[AVR]  Optimize 16-bit ANDs with '1'

Summary: Fixes PR 31345

Reviewers: dylanmckay

Subscribers: fhahn, llvm-commits

Differential Revision: https://reviews.llvm.org/D28186

llvm-svn: 290778
diff --git a/llvm/test/CodeGen/AVR/and.ll b/llvm/test/CodeGen/AVR/and.ll
index 7f0e8ac..de5bdf9 100644
--- a/llvm/test/CodeGen/AVR/and.ll
+++ b/llvm/test/CodeGen/AVR/and.ll
@@ -67,7 +67,8 @@
 define i64 @and64_reg_imm(i64 %a) {
 ; CHECK-LABEL: and64_reg_imm:
 ; CHECK: andi r18, 253
-; CHECK: andi r19, 255
+; Per PR 31345, we optimize away ANDI Rd, 0xff
+; CHECK-NOT: andi r19, 255
 ; CHECK: andi r20, 155
 ; CHECK: andi r21, 88
 ; CHECK: andi r22, 76