Add regression tests for null-byte handling when assigning to SV strings

Check that when assigning or casting a string literal or vector to a SV
string type that null-bytes are removed.

Also check that writing a null-byte to an element of a string variable is
ignored.

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

ivtest/ivltests/sv_string8.v

@@ -0,0 +1,43 @@
+// Check that null-bytes are removed when converting to string type.
+
+module test;
+
+  reg failed = 1'b0;
+
+  `define check(val, exp) \
+    if (val != exp) begin \
+      $display("FAILED(%0d): Expected '%0s', got '%0s'.", `__LINE__, exp, val); \
+      failed = 1'b1; \
+    end
+
+  string s;
+  reg [47:0] x;
+
+  initial begin
+    s = "\000a\000b\000";
+    `check(s, "ab");
+
+    s = string'("\000a\000b\000");
+    `check(s, "ab");
+
+    s = string'(48'h0061006200);
+    `check(s, "ab");
+
+    x = 48'h0061006200;
+    s = string'(x);
+    `check(s, "ab");
+
+    s = "cd";
+    s = {s, "\000a\000b\000"};
+    `check(s, "cdab");
+
+    s = "cd";
+    s = {"\000a\000b\000", s};
+    `check(s, "abcd");
+
+    if (!failed) begin
+      $display("PASSED");
+    end
+  end
+
+endmodule

ivtest/ivltests/sv_string9.v

@@ -0,0 +1,33 @@
+// Check that null-bytes are ignored when assigning to an element of a string
+// type variable.
+
+module test;
+
+  reg failed = 1'b0;
+
+  `define check(val, exp) \
+    if (val != exp) begin \
+      $display("FAILED(%0d): Expected '%0s', got '%0s'.", `__LINE__, exp, val); \
+      failed = 1'b1; \
+    end
+
+  string s;
+  byte x;
+
+  initial begin
+    s = "Test";
+
+    s[1] = 8'h00; // This should be ignored
+    `check(s, "Test");
+    s[1] = "\000"; // This should be ignored
+    `check(s, "Test");
+    x = 8'h00;
+    s[1] = x; // This should be ignored
+    `check(s, "Test");
+
+    if (!failed) begin
+      $display("PASSED");
+    end
+  end
+
+endmodule

ivtest/regress-sv.list

@@ -753,6 +753,8 @@ sv_string5		normal,-g2009		ivltests
 sv_string6		normal,-g2009		ivltests
 sv_string7		normal,-g2009		ivltests
 sv_string7b		normal,-g2009		ivltests
+sv_string8		normal,-g2009		ivltests
+sv_string9		normal,-g2009		ivltests
 sv_timeunit_prec1	normal,-g2005-sv	ivltests
 sv_timeunit_prec2	normal,-g2009		ivltests
 sv_timeunit_prec3a	normal,-g2005-sv	ivltests gold=sv_timeunit_prec3a.gold

ivtest/regress-vlog95.list

@@ -309,6 +309,8 @@ sv_string5		CE,-g2009		ivltests
 sv_string6		CE,-g2009,-pallowsigned=1	ivltests
 sv_string7		CE,-g2009,-pallowsigned=1	ivltests
 sv_string7b		CE,-g2009,-pallowsigned=1	ivltests
+sv_string8		CE,-g2009		ivltests
+sv_string9		CE,-g2009		ivltests
 sv_ps_function6		CE,-g2009,-pallowsigned=1	ivltests
 sv_typedef_fwd_base	CE,-g2009		ivltests
 vhdl_string_lim		CE,-g2005-sv,-pallowsigned=1,ivltests/vhdl_string_lim.vhd	ivltests