dfa: remove word delimiter support for multibyte locales

DFA supports word delimiter expressions, but it does not behave
correctly for multibyte locales.  Even if it were to be fixed,
the DFA matcher's performance would be no better than that of regex.
Thus, this change removes DFA support for word delimiter expressions
in multibyte locales.

* src/dfa.c (dfa_supported): Return false also when a pattern uses any
word delimiter expression in a multibyte locale.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/dfa.c b/src/dfa.c
index a28404be..d1e76e14 100644
--- a/src/dfa.c
+++ b/src/dfa.c
@@ -3358,6 +3358,7 @@ skip_remains_mb (struct dfa *d, unsigned char const *p,
    Here is the list of features that make this DFA matcher punt:
     - [M-N]-range-in-MB-locale: regex is up to 25% faster on [a-z]
     - back-reference: (.)\1
+    - word-delimiter-in-MB-locale: \<, \>, \b
     */
 static inline char *
 dfaexec_main (struct dfa *d, char const *begin, char *end, int allow_nl,
@@ -3645,6 +3646,14 @@ dfa_supported (struct dfa const *d)
     {
       switch (d->tokens[i])
         {
+        case BEGWORD:
+        case ENDWORD:
+        case LIMWORD:
+        case NOTLIMWORD:
+          if (!d->multibyte)
+            continue;
+          /* fallthrough */
+
         case BACKREF:
         case MBCSET:
           return false;