Avoid redundant copies in string evals

Perl_lex_start copies the string passed to it unconditionally.
Sometimes pp_entereval makes a copy before passing the string
to lex_start.  So in those cases we can pass a flag to avoid a
redundant copy.

1 files changed, 3 insertions, 1 deletions

diff --git a/parser.h b/parser.h
index 9167e6c07f..3531631e62 100644
--- a/parser.h
+++ b/parser.h
@@ -119,8 +119,10 @@ typedef struct yy_parser {
 # define LEX_START_SAME_FILTER	0x00000001
 # define LEX_IGNORE_UTF8_HINTS	0x00000002
 # define LEX_EVALBYTES		0x00000004
+# define LEX_START_COPIED	0x00000008
 # define LEX_START_FLAGS \
-	(LEX_START_SAME_FILTER|LEX_IGNORE_UTF8_HINTS|LEX_EVALBYTES)
+	(LEX_START_SAME_FILTER|LEX_START_COPIED \
+	|LEX_IGNORE_UTF8_HINTS|LEX_EVALBYTES)
 #endif
 
 /* flags for parser API */