siggoto+pad: fix cvdepth

with goto signatures, true tailcalls, we might overshoot
CvDEPTH(cv) over PadlistMAX(padlist). When we do that store
the adjusted cx->blk_sub.olddepth also.

Closes #162, a SEGV in Test::CleanNamespaces with many
tailcalls and overshooting CvDEPTH.

Also harmonize -DXv Pad diagnostics.
Fix -Dt for entersub/enterxssub: correct function name (if a CV)

Author: Reini Urban

dump.c

@@ -2731,10 +2731,10 @@ Perl_debop(pTHX_ const OP *o)
     case OP_ENTERSUB:
     case OP_ENTERXSSUB:
         {
-            CV* cv = deb_curcv(cxstack_ix);
-            if (cv && CvGV(cv))
+            SV* const sv = *PL_stack_sp;
+            if (sv && SvTYPE(sv) == SVt_PVCV) /* no GV or PV yet */
                 PerlIO_printf(Perl_debug_log, "(%"SVf")",
-                    SVfARG(cv_name(cv,NULL,CV_NAME_NOMAIN)));
+                    SVfARG(cv_name((CV*)sv, NULL, CV_NAME_NOMAIN)));
             break;
         }
     case OP_METHOD_NAMED:

pad.c

@@ -1396,8 +1396,8 @@ Perl_pad_sv(pTHX_ PADOFFSET po)
     if (!po)
 	Perl_croak(aTHX_ "panic: pad_sv po");
     DEBUG_X(PerlIO_printf(Perl_debug_log,
-	"Pad 0x%"UVxf" 0x%"UVxf"[%ld] [%d] sv=0x%"UVxf"\n",
-        PTR2UV(PL_comppad), PTR2UV(PL_curpad), (long)AvFILLp(PL_comppad),
+	"Pad 0x%"UVxf"[%ld] 0x%"UVxf" pad_sv: %d sv=0x%"UVxf"\n",
+        PTR2UV(PL_comppad), (long)AvFILLp(PL_comppad), PTR2UV(PL_curpad),
         (int)po, PTR2UV(PL_curpad[po])));
     assert(PL_comppad ? po <= (PADOFFSET)AvFILLp(PL_comppad) : 1);
     return PL_curpad[po];

pp_ctl.c

@@ -2041,8 +2041,8 @@ PP(pp_dbstate)
 	    if (CvDEPTH(cv) >= 2) {
                 PADLIST *padlist = CvPADLIST(cv);
                 DEBUG_Xv(PerlIO_printf(Perl_debug_log,
-                                   "Pad push padlist max=%d, CvDEPTH=%d (dbstate)\n",
-                                   (int)PadlistMAX(padlist), (int)CvDEPTH(cv)));
+                    "Pad push padlist max=%d, CvDEPTH=%d (dbstate)\n",
+                    (int)PadlistMAX(padlist), (int)CvDEPTH(cv)));
                 if (CvDEPTH(cv) == PERL_SUB_DEPTH_WARN && ckWARN(WARN_RECURSION))
                     sub_crush_depth(cv);
                 if (CvDEPTH(cv) > PadlistMAX(padlist)+1) { /* adjust siggoto */
@@ -2774,6 +2774,7 @@ PP(pp_goto)
                     CV* cursub = cx->blk_sub.cv;
                     PADLIST * const padlist = CvPADLIST(cv);
                     cx->blk_sub.cv = cv; /* adjust context */
+                    cx->blk_sub.olddepth = CvDEPTH(cv);
                     if (CvHASSIG(cursub)) { /* sig2sig: no @_, just SP-MARK */
                         arg = av; /* mark */
                         DEBUG_kv(PerlIO_printf(Perl_debug_log,
@@ -2782,8 +2783,9 @@ PP(pp_goto)
                              (long int)(cx->blk_sub.savearray - av + 1))); /* sp-mark+1 */
                         /*PUSHMARK((SV**)cx->blk_sub.savearray);*/
                         DEBUG_Xv(PerlIO_printf(Perl_debug_log,
-                            "Pad padlist max=%d, CvDEPTH=%d (goto sig2sig)\n",
-                            (int)PadlistMAX(padlist), (int)CvDEPTH(cv)));
+                            "Pad padlist max=%d, CvDEPTH=%d (goto sig2sig %s)\n",
+                            (int)PadlistMAX(padlist), (int)CvDEPTH(cv),
+                            SvPVX_const(cv_name(cv, NULL, CV_NAME_NOMAIN))));
                         PAD_SET_CUR(padlist, PadlistMAX(padlist));
                         goto call_pp_sub;
                     }
@@ -2827,6 +2829,10 @@ PP(pp_goto)
 	    }
 
