This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
prevent multiple evaluations of ERRSV
[perl5.git] / op.c
diff --git a/op.c b/op.c
index c62e943..1b4cf8d 100644 (file)
--- a/op.c
+++ b/op.c
@@ -261,18 +261,13 @@ Perl_Slab_to_ro(pTHX_ OPSLAB *slab)
     }
 }
 
-STATIC void
-S_Slab_to_rw(pTHX_ void *op)
+void
+Perl_Slab_to_rw(pTHX_ OPSLAB *const slab)
 {
-    OP * const o = (OP *)op;
-    OPSLAB *slab;
     OPSLAB *slab2;
 
     PERL_ARGS_ASSERT_SLAB_TO_RW;
 
-    if (!o->op_slabbed) return;
-
-    slab = OpSLAB(o);
     if (!slab->opslab_readonly) return;
     slab2 = slab;
     for (; slab2; slab2 = slab2->opslab_next) {
@@ -308,7 +303,8 @@ Perl_Slab_Free(pTHX_ void *op)
     PERL_ARGS_ASSERT_SLAB_FREE;
 
     if (!o->op_slabbed) {
-       PerlMemShared_free(op);
+        if (!o->op_static)
+           PerlMemShared_free(op);
        return;
     }
 
@@ -384,9 +380,8 @@ Perl_opslab_force_free(pTHX_ OPSLAB *slab)
                 )
            ) {
                assert(slot->opslot_op.op_slabbed);
-               slab->opslab_refcnt++; /* op_free may free slab */
                op_free(&slot->opslot_op);
-               if (!--slab->opslab_refcnt) goto free;
+               if (slab->opslab_refcnt == 1) goto free;
            }
        }
     } while ((slab2 = slab2->opslab_next));
@@ -395,6 +390,8 @@ Perl_opslab_force_free(pTHX_ OPSLAB *slab)
 #ifdef DEBUGGING
        assert(savestack_count == slab->opslab_refcnt-1);
 #endif
+       /* Remove the CV’s reference count. */
+       slab->opslab_refcnt--;
        return;
     }
    free:
@@ -406,8 +403,14 @@ OP *
 Perl_op_refcnt_inc(pTHX_ OP *o)
 {
     if(o) {
-       Slab_to_rw(o);
-       ++o->op_targ;
+        OPSLAB *const slab = o->op_slabbed ? OpSLAB(o) : NULL;
+        if (slab && slab->opslab_readonly) {
+            Slab_to_rw(slab);
+            ++o->op_targ;
+            Slab_to_ro(slab);
+        } else {
+            ++o->op_targ;
+        }
     }
     return o;
 
@@ -416,9 +419,19 @@ Perl_op_refcnt_inc(pTHX_ OP *o)
 PADOFFSET
 Perl_op_refcnt_dec(pTHX_ OP *o)
 {
+    PADOFFSET result;
+    OPSLAB *const slab = o->op_slabbed ? OpSLAB(o) : NULL;
+
     PERL_ARGS_ASSERT_OP_REFCNT_DEC;
-    Slab_to_rw(o);
-    return --o->op_targ;
+
+    if (slab && slab->opslab_readonly) {
+        Slab_to_rw(slab);
+        result = --o->op_targ;
+        Slab_to_ro(slab);
+    } else {
+        result = --o->op_targ;
+    }
+    return result;
 }
 #endif
 /*
@@ -698,7 +711,9 @@ Perl_op_free(pTHX_ OP *o)
     if (type == OP_NULL)
        type = (OPCODE)o->op_targ;
 
-    Slab_to_rw(o);
+    if (o->op_slabbed) {
+       Slab_to_rw(OpSLAB(o));
+    }
 
     /* COP* is not cleared by op_clear() so that we may track line
      * numbers etc even after null() */
@@ -1085,8 +1100,11 @@ S_scalarboolean(pTHX_ OP *o)
        if (ckWARN(WARN_SYNTAX)) {
            const line_t oldline = CopLINE(PL_curcop);
 
-           if (PL_parser && PL_parser->copline != NOLINE)
+           if (PL_parser && PL_parser->copline != NOLINE) {
+               /* This ensures that warnings are reported at the first line
+                   of the conditional, not the last.  */
                CopLINE_set(PL_curcop, PL_parser->copline);
+            }
            Perl_warner(aTHX_ packWARN(WARN_SYNTAX), "Found = in conditional, should be ==");
            CopLINE_set(PL_curcop, oldline);
        }
@@ -1744,7 +1762,7 @@ S_finalize_op(pTHX_ OP* o)
                /* If op_sv is already a PADTMP/MY then it is being used by
                 * some pad, so make a copy. */
                sv_setsv(PAD_SVl(ix),cSVOPo->op_sv);
-               SvREADONLY_on(PAD_SVl(ix));
+               if (!SvIsCOW(PAD_SVl(ix))) SvREADONLY_on(PAD_SVl(ix));
                SvREFCNT_dec(cSVOPo->op_sv);
            }
            else if (o->op_type != OP_METHOD_NAMED
@@ -1764,7 +1782,7 @@ S_finalize_op(pTHX_ OP* o)
                SvPADTMP_on(cSVOPo->op_sv);
                PAD_SETSV(ix, cSVOPo->op_sv);
                /* XXX I don't know how this isn't readonly already. */
-               SvREADONLY_on(PAD_SVl(ix));
+               if (!SvIsCOW(PAD_SVl(ix))) SvREADONLY_on(PAD_SVl(ix));
            }
            cSVOPo->op_sv = NULL;
            o->op_targ = ix;
@@ -1785,7 +1803,7 @@ S_finalize_op(pTHX_ OP* o)
 
        /* Make the CONST have a shared SV */
        svp = cSVOPx_svp(((BINOP*)o)->op_last);
-       if ((!SvFAKE(sv = *svp) || !SvREADONLY(sv))
+       if ((!SvIsCOW(sv = *svp))
            && SvTYPE(sv) < SVt_PVMG && !SvROK(sv)) {
            key = SvPV_const(sv, keylen);
            lexname = newSVpvn_share(key,
@@ -1874,6 +1892,7 @@ S_finalize_op(pTHX_ OP* o)
        }
        break;
     }
+
     case OP_SUBST: {
        if (cPMOPo->op_pmreplrootu.op_pmreplroot)
            finalize_op(cPMOPo->op_pmreplrootu.op_pmreplroot);
@@ -2370,7 +2389,7 @@ Perl_doref(pTHX_ OP *o, I32 type, bool set_op_ref)
 
     case OP_SCALAR:
     case OP_NULL:
-       if (!(o->op_flags & OPf_KIDS))
+       if (!(o->op_flags & OPf_KIDS) || type == OP_DEFINED)
            break;
        doref(cBINOPo->op_first, type, set_op_ref);
        break;
@@ -2434,31 +2453,20 @@ S_dup_attrlist(pTHX_ OP *o)
 }
 
 STATIC void
-S_apply_attrs(pTHX_ HV *stash, SV *target, OP *attrs, bool for_my)
+S_apply_attrs(pTHX_ HV *stash, SV *target, OP *attrs)
 {
     dVAR;
-    SV *stashsv;
+    SV * const stashsv = stash ? newSVhek(HvNAME_HEK(stash)) : &PL_sv_no;
 
     PERL_ARGS_ASSERT_APPLY_ATTRS;
 
     /* fake up C<use attributes $pkg,$rv,@attrs> */
     ENTER;             /* need to protect against side-effects of 'use' */
-    stashsv = stash ? newSVhek(HvNAME_HEK(stash)) : &PL_sv_no;
 
 #define ATTRSMODULE "attributes"
 #define ATTRSMODULE_PM "attributes.pm"
 
-    if (for_my) {
-       /* Don't force the C<use> if we don't need it. */
-       SV * const * const svp = hv_fetchs(GvHVn(PL_incgv), ATTRSMODULE_PM, FALSE);
-       if (svp && *svp != &PL_sv_undef)
-           NOOP;       /* already in %INC */
-       else
-           Perl_load_module(aTHX_ PERL_LOADMOD_NOIMPORT,
-                            newSVpvs(ATTRSMODULE), NULL);
-    }
-    else {
-       Perl_load_module(aTHX_ PERL_LOADMOD_IMPORT_OPS,
+    Perl_load_module(aTHX_ PERL_LOADMOD_IMPORT_OPS,
                         newSVpvs(ATTRSMODULE),
                         NULL,
                         op_prepend_elem(OP_LIST,
@@ -2467,7 +2475,6 @@ S_apply_attrs(pTHX_ HV *stash, SV *target, OP *attrs, bool for_my)
                                                   newSVOP(OP_CONST, 0,
                                                           newRV(target)),
                                                   dup_attrlist(attrs))));
-    }
     LEAVE;
 }
 
