svn commit: r316100 - head/sys/boot/i386/boot2

[Warner Losh]

Author: imp
Date: Tue Mar 28 18:09:01 2017
New Revision: 316100
URL: https://svnweb.freebsd.org/changeset/base/316100

Log:
  Remove -fno-guess-branch-probability and -fno-unit-at-a-time.
  
  bde enabled -fno-guess-branch-probability in 2003, well before our
  current compiler was imported. At the time it produced weirdly orded
  code. It no longer does that. It also saves 0-4 bytes depending on
  other options.
  
  kan disabled unit-at-a-time in 2004 because it badly mangled boot2 so
  it wouldn't work. That too was before the 4.2.1 compiler, where it no
  longer does that. This saves 44 bytes.
  
  I had planned to document why they were needed, but when I discovered
  their antiquity, I removed them and boot2 still works and is
  smaller. In qemu, the old and new boot2's behaved identically.
  
  These are gcc specific hacks, and won't affect clang-built boot2
  at all.

Modified:
  head/sys/boot/i386/boot2/Makefile

Modified: head/sys/boot/i386/boot2/Makefile
==============================================================================
--- head/sys/boot/i386/boot2/Makefile	Tue Mar 28 17:37:49 2017	(r316099)
+++ head/sys/boot/i386/boot2/Makefile	Tue Mar 28 18:09:01 2017	(r316100)
@@ -38,8 +38,6 @@ CFLAGS=	-fomit-frame-pointer \
 	-Winline
 
 CFLAGS.gcc+=	-Os \
-		-fno-guess-branch-probability \
-		-fno-unit-at-a-time \
 		--param max-inline-insns-single=100
 .if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} <= 40201
 CFLAGS.gcc+=   -mno-align-long-strings