Date: Fri, 2 Dec 2016 16:28:19 +0000 (UTC) From: "Pedro F. Giffuni" <pfg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r309415 - head/usr.bin/indent Message-ID: <201612021628.uB2GSJVP004892@repo.freebsd.org>
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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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