@@ -2476,7 +2483,7 @@ S_apply_attrs_my(pTHX_ HV *stash, OP *target, OP *attrs, OP **imopsp)
 {
     dVAR;
     OP *pack, *imop, *arg;
-    SV *meth, *stashsv;
+    SV *meth, *stashsv, **svp;
 
     PERL_ARGS_ASSERT_APPLY_ATTRS_MY;
 
@@ -2488,7 +2495,15 @@ S_apply_attrs_my(pTHX_ HV *stash, OP *target, OP *attrs, OP **imopsp)
           target->op_type == OP_PADAV);
 
     /* Ensure that attributes.pm is loaded. */
-    apply_attrs(stash, PAD_SV(target->op_targ), attrs, TRUE);
+    ENTER;             /* need to protect against side-effects of 'use' */
+    /* Don't force the C<use> if we don't need it. */
+    svp = hv_fetchs(GvHVn(PL_incgv), ATTRSMODULE_PM, FALSE);
+    if (svp && *svp != &PL_sv_undef)
+       NOOP;   /* already in %INC */
+    else
+       Perl_load_module(aTHX_ PERL_LOADMOD_NOIMPORT,
+                              newSVpvs(ATTRSMODULE), NULL);
+    LEAVE;
 
     /* Need package name for method call. */
     pack = newSVOP(OP_CONST, 0, newSVpvs(ATTRSMODULE));
@@ -2608,7 +2623,7 @@ S_my_kid(pTHX_ OP *o, OP *attrs, OP **imopsp)
                        (type == OP_RV2SV ? GvSV(gv) :
                         type == OP_RV2AV ? MUTABLE_SV(GvAV(gv)) :
                         type == OP_RV2HV ? MUTABLE_SV(GvHV(gv)) : MUTABLE_SV(gv)),
-                       attrs, FALSE);
+                       attrs);
        }
        o->op_private |= OPpOUR_INTRO;
        return o;
@@ -2817,7 +2832,7 @@ Perl_op_scope(pTHX_ OP *o)
 {
     dVAR;
     if (o) {
-       if (o->op_flags & OPf_PARENS || PERLDB_NOOPT || PL_tainting) {
+       if (o->op_flags & OPf_PARENS || PERLDB_NOOPT || TAINTING_get) {
            o = op_prepend_elem(OP_LINESEQ, newOP(OP_ENTER, 0), o);
            o->op_type = OP_LEAVE;
            o->op_ppaddr = PL_ppaddr[OP_LEAVE];
@@ -2878,6 +2893,7 @@ Perl_block_end(pTHX_ I32 floor, OP *seq)
     dVAR;
     const int needblockscope = PL_hints & HINT_BLOCK_SCOPE;
     OP* retval = scalarseq(seq);
+    OP *o;
 
     CALL_BLOCK_HOOKS(bhk_pre_end, &retval);
 
@@ -2885,7 +2901,66 @@ Perl_block_end(pTHX_ I32 floor, OP *seq)
     CopHINTS_set(&PL_compiling, PL_hints);
     if (needblockscope)
        PL_hints |= HINT_BLOCK_SCOPE; /* propagate out */
-    pad_leavemy();
+    o = pad_leavemy();
+
+    if (o) {
+       /* pad_leavemy has created a sequence of introcv ops for all my
+          subs declared in the block.  We have to replicate that list with
+          clonecv ops, to deal with this situation:
+
+              sub {
+                  my sub s1;
+                  my sub s2;
+                  sub s1 { state sub foo { \&s2 } }
+              }->()
+
+          Originally, I was going to have introcv clone the CV and turn
+          off the stale flag.  Since &s1 is declared before &s2, the
+          introcv op for &s1 is executed (on sub entry) before the one for
+          &s2.  But the &foo sub inside &s1 (which is cloned when &s1 is
+          cloned, since it is a state sub) closes over &s2 and expects
+          to see it in its outer CV’s pad.  If the introcv op clones &s1,
+          then &s2 is still marked stale.  Since &s1 is not active, and
+          &foo closes over &s1’s implicit entry for &s2, we get a ‘Varia-
+          ble will not stay shared’ warning.  Because it is the same stub
+          that will be used when the introcv op for &s2 is executed, clos-
+          ing over it is safe.  Hence, we have to turn off the stale flag
+          on all lexical subs in the block before we clone any of them.
+          Hence, having introcv clone the sub cannot work.  So we create a
+          list of ops like this:
+
+              lineseq
+                 |
+                 +-- introcv
+                 |
+                 +-- introcv
+                 |
+                 +-- introcv
+                 |
+                 .
+                 .
+                 .
+                 |
+                 +-- clonecv
+                 |
+                 +-- clonecv
+                 |
+                 +-- clonecv
+                 |
+                 .
+                 .
+                 .
+        */
+       OP *kid = o->op_flags & OPf_KIDS ? cLISTOPo->op_first : o;
+       OP * const last = o->op_flags & OPf_KIDS ? cLISTOPo->op_last : o;
+       for (;; kid = kid->op_sibling) {
+           OP *newkid = newOP(OP_CLONECV, 0);
+           newkid->op_targ = kid->op_targ;
+           o = op_append_elem(OP_LINESEQ, o, newkid);
+           if (kid == last) break;
+       }
+       retval = op_prepend_elem(OP_LINESEQ, o, retval);
+    }
 
     CALL_BLOCK_HOOKS(bhk_post_end, &retval);
 
@@ -2966,6 +3041,32 @@ Perl_newPROG(pTHX_ OP *o)
     }
     else {
        if (o->op_type == OP_STUB) {
+            /* This block is entered if nothing is compiled for the main
+               program. This will be the case for an genuinely empty main
+               program, or one which only has BEGIN blocks etc, so already
+               run and freed.
+
+               Historically (5.000) the guard above was !o. However, commit
+               f8a08f7b8bd67b28 (Jun 2001), integrated to blead as
+               c71fccf11fde0068, changed perly.y so that newPROG() is now
+               called with the output of block_end(), which returns a new
+               OP_STUB for the case of an empty optree. ByteLoader (and
+               maybe other things) also take this path, because they set up
+               PL_main_start and PL_main_root directly, without generating an
+               optree.
+
+               If the parsing the main program aborts (due to parse errors,
+               or due to BEGIN or similar calling exit), then newPROG()
+               isn't even called, and hence this code path and its cleanups
+               are skipped. This shouldn't make a make a difference:
+               * a non-zero return from perl_parse is a failure, and
+                 perl_destruct() should be called immediately.
+               * however, if exit(0) is called during the parse, then
+                 perl_parse() returns 0, and perl_run() is called. As
+                 PL_main_start will be NULL, perl_run() will return
+                 promptly, and the exit code will remain 0.
+            */
+
            PL_comppad_name = 0;
            PL_compcv = 0;
            S_op_destroy(aTHX_ o);
@@ -3697,7 +3798,7 @@ Perl_mad_free(pTHX_ MADPROP* mp)
     case MAD_NULL:
        break;
     case MAD_PV:
-       Safefree((char*)mp->mad_val);
+       Safefree(mp->mad_val);
        break;
     case MAD_OP:
        if (mp->mad_vlen)       /* vlen holds "strong/weak" boolean */
@@ -4496,9 +4597,6 @@ Perl_pmruntime(pTHX_ OP *o, OP *expr, bool isreg, I32 floor)
        U32 rx_flags = pm->op_pmflags & RXf_PMf_COMPILETIME;
        regexp_engine const *eng = current_re_engine();
 
-       if (o->op_flags & OPf_SPECIAL)
-           rx_flags |= RXf_SPLIT;
-
        if (!has_code || !eng->op_comp) {
            /* compile-time simple constant pattern */
 
@@ -4548,7 +4646,7 @@ Perl_pmruntime(pTHX_ OP *o, OP *expr, bool isreg, I32 floor)
                /* handle the implicit sub{} wrapped round the qr/(?{..})/ */
                SvREFCNT_inc_simple_void(PL_compcv);
                cv = newATTRSUB(floor, 0, NULL, NULL, qr);
-               ((struct regexp *)SvANY(re))->qr_anoncv = cv;
+               ReANY(re)->qr_anoncv = cv;
 
