The compiler options for -mmmx, -msse, etc, serve two purposes: 1. They allow the programmer to use the compiler built-ins for easily writing MMX/SSE code. 2. They allow the compiler to use MMX/SSE instructions in generated code. However, the documentation does not explicitly state the second point, only the first. This had caused much confusion in the development community, as programmers using the MMX/SSE intrinsics often use runtime CPU detection. The attached patch updates the documentation to be more explicit about the effect of these options.
Created attachment 9706 [details] Patch
Created attachment 9707 [details] Path This patch updates both the documentation of the command line options, and the documentation for the built-ins.
Target bug and not related to the C front-end at all.
*** Bug 23892 has been marked as a duplicate of this bug. ***
Subject: Bug 23809 CVSROOT: /cvs/gcc Module name: gcc Changes by: bonzini@gcc.gnu.org 2005-10-05 08:27:44 Modified files: gcc : ChangeLog gcc/doc : extend.texi invoke.texi Log message: 2005-10-05 Billy Biggs <billy.biggs@gmail.com> Paolo Bonzini <bonzini@gnu.org> PR target/23809 * doc/extend.texi (x86 Built-ins): Document that -msse and friends enable the instructions and not just the built-ins. * doc/invoke.texi (x86 Options): Likewise. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.10086&r2=2.10087 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/doc/extend.texi.diff?cvsroot=gcc&r1=1.267&r2=1.268 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/doc/invoke.texi.diff?cvsroot=gcc&r1=1.682&r2=1.683
Patch committed with some changes.