[SystemZ] Use zeroing form of RISBG for some AND sequences

RISBG can handle some ANDs for which no AND IMMEDIATE exists.
It also acts as a three-operand AND for some cases where an
AND IMMEDIATE could be used instead.

It might be worth adding a pass to replace RISBG with AND IMMEDIATE
in cases where the register operands end up being the same and where
AND IMMEDIATE is smaller.

llvm-svn: 186072
diff --git a/llvm/test/CodeGen/SystemZ/atomicrmw-nand-01.ll b/llvm/test/CodeGen/SystemZ/atomicrmw-nand-01.ll
index b5f2c10..260286f 100644
--- a/llvm/test/CodeGen/SystemZ/atomicrmw-nand-01.ll
+++ b/llvm/test/CodeGen/SystemZ/atomicrmw-nand-01.ll
@@ -14,15 +14,15 @@
 ;   independent of the other loop prologue instructions.
 define i8 @f1(i8 *%src, i8 %b) {
 ; CHECK: f1:
-; CHECK: sllg [[SHIFT:%r[1-9]+]], %r2, 3
-; CHECK: nill %r2, 65532
-; CHECK: l [[OLD:%r[0-9]+]], 0(%r2)
+; CHECK-DAG: sllg [[SHIFT:%r[1-9]+]], %r2, 3
+; CHECK-DAG: risbg [[BASE:%r[1-9]+]], %r2, 0, 189, 0
+; CHECK: l [[OLD:%r[0-9]+]], 0([[BASE]])
 ; CHECK: [[LABEL:\.[^:]*]]:
 ; CHECK: rll [[ROT:%r[0-9]+]], [[OLD]], 0([[SHIFT]])
 ; CHECK: nr [[ROT]], %r3
 ; CHECK: xilf [[ROT]], 4278190080
 ; CHECK: rll [[NEW:%r[0-9]+]], [[ROT]], 0({{%r[1-9]+}})
-; CHECK: cs [[OLD]], [[NEW]], 0(%r2)
+; CHECK: cs [[OLD]], [[NEW]], 0([[BASE]])
 ; CHECK: jlh [[LABEL]]
 ; CHECK: rll %r2, [[OLD]], 8([[SHIFT]])
 ; CHECK: br %r14
@@ -50,15 +50,15 @@
 ; Check the minimum signed value.  We AND the rotated word with 0x80ffffff.
 define i8 @f2(i8 *%src) {
 ; CHECK: f2:
-; CHECK: sllg [[SHIFT:%r[1-9]+]], %r2, 3
-; CHECK: nill %r2, 65532
-; CHECK: l [[OLD:%r[0-9]+]], 0(%r2)
+; CHECK-DAG: sllg [[SHIFT:%r[1-9]+]], %r2, 3
+; CHECK-DAG: risbg [[BASE:%r[1-9]+]], %r2, 0, 189, 0
+; CHECK: l [[OLD:%r[0-9]+]], 0([[BASE]])
 ; CHECK: [[LABEL:\.[^:]*]]:
 ; CHECK: rll [[ROT:%r[0-9]+]], [[OLD]], 0([[SHIFT]])
 ; CHECK: nilh [[ROT]], 33023
 ; CHECK: xilf [[ROT]], 4278190080
 ; CHECK: rll [[NEW:%r[0-9]+]], [[ROT]], 0([[NEGSHIFT:%r[1-9]+]])
-; CHECK: cs [[OLD]], [[NEW]], 0(%r2)
+; CHECK: cs [[OLD]], [[NEW]], 0([[BASE]])
 ; CHECK: jlh [[LABEL]]
 ; CHECK: rll %r2, [[OLD]], 8([[SHIFT]])
 ; CHECK: br %r14