                /* attach the anon CV to the pad so that
                 * pad_fixup_inner_anons() can find it */
@@ -4580,8 +4678,8 @@ Perl_pmruntime(pTHX_ OP *o, OP *expr, bool isreg, I32 floor)
         * preceding stacking ops;
         * OP_REGCRESET is there to reset taint before executing the
         * stacking ops */
-       if (pm->op_pmflags & PMf_KEEP || PL_tainting)
-           expr = newUNOP((PL_tainting ? OP_REGCRESET : OP_REGCMAYBE),0,expr);
+       if (pm->op_pmflags & PMf_KEEP || TAINTING_get)
+           expr = newUNOP((TAINTING_get ? OP_REGCRESET : OP_REGCMAYBE),0,expr);
 
        if (pm->op_pmflags & PMf_HAS_CV) {
            /* we have a runtime qr with literal code. This means
@@ -4657,62 +4755,48 @@ Perl_pmruntime(pTHX_ OP *o, OP *expr, bool isreg, I32 floor)
     }
 
     if (repl) {
-       OP *curop;
+       OP *curop = repl;
+       bool konst;
        if (pm->op_pmflags & PMf_EVAL) {
-           curop = NULL;
            if (CopLINE(PL_curcop) < (line_t)PL_parser->multi_end)
                CopLINE_set(PL_curcop, (line_t)PL_parser->multi_end);
        }
-       else if (repl->op_type == OP_CONST)
-           curop = repl;
-       else {
-           OP *lastop = NULL;
-           for (curop = LINKLIST(repl); curop!=repl; curop = LINKLIST(curop)) {
-               if (curop->op_type == OP_SCOPE
-                       || curop->op_type == OP_LEAVE
-                       || (PL_opargs[curop->op_type] & OA_DANGEROUS)) {
-                   if (curop->op_type == OP_GV) {
-                       GV * const gv = cGVOPx_gv(curop);
-                       repl_has_vars = 1;
-                       if (strchr("&`'123456789+-\016\022", *GvENAME(gv)))
-                           break;
-                   }
-                   else if (curop->op_type == OP_RV2CV)
-                       break;
-                   else if (curop->op_type == OP_RV2SV ||
-                            curop->op_type == OP_RV2AV ||
-                            curop->op_type == OP_RV2HV ||
-                            curop->op_type == OP_RV2GV) {
-                       if (lastop && lastop->op_type != OP_GV) /*funny deref?*/
-                           break;
-                   }
-                   else if (curop->op_type == OP_PADSV ||
-                            curop->op_type == OP_PADAV ||
-                            curop->op_type == OP_PADHV ||
-                            curop->op_type == OP_PADANY)
-                   {
-                       repl_has_vars = 1;
-                   }
-                   else if (curop->op_type == OP_PUSHRE)
-                       NOOP; /* Okay here, dangerous in newASSIGNOP */
-                   else
-                       break;
-               }
-               lastop = curop;
-           }
-       }
-       if (curop == repl
+       /* If we are looking at s//.../e with a single statement, get past
+          the implicit do{}. */
+       if (curop->op_type == OP_NULL && curop->op_flags & OPf_KIDS
+        && cUNOPx(curop)->op_first->op_type == OP_SCOPE
+        && cUNOPx(curop)->op_first->op_flags & OPf_KIDS) {
+           OP *kid = cUNOPx(cUNOPx(curop)->op_first)->op_first;
+           if (kid->op_type == OP_NULL && kid->op_sibling
+            && !kid->op_sibling->op_sibling)
+               curop = kid->op_sibling;
+       }
+       if (curop->op_type == OP_CONST)
+           konst = TRUE;
+       else if (( (curop->op_type == OP_RV2SV ||
+                   curop->op_type == OP_RV2AV ||
+                   curop->op_type == OP_RV2HV ||
+                   curop->op_type == OP_RV2GV)
+                  && cUNOPx(curop)->op_first
+                  && cUNOPx(curop)->op_first->op_type == OP_GV )
+               || curop->op_type == OP_PADSV
+               || curop->op_type == OP_PADAV
+               || curop->op_type == OP_PADHV
+               || curop->op_type == OP_PADANY) {
+           repl_has_vars = 1;
+           konst = TRUE;
+       }
+       else konst = FALSE;
+       if (konst
            && !(repl_has_vars
                 && (!PM_GETRE(pm)
+                    || !RX_PRELEN(PM_GETRE(pm))
                     || RX_EXTFLAGS(PM_GETRE(pm)) & RXf_EVAL_SEEN)))
        {
            pm->op_pmflags |= PMf_CONST;        /* const for long enough */
            op_prepend_elem(o->op_type, scalar(repl), o);
        }
        else {
-           if (curop == repl && !PM_GETRE(pm)) { /* Has variables. */
-               pm->op_pmflags |= PMf_MAYBE_CONST;
-           }
            NewOp(1101, rcop, 1, LOGOP);
            rcop->op_type = OP_SUBSTCONT;
            rcop->op_ppaddr = PL_ppaddr[OP_SUBSTCONT];
@@ -5605,8 +5689,7 @@ Perl_newSTATEOP(pTHX_ I32 flags, char *label, OP *o)
         CopLINE_set(cop, CopLINE(PL_curcop));
     else {
        CopLINE_set(cop, PL_parser->copline);
-       if (PL_parser)
-           PL_parser->copline = NOLINE;
+       PL_parser->copline = NOLINE;
     }
 #ifdef USE_ITHREADS
     CopFILE_set(cop, CopFILE(PL_curcop));      /* XXX share in a pvtable? */
@@ -5832,6 +5915,8 @@ S_new_logop(pTHX_ I32 type, I32 flags, OP** firstp, OP** otherp)
        }
        if (warnop) {
            const line_t oldline = CopLINE(PL_curcop);
+            /* This ensures that warnings are reported at the first line
+               of the construction, not the last.  */
            CopLINE_set(PL_curcop, PL_parser->copline);
            Perl_warner(aTHX_ packWARN(WARN_MISC),
                 "Value of %s%s can be \"0\"; test with defined()",
@@ -6616,7 +6701,7 @@ I<cond> supplies the expression that will be locally assigned to a lexical
 variable, and I<block> supplies the body of the C<given> construct; they
 are consumed by this function and become part of the constructed op tree.
 I<defsv_off> is the pad offset of the scalar lexical variable that will
-be affected.
+be affected.  If it is 0, the global $_ will be used.
 
 =cut
 */
@@ -6694,6 +6779,9 @@ Perl_cv_ckproto_len_flags(pTHX_ const CV *cv, const GV *gv, const char *p,
        {
          if (isGV(gv))
            gv_efullname3(name = sv_newmortal(), gv, NULL);
+         else if (SvPOK(gv) && *SvPVX((SV *)gv) == '&')
+           name = newSVpvn_flags(SvPVX((SV *)gv)+1, SvCUR(gv)-1,
+                                 SvUTF8(gv)|SVs_TEMP);
          else name = (SV *)gv;
        }
        sv_setpvs(msg, "Prototype mismatch:");
@@ -6824,32 +6912,385 @@ Perl_op_const_sv(pTHX_ const OP *o, CV *cv)
     return sv;
 }
 
