Better fix for perl #107440

> > Actually, the simplest solution seem to be to put the av or hv on
> > the mortals stack in pp_aassign and pp_undef, rather than in
> > [ah]v_undef/clear.
>
> This makes me nervous. The tmps stack is typically cleared only on
> statement boundaries, so we run the risks of
>
>     * user-visible delaying of freeing elements;
>     * large tmps stack growth might be possible with
>       certain types of loop that repeatedly assign to an array without
>       freeing tmps (eg map? I think I fixed most map/grep tmps leakage
> a
>       while back, but there may still be some edge cases).
>
> Surely an ENTER/SAVEFREESV/LEAVE inside pp_aassign is just as
> efficient,
> without any attendant risks?
>
> Also, although pp_aassign and pp_undef are now fixed, the
> [ah]v_undef/clear functions aren't, and they're part of the public API
> that can be called independently of pp_aassign etc. Ideally they
> should
> be fixed (so they don't crash in mid-loop), and their documentation
> updated to point out that on return, their AV/HV arg may have been
> freed.

This commit takes care of the first part; it changes pp_aassign to use
ENTER/SAVEFREESV/LEAVE and adds the same to h_freeentries (called both
by hv_undef and hv_clear), av_undef and av_clear.

It effectively reverts the C code part of 9f71cfe6ef2.

1 files changed, 8 insertions, 2 deletions

diff --git a/pp_hot.c b/pp_hot.c
index add940049b..ff834a924e 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -993,8 +993,10 @@ PP(pp_aassign)
 	sv = *lelem++;
 	switch (SvTYPE(sv)) {
 	case SVt_PVAV:
-	    ary = MUTABLE_AV(sv_2mortal(SvREFCNT_inc_simple_NN(sv)));
+	    ary = MUTABLE_AV(sv);
 	    magic = SvMAGICAL(ary) != 0;
+	    ENTER;
+	    SAVEFREESV(SvREFCNT_inc_simple_NN(sv));
 	    av_clear(ary);
 	    av_extend(ary, lastrelem - relem);
 	    i = 0;
@@ -1015,13 +1017,16 @@ PP(pp_aassign)
 	    }
 	    if (PL_delaymagic & DM_ARRAY_ISA)
 		SvSETMAGIC(MUTABLE_SV(ary));
+	    LEAVE;
 	    break;
 	case SVt_PVHV: {				/* normal hash */
 		SV *tmpstr;
 		SV** topelem = relem;
 
-		hash = MUTABLE_HV(sv_2mortal(SvREFCNT_inc_simple_NN(sv)));
+		hash = MUTABLE_HV(sv);
 		magic = SvMAGICAL(hash) != 0;
+		ENTER;
+		SAVEFREESV(SvREFCNT_inc_simple_NN(sv));
 		hv_clear(hash);
 		firsthashrelem = relem;
 
@@ -1058,6 +1063,7 @@ PP(pp_aassign)
 		    do_oddball(hash, relem, firstrelem);
 		    relem++;
 		}
+		LEAVE;
 	    }
 	    break;
 	default: