wip

Only array slices (not list slices) are handled so far, and they are buggy:
• Negative indices do not work yet.
• @A[1.., 2..] dies at compile time.

embed.h

@@ -1056,6 +1056,7 @@
 #define ck_sassign(a)		Perl_ck_sassign(aTHX_ a)
 #define ck_select(a)		Perl_ck_select(aTHX_ a)
 #define ck_shift(a)		Perl_ck_shift(aTHX_ a)
+#define ck_slice(a)		Perl_ck_slice(aTHX_ a)
 #define ck_smartmatch(a)	Perl_ck_smartmatch(aTHX_ a)
 #define ck_sort(a)		Perl_ck_sort(aTHX_ a)
 #define ck_spair(a)		Perl_ck_spair(aTHX_ a)

ext/Opcode/Opcode.pm

@@ -6,7 +6,7 @@ use strict;
 
 our($VERSION, @ISA, @EXPORT_OK);
 
-$VERSION = "1.25";
+$VERSION = "1.26";
 
 use Carp;
 use Exporter ();
@@ -350,7 +350,7 @@ These memory related ops are not included in :base_core because they
 can easily be used to implement a resource attack (e.g., consume all
 available memory).
 
-    concat repeat join range
+    concat repeat join range postdotdot
 
     anonlist anonhash
 

op.c

@@ -1752,7 +1752,7 @@ S_finalize_op(pTHX_ OP* o)
 	/* Relocate sv to the pad for thread safety.
 	 * Despite being a "constant", the SV is written to,
 	 * for reference counts, sv_upgrade() etc. */
-	if (cSVOPo->op_sv) {
+	if (cSVOPo->op_sv && cSVOPo->op_sv != &PL_sv_placeholder) {
 	    const PADOFFSET ix = pad_alloc(OP_CONST, SVf_READONLY);
 	    if (o->op_type != OP_METHOD_NAMED
 		&& cSVOPo->op_sv == &PL_sv_undef) {
@@ -1881,6 +1881,8 @@ S_finalize_op(pTHX_ OP* o)
 	break;
     }
 
+    case OP_POSTDOTDOT: Perl_croak(aTHX_ "Postfix .. outside of slice");
+
     case OP_SUBST: {
 	if (cPMOPo->op_pmreplrootu.op_pmreplroot)
 	    finalize_op(cPMOPo->op_pmreplrootu.op_pmreplroot);
@@ -9602,6 +9604,28 @@ Perl_ck_shift(pTHX_ OP *o)
     return scalar(ck_fun(o));
 }
 
+OP *
+Perl_ck_slice(pTHX_ OP *o)
+{
+    dVAR;
+    OP *kid;
+
+    PERL_ARGS_ASSERT_CK_SLICE;
+
+    kid = cBINOPo->op_first;
+    if (kid->op_type != OP_PUSHMARK && kid->op_flags & OPf_KIDS)
+	kid = kUNOP->op_first;
+
+    for (kid = kid->op_sibling; kid; kid = kid->op_sibling) {
+	if (kid->op_type == OP_POSTDOTDOT) {
+	    kid->op_type = OP_CONST;
+	    kid->op_ppaddr = PL_ppaddr[OP_CONST];
+	}
+    }
+
+    return o;
+}
+
 OP *
 Perl_ck_sort(pTHX_ OP *o)
 {

opcode.h

@@ -142,6 +142,7 @@
 #define Perl_pp_custom Perl_unimplemented_op
 #define Perl_pp_reach Perl_pp_rkeys
 #define Perl_pp_rvalues Perl_pp_rkeys
+#define Perl_pp_postdotdot Perl_unimplemented_op
 START_EXTERN_C
 
 #ifndef DOINIT
@@ -525,6 +526,7 @@ EXTCONST char* const PL_op_name[] = {
 	"introcv",
 	"clonecv",
 	"padrange",
+	"postdotdot",
 	"freed",
 };
 #endif
@@ -910,6 +912,7 @@ EXTCONST char* const PL_op_desc[] = {
 	"private subroutine",
 	"private subroutine",
 	"list of private variables",
+	"postfix .. in slice",
 	"freed op",
 };
 #endif
@@ -1309,6 +1312,7 @@ EXT Perl_ppaddr_t PL_ppaddr[] /* or perlvars.h */
 	Perl_pp_introcv,
 	Perl_pp_clonecv,
 	Perl_pp_padrange,
+	Perl_pp_postdotdot,	/* implemented by Perl_unimplemented_op */
 }
 #endif
 #ifdef PERL_PPADDR_INITED
@@ -1458,7 +1462,7 @@ EXT Perl_check_t PL_check[] /* or perlvars.h */
 	Perl_ck_null,		/* aelemfast */
 	Perl_ck_null,		/* aelemfast_lex */
 	Perl_ck_null,		/* aelem */
-	Perl_ck_null,		/* aslice */
+	Perl_ck_slice,		/* aslice */
 	Perl_ck_each,		/* aeach */
 	Perl_ck_each,		/* akeys */
 	Perl_ck_each,		/* avalues */
@@ -1475,7 +1479,7 @@ EXT Perl_check_t PL_check[] /* or perlvars.h */
 	Perl_ck_split,		/* split */
 	Perl_ck_join,		/* join */
 	Perl_ck_null,		/* list */
-	Perl_ck_null,		/* lslice */
+	Perl_ck_slice,		/* lslice */
 	Perl_ck_fun,		/* anonlist */
 	Perl_ck_fun,		/* anonhash */
 	Perl_ck_fun,		/* splice */
@@ -1704,6 +1708,7 @@ EXT Perl_check_t PL_check[] /* or perlvars.h */
 	Perl_ck_null,		/* introcv */
 	Perl_ck_null,		/* clonecv */
 	Perl_ck_null,		/* padrange */
+	Perl_ck_null,		/* postdotdot */
 }
 #endif
 #ifdef PERL_CHECK_INITED
@@ -2093,6 +2098,7 @@ EXTCONST U32 PL_opargs[] = {
 	0x00000040,	/* introcv */
 	0x00000040,	/* clonecv */
 	0x00000040,	/* padrange */
+	0x00000600,	/* postdotdot */
 };
 #endif
 

opnames.h

@@ -391,10 +391,11 @@ typedef enum opcode {
 	OP_INTROCV	 = 374,
 	OP_CLONECV	 = 375,
 	OP_PADRANGE	 = 376,
+	OP_POSTDOTDOT	 = 377,
 	OP_max		
 } opcode;
 
-#define MAXO 377
+#define MAXO 378
 #define OP_FREED MAXO
 
 /* the OP_IS_* macros are optimized to a simple range check because