[LV] Precommit additional early-exit tests from llvm#174864.

Pre-commit tests from llvm#174864.

Author: fhahn

llvm/test/Transforms/LoopVectorize/early_exit_legality.ll

@@ -593,6 +593,45 @@ loop.end:
 }
 
 
+; Two early exits on parallel branches (neither dominates the other).
+define i64 @uncountable_exits_on_parallel_branches() {
+; CHECK-LABEL: LV: Checking a loop in 'uncountable_exits_on_parallel_branches'
+; CHECK:       LV: Not vectorizing: Loop has too many uncountable exits.
+entry:
+  %p1 = alloca [1024 x i8]
+  %p2 = alloca [1024 x i8]
+  call void @init_mem(ptr %p1, i64 1024)
+  call void @init_mem(ptr %p2, i64 1024)
+  br label %header
+
+header:
+  %index = phi i64 [ %index.next, %latch ], [ 3, %entry ]
+  %arrayidx = getelementptr inbounds i8, ptr %p1, i64 %index
+  %ld1 = load i8, ptr %arrayidx, align 1
+  %branch.cond = icmp sgt i8 %ld1, 0
+  br i1 %branch.cond, label %left, label %right
+
+left:
+  %arrayidx.left = getelementptr inbounds i8, ptr %p2, i64 %index
+  %ld.left = load i8, ptr %arrayidx.left, align 1
+  %cmp.left = icmp eq i8 %ld1, %ld.left
+  br i1 %cmp.left, label %loop.end, label %latch
+
+right:
+  %cmp.right = icmp ult i8 %ld1, 34
+  br i1 %cmp.right, label %loop.end, label %latch
+
+latch:
+  %index.next = add i64 %index, 1
+  %exitcond = icmp ne i64 %index.next, 67
+  br i1 %exitcond, label %header, label %loop.end
+
+loop.end:
+  %retval = phi i64 [ %index, %left ], [ 100, %right ], [ 43, %latch ]
+  ret i64 %retval
+}
+
+
 declare i32 @foo(i32) readonly
 declare <vscale x 4 x i32> @foo_vec(<vscale x 4 x i32>)