 	    if (CxTYPE(cx) == CXt_SUB) {
+                DEBUG_Xv(PerlIO_printf(Perl_debug_log,
+                    "Pad CvDEPTH %d => %d (%s)\n",
+                    (int)CvDEPTH(cx->blk_sub.cv), (int) cx->blk_sub.olddepth,
+                    SvPVX_const(cv_name(cx->blk_sub.cv, NULL, CV_NAME_NOMAIN))));
 		CvDEPTH(cx->blk_sub.cv) = cx->blk_sub.olddepth;
                 SvREFCNT_dec_NN(cx->blk_sub.cv);
             }
@@ -2869,6 +2875,7 @@ PP(pp_goto)
                        without new cx and padframe, reusing the old pads. retop is CvSTART */
                     PADLIST * const padlist = CvPADLIST(cv);
                     I32 depth = CvDEPTH(cv);
+                    cx->blk_sub.cv = cv;
                     cx->blk_sub.argarray  = MARK+1;
                     cx->blk_sub.savearray = (AV*)SP;
                     cx->blk_sub.olddepth = depth;
@@ -2892,13 +2899,13 @@ PP(pp_goto)
                         /* cpan/Test-Simple/t/capture.t? */
                         depth = PadlistMAX(padlist);
                         DEBUG_Xv(PerlIO_printf(Perl_debug_log,
-                            "Pad padlist max=%d, CvDEPTH=%d (tailcall)\n",
-                            (int)depth, (int)CvDEPTH(cv)));
-                        if (CvDEPTH(cv) <= depth) {
+                            "Pad padlist max=%d, CvDEPTH=%d (tailcall %s)\n",
+                            (int)depth, (int)CvDEPTH(cv),
+                            SvPVX_const(cv_name(cv, NULL, CV_NAME_NOMAIN))));
+                        if (CvDEPTH(cv) <= depth)
                             CvDEPTH(cv) = depth;
-                        }
 #endif
-                        PAD_SET_CUR(padlist, depth);
+                        PAD_SET_CUR_NOSAVE(padlist, depth);
                         goto call_pp_sub;
                     }
                 }
@@ -2939,8 +2946,9 @@ PP(pp_goto)
 		    if (CvDEPTH(cv) == PERL_SUB_DEPTH_WARN && ckWARN(WARN_RECURSION))
 			sub_crush_depth(cv);
                     DEBUG_Xv(PerlIO_printf(Perl_debug_log,
-                                   "Pad push padlist max=%d, CvDEPTH=%d (goto pp)\n",
-                                   (int)PadlistMAX(padlist), (int)CvDEPTH(cv)));
+                        "Pad push padlist max=%d, CvDEPTH=%d (goto %s)\n",
+                        (int)PadlistMAX(padlist), (int)CvDEPTH(cv),
+                        SvPVX_const(cv_name(cv, NULL, CV_NAME_NOMAIN))));
 		    pad_push(padlist, CvDEPTH(cv));
 		}
 		PL_curcop = cx->blk_oldcop;

pp_hot.c

@@ -4033,6 +4033,7 @@ PP(pp_entersub)
             if (CvDEPTH(cv) > PadlistMAX(padlist)+1) { /* not with siggoto */
                 depth = PadlistMAX(padlist)+1;
                 CvDEPTH(cv) = depth;
+                cx->blk_sub.olddepth = depth-1;
             }
 	    pad_push(padlist, depth);
         }

scope.c

@@ -1138,7 +1138,7 @@ Perl_leave_scope(pTHX_ I32 base)
                 sv = *svp;
 
                 DEBUG_Xv(PerlIO_printf(Perl_debug_log,
-             "Pad 0x%"UVxf"[%ld] 0x%"UVxf" clearsv: %ld sv=0x%"UVxf"<%"IVdf"> %s\n",
+                    "Pad 0x%"UVxf"[%ld] 0x%"UVxf" clearsv: %ld sv=0x%"UVxf"<%"IVdf"> %s\n",
                     PTR2UV(PL_comppad), (long)AvFILLp(PL_comppad), PTR2UV(PL_curpad),
                     (long)(svp-PL_curpad), PTR2UV(sv), (IV)SvREFCNT(sv),
                     (SvREFCNT(sv) <= 1 && !SvOBJECT(sv)) ? "clear" : "abandon"));