Local function inside generate statement can't be resolved

[hzeller]

Consider the following; important is the local function inside the generate statement which then is used right after it is defined

module C #(
    parameter int width = 2,
    parameter DO_INCREMENT = 1
) (
    input clk,
    output [width-1:0] counter
);

  logic [width-1:0] foo;
  generate
    if (DO_INCREMENT == 1) begin
      function automatic [width-1:0] local_increment_function(input [width-1:0] x);
        local_increment_function = x + 1;
      endfunction
      assign foo = local_increment_function(counter);
    end else begin
      assign foo = counter;
    end
  endgenerate
  // ... do stuff with foo
endmodule

module make_instances (
    input clk,
    output logic [31:0] foo
);
  C #(
      .DO_INCREMENT(1)
  ) c (
      clk,
      foo
  );
endmodule

Generating UHDM with Surelog and then reading it with yosys with the systemverilog plugin compiled in

surelog -nobuiltin -verbose -parse -sv filename-above.sv
yosys -p "read_uhdm slpp_all/surelog.uhdm"

... will then complain that it can't resolve the function \local_increment_function

1. Executing UHDM frontend.
Warning: Removing unused module: \C from the design.
Generating RTLIL representation for module `$paramod\C\width=32'd2\DO_INCREMENT=32'd1'.
fun_in_generate.sv:15: ERROR: Can't resolve function name `\local_increment_function'.

Expectation is that the function can be resolved and used (processing the same file with 'plain' yosys works fine).

It is unclear if this is a Surelog -> UHDM name manglilng problem or a UHDM -> Yosys plugin problem. So adding here to triage.

CC @alaindargelas

[alaindargelas]

I'll check the former possibility

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---

From: Henner Zeller @.> Sent: Friday, May 6, 2022 12:43:01 PM To: chipsalliance/yosys-f4pga-plugins @.> Cc: alaindargelas @.>; Mention @.> Subject: [chipsalliance/yosys-f4pga-plugins] Local function inside generate statement can't be resolved (Issue #313)

Consider the following; important is the local function inside the generate statement which then is used right after it is defined

module C #( parameter int width = 2, parameter DO_INCREMENT = 1 ) ( input clk, output [width-1:0] counter );

logic [width-1:0] foo; generate if (DO_INCREMENT == 1) begin function automatic [width-1:0] local_increment_function(input [width-1:0] x); local_increment_function = x + 1; endfunction assign foo = local_increment_function(counter); end else begin assign foo = counter; end endgenerate // ... do stuff with foo endmodule

module make_instances ( input clk, output logic [31:0] foo ); C #( .DO_INCREMENT(1) ) c ( clk, foo ); endmodule

Generating UHDM with Surelog and then reading it with yosys with the systemverilog pluginhttps://github.com/chipsalliance/yosys-f4pga-plugins/tree/main/systemverilog-plugin compiled in

surelog -nobuiltin -verbose -parse -sv filename-above.sv yosys -p "read_uhdm ${SURELOG_TMP}/slpp_all/surelog.uhdm"

... will then complain that it can't resolve the function \local_increment_function

1. Executing UHDM frontend. Warning: Removing unused module: \C from the design. Generating RTLIL representation for module $paramod\C\width=32'd2\DO_INCREMENT=32'd1'. fun_in_generate.sv:15: ERROR: Can't resolve function name\local_increment_function'.

Expectation is that the function can be resolved and used (processing the same file with 'plain' yosys works fine).

It is unclear if this is a Surelog -> UHDM name manglilng problem or a UHDM -> Yosys plugin problem. So adding here to triage.

CC @alaindargelashttps://github.com/alaindargelas

— Reply to this email directly, view it on GitHubhttps://github.com/chipsalliance/yosys-f4pga-plugins/issues/313, or unsubscribehttps://github.com/notifications/unsubscribe-auth/APFYJ5CYSVSECHFE7ICFJB3VIVY4LANCNFSM5VJCTMIA. You are receiving this because you were mentioned.Message ID: @.***>

[alaindargelas]

After checking several scenario with commercial simulator I concluded that the VPI Object model for gen_scope is wrong, I added a task_func property in the model and now this allows to have local declaration of tasks and funcs local to the gen_scope. Prior to this UHDM was storing the function definition in the parent module of the gen_scope (Due to the limitation of the Standard Object Model). There must be a corresponding change that needs to happen in the plugin to iterate through the newly added function declaration in the gen_scope.

https://github.com/chipsalliance/UHDM/pull/711 https://github.com/chipsalliance/Surelog/pull/2915

[hzeller]

Thanks @alaindargelas @tgorochowik @rkapuscik Adding the corresponding relevant support in the plugin would be a high priority request from us.

[alaindargelas]

Please also note that this slightly different case is legal (The hier path access into the gen_scope from outside the gen_scope part): https://github.com/chipsalliance/Surelog/blob/master/tests/GenScopeFunc/dut.sv And is now supported: https://github.com/chipsalliance/Surelog/pull/2916

[rkapuscik]

@hzeller #314 should make this work (your example passes for me now), please confirm.

[hzeller]

affirmative :)