Merge pull request herd#1797 from herd/one-more-self-test

[test] New test
The new test restores S27 previous intent more explicitly.

Author: maranget

herd/tests/instructions/AArch64.self/S27.litmus

@@ -12,13 +12,13 @@ ins_t* 0:X3;
  LDR W4,[X0]  ;
  ADD W6,W6,#2 ;
  B .+8        ;
-L0:           ;              
+L0:           ;
  ADR X3,L0    ;
  STR W4,[X1]  ;
 L1:           ;
  MOV W6,W2    ;
  LDR W5,[X1]  ;
 locations [0:X3;0:X6;]
 exists 0:X3=label:"P0:L1" /\ 0:X6=2
- 
+
 

herd/tests/instructions/AArch64.self/S30.litmus

@@ -0,0 +1,14 @@
+AArch64 S30
+(* Executing and reading as data may differ *)
+{
+0:X0=P0:L0;
+0:X2=NOP;
+}
+  P0          ;
+ ADD W1,W1,#1 ;
+ STR W2,[X0]  ;
+L0:           ;
+ B .+8        ;
+ ADD W1,W1,#2 ;
+ LDR W3,[X0]  ;
+exists 0:X3=NOP /\ 0:X1=3

herd/tests/instructions/AArch64.self/S30.litmus.expected

@@ -0,0 +1,11 @@
+Test S30 Allowed
+States 2
+0:X1=1; 0:X3=NOP;
+0:X1=3; 0:X3=NOP;
+Ok
+Witnesses
+Positive: 1 Negative: 1
+Condition exists (0:X3=NOP /\ 0:X1=3)
+Observation S30 Sometimes 1 1
+Hash=6180f61ca45d616cf867dd1481ec4e20
+