Add TCG native negation op.


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4426 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/tcg/README b/tcg/README
index c47d3b0..c879142 100644
--- a/tcg/README
+++ b/tcg/README
@@ -203,6 +203,10 @@
 
 t0=t1-t2
 
+* neg_i32/i64 t0, t1
+
+t0=-t1 (two's complement)
+
 * mul_i32/i64 t0, t1, t2
 
 t0=t1*t2