-#ifdef PERL_MAD
-OP *
-#else
-void
-#endif
+CV *
 Perl_newMYSUB(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs, OP *block)
 {
-#if 0
-    /* This would be the return value, but the return cannot be reached.  */
-    OP* pegop = newOP(OP_NULL, 0);
+    dVAR;
+    CV **spot;
+    SV **svspot;
+    const char *ps;
+    STRLEN ps_len = 0; /* init it to avoid false uninit warning from icc */
+    U32 ps_utf8 = 0;
+    register CV *cv = NULL;
+    register CV *compcv = PL_compcv;
+    SV *const_sv;
+    PADNAME *name;
+    PADOFFSET pax = o->op_targ;
+    CV *outcv = CvOUTSIDE(PL_compcv);
+    CV *clonee = NULL;
+    HEK *hek = NULL;
+    bool reusable = FALSE;
+
+    PERL_ARGS_ASSERT_NEWMYSUB;
+
+    /* Find the pad slot for storing the new sub.
+       We cannot use PL_comppad, as it is the pad owned by the new sub.  We
+       need to look in CvOUTSIDE and find the pad belonging to the enclos-
+       ing sub.  And then we need to dig deeper if this is a lexical from
+       outside, as in:
+          my sub foo; sub { sub foo { } }
+     */
+   redo:
+    name = PadlistNAMESARRAY(CvPADLIST(outcv))[pax];
+    if (PadnameOUTER(name) && PARENT_PAD_INDEX(name)) {
+       pax = PARENT_PAD_INDEX(name);
+       outcv = CvOUTSIDE(outcv);
+       assert(outcv);
+       goto redo;
+    }
+    svspot =
+       &PadARRAY(PadlistARRAY(CvPADLIST(outcv))
+                       [CvDEPTH(outcv) ? CvDEPTH(outcv) : 1])[pax];
+    spot = (CV **)svspot;
+
+    if (proto) {
+       assert(proto->op_type == OP_CONST);
+       ps = SvPV_const(((SVOP*)proto)->op_sv, ps_len);
+        ps_utf8 = SvUTF8(((SVOP*)proto)->op_sv);
+    }
+    else
+       ps = NULL;
+
+    if (!PL_madskills) {
+       if (proto)
+           SAVEFREEOP(proto);
+       if (attrs)
+           SAVEFREEOP(attrs);
+    }
+
+    if (PL_parser && PL_parser->error_count) {
+       op_free(block);
+       SvREFCNT_dec(PL_compcv);
+       PL_compcv = 0;
+       goto done;
+    }
+
+    if (CvDEPTH(outcv) && CvCLONE(compcv)) {
+       cv = *spot;
+       svspot = (SV **)(spot = &clonee);
+    }
+    else if (PadnameIsSTATE(name) || CvDEPTH(outcv))
+       cv = *spot;
+    else {
+       MAGIC *mg;
+       SvUPGRADE(name, SVt_PVMG);
+       mg = mg_find(name, PERL_MAGIC_proto);
+       assert (SvTYPE(*spot) == SVt_PVCV);
+       if (CvNAMED(*spot))
+           hek = CvNAME_HEK(*spot);
+       else {
+           CvNAME_HEK_set(*spot, hek =
+               share_hek(
+                   PadnamePV(name)+1,
+                   PadnameLEN(name)-1 * (PadnameUTF8(name) ? -1 : 1), 0
+               )
+           );
+       }
+       if (mg) {
+           assert(mg->mg_obj);
+           cv = (CV *)mg->mg_obj;
+       }
+       else {
+           sv_magic(name, &PL_sv_undef, PERL_MAGIC_proto, NULL, 0);
+           mg = mg_find(name, PERL_MAGIC_proto);
+       }
+       spot = (CV **)(svspot = &mg->mg_obj);
+    }
+
+    if (!block || !ps || *ps || attrs
+       || (CvFLAGS(compcv) & CVf_BUILTIN_ATTRS)
+#ifdef PERL_MAD
+       || block->op_type == OP_NULL
 #endif
+       )
+       const_sv = NULL;
+    else
+       const_sv = op_const_sv(block, NULL);
 
-    PERL_UNUSED_ARG(floor);
+    if (cv) {
+        const bool exists = CvROOT(cv) || CvXSUB(cv);
 
-    if (o)
-       SAVEFREEOP(o);
-    if (proto)
-       SAVEFREEOP(proto);
-    if (attrs)
-       SAVEFREEOP(attrs);
-    if (block)
-       SAVEFREEOP(block);
-    Perl_croak(aTHX_ "\"my sub\" not yet implemented");
+        /* if the subroutine doesn't exist and wasn't pre-declared
+         * with a prototype, assume it will be AUTOLOADed,
+         * skipping the prototype check
+         */
+        if (exists || SvPOK(cv))
+            cv_ckproto_len_flags(cv, (GV *)name, ps, ps_len, ps_utf8);
+       /* already defined? */
+       if (exists) {
+           if ((!block
+#ifdef PERL_MAD
+                || block->op_type == OP_NULL
+#endif
+                )) {
+               if (CvFLAGS(compcv)) {
+                   /* might have had built-in attrs applied */
+                   const bool pureperl = !CvISXSUB(cv) && CvROOT(cv);
+                   if (CvLVALUE(compcv) && ! CvLVALUE(cv) && pureperl
+                    && ckWARN(WARN_MISC))
+                       Perl_warner(aTHX_ packWARN(WARN_MISC), "lvalue attribute ignored after the subroutine has been defined");
+                   CvFLAGS(cv) |=
+                       (CvFLAGS(compcv) & CVf_BUILTIN_ATTRS
+                         & ~(CVf_LVALUE * pureperl));
+               }
+               if (attrs) goto attrs;
+               /* just a "sub foo;" when &foo is already defined */
+               SAVEFREESV(compcv);
+               goto done;
+           }
+           else {
+               /* redundant check that avoids creating the extra SV
+                  most of the time: */
+               if (const_sv || ckWARN(WARN_REDEFINE)) {
+                   const line_t oldline = CopLINE(PL_curcop);
+                   SV *noamp = sv_2mortal(newSVpvn_utf8(
+                                   PadnamePV(name)+1,PadnameLEN(name)-1,
+                                    PadnameUTF8(name)
+                               ));
+                   if (PL_parser && PL_parser->copline != NOLINE)
+                       CopLINE_set(PL_curcop, PL_parser->copline);
+                   report_redefined_cv(noamp, cv, &const_sv);
+                   CopLINE_set(PL_curcop, oldline);
+               }
+#ifdef PERL_MAD
+               if (!PL_minus_c)        /* keep old one around for madskills */
+#endif
+                   {
+                       /* (PL_madskills unset in used file.) */
+                       SvREFCNT_dec(cv);
+                   }
+               cv = NULL;
+           }
+       }
+       else if (CvDEPTH(outcv) && CvCLONE(compcv)) {
+           cv = NULL;
+           reusable = TRUE;
+       }
+    }
+    if (const_sv) {
+       SvREFCNT_inc_simple_void_NN(const_sv);
+       if (cv) {
+           assert(!CvROOT(cv) && !CvCONST(cv));
+           cv_forget_slab(cv);
+       }
+       else {
+           cv = MUTABLE_CV(newSV_type(SVt_PVCV));
+           CvFILE_set_from_cop(cv, PL_curcop);
+           CvSTASH_set(cv, PL_curstash);
+           *spot = cv;
+       }
+       sv_setpvs(MUTABLE_SV(cv), "");  /* prototype is "" */
+       CvXSUBANY(cv).any_ptr = const_sv;
+       CvXSUB(cv) = const_sv_xsub;
+       CvCONST_on(cv);
+       CvISXSUB_on(cv);
+       if (PL_madskills)
+           goto install_block;
+       op_free(block);
+       SvREFCNT_dec(compcv);
+       PL_compcv = NULL;
+       goto clone;
+    }
+    /* Checking whether outcv is CvOUTSIDE(compcv) is not sufficient to
+       determine whether this sub definition is in the same scope as its
+       declaration.  If this sub definition is inside an inner named pack-
+       age sub (my sub foo; sub bar { sub foo { ... } }), outcv points to
+       the package sub.  So check PadnameOUTER(name) too.
+     */
+    if (outcv == CvOUTSIDE(compcv) && !PadnameOUTER(name)) { 
+       assert(!CvWEAKOUTSIDE(compcv));
+       SvREFCNT_dec(CvOUTSIDE(compcv));
+       CvWEAKOUTSIDE_on(compcv);
+    }
+    /* XXX else do we have a circular reference? */
+    if (cv) {  /* must reuse cv in case stub is referenced elsewhere */
+       /* transfer PL_compcv to cv */
+       if (block
+#ifdef PERL_MAD
+                  && block->op_type != OP_NULL
+#endif
+       ) {
+           cv_flags_t preserved_flags =
+               CvFLAGS(cv) & (CVf_BUILTIN_ATTRS|CVf_NAMED);
+           PADLIST *const temp_padl = CvPADLIST(cv);
+           CV *const temp_cv = CvOUTSIDE(cv);
+           const cv_flags_t other_flags =
+               CvFLAGS(cv) & (CVf_SLABBED|CVf_WEAKOUTSIDE);
+           OP * const cvstart = CvSTART(cv);
+
+           SvPOK_off(cv);
+           CvFLAGS(cv) =
+               CvFLAGS(compcv) | preserved_flags;
+           CvOUTSIDE(cv) = CvOUTSIDE(compcv);
+           CvOUTSIDE_SEQ(cv) = CvOUTSIDE_SEQ(compcv);
+           CvPADLIST(cv) = CvPADLIST(compcv);
+           CvOUTSIDE(compcv) = temp_cv;
+           CvPADLIST(compcv) = temp_padl;
+           CvSTART(cv) = CvSTART(compcv);
+           CvSTART(compcv) = cvstart;
+           CvFLAGS(compcv) &= ~(CVf_SLABBED|CVf_WEAKOUTSIDE);
+           CvFLAGS(compcv) |= other_flags;
+
+           if (CvFILE(cv) && CvDYNFILE(cv)) {
+               Safefree(CvFILE(cv));
+           }
+
+           /* inner references to compcv must be fixed up ... */
+           pad_fixup_inner_anons(CvPADLIST(cv), compcv, cv);
+           if (PERLDB_INTER)/* Advice debugger on the new sub. */
+             ++PL_sub_generation;
+       }
+       else {
+           /* Might have had built-in attributes applied -- propagate them. */
+           CvFLAGS(cv) |= (CvFLAGS(compcv) & CVf_BUILTIN_ATTRS);
+       }
+       /* ... before we throw it away */
+       SvREFCNT_dec(compcv);
+       PL_compcv = compcv = cv;
+    }
+    else {
+       cv = compcv;
+       *spot = cv;
+    }
+    if (!CvNAME_HEK(cv)) {
+       CvNAME_HEK_set(cv,
+        hek
+         ? share_hek_hek(hek)
+         : share_hek(PadnamePV(name)+1,
+                     PadnameLEN(name)-1 * (PadnameUTF8(name) ? -1 : 1),
+                     0)
+       );
+    }
+    CvFILE_set_from_cop(cv, PL_curcop);
+    CvSTASH_set(cv, PL_curstash);
+
+    if (ps) {
+       sv_setpvn(MUTABLE_SV(cv), ps, ps_len);
+        if ( ps_utf8 ) SvUTF8_on(MUTABLE_SV(cv));
+    }
+
+ install_block:
+    if (!block)
+       goto attrs;
+
+    /* If we assign an optree to a PVCV, then we've defined a subroutine that
+       the debugger could be able to set a breakpoint in, so signal to
+       pp_entereval that it should not throw away any saved lines at scope
+       exit.  */
+       
+    PL_breakable_sub_gen++;
+    /* This makes sub {}; work as expected.  */
+    if (block->op_type == OP_STUB) {
+           OP* const newblock = newSTATEOP(0, NULL, 0);
 #ifdef PERL_MAD
-    NORETURN_FUNCTION_END;
+           op_getmad(block,newblock,'B');
+#else
+           op_free(block);
 #endif
+           block = newblock;
+    }
+    CvROOT(cv) = CvLVALUE(cv)
+                  ? newUNOP(OP_LEAVESUBLV, 0,
+                            op_lvalue(scalarseq(block), OP_LEAVESUBLV))
+                  : newUNOP(OP_LEAVESUB, 0, scalarseq(block));
+    CvROOT(cv)->op_private |= OPpREFCOUNTED;
+    OpREFCNT_set(CvROOT(cv), 1);
+    /* The cv no longer needs to hold a refcount on the slab, as CvROOT
+       itself has a refcount. */
+    CvSLABBED_off(cv);
+    OpslabREFCNT_dec_padok((OPSLAB *)CvSTART(cv));
+    CvSTART(cv) = LINKLIST(CvROOT(cv));
+    CvROOT(cv)->op_next = 0;
+    CALL_PEEP(CvSTART(cv));
+    finalize_optree(CvROOT(cv));
+
+    /* now that optimizer has done its work, adjust pad values */
+
+    pad_tidy(CvCLONE(cv) ? padtidy_SUBCLONE : padtidy_SUB);
+
+    if (CvCLONE(cv)) {
+       assert(!CvCONST(cv));
+       if (ps && !*ps && op_const_sv(block, cv))
+           CvCONST_on(cv);
+    }
+
+  attrs:
+    if (attrs) {
+       /* Need to do a C<use attributes $stash_of_cv,\&cv,@attrs>. */
+       apply_attrs(PL_curstash, MUTABLE_SV(cv), attrs);
+    }
+
+    if (block) {
+       if (PERLDB_SUBLINE && PL_curstash != PL_debstash) {
+           SV * const tmpstr = sv_newmortal();
+           GV * const db_postponed = gv_fetchpvs("DB::postponed",
+                                                 GV_ADDMULTI, SVt_PVHV);
+           HV *hv;
+           SV * const sv = Perl_newSVpvf(aTHX_ "%s:%ld-%ld",
+                                         CopFILE(PL_curcop),
+                                         (long)PL_subline,
+                                         (long)CopLINE(PL_curcop));
+           if (HvNAME_HEK(PL_curstash)) {
+               sv_sethek(tmpstr, HvNAME_HEK(PL_curstash));
+               sv_catpvs(tmpstr, "::");
+           }
+           else sv_setpvs(tmpstr, "__ANON__::");
+           sv_catpvn_flags(tmpstr, PadnamePV(name)+1, PadnameLEN(name)-1,
+                           PadnameUTF8(name) ? SV_CATUTF8 : SV_CATBYTES);
+           (void)hv_store(GvHV(PL_DBsub), SvPVX_const(tmpstr),
+                   SvUTF8(tmpstr) ? -(I32)SvCUR(tmpstr) : (I32)SvCUR(tmpstr), sv, 0);
+           hv = GvHVn(db_postponed);
+           if (HvTOTALKEYS(hv) > 0 && hv_exists(hv, SvPVX_const(tmpstr), SvUTF8(tmpstr) ? -(I32)SvCUR(tmpstr) : (I32)SvCUR(tmpstr))) {
+               CV * const pcv = GvCV(db_postponed);
+               if (pcv) {
+                   dSP;
+                   PUSHMARK(SP);
+                   XPUSHs(tmpstr);
+                   PUTBACK;
+                   call_sv(MUTABLE_SV(pcv), G_DISCARD);
+               }
+           }
+       }
+    }
+
+  clone:
+    if (clonee) {
+       assert(CvDEPTH(outcv));
+       spot = (CV **)
+           &PadARRAY(PadlistARRAY(CvPADLIST(outcv))[CvDEPTH(outcv)])[pax];
+       if (reusable) cv_clone_into(clonee, *spot);
+       else *spot = cv_clone(clonee);
+       SvREFCNT_dec(clonee);
+       cv = *spot;
+       SvPADMY_on(cv);
+    }
+    if (CvDEPTH(outcv) && !reusable && PadnameIsSTATE(name)) {
+       PADOFFSET depth = CvDEPTH(outcv);
+       while (--depth) {
+           SV *oldcv;
+           svspot = &PadARRAY(PadlistARRAY(CvPADLIST(outcv))[depth])[pax];
+           oldcv = *svspot;
+           *svspot = SvREFCNT_inc_simple_NN(cv);
+           SvREFCNT_dec(oldcv);
+       }
+    }
+
+  done:
+    if (PL_parser)
+       PL_parser->copline = NOLINE;
+    LEAVE_SCOPE(floor);
+    if (o) op_free(o);
+    return cv;
 }
 
