ivtest: Add regression test to check that shift rhs is always unsigned

Add a regression test to check that the right-hand side of a shift
operation is always treated as unsigned, even if it is a signed registers
or a variation thereof.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

ivtest/ivltests/shift6.v

@@ -0,0 +1,51 @@
+module test;
+
+// Check that the right hand side for a shift instruction is always treated as
+// unsigned. Even if its a signed register, or a transformation thereof.
+
+  reg failed = 1'b0;
+
+  `define check(val, exp) \
+    if ((val) !== (exp)) begin \
+      $display("FAILED(%0d): `%s`, expected `%0d`, got `%0d`.", `__LINE__, \
+               `"val`", (exp), (val), 4); \
+      failed = 1'b1; \
+    end
+
+  reg signed [1:0] shift = 2'b10;
+
+  initial begin
+    `check(1 << shift, 4)
+    `check(1 << shift[1:0], 4)
+    `check(2 << shift[1], 4)
+    `check(1 << $unsigned(shift), 4)
+    `check(1 << $signed(shift), 4)
+    `check(1 << {shift}, 4)
+
+    `check(1 <<< shift, 4)
+    `check(1 <<< shift[1:0], 4)
+    `check(2 <<< shift[1], 4)
+    `check(1 <<< $unsigned(shift), 4)
+    `check(1 <<< $signed(shift), 4)
+    `check(1 <<< {shift}, 4)
+
+    `check(16 >> shift, 4)
+    `check(16 >> shift[1:0], 4)
+    `check(8 >> shift[1], 4)
+    `check(16 >> $unsigned(shift), 4)
+    `check(16 >> $signed(shift), 4)
+    `check(16 >> {shift}, 4)
+
+    `check(16 >>> shift, 4)
+    `check(16 >>> shift[1:0], 4)
+    `check(8 >>> shift[1], 4)
+    `check(16 >>> $unsigned(shift), 4)
+    `check(16 >>> $signed(shift), 4)
+    `check(16 >>> {shift}, 4)
+
+    if (!failed) begin
+      $display("PASSED");
+    end
+  end
+
+endmodule

ivtest/regress-vvp.list

@@ -185,6 +185,7 @@ sf_countones_fail		vvp_tests/sf_countones_fail.json
 sf_isunknown_fail		vvp_tests/sf_isunknown_fail.json
 sf_onehot_fail			vvp_tests/sf_onehot_fail.json
 sf_onehot0_fail			vvp_tests/sf_onehot0_fail.json
+shift6				vvp_tests/shift6.json
 single_element_array		vvp_tests/single_element_array.json
 struct_enum_partsel		vvp_tests/struct_enum_partsel.json
 struct_field_left_right		vvp_tests/struct_field_left_right.json

ivtest/vvp_tests/shift6.json

@@ -0,0 +1,5 @@
+
+{
+    "type" : "normal",
+    "source" : "shift6.v"
+}