[HW] Enable parametric polymorphism for module parameters

[bubblepipe42]

The current implementation of parametric polymorphism in modules, as described in the CIRCT documentation, supports input and output types but does not extend to parameters.

For example, given a parameter <DATA_WIDTH: i32>, it is possible to define an argument like in %input : !hw.int<#hw.param.decl.ref<"DATA_WIDTH">> , but it is not possible to define a parameter such as <RESET_VALUE: !hw.int<#hw.param.decl.ref<"DATA_WIDTH">>>

Consider the following code snippet:

hw.module.extern @param_in_param< 
  RESET_VALUE: !hw.int<#hw.param.decl.ref<"DATA_WIDTH">>, 
  DATA_WIDTH: i32 = 32
>( 
  in %input : !hw.int<#hw.param.decl.ref<"DATA_WIDTH">>, 
  out output : !hw.int<#hw.param.decl.ref<"DATA_WIDTH">>
)

hw.module @param_in_param_inst(
  in %input : i96,
  in %clk : i1, 
  in %rst : i1, 
  out output : i96
) {
  %a.output = hw.instance "a" @param_in_param<
    RESET_VALUE: i96 = 0, 
    DATA_WIDTH: i32 = 96
  >(
    input: %input: i96
  ) -> (output: i96)
  hw.output %a.output : i96
}

In this example, with the parameter DATA_WIDTH: i32 = 96 , the argument in %input of type hw.int<#hw.param.decl.ref<"DATA_WIDTH">> is correctly matched with input: %input: i96 through a simple substitution. However, circt-opt fails to recognize that RESET_VALUE: i96 is the equivalent to RESET_VALUE: !hw.int<#hw.param.decl.ref<"DATA_WIDTH">> . Instead it emits the following error message:

<source>:4:15: error: 'hw.instance' op parameter "RESET_VALUE" should have type '!hw.int<#hw.param.decl.ref<"DATA_WIDTH">>' but has type 'i96'
  %a.output = hw.instance "a" @param_in_param<RESET_VALUE: i96 = 0, DATA_WIDTH: i32 = 96>(input: %input: i96) -> (output: i96)
              ^
<source>:4:15: note: see current operation: %0 = "hw.instance"(%arg0) <{argNames = ["input"], instanceName = "a", moduleName = @param_in_param, parameters = [#hw.param.decl<"RESET_VALUE": i96 = 0> : i96, #hw.param.decl<"DATA_WIDTH": i32 = 96> : i32], resultNames = ["output"]}> : (i96) -> i96
<source>:1:1: note: module declared here
hw.module.extern @param_in_param<RESET_VALUE: !hw.int<#hw.param.decl.ref<"DATA_WIDTH">>, DATA_WIDTH: i32 = 32>(in %input : !hw.int<#hw.param.decl.ref<"DATA_WIDTH">>, out output : !hw.int<#hw.param.decl.ref<"DATA_WIDTH">>)
^
Compiler returned: 1

This issue can be reproduced using the following demo: Godbolt Link.

My proposed PR addresses this limitation and enables parametric polymorphism for module parameters, ensuring that types like !hw.int<#hw.param.decl.ref<"DATA_WIDTH">> are correctly recognized and validated.