 CV *
@@ -6931,22 +7372,23 @@ Perl_newATTRSUB_flags(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs,
 
     if (ec) {
        op_free(block);
+       if (name) SvREFCNT_dec(PL_compcv);
+       else cv = PL_compcv;
+       PL_compcv = 0;
        if (name && block) {
            const char *s = strrchr(name, ':');
            s = s ? s+1 : name;
            if (strEQ(s, "BEGIN")) {
-               const char not_safe[] =
-                   "BEGIN not safe after errors--compilation aborted";
                if (PL_in_eval & EVAL_KEEPERR)
-                   Perl_croak(aTHX_ not_safe);
+                   Perl_croak_nocontext("BEGIN not safe after errors--compilation aborted");
                else {
+                    SV * const errsv = ERRSV;
                    /* force display of errors found but not reported */
-                   sv_catpv(ERRSV, not_safe);
-                   Perl_croak(aTHX_ "%"SVf, SVfARG(ERRSV));
+                   sv_catpvs(errsv, "BEGIN not safe after errors--compilation aborted");
+                   Perl_croak_nocontext("%"SVf, SVfARG(errsv));
                }
            }
        }
-       cv = PL_compcv;
        goto done;
     }
 
@@ -7018,8 +7460,11 @@ Perl_newATTRSUB_flags(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs,
 #endif
                ) {
                const line_t oldline = CopLINE(PL_curcop);
-               if (PL_parser && PL_parser->copline != NOLINE)
+               if (PL_parser && PL_parser->copline != NOLINE) {
+                        /* This ensures that warnings are reported at the first
+                           line of a redefinition, not the last.  */
                        CopLINE_set(PL_curcop, PL_parser->copline);
+                }
                report_redefined_cv(cSVOPo->op_sv, cv, &const_sv);
                CopLINE_set(PL_curcop, oldline);
 #ifdef PERL_MAD
@@ -7111,13 +7556,6 @@ Perl_newATTRSUB_flags(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs,
        cv = PL_compcv;
        if (name) {
            GvCV_set(gv, cv);
-           if (PL_madskills) {
-               if (strEQ(name, "import")) {
-                   PL_formfeed = MUTABLE_SV(cv);
-                   /* diag_listed_as: SKIPME */
-                   Perl_warner(aTHX_ packWARN(WARN_VOID), "0x%"UVxf"\n", PTR2UV(cv));
-               }
-           }
            GvCVGEN(gv) = 0;
            if (HvENAME_HEK(GvSTASH(gv)))
                /* sub Foo::bar { (shift)+1 } */
@@ -7187,7 +7625,9 @@ Perl_newATTRSUB_flags(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs,
     if (attrs) {
        /* Need to do a C<use attributes $stash_of_cv,\&cv,@attrs>. */
        HV *stash = name && GvSTASH(CvGV(cv)) ? GvSTASH(CvGV(cv)) : PL_curstash;
-       apply_attrs(stash, MUTABLE_SV(cv), attrs, FALSE);
+       if (!name) SAVEFREESV(cv);
+       apply_attrs(stash, MUTABLE_SV(cv), attrs);
+       if (!name) SvREFCNT_inc_simple_void_NN(cv);
     }
 
     if (block && has_name) {
@@ -7217,7 +7657,7 @@ Perl_newATTRSUB_flags(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs,
        }
 
        if (name && ! (PL_parser && PL_parser->error_count))
-           process_special_blocks(name, gv, cv);
+           process_special_blocks(floor, name, gv, cv);
     }
 
   done:
@@ -7232,7 +7672,8 @@ Perl_newATTRSUB_flags(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs,
 }
 
