Date: Sat, 29 Jan 2011 00:02:39 GMT From: Yuri Karaban <tech@askold.net> To: freebsd-gnats-submit@FreeBSD.org Subject: ports/154364: lang/gcc45: generate i486 code by default for i386 architecture Message-ID: <201101290002.p0T02dbH072281@red.freebsd.org> Resent-Message-ID: <201101290010.p0T0A9oE092256@freefall.freebsd.org>
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>Number: 154364
>Category: ports
>Synopsis: lang/gcc45: generate i486 code by default for i386 architecture
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-ports-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Sat Jan 29 00:10:09 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator: Yuri Karaban
>Release: 8.1-RELEASE
>Organization:
>Environment:
>Description:
Since genuine 80386 machines is officially not supported by FreeBSD. It is safe to enable generation of i486 code by default.
This needed to enable atomic built-ins, which greatly speed up concurrent code. In standard C++ library std::string, using locking extensively and atomic built-ins will give noticeable speedup.
Needless to say, granting to use i486 instructions by default will speed up some programs which does not explicitly set -march.
I opened similar bug report (gnu/148926) regarding system gcc. The problem were solved by enabling some defines in c++config.h related to atomic builtins (since system gcc already generates i486 code by default).
Adding -with-arch=i486 to configure options is sufficient for lang/gcc45. The gcc will generate i486 code by default and libstdc++ shipped with it will be auto-configured to use atomic built-ins without need to edit c++config.h manually.
I'm attaching the patch which adds -with-arch=i486 for i386 architecture.
>How-To-Repeat:
>Fix:
Patch attached with submission follows:
--- Makefile.orig 2011-01-28 21:33:11.000000000 +0200
+++ Makefile 2011-01-29 00:44:53.000000000 +0200
@@ -66,6 +66,10 @@
CONFIGURE_TARGET= ${ARCH}-portbld-freebsd${OSREL}
.endif
+.if ${ARCH} == "i386"
+CONFIGURE_ARGS+= --with-arch=i486
+.endif
+
SRCDIR= ${WRKDIR}/gcc-${VERSIONSTRING}
WRKSRC= ${WRKDIR}/build
TARGLIB= ${PREFIX}/lib/gcc${SUFFIX}
>Release-Note:
>Audit-Trail:
>Unformatted:
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