Add test for non-contiguous memory init

Also negative memory addresses.

tests/check_mem/init_correct.ys

@@ -0,0 +1,44 @@
+read -sv << EOT
+module top;
+  (* nomem2reg *)
+  logic a1 [2:3][3:1] = '{'{0, 1, 1}, '{1, 0, 1}};
+
+  always_comb begin
+    assert(a1[2][3] == 0);
+    assert(a1[2][2] == 1);
+    assert(a1[2][1] == 1);
+    assert(a1[3][3] == 1);
+    assert(a1[3][2] == 0);
+    assert(a1[3][1] == 1);
+  end
+
+  (* nomem2reg *)
+  logic [1:0] a2 [6:5][2:4] = '{'{0, 1, 2}, '{1, 0, 3}};
+
+  always_comb begin
+    assert(a2[6][2] == 0);
+    assert(a2[6][3] == 1);
+    assert(a2[6][4] == 2);
+    assert(a2[5][2] == 1);
+    assert(a2[5][3] == 0);
+    assert(a2[5][4] == 3);
+  end
+
+  (* nomem2reg *)
+  logic [1:0] a3 [-2:-1][-1:1] = '{'{0, 1, 2}, '{1, 0, 3}};
+
+  always_comb begin
+    assert(a3[-2][-1] == 0);
+    assert(a3[-2][0] == 1);
+    assert(a3[-2][1] == 2);
+    assert(a3[-1][-1] == 1);
+    assert(a3[-1][0] == 0);
+    assert(a3[-1][1] == 3);
+  end
+endmodule
+EOT
+hierarchy
+proc
+memory
+async2sync
+sat -enable_undef -verify -prove-asserts

tests/check_mem/negative_idx.sv

@@ -0,0 +1,13 @@
+module top;
+  (* nomem2reg *)
+  logic [1:0] a3 [-2:-1][-1:1] = '{'{0, 1, 2}, '{1, 0, 3}};
+
+  always_comb begin
+    assert(a3[-2][-1] == 0);
+    assert(a3[-2][0] == 1);
+    assert(a3[-2][1] == 2);
+    assert(a3[-1][-1] == 1);
+    assert(a3[-1][0] == 0);
+    assert(a3[-1][1] == 3);
+  end
+endmodule