From 8141ca5d63f54cb9ba86b18d3b7cc377af17edfb Mon Sep 17 00:00:00 2001
From: Michael Munday <munday@ca.ibm.com>
Date: Mon, 30 Jan 2017 16:24:06 -0500
Subject: [PATCH] Simplify right rotations.

---
 src/vm_s390x.dasc | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/src/vm_s390x.dasc b/src/vm_s390x.dasc
index ce5e14c8..5ebd20c0 100644
--- a/src/vm_s390x.dasc
+++ b/src/vm_s390x.dasc
@@ -1899,7 +1899,6 @@ static void build_subroutines(BuildCtx *ctx)
   |  // Note: no inline conversion from number for 2nd argument!
   |  lg RA, 8(BASE)
   |  checkint RA, ->fff_fallback
-  |  // Note: no need to limit rotate to 5-bits (wraps).
   |  rll RB, RB, 0(RA)
   |  j ->fff_resbit
   |
@@ -1907,11 +1906,7 @@ static void build_subroutines(BuildCtx *ctx)
   |  // Note: no inline conversion from number for 2nd argument!
   |  lg RA, 8(BASE)
   |  checkint RA, ->fff_fallback
-  |  // TODO: shorter sequence of instructions to convert right rotate into left rotate.
-  |  nill RA, 0x1f
-  |  lghi TMPR0, 32
-  |  sr TMPR0, RA
-  |  lr RA, TMPR0
+  |  lcr RA, RA		// Right rotate equivalent to negative left rotate.
   |  rll RB, RB, 0(RA)
   |  j ->fff_resbit
   |