Refactor Perl_get_vtbl() to a small array lookup from a large switch statement.

Provide magic_vtable_max, the number of elements in PL_magic_vtables[].

3 files changed, 9 insertions, 100 deletions

diff --git a/mg_vtable.h b/mg_vtable.h
index 21f2e7a874..2db8f3fe8c 100644
--- a/mg_vtable.h
+++ b/mg_vtable.h
@@ -38,7 +38,8 @@ enum {		/* pass one of these to get_vtbl */
     want_vtbl_utf8,
     want_vtbl_collxfrm,
     want_vtbl_hintselem,
-    want_vtbl_hints
+    want_vtbl_hints,
+    magic_vtable_max
 };
 
 /* These all need to be 0, not NULL, as NULL can be (void*)0, which is a
@@ -59,7 +60,7 @@ enum {		/* pass one of these to get_vtbl */
 */
 
 #ifdef DOINIT
-EXT_MGVTBL PL_magic_vtables[] = {
+EXT_MGVTBL PL_magic_vtables[magic_vtable_max] = {
   { Perl_magic_get, Perl_magic_set, Perl_magic_len, 0, 0, 0, 0, 0 },
   { 0, Perl_magic_set_all_env, 0, Perl_magic_clear_all_env, 0, 0, 0, 0 },
   { 0, Perl_magic_setenv, 0, Perl_magic_clearenv, 0, 0, 0, 0 },
@@ -102,7 +103,7 @@ EXT_MGVTBL PL_magic_vtables[] = {
   { 0, 0, 0, Perl_magic_clearhints, 0, 0, 0, 0 }
 };
 #else
-EXT_MGVTBL PL_magic_vtables[];
+EXT_MGVTBL PL_magic_vtables[magic_vtable_max];
 #endif
 
 #define PL_vtbl_amagic PL_magic_vtables[want_vtbl_amagic]
diff --git a/regen/mg_vtable.pl b/regen/mg_vtable.pl
index d09bfdaaf5..3419070484 100644
--- a/regen/mg_vtable.pl
+++ b/regen/mg_vtable.pl
@@ -63,6 +63,7 @@ my $h = open_new('mg_vtable.h', '>',
 
 {
     my @names = map {"want_vtbl_$_"} grep {!ref $_} @sig;
+    push @names, 'magic_vtable_max';
     local $" = ",\n    ";
     print $h <<"EOH";
 enum {		/* pass one of these to get_vtbl */
@@ -91,7 +92,7 @@ print $h <<'EOH';
 */
 
 #ifdef DOINIT
-EXT_MGVTBL PL_magic_vtables[] = {
+EXT_MGVTBL PL_magic_vtables[magic_vtable_max] = {
 EOH
 
 my @vtable_names;
@@ -120,7 +121,7 @@ EOH
 print $h <<'EOH';
 };
 #else
-EXT_MGVTBL PL_magic_vtables[];
+EXT_MGVTBL PL_magic_vtables[magic_vtable_max];
 #endif
 
 EOH
diff --git a/util.c b/util.c
index 7355d0330e..19fec65fe3 100644
--- a/util.c
+++ b/util.c
@@ -3736,103 +3736,10 @@ Perl_getenv_len(pTHX_ const char *env_elem, unsigned long *len)
 MGVTBL*
 Perl_get_vtbl(pTHX_ int vtbl_id)
 {
-    const MGVTBL* result;
     PERL_UNUSED_CONTEXT;
 
-    switch(vtbl_id) {
-    case want_vtbl_sv:
-	result = &PL_vtbl_sv;
-	break;
-    case want_vtbl_env:
-	result = &PL_vtbl_env;
-	break;
-    case want_vtbl_envelem:
-	result = &PL_vtbl_envelem;
-	break;
-#ifndef PERL_MICRO
-    case want_vtbl_sigelem:
-	result = &PL_vtbl_sigelem;
-	break;
-#endif
-    case want_vtbl_pack:
-	result = &PL_vtbl_pack;
-	break;
-    case want_vtbl_packelem:
-	result = &PL_vtbl_packelem;
-	break;
-    case want_vtbl_dbline:
-	result = &PL_vtbl_dbline;
-	break;
-    case want_vtbl_isa:
-	result = &PL_vtbl_isa;
-	break;
-    case want_vtbl_isaelem:
-	result = &PL_vtbl_isaelem;
-	break;
-    case want_vtbl_arylen:
-	result = &PL_vtbl_arylen;
-	break;
-    case want_vtbl_mglob:
-	result = &PL_vtbl_mglob;
-	break;
-    case want_vtbl_nkeys:
-	result = &PL_vtbl_nkeys;
-	break;
-    case want_vtbl_taint:
-	result = &PL_vtbl_taint;
-	break;
-    case want_vtbl_substr:
-	result = &PL_vtbl_substr;
-	break;
-    case want_vtbl_vec:
-	result = &PL_vtbl_vec;
-	break;
-    case want_vtbl_pos:
-	result = &PL_vtbl_pos;
-	break;
-    case want_vtbl_bm:
-	result = &PL_vtbl_bm;
-	break;
-    case want_vtbl_fm:
-	result = &PL_vtbl_fm;
-	break;
-    case want_vtbl_uvar:
-	result = &PL_vtbl_uvar;
-	break;
-    case want_vtbl_defelem:
-	result = &PL_vtbl_defelem;
-	break;
-    case want_vtbl_regexp:
-	result = &PL_vtbl_regexp;
-	break;
-    case want_vtbl_regdata:
-	result = &PL_vtbl_regdata;
-	break;
-    case want_vtbl_regdatum:
-	result = &PL_vtbl_regdatum;
-	break;
-#ifdef USE_LOCALE_COLLATE
-    case want_vtbl_collxfrm:
-	result = &PL_vtbl_collxfrm;
-	break;
-#endif
-    case want_vtbl_amagic:
-	result = &PL_vtbl_amagic;
-	break;
-    case want_vtbl_amagicelem:
-	result = &PL_vtbl_amagicelem;
-	break;
-    case want_vtbl_backref:
-	result = &PL_vtbl_backref;
-	break;
-    case want_vtbl_utf8:
-	result = &PL_vtbl_utf8;
-	break;
-    default:
-	result = NULL;
-	break;
-    }
-    return (MGVTBL*)result;
+    return (vtbl_id < 0 || vtbl_id >= magic_vtable_max)
+	? NULL : PL_magic_vtables + vtbl_id;
 }
 
 I32