 STATIC void
-S_process_special_blocks(pTHX_ const char *const fullname, GV *const gv,
+S_process_special_blocks(pTHX_ I32 floor, const char *const fullname,
+                        GV *const gv,
                         CV *const cv)
 {
     const char *const colon = strrchr(fullname,':');
@@ -7243,6 +7684,7 @@ S_process_special_blocks(pTHX_ const char *const fullname, GV *const gv,
     if (*name == 'B') {
        if (strEQ(name, "BEGIN")) {
            const I32 oldscope = PL_scopestack_ix;
+           if (floor) LEAVE_SCOPE(floor);
            ENTER;
            SAVECOPFILE(&PL_compiling);
            SAVECOPLINE(&PL_compiling);
@@ -7403,13 +7845,11 @@ Perl_newXS_len_flags(pTHX_ const char *name, STRLEN len,
     PERL_ARGS_ASSERT_NEWXS_LEN_FLAGS;
 
     {
-        GV * const gv = name
-                        ? gv_fetchpvn(
-                               name,len,GV_ADDMULTI|flags,SVt_PVCV
-                          )
-                        : gv_fetchpv(
-                            (PL_curstash ? "__ANON__" : "__ANON__::__ANON__"),
-                            GV_ADDMULTI | flags, SVt_PVCV);
+        GV * const gv = gv_fetchpvn(
+                           name ? name : PL_curstash ? "__ANON__" : "__ANON__::__ANON__",
+                           name ? len : PL_curstash ? sizeof("__ANON__") - 1:
+                               sizeof("__ANON__::__ANON__") - 1,
+                           GV_ADDMULTI | flags, SVt_PVCV);
     
         if (!subaddr)
             Perl_croak(aTHX_ "panic: no address for '%s' in '%s'", name, filename);
@@ -7425,14 +7865,10 @@ Perl_newXS_len_flags(pTHX_ const char *name, STRLEN len,
                 /* Redundant check that allows us to avoid creating an SV
                    most of the time: */
                 if (CvCONST(cv) || ckWARN(WARN_REDEFINE)) {
-                    const line_t oldline = CopLINE(PL_curcop);
-                    if (PL_parser && PL_parser->copline != NOLINE)
-                        CopLINE_set(PL_curcop, PL_parser->copline);
                     report_redefined_cv(newSVpvn_flags(
                                          name,len,(flags&SVf_UTF8)|SVs_TEMP
                                         ),
                                         cv, const_svp);
-                    CopLINE_set(PL_curcop, oldline);
                 }
                 SvREFCNT_dec(cv);
                 cv = NULL;
@@ -7461,7 +7897,7 @@ Perl_newXS_len_flags(pTHX_ const char *name, STRLEN len,
         CvXSUB(cv) = subaddr;
     
         if (name)
-            process_special_blocks(name, gv, cv);
+            process_special_blocks(0, name, gv, cv);
     }
 
     if (flags & XS_DYNAMIC_FILENAME) {
@@ -7709,6 +8145,12 @@ Perl_newHVREF(pTHX_ OP *o)
 OP *
 Perl_newCVREF(pTHX_ I32 flags, OP *o)
 {
+    if (o->op_type == OP_PADANY) {
+       dVAR;
+       o->op_type = OP_PADCV;
+       o->op_ppaddr = PL_ppaddr[OP_PADCV];
+       return o;
+    }
     return newUNOP(OP_RV2CV, flags, scalar(o));
 }
 
@@ -8577,12 +9019,14 @@ Perl_ck_glob(pTHX_ OP *o)
        LEAVE;
     }
 #endif /* !PERL_EXTERNAL_GLOB */
-    gv = newGVgen("main");
+    gv = (GV *)newSV(0);
+    gv_init(gv, 0, "", 0, 0);
     gv_IOadd(gv);
 #ifndef PERL_EXTERNAL_GLOB
     sv_setiv(GvSVn(gv),PL_glob_index++);
 #endif
     op_append_elem(OP_GLOB, o, newGVOP(OP_GV, 0, gv));
+    SvREFCNT_dec(gv); /* newGVOP increased it */
     scalarkids(o);
     return o;
 }
@@ -8654,9 +9098,9 @@ Perl_ck_index(pTHX_ OP *o)
        if (kid)
            kid = kid->op_sibling;                      /* get past "big" */
        if (kid && kid->op_type == OP_CONST) {
-           const bool save_taint = PL_tainted;
+           const bool save_taint = TAINT_get; /* accepted unused var warning if NO_TAINT_SUPPORT */
            fbm_compile(((SVOP*)kid)->op_sv, 0);
-           PL_tainted = save_taint;
+           TAINT_set(save_taint);
        }
     }
     return ck_fun(o);
@@ -8899,7 +9343,7 @@ Perl_ck_method(pTHX_ OP *o)
        const char * const method = SvPVX_const(sv);
        if (!(strchr(method, ':') || strchr(method, '\''))) {
            OP *cmop;
-           if (!SvREADONLY(sv) || !SvFAKE(sv)) {
+           if (!SvIsCOW(sv)) {
                sv = newSVpvn_share(method, SvUTF8(sv) ? -(I32)SvCUR(sv) : (I32)SvCUR(sv), 0);
            }
            else {
@@ -9024,14 +9468,9 @@ Perl_ck_require(pTHX_ OP *o)
            const char *end;
 
            if (was_readonly) {
-               if (SvFAKE(sv)) {
-                   sv_force_normal_flags(sv, 0);
-                   assert(!SvREADONLY(sv));
-                   was_readonly = 0;
-               } else {
                    SvREADONLY_off(sv);
-               }
            }   
+           if (SvIsCOW(sv)) sv_force_normal_flags(sv, 0);
 
            s = SvPVX(sv);
            len = SvCUR(sv);
@@ -9333,10 +9772,15 @@ Perl_ck_split(pTHX_ OP *o)
        cLISTOPo->op_last = kid; /* There was only one element previously */
     }
 
