From 2b0ff67df6dfed7d93ebe753eab9ea67bea99e86 Mon Sep 17 00:00:00 2001 From: pfg Date: Fri, 2 Dec 2016 16:28:18 +0000 Subject: [PATCH] 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 --- usr.bin/indent/parse.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/usr.bin/indent/parse.c b/usr.bin/indent/parse.c index 52f21270096e..b2afe54413bd 100644 --- a/usr.bin/indent/parse.c +++ b/usr.bin/indent/parse.c @@ -94,7 +94,13 @@ parse(int tk) /* tk: the code for the construct scanned */ 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 (...) */