an old fix made for inferno on nintendo that i made
in 5l locally but apparently didn't pass on.
in the mov/mvn instructions there's a field that must be zero.

Reference: /n/sources/patch/applied/5l-mbz
Date: Sun Feb  7 17:43:29 CET 2010
Signed-off-by: forsyth@terzarima.net

--- /sys/src/cmd/5l/asm.c	Sun Feb  7 17:41:48 2010
+++ /sys/src/cmd/5l/asm.c	Sun Feb  7 17:41:44 2010
@@ -638,7 +638,9 @@
 		r = p->reg;
 		if(p->to.type == D_NONE)
 			rt = 0;
-		if(r == NREG)
+		if(p->as == AMOVW || p->as == AMVN)
+			r = 0;
+		else if(r == NREG)
 			r = rt;
 		o1 |= rf | (r<<16) | (rt<<12);
 		break;
@@ -651,7 +653,9 @@
 		r = p->reg;
 		if(p->to.type == D_NONE)
 			rt = 0;
-		if(r == NREG)
+		if(p->as == AMOVW || p->as == AMVN)
+			r = 0;
+		else if(r == NREG)
 			r = rt;
 		o1 |= (r<<16) | (rt<<12);
 		break;
@@ -665,7 +669,9 @@
 		r = p->reg;
 		if(p->to.type == D_NONE)
 			rt = 0;
-		if(r == NREG)
+		if(p->as == AMOVW || p->as == AMVN)
+			r = 0;
+		else if(r == NREG)
 			r = rt;
 		o1 |= (r<<16) | (rt<<12);
 		break;
@@ -772,7 +778,9 @@
 		o2 = oprrr(p->as, p->scond);
 		o2 |= REGTMP;
 		r = p->reg;
-		if(r == NREG)
+		if(p->as == AMOVW || p->as == AMVN)
+			r = 0;
+		else if(r == NREG)
 			r = p->to.reg;
 		o2 |= r << 16;
 		if(p->to.type != D_NONE)