Use both cache entries for Perl_sv_pos_b2u().

p4raw-id: //depot/perl@27584

diff --git a/sv.c b/sv.c
index 5360a30..62f6107 100644 (file)
--- a/sv.c
+++ b/sv.c
@@ -5763,9 +5763,19 @@ Perl_sv_pos_b2u(pTHX_ register SV* sv, I32* offsetp)
                        + S_sv_pos_b2u_forwards(aTHX_ s + cache[1], send);
                }
            }
-           else { /* cache[1] > byte */
-               len = S_sv_pos_b2u_midway(aTHX_ s, send, s + cache[1],
-                                         cache[0]);
+           else if (cache[3] < byte) {
+               /* We're between the two cached pairs, so we do the calculation
+                  offset by the byte/utf-8 positions for the earlier pair,
+                  then add the utf-8 characters from the string start to
+                  there.  */
+               len = S_sv_pos_b2u_midway(aTHX_ s + cache[3], send,
+                                         s + cache[1], cache[0] - cache[2])
+                   + cache[2];
+
+           }
+           else { /* cache[3] > byte */
+               len = S_sv_pos_b2u_midway(aTHX_ s, send, s + cache[3],
+                                         cache[2]);
 
            }
            ASSERT_UTF8_CACHE(cache);