yyparse(): only check stack size in outer loop

Rather than checking before each individual shift whether the parse stack
needs extending, only check once per rule, making sure there's enough
space to shift all the items for the longest possible rule

1 files changed, 3 insertions, 1 deletions

diff --git a/parser.h b/parser.h
index c5a59abc5d..3c7bb4e97d 100644
--- a/parser.h
+++ b/parser.h
@@ -44,7 +44,9 @@ typedef struct yy_parser {
 
     int		    yylen;	/* length of active reduction */
     yy_stack_frame  *stack;	/* base of stack */
-    yy_stack_frame  *stack_max1;/* (top-1)th element of alloacted stack */
+    yy_stack_frame  *stack_maxbase;/* (stack + alloced size - YY_MAXRULE)
+                                    * it's offset by -YY_MAXRULE to make
+                                    * overflow checks quicker */
     yy_stack_frame  *ps;	/* current stack frame */
 
     /* lexer state */