fixes for mortalization bug in xsubpp, other efficiency tweaks

	Message-Id: <H00000e500086fb3@MHS>
	Subject: [PATCH _69] sv_2mortal fix

p4raw-id: //depot/perl@1306

1 files changed, 17 insertions, 14 deletions

diff --git a/sv.c b/sv.c
index 94fb230bdc..d4cac52e9a 100644
--- a/sv.c
+++ b/sv.c
@@ -2959,15 +2959,16 @@ sv_free(SV *sv)
 
     if (!sv)
 	return;
-    if (SvREADONLY(sv)) {
-	if (sv == &sv_undef || sv == &sv_yes || sv == &sv_no)
-	    return;
-    }
     if (SvREFCNT(sv) == 0) {
 	if (SvFLAGS(sv) & SVf_BREAK)
 	    return;
 	if (in_clean_all) /* All is fair */
 	    return;
+	if (SvREADONLY(sv) && SvIMMORTAL(sv)) {
+	    /* make sure SvREFCNT(sv)==0 happens very seldom */
+	    SvREFCNT(sv) = (~(U32)0)/2;
+	    return;
+	}
 	warn("Attempt to free unreferenced scalar");
 	return;
     }
@@ -2980,6 +2981,11 @@ sv_free(SV *sv)
 	return;
     }
 #endif
+    if (SvREADONLY(sv) && SvIMMORTAL(sv)) {
+	/* make sure SvREFCNT(sv)==0 happens very seldom */
+	SvREFCNT(sv) = (~(U32)0)/2;
+	return;
+    }
     sv_clear(sv);
     if (! SvREFCNT(sv))
 	del_SV(sv);
@@ -3602,8 +3608,8 @@ sv_2mortal(register SV *sv)
     dTHR;
     if (!sv)
 	return sv;
-    if (SvREADONLY(sv) && curcop != &compiling)
-	croak(no_modify);
+    if (SvREADONLY(sv) && SvIMMORTAL(sv))
+	return;
     if (++tmps_ix >= tmps_max)
 	sv_mortalgrow();
     tmps_stack[tmps_ix] = sv;
@@ -3683,7 +3689,7 @@ newSViv(IV i)
 }
 
 SV *
-newRV(SV *tmpRef)
+newRV_noinc(SV *tmpRef)
 {
     dTHR;
     register SV *sv;
@@ -3694,20 +3700,17 @@ newRV(SV *tmpRef)
     SvFLAGS(sv) = 0;
     sv_upgrade(sv, SVt_RV);
     SvTEMP_off(tmpRef);
-    SvRV(sv) = SvREFCNT_inc(tmpRef);
+    SvRV(sv) = tmpRef;
     SvROK_on(sv);
     return sv;
 }
 
-
-
 SV *
-Perl_newRV_noinc(SV *tmpRef)
+newRV(SV *tmpRef)
 {
     register SV *sv;
-
-    sv = newRV(tmpRef);
-    SvREFCNT_dec(tmpRef);
+    sv = newRV_noinc(tmpRef);
+    SvREFCNT_inc(tmpRef);
     return sv;
 }