pp_subst: exit earlier after failed match

If the match fails, don't bother to execute some code that prepares the
source and replacement strings for a substitution (e.g. matching
UTF8-ness).

(This is an enhancement to ff6e92e827a143094fdf3af374056b524759194b)

diff --git a/pp_hot.c b/pp_hot.c
index 8fb2f61..4fb5f01 100644 (file)
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -2252,6 +2252,15 @@ PP(pp_subst)
 
     matched = CALLREGEXEC(rx, s, strend, orig, 0, TARG, NULL,
                         r_flags | REXEC_CHECKED);
+
+    if (!matched) {
+      ret_no:
+       SPAGAIN;
+       PUSHs(rpm->op_pmflags & PMf_NONDESTRUCT ? TARG : &PL_sv_no);
+       LEAVE_SCOPE(oldsave);
+       RETURN;
+    }
+
     /* known replacement string? */
     if (dstr) {
        if (SvTAINTED(dstr))
@@ -2261,7 +2270,7 @@ PP(pp_subst)
         * but only if it matched; see
         * http://www.nntp.perl.org/group/perl.perl5.porters/2010/04/msg158809.html
         */
-       if (matched && DO_UTF8(dstr) && ! DO_UTF8(TARG)) {
+       if (DO_UTF8(dstr) && ! DO_UTF8(TARG)) {
            char * const orig_pvx =  SvPVX(TARG);
            const STRLEN new_len = sv_utf8_upgrade_nomg(TARG);
 
@@ -2294,14 +2303,6 @@ PP(pp_subst)
        doutf8 = FALSE;
     }
     
-    if (!matched) {
-      ret_no:
-       SPAGAIN;
-       PUSHs(rpm->op_pmflags & PMf_NONDESTRUCT ? TARG : &PL_sv_no);
-       LEAVE_SCOPE(oldsave);
-       RETURN;
-    }
-
     /* can do inplace substitution? */
     if (c
 #ifdef PERL_OLD_COPY_ON_WRITE