fixup! [M68k] Fix backwards BTST condition

Add a CodeGen test case for lowering AND mask to BTST

Author: dansalvato

llvm/test/CodeGen/M68k/Bits/btst.ll

@@ -1,8 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc < %s -mtriple=m68k-freestanding -verify-machineinstrs | FileCheck %s
 
-define fastcc i16 @test1(i16 %a) nounwind {
-; CHECK-LABEL: test1:
+define fastcc i16 @switch_to_btst(i16 %a) nounwind {
+; CHECK-LABEL: switch_to_btst:
 ; CHECK:       ; %bb.0: ; %entry
 ; CHECK-NEXT:    move.l %d0, %d1
 ; CHECK-NEXT:    and.l #65535, %d1
@@ -35,3 +35,28 @@ define fastcc i16 @test1(i16 %a) nounwind {
   no_match:
     ret i16 0
 }
+
+define fastcc i16 @and_mask_to_btst(i8 %a, i8 %b) nounwind {
+; CHECK-LABEL: and_mask_to_btst:
+; CHECK:       ; %bb.0:
+; CHECK-NEXT:    and.l #7, %d1
+; CHECK-NEXT:    btst %d1, %d0
+; CHECK-NEXT:    beq .LBB1_1
+; CHECK-NEXT:  ; %bb.2: ; %cond_false
+; CHECK-NEXT:    moveq #0, %d0
+; CHECK-NEXT:    rts
+; CHECK-NEXT:  .LBB1_1: ; %cond_true
+; CHECK-NEXT:    moveq #1, %d0
+; CHECK-NEXT:    rts
+  %33 = and i8 %b, 7
+  %34 = shl nuw i8 1, %33
+  %35 = and i8 %34, %a
+  %.not = icmp eq i8 %35, 0
+  br i1 %.not, label %cond_true, label %cond_false
+
+  cond_true:
+    ret i16 1
+
+  cond_false:
+    ret i16 0
+}