+    if (kid->op_type == OP_CONST && !(kid->op_private & OPpCONST_FOLDED)) {
+       SV * const sv = kSVOP->op_sv;
+       if (SvPOK(sv) && SvCUR(sv) == 1 && *SvPVX(sv) == ' ')
+           o->op_flags |= OPf_SPECIAL;
+    }
     if (kid->op_type != OP_MATCH || kid->op_flags & OPf_STACKED) {
        OP * const sibl = kid->op_sibling;
        kid->op_sibling = 0;
-       kid = pmruntime( newPMOP(OP_MATCH, OPf_SPECIAL), kid, 0, 0);
+       kid = pmruntime( newPMOP(OP_MATCH, 0), kid, 0, 0);
        if (cLISTOPo->op_first == cLISTOPo->op_last)
            cLISTOPo->op_last = kid;
        cLISTOPo->op_first = kid;
@@ -9464,6 +9908,27 @@ Perl_rv2cv_op_cv(pTHX_ OP *cvop, U32 flags)
            cv = (CV*)SvRV(rv);
            gv = NULL;
        } break;
+       case OP_PADCV: {
+           PADNAME *name = PAD_COMPNAME(rvop->op_targ);
+           CV *compcv = PL_compcv;
+           PADOFFSET off = rvop->op_targ;
+           while (PadnameOUTER(name)) {
+               assert(PARENT_PAD_INDEX(name));
+               compcv = CvOUTSIDE(PL_compcv);
+               name = PadlistNAMESARRAY(CvPADLIST(compcv))
+                       [off = PARENT_PAD_INDEX(name)];
+           }
+           assert(!PadnameIsOUR(name));
+           if (!PadnameIsSTATE(name)) {
+               MAGIC * mg = mg_find(name, PERL_MAGIC_proto);
+               assert(mg);
+               assert(mg->mg_obj);
+               cv = (CV *)mg->mg_obj;
+           }
+           else cv =
+                   (CV *)AvARRAY(PadlistARRAY(CvPADLIST(compcv))[1])[off];
+           gv = NULL;
+       } break;
        default: {
            return NULL;
        } break;
@@ -10050,6 +10515,19 @@ Perl_ck_subr(pTHX_ OP *o)
        Perl_call_checker ckfun;
        SV *ckobj;
        cv_get_call_checker(cv, &ckfun, &ckobj);
+       if (!namegv) { /* expletive! */
+           /* XXX The call checker API is public.  And it guarantees that
+                  a GV will be provided with the right name.  So we have
+                  to create a GV.  But it is still not correct, as its
+                  stringification will include the package.  What we
+                  really need is a new call checker API that accepts a
+                  GV or string (or GV or CV). */
+           HEK * const hek = CvNAME_HEK(cv);
+           assert(hek);
+           namegv = (GV *)sv_newmortal();
+           gv_init_pvn(namegv, PL_curstash, HEK_KEY(hek), HEK_LEN(hek),
+                       SVf_UTF8 * !!HEK_UTF8(hek));
+       }
        return ckfun(aTHX_ o, namegv, ckobj);
     }
 }
@@ -10059,7 +10537,7 @@ Perl_ck_svconst(pTHX_ OP *o)
 {
     PERL_ARGS_ASSERT_CK_SVCONST;
     PERL_UNUSED_CONTEXT;
-    SvREADONLY_on(cSVOPo->op_sv);
+    if (!SvIsCOW(cSVOPo->op_sv)) SvREADONLY_on(cSVOPo->op_sv);
     return o;
 }
 
@@ -10206,34 +10684,6 @@ Perl_ck_length(pTHX_ OP *o)
     return o;
 }
 
-/* caller is supposed to assign the return to the 
-   container of the rep_op var */
-STATIC OP *
-S_opt_scalarhv(pTHX_ OP *rep_op) {
-    dVAR;
-    UNOP *unop;
-
-    PERL_ARGS_ASSERT_OPT_SCALARHV;
-
-    NewOp(1101, unop, 1, UNOP);
-    unop->op_type = (OPCODE)OP_BOOLKEYS;
-    unop->op_ppaddr = PL_ppaddr[OP_BOOLKEYS];
-    unop->op_flags = (U8)(OPf_WANT_SCALAR | OPf_KIDS );
-    unop->op_private = (U8)(1 | ((OPf_WANT_SCALAR | OPf_KIDS) >> 8));
-    unop->op_first = rep_op;
-    unop->op_next = rep_op->op_next;
-    rep_op->op_next = (OP*)unop;
-    rep_op->op_flags|=(OPf_REF | OPf_MOD);
-    unop->op_sibling = rep_op->op_sibling;
-    rep_op->op_sibling = NULL;
-    unop->op_targ = pad_alloc(OP_BOOLKEYS, SVs_PADTMP);
-    if (rep_op->op_type == OP_PADHV) { 
-        rep_op->op_flags &= ~OPf_WANT_SCALAR;
-        rep_op->op_flags |= OPf_WANT_LIST;
-    }
-    return (OP*)unop;
-}                        
-
 /* Check for in place reverse and sort assignments like "@a = reverse @a"
    and modify the optree to make them work inplace */
 
@@ -10338,6 +10788,7 @@ Perl_rpeep(pTHX_ register OP *o)
 {
     dVAR;
     OP* oldop = NULL;
+    OP* oldoldop = NULL;
     OP* defer_queue[MAX_DEFERRED]; /* small queue of deferred branches */
     int defer_base = 0;
     int defer_ix = -1;
@@ -10462,6 +10913,247 @@ Perl_rpeep(pTHX_ register OP *o)
            }
            break;
 
