manpage: -flegacy-vector-maths

diff --git a/doc/gmqcc.1 b/doc/gmqcc.1
index fe4909bbeeac5295a73b3c176227900c2416761e..5240c4ea516026307d08ff85fda4a66016ee0443 100644 (file)
--- a/doc/gmqcc.1
+++ b/doc/gmqcc.1
@@ -498,6 +498,10 @@ void vafunc(string...count) {
 }
 .fi
 .in
+.TP -flegacy-vector-maths
+Most Quake VMs, including the one from FTEQW or up till recently
+Darkplaces, do not cope well with vector instructions with overlapping
+input and output. This option will avoid producing such code.
 .SH OPTIMIZATIONS
 .TP
 .B -Opeephole