Add Perl_amagic_deref_call() to implement the bulk of tryAMAGICunDEREF_var().

This removes around 300 bytes of object code from each place it was previously
inlined. It also provides a better interface - quite a lot of the core
currently bodges things by creating a local variable C<SV **sp = &sv> to use
the macro.

Change the XS::APItest wrapper to amagic_deref_call().

1 files changed, 19 insertions, 0 deletions

diff --git a/gv.c b/gv.c
index 080db567be..32b5908c99 100644
--- a/gv.c
+++ b/gv.c
@@ -2010,6 +2010,25 @@ Perl_try_amagic_bin(pTHX_ int method, int flags) {
     return FALSE;
 }
 
+SV *
+Perl_amagic_deref_call(pTHX_ SV *ref, int method) {
+    SV *tmpsv = NULL;
+
+    PERL_ARGS_ASSERT_AMAGIC_DEREF_CALL;
+
+    while (SvAMAGIC(ref) && 
+	   (tmpsv = amagic_call(ref, &PL_sv_undef, method,
+				AMGf_noright | AMGf_unary))) { 
+	if (!SvROK(tmpsv))
+	    Perl_croak(aTHX_ "Overloaded dereference did not return a reference");
+	if (tmpsv == ref || SvRV(tmpsv) == SvRV(ref)) {
+	    /* Bail out if it returns us the same reference.  */
+	    return tmpsv;
+	}
+	ref = tmpsv;
+    }
+    return tmpsv ? tmpsv : ref;
+}
 
 SV*
 Perl_amagic_call(pTHX_ SV *left, SV *right, int method, int flags)