Implement OP_PADSV_STORE - combined sassign/padsv OP

This commit introduces a new OP to replace simple cases
of OP_SASSIGN and OP_PADSV.

For example, 'my $x = 1' is currently implemented as:

1  <;> nextstate(main 1 -e:1) v:{
2  <$> const(IV 1) s
3  <0> padsv[$x:1,2] sRM*/LVINTRO
4  <2> sassign vKS/2

But now will be turned into:

1  <;> nextstate(main 1 -e:1) v:{
2  <$> const(IV 1) s
3  <1> padsv_store[$x:1,2] vKMS/LVINTRO

This intended to be a transparent performance optimization.
It should be applicable for RHS optrees of varying complexity.

1 files changed, 10 insertions, 2 deletions

diff --git a/t/perf/opcount.t b/t/perf/opcount.t
index 30e0676660..0c21247bd2 100644
--- a/t/perf/opcount.t
+++ b/t/perf/opcount.t
@@ -712,8 +712,8 @@ test_opcount(0, "builtin::is_bool is replaced with direct opcode",
                 {
                     entersub => 0,
                     is_bool  => 1,
-                    padsv    => 4,
-                    sassign  => 1,
+                    padsv    => 3,
+                    padsv_store  => 1,
                 });
 
 test_opcount(0, "builtin::is_bool gets constant-folded",
@@ -788,4 +788,12 @@ test_opcount(0, "builtin::is_tainted is replaced with direct opcode",
                     is_tainted => 1,
                 });
 
+# sassign + padsv combinations are replaced by padsv_store
+test_opcount(0, "sassign + padsv replaced by padsv_store",
+                sub { my $y; my $z = $y = 3; },
+                {
+                    padsv        => 1,
+                    padsv_store  => 2,
+                });
+
 done_testing();