Author: pfg
Date: Fri Dec 2 16:28:18 2016
New Revision: 309415
URL: https://svnweb.freebsd.org/changeset/base/309415
Log:
indent(1): Optimize parser stack usage.
When special else-if processing is enabled (-ei), we can assume "else if"
and "if" to be equivalent for indentation purposes.
This reduction saves a lot of stack space in case of a long "if-else-if
... else-if" sequence; with this change,
Postgres/src/bin/psql/tab-complete.c as of 9.6beta3
requires minimum of the stack length to be 31 instead of 444.
Submitted by: Piotr Sephaniak
Modified:
head/usr.bin/indent/parse.c
Modified: head/usr.bin/indent/parse.c
==============================================================================
--- head/usr.bin/indent/parse.c Fri Dec 2 15:38:34 2016 (r309414)
+++ head/usr.bin/indent/parse.c Fri Dec 2 16:28:18 2016 (r309415)
@@ -94,7 +94,13 @@ parse(int tk) /* tk: the code for the co
case ifstmt: /* scanned if (...) */
if (ps.p_stack[ps.tos] == elsehead && ps.else_if) /* "else if
..." */
- ps.i_l_follow = ps.il[ps.tos];
+ /*
+ * Note that the stack pointer here is decremented, effectively
+ * reducing "else if" to "if". This saves a lot of stack space
+ * in case of a long "if-else-if ... else-if" sequence.
+ */
+ ps.i_l_follow = ps.il[ps.tos--];
+
/* the rest is the same as for dolit and forstmt */
case dolit: /* 'do' */
case forstmt: /* for (...) */
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