AR #32985 - 11.2 XST - "WARNING:HDLCompiler:871 - "<file>.vhd" Line xx: Using initial value -2147483647 for tmp since it is never assigned"
11.2 XST - "WARNING:HDLCompiler:871 - "<file>.vhd" Line xx: Using initial value -2147483647 for tmp since it is never assigned"
| AR# | 32985 |
| Part | SW-XST |
| Last Modified | 2009-06-24 00:00:00.0 |
| Status | Active |
| Keywords | XST, Spartan-6, Virtex-6, 11.2 , Parser, HDLCompiler:871,WARNING:Xst:653 |
Description
Keywords: XST, Spartan-6, Virtex-6, 11.2 , Parser, HDLCompiler:871,WARNING:Xst:653
The following warning occurs in XST when I target Virtex-6 or Spartan-6 devices, but I do not have any issues when targeting older devices. Why?
WARNING:HDLCompiler:871 - "<file>.vhd" Line xx: Using initial value -2147483647 for tmp since it is never assigned
Example Code:
library ieee;
use ieee.std_logic_1164.all;
entity ex_0013 is
port(res: out integer
);
end ex_0013;
architecture bhv of ex_0013 is
signal tmp: integer; -- Note: Warning points here
begin
res <= tmp;
end;
Solution
XST takes into account initial values of VHDL types in the synthesis process. According to VHDL LRM, the initial value of type integer or float is the left-most value.XST for Virtex-6 and Spartan-6 families follows VHDL LRM rules and takes the left-most value for non-initialized integer or float type, resulting in the warning message in the case of integer type.
In 11.2, XST introduced a new VHDL/Verilog parser for Virtex-6 and Spartan-6 families. For more information on this change, see (Xilinx Answer 32927).