Unit test for SCEV fix r182989, PR16130.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183017 91177308-0d34-0410-b5e6-96231b3b80d8

test/Analysis/ScalarEvolution/trip-count10.ll

@@ -3,7 +3,7 @@
 ; Trip counts with trivial exit conditions.
 
 ; CHECK: Determining loop execution counts for: @a
-; CHECK: Loop %loop: Unpredictable backedge-taken count. 
+; CHECK: Loop %loop: Unpredictable backedge-taken count.
 ; CHECK: Loop %loop: Unpredictable max backedge-taken count.
 
 ; CHECK: Determining loop execution counts for: @b
@@ -15,8 +15,8 @@
 ; CHECK: Loop %loop: max backedge-taken count is false
 
 ; CHECK: Determining loop execution counts for: @d
-; CHECK: Loop %loop: Unpredictable backedge-taken count. 
-; CHECK: Loop %loop: Unpredictable max backedge-taken count. 
+; CHECK: Loop %loop: Unpredictable backedge-taken count.
+; CHECK: Loop %loop: Unpredictable max backedge-taken count.
 
 define void @a(i64 %n) nounwind {
 entry:
@@ -124,3 +124,28 @@ loop:
 return:
   ret void
 }
+
+; PR16130: Loop exit depends on an 'or' expression.
+; One side of the expression test against a value that will be skipped.
+; We can't assume undefined behavior just because we have an NSW flag.
+;
+; CHECK: Determining loop execution counts for: @exit_orcond_nsw
+; CHECK: Loop %for.body.i: Unpredictable backedge-taken count.
+; CHECK: Loop %for.body.i: max backedge-taken count is 1
+define void @exit_orcond_nsw(i32 *%a) nounwind {
+entry:
+  br label %for.body.i
+
+for.body.i:                                       ; preds = %for.body.i, %entry
+  %b.01.i = phi i32 [ 0, %entry ], [ %add.i, %for.body.i ]
+  %tobool.i = icmp ne i32 %b.01.i, 0
+  %add.i = add nsw i32 %b.01.i, 8
+  %cmp.i = icmp eq i32 %add.i, 13
+  %or.cond = or i1 %tobool.i, %cmp.i
+  br i1 %or.cond, label %exit, label %for.body.i
+
+exit:                                     ; preds = %for.body.i
+  %b.01.i.lcssa = phi i32 [ %b.01.i, %for.body.i ]
+  store i32 %b.01.i.lcssa, i32* %a, align 4
+  ret void
+}