>From b90841e2583237a4132bbbd74752e0e9563660cd Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Sun, 21 May 2023 12:16:11 -0400 Subject: [PATCH] configure: replace -Os with equivalent based on -O2 aside from the documented differences, which are the contents of this patch, GCC's -Os also has hard-coded unwanted behaviors which are impossible to override, like refusing to strength-reduce division by a constant to multiplication, presumably because the div saves a couple bytes of code. for this reason, getting rid of -Os and switching to an equivalent default optimization profile based on -O2 has been a long-term goal. as follow-ups, it may make sense to evaluate which of these variations from -O2 actually do anything useful, and eliminate the ones which are not helpful or which throw away performance for insignificant size savings. but for now, I've replicated -Os as closely as possible to provide a baseline for such evaluation. --- configure | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/configure b/configure index 853bf05e..0b966ede 100755 --- a/configure +++ b/configure @@ -444,7 +444,20 @@ xno|x) printf "disabled\n" ; optimize=no ;; *) printf "custom\n" ;; esac -test "$optimize" = no || tryflag CFLAGS_AUTO -Os || tryflag CFLAGS_AUTO -O2 +if test "$optimize" = no ; then : +else +tryflag CFLAGS_AUTO -O2 +tryflag CFLAGS_AUTO -fno-align-jumps +tryflag CFLAGS_AUTO -fno-align-functions +tryflag CFLAGS_AUTO -fno-align-loops +tryflag CFLAGS_AUTO -fno-align-labels +tryflag CFLAGS_AUTO -fira-region=one +tryflag CFLAGS_AUTO -fira-hoist-pressure +tryflag CFLAGS_AUTO -freorder-blocks-algorithm=simple \ +|| tryflag CFLAGS_AUTO -fno-reorder-blocks +tryflag CFLAGS_AUTO -fno-prefetch-loop-arrays +tryflag CFLAGS_AUTO -fno-tree-ch +fi test "$optimize" = yes && optimize="internal,malloc,string" if fnmatch 'no|size' "$optimize" ; then : -- 2.21.0