+        case OP_PUSHMARK:
+
+            /* Convert a series of PAD ops for my vars plus support into a
+             * single padrange op. Basically
+             *
+             *    pushmark -> pad[ahs]v -> pad[ahs]?v -> ... -> (list) -> rest
+             *
+             * becomes, depending on circumstances, one of
+             *
+             *    padrange  ----------------------------------> (list) -> rest
+             *    padrange  --------------------------------------------> rest
+             *
+             * where all the pad indexes are sequential and of the same type
+             * (INTRO or not).
+             * We convert the pushmark into a padrange op, then skip
+             * any other pad ops, and possibly some trailing ops.
+             * Note that we don't null() the skipped ops, to make it
+             * easier for Deparse to undo this optimisation (and none of
+             * the skipped ops are holding any resourses). It also makes
+             * it easier for find_uninit_var(), as it can just ignore
+             * padrange, and examine the original pad ops.
+             */
+        {
+            OP *p;
+            OP *followop = NULL; /* the op that will follow the padrange op */
+            U8 count = 0;
+            U8 intro = 0;
+            PADOFFSET base = 0; /* init only to stop compiler whining */
+            U8 gimme       = 0; /* init only to stop compiler whining */
+            bool defav = 0;  /* seen (...) = @_ */
+            bool reuse = 0;  /* reuse an existing padrange op */
+
+            /* look for a pushmark -> gv[_] -> rv2av */
+
+            {
+                GV *gv;
+                OP *rv2av, *q;
+                p = o->op_next;
+                if (   p->op_type == OP_GV
+                    && (gv = cGVOPx_gv(p))
+                    && GvNAMELEN_get(gv) == 1
+                    && *GvNAME_get(gv) == '_'
+                    && GvSTASH(gv) == PL_defstash
+                    && (rv2av = p->op_next)
+                    && rv2av->op_type == OP_RV2AV
+                    && !(rv2av->op_flags & OPf_REF)
+                    && !(rv2av->op_private & (OPpLVAL_INTRO|OPpMAYBE_LVSUB))
+                    && ((rv2av->op_flags & OPf_WANT) == OPf_WANT_LIST)
+                    && o->op_sibling == rv2av /* these two for Deparse */
+                    && cUNOPx(rv2av)->op_first == p
+                ) {
+                    q = rv2av->op_next;
+                    if (q->op_type == OP_NULL)
+                        q = q->op_next;
+                    if (q->op_type == OP_PUSHMARK) {
+                        defav = 1;
+                        p = q;
+                    }
+                }
+            }
+            if (!defav) {
+                /* To allow Deparse to pessimise this, it needs to be able
+                 * to restore the pushmark's original op_next, which it
+                 * will assume to be the same as op_sibling. */
+                if (o->op_next != o->op_sibling)
+                    break;
+                p = o;
+            }
+
+            /* scan for PAD ops */
+
+            for (p = p->op_next; p; p = p->op_next) {
+                if (p->op_type == OP_NULL)
+                    continue;
+
+                if ((     p->op_type != OP_PADSV
+                       && p->op_type != OP_PADAV
+                       && p->op_type != OP_PADHV
+                    )
+                      /* any private flag other than INTRO? e.g. STATE */
+                   || (p->op_private & ~OPpLVAL_INTRO)
+                )
+                    break;
+
+                /* let $a[N] potentially be optimised into ALEMFAST_LEX
+                 * instead */
+                if (   p->op_type == OP_PADAV
+                    && p->op_next
+                    && p->op_next->op_type == OP_CONST
+                    && p->op_next->op_next
+                    && p->op_next->op_next->op_type == OP_AELEM
+                )
+                    break;
+
+                /* for 1st padop, note what type it is and the range
+                 * start; for the others, check that it's the same type
+                 * and that the targs are contiguous */
+                if (count == 0) {
+                    intro = (p->op_private & OPpLVAL_INTRO);
+                    base = p->op_targ;
+                    gimme = (p->op_flags & OPf_WANT);
+                }
+                else {
+                    if ((p->op_private & OPpLVAL_INTRO) != intro)
+                        break;
+                    /* Note that you'd normally  expect targs to be
+                     * contiguous in my($a,$b,$c), but that's not the case
+                     * when external modules start doing things, e.g.
+                     i* Function::Parameters */
+                    if (p->op_targ != base + count)
+                        break;
+                    assert(p->op_targ == base + count);
+                    /* all the padops should be in the same context */
+                    if (gimme != (p->op_flags & OPf_WANT))
+                        break;
+                }
+
+                /* for AV, HV, only when we're not flattening */
+                if (   p->op_type != OP_PADSV
+                    && gimme != OPf_WANT_VOID
+                    && !(p->op_flags & OPf_REF)
+                )
+                    break;
+
+                if (count >= OPpPADRANGE_COUNTMASK)
+                    break;
+
+                /* there's a biggest base we can fit into a
+                 * SAVEt_CLEARPADRANGE in pp_padrange */
+                if (intro && base >
+                        (UV_MAX >> (OPpPADRANGE_COUNTSHIFT+SAVE_TIGHT_SHIFT)))
+                    break;
+
+                /* Success! We've got another valid pad op to optimise away */
+                count++;
+                followop = p->op_next;
+            }
+
+            if (count < 1)
+                break;
+
+            /* pp_padrange in specifically compile-time void context
+             * skips pushing a mark and lexicals; in all other contexts
+             * (including unknown till runtime) it pushes a mark and the
+             * lexicals. We must be very careful then, that the ops we
+             * optimise away would have exactly the same effect as the
+             * padrange.
+             * In particular in void context, we can only optimise to
+             * a padrange if see see the complete sequence
+             *     pushmark, pad*v, ...., list, nextstate
+             * which has the net effect of of leaving the stack empty
+             * (for now we leave the nextstate in the execution chain, for
+             * its other side-effects).
+             */
+            assert(followop);
+            if (gimme == OPf_WANT_VOID) {
+                if (followop->op_type == OP_LIST
+                        && gimme == (followop->op_flags & OPf_WANT)
+                        && (   followop->op_next->op_type == OP_NEXTSTATE
+                            || followop->op_next->op_type == OP_DBSTATE))
+                {
+                    followop = followop->op_next; /* skip OP_LIST */
+
+                    /* consolidate two successive my(...);'s */
+
+                    if (   oldoldop
+                        && oldoldop->op_type == OP_PADRANGE
+                        && (oldoldop->op_flags & OPf_WANT) == OPf_WANT_VOID
+                        && (oldoldop->op_private & OPpLVAL_INTRO) == intro
+                        && !(oldoldop->op_flags & OPf_SPECIAL)
+                    ) {
+                        U8 old_count;
+                        assert(oldoldop->op_next == oldop);
+                        assert(   oldop->op_type == OP_NEXTSTATE
+                               || oldop->op_type == OP_DBSTATE);
+                        assert(oldop->op_next == o);
+
+                        old_count
+                            = (oldoldop->op_private & OPpPADRANGE_COUNTMASK);
+                        assert(oldoldop->op_targ + old_count == base);
+
+                        if (old_count < OPpPADRANGE_COUNTMASK - count) {
+                            base = oldoldop->op_targ;
+                            count += old_count;
+                            reuse = 1;
+                        }
+                    }
+
+                    /* if there's any immediately following singleton
+                     * my var's; then swallow them and the associated
+                     * nextstates; i.e.
+                     *    my ($a,$b); my $c; my $d;
+                     * is treated as
+                     *    my ($a,$b,$c,$d);
+                     */
+
+                    while (    ((p = followop->op_next))
+                            && (  p->op_type == OP_PADSV
+                               || p->op_type == OP_PADAV
+                               || p->op_type == OP_PADHV)
+                            && (p->op_flags & OPf_WANT) == OPf_WANT_VOID
+                            && (p->op_private & OPpLVAL_INTRO) == intro
+                            && p->op_next
+                            && (   p->op_next->op_type == OP_NEXTSTATE
+                                || p->op_next->op_type == OP_DBSTATE)
+                            && count < OPpPADRANGE_COUNTMASK
+                    ) {
+                        assert(base + count == p->op_targ);
+                        count++;
+                        followop = p->op_next;
+                    }
+                }
+                else
+                    break;
+            }
+
+            if (reuse) {
+                assert(oldoldop->op_type == OP_PADRANGE);
+                oldoldop->op_next = followop;
+                oldoldop->op_private = (intro | count);
+                o = oldoldop;
+                oldop = NULL;
+                oldoldop = NULL;
+            }
+            else {
+                /* Convert the pushmark into a padrange.
+                 * To make Deparse easier, we guarantee that a padrange was
+                 * *always* formerly a pushmark */
+                assert(o->op_type == OP_PUSHMARK);
+                o->op_next = followop;
+                o->op_type = OP_PADRANGE;
+                o->op_ppaddr = PL_ppaddr[OP_PADRANGE];
+                o->op_targ = base;
+                /* bit 7: INTRO; bit 6..0: count */
+                o->op_private = (intro | count);
+                o->op_flags = ((o->op_flags & ~(OPf_WANT|OPf_SPECIAL))
+                                    | gimme | (defav ? OPf_SPECIAL : 0));
+            }
+            break;
+        }
+
        case OP_PADAV:
        case OP_GV:
            if (o->op_type == OP_PADAV || o->op_next->op_type == OP_RV2AV) {
@@ -10524,12 +11216,19 @@ Perl_rpeep(pTHX_ register OP *o)
         {
             OP *fop;
             OP *sop;
-            bool fopishv, sopishv;
             
+#define HV_OR_SCALARHV(op)                                   \
+    (  (op)->op_type == OP_PADHV || (op)->op_type == OP_RV2HV \
+       ? (op)                                                  \
+       : (op)->op_type == OP_SCALAR && (op)->op_flags & OPf_KIDS \
+       && (  cUNOPx(op)->op_first->op_type == OP_PADHV          \
+          || cUNOPx(op)->op_first->op_type == OP_RV2HV)          \
+         ? cUNOPx(op)->op_first                                   \
+         : NULL)
+
         case OP_NOT:
-            fop = cUNOP->op_first;
-            sop = NULL;
-            goto stitch_keys;
+            if ((fop = HV_OR_SCALARHV(cUNOP->op_first)))
+                fop->op_private |= OPpTRUEBOOL;
             break;
 
         case OP_AND:
@@ -10544,17 +11243,10 @@ Perl_rpeep(pTHX_ register OP *o)
                o->op_next = o->op_next->op_next;
            DEFER(cLOGOP->op_other);
           
-          stitch_keys:     
            o->op_opt = 1;
-#define HV_OR_SCALARHV(op)                                   \
-    (  (op)->op_type == OP_PADHV || (op)->op_type == OP_RV2HV \
-    || (  (op)->op_type == OP_SCALAR && (op)->op_flags & OPf_KIDS \
-       && (  cUNOPx(op)->op_first->op_type == OP_PADHV          \
-          || cUNOPx(op)->op_first->op_type == OP_RV2HV)))        \
-
-            fopishv = HV_OR_SCALARHV(fop);
-            sopishv = sop && HV_OR_SCALARHV(sop);
-            if (fopishv || sopishv
+            fop = HV_OR_SCALARHV(fop);
+            if (sop) sop = HV_OR_SCALARHV(sop);
+            if (fop || sop
             ){ 
                 OP * nop = o;
                 OP * lop = o;
@@ -10576,29 +11268,27 @@ Perl_rpeep(pTHX_ register OP *o)
                         }
                     }            
                 }
-                if (  (  (lop->op_flags & OPf_WANT) == OPf_WANT_VOID
+                if (fop) {
+                    if (  (lop->op_flags & OPf_WANT) == OPf_WANT_VOID
                       || o->op_type == OP_AND  )
-                   && fopishv)
-                        cLOGOP->op_first = opt_scalarhv(fop);
-                else if (!(lop->op_flags & OPf_WANT)) {
-                    if (fop->op_type == OP_SCALAR)
-                        fop = cUNOPx(fop)->op_first;
-                    fop->op_private |= OpMAYBE_TRUEBOOL;
+                        fop->op_private |= OPpTRUEBOOL;
+                    else if (!(lop->op_flags & OPf_WANT))
+                        fop->op_private |= OPpMAYBE_TRUEBOOL;
                 }
                 if (  (lop->op_flags & OPf_WANT) == OPf_WANT_VOID
-                   && sopishv)
-                        cLOGOP->op_first->op_sibling = opt_scalarhv(sop);
+                   && sop)
+                    sop->op_private |= OPpTRUEBOOL;
             }                  
             
            
            break;
-       }    
        
        case OP_COND_EXPR:
-           if (HV_OR_SCALARHV(cLOGOP->op_first))
-               cLOGOP->op_first = opt_scalarhv(cLOGOP->op_first);
+           if ((fop = HV_OR_SCALARHV(cLOGOP->op_first)))
+               fop->op_private |= OPpTRUEBOOL;
 #undef HV_OR_SCALARHV
            /* GERONIMO! */
+       }    
 
        case OP_MAPWHILE:
        case OP_GREPWHILE:
@@ -10820,6 +11510,7 @@ Perl_rpeep(pTHX_ register OP *o)
        }
            
        }
+       oldoldop = oldop;
        oldop = o;
     }
     LEAVE;