op_dump(): handle SVOPs and METHOPs separately

Currently SVOPs and METHOPs are dumped using the same case branch within
op_dump(). This works at the moment because the op_sv field and the
op_meth_sv field happen to occupy the same offset within their
respective structs.

This commit separates out the handling of those two OP classes, which will
also allow another commit shortly to handle METHOD ops more specifically.

OP_COREARGS is also added as another dumpable SVOP type (i.e. an op
which may have an SV hanging off op_sv).

This commit also makes it so that it now always displays the value of the
op_sv field of SVOPs, which on threaded builds starts off holding an SV,
but later gets set to 0 to indicate that the SV has been moved to the
pad.

Author: iabyn

dump.c

@@ -1380,6 +1380,25 @@ S_do_op_dump_bar(pTHX_ I32 level, UV bar, PerlIO *file, const OP *o)
 
     case OP_CONST:
     case OP_HINTSEVAL:
+    case OP_COREARGS:
+        /* an SVOP. On non-threaded builds, these OPs use op_sv to hold
+         * the SV associated with the const / hints hash / op num.
+         * On threaded builds, op_sv initially holds the SV, then at the
+         * end of compiling the sub, the SV is moved into the pad by
+         * op_relocate_sv() and indexed by op_targ.
+         * XXX Currently the SV isn't relocated for OP_COREARGS.
+         */
+        S_opdump_indent(aTHX_ o, level, bar, file,
+                            "OP_SV = 0x%" UVxf "\n", cSVOPo->op_sv);
+#ifdef USE_ITHREADS
+        /* SV is stored in the pad, and the right pad may not be active
+         * here, so skip dumping the SV */
+#else
+        S_opdump_indent(aTHX_ o, level, bar, file, "SV = %s\n",
+                        SvPEEK(cSVOP_sv));
+#endif
+        break;
+
     case OP_METHOD_NAMED:
     case OP_METHOD_SUPER:
     case OP_METHOD_REDIR:
@@ -1391,6 +1410,7 @@ S_do_op_dump_bar(pTHX_ I32 level, UV bar, PerlIO *file, const OP *o)
                         SvPEEK(cMETHOPo_meth));
 #endif
         break;
+
     case OP_NULL:
         if (o->op_targ != OP_NEXTSTATE && o->op_targ != OP_DBSTATE)
             break;