diff -r 01125acb5565 sys/src/cmd/5l/asm.c
--- a/sys/src/cmd/5l/asm.c	Tue Jan 19 19:56:38 2021 -0800
+++ b/sys/src/cmd/5l/asm.c	Wed Jan 20 07:48:56 2021 -0800
@@ -789,6 +789,12 @@
 		r = p->reg;
 		if(r == NREG)
 			r = p->to.reg;
+		/*
+		 * R>>32 is encoded as R>>0, so flip to the
+		 * equivalent R<<0.
+		 */
+		if(instoffset == 0)
+			o1 &= ~(3<<5);
 		o1 |= r;
 		o1 |= (instoffset&31) << 7;
 		o1 |= p->to.reg << 12;