},{za1,0},{za2,0}]}.
 
 {attributes, []}.
 
-{labels, 15}.
+{labels, 32}.
 
 
 {function, x, 0, 2}.
@@ -52,6 +53,81 @@
   {label,10}.
     {case_end,{float,34.0000}}.
 
+{function, zi1, 0, 16}.
+  {label,15}.
+    {func_info,{atom,literal_case_expression},{atom,zi1},0}.
+  {label,16}.
+    {test,is_integer,{f,19},[{integer,42}]}.
+    {select_val,{integer,42},
+                {f,18},
+                {list,[{integer,42},
+                       {f,17},
+                       {integer,1000},
+                       {f,18}]}}.
+  {label,17}.
+    {move,{atom,ok},{x,0}}.
+    return.
+  {label,18}.
+    {move,{atom,error},{x,0}}.
+    return.
+  {label,19}.
+    {case_end,{integer,42}}.
+
+{function, zi2, 0, 16}.
+  {label,20}.
+    {func_info,{atom,literal_case_expression},{atom,zi2},0}.
+  {label,21}.
+    {test,is_integer,{f,23},[{integer,42}]}.
+    {select_val,{integer,42},
+                {f,23},
+                {list,[{integer,42},
+                       {f,22},
+                       {integer,1000},
+                       {f,23}]}}.
+  {label,22}.
+    {move,{atom,ok},{x,0}}.
+    return.
+  {label,23}.
+    {move,{atom,error},{x,0}}.
+    return.
+
+{function, za1, 0, 25}.
+  {label,24}.
+    {func_info,{atom,literal_case_expression},{atom,za1},0}.
+  {label,25}.
+    {test,is_atom,{f,28},[{atom,x}]}.
+    {select_val,{atom,x},
+                {f,27},
+                {list,[{atom,a},
+                       {f,27},
+                       {atom,x},
+                       {f,26}]}}.
+  {label,26}.
+    {move,{atom,ok},{x,0}}.
+    return.
+  {label,27}.
+    {move,{atom,error},{x,0}}.
+    return.
+  {label,28}.
+    {case_end,{atom,x}}.
+
+{function, za2, 0, 30}.
+  {label,29}.
+    {func_info,{atom,literal_case_expression},{atom,za2},0}.
+  {label,30}.
+    {test,is_atom,{f,32},[{atom,x}]}.
+    {select_val,{atom,x},
+                {f,32},
+                {list,[{atom,a},
+                       {f,32},
+                       {atom,x},
+                       {f,31}]}}.
+  {label,31}.
+    {move,{atom,ok},{x,0}}.
+    return.
+  {label,32}.
+    {move,{atom,error},{x,0}}.
+    return.
 
 {function, module_info, 0, 12}.
   {label,11}.