X-Git-Url: https://perl5.git.perl.org/perl5.git/blobdiff_plain/7b52d6569c115e4522e1cbe14cfd730e60c84bf1..a2373b32b1b1b8979cf9c5bb27478555d4ac2bde:/pp_hot.c

diff --git a/pp_hot.c b/pp_hot.c
index 5eedf24..1094510 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -76,7 +76,8 @@ PP(pp_null)
     return NORMAL;
 }
 
-/* This is sometimes called directly by pp_coreargs and pp_grepstart. */
+/* This is sometimes called directly by pp_coreargs, pp_grepstart and
+   amagic_call. */
 PP(pp_pushmark)
 {
     PUSHMARK(PL_stack_sp);
@@ -1632,8 +1633,7 @@ Perl_do_readline(pTHX)
 	if (gimme == G_SCALAR) {
 	    /* undef TARG, and push that undefined value */
 	    if (type != OP_RCATLINE) {
-		SV_CHECK_THINKFIRST_COW_DROP(TARG);
-		SvOK_off(TARG);
+		sv_setsv(TARG,NULL);
 	    }
 	    PUSHTARG;
 	}
@@ -1877,14 +1877,14 @@ S_softref2xv_lite(pTHX_ SV *const sv, const char *const what,
 }
 
 
-/* handle one or more derefs and array/hash indexings, e.g.
- * $h->{foo} or $a[0]{$key}[$i] or f()->[1]
+/* Handle one or more aggregate derefs and array/hash indexings, e.g.
+ * $h->{foo}  or  $a[0]{$key}[$i]  or  f()->[1]
  *
  * op_aux points to an array of unions of UV / IV / SV* / PADOFFSET.
- * Each of these either contains an action, or an argument, such as
- * a UV to use as an array index, or a lexical var to retrieve.
- * In fact, several actions re stored per UV; we keep shifting new actions
- * of the one UV, and only reload when it becomes zero.
+ * Each of these either contains a set of actions, or an argument, such as
+ * an IV to use as an array index, or a lexical var to retrieve.
+ * Several actions re stored per UV; we keep shifting new actions off the
+ * one UV, and only reload when it becomes zero.
  */
 
 PP(pp_multideref)
@@ -2947,8 +2947,12 @@ PP(pp_leavesub)
     PERL_CONTEXT *cx;
     SV *sv;
 
-    if (CxMULTICALL(&cxstack[cxstack_ix]))
+    if (CxMULTICALL(&cxstack[cxstack_ix])) {
+        /* entry zero of a stack is always PL_sv_undef, which
+         * simplifies converting a '()' return into undef in scalar context */
+        assert(PL_stack_sp > PL_stack_base || *PL_stack_base == &PL_sv_undef);
 	return 0;
+    }
 
     POPBLOCK(cx,newpm);
     cxstack_ix++; /* temporarily protect top context */
@@ -3611,11 +3615,5 @@ PP(pp_method_redir_super)
 }
 
 /*
- * Local variables:
- * c-indentation-style: bsd
- * c-basic-offset: 4
- * indent-tabs-mode: nil
- * End:
- *
  * ex: set ts=8 sts=4 sw=4 et:
  */