C++ multithreading in IcarusVerilog

[esther-78]

Hello,
I added a C++ code directory at the same hierarchy as tgt-vvp, that I call tgt-cmp. In that code, I retrieve the C++ structure of the design of a verilog netlist, and then I do heavy operations on that structure. To make the execution faster, I would like to multithread the operations. So I multithreaded my functions, I added the -pthread flag in the tgt-cmp/Makefile.in file, I generated the Makefile with the ./configure etc. But when I run the program, it gives me the famous error "Enable multithreading to use std::thread: Operation not permitted". Then I saw this post: #495 and I wondered if things evolved from the date of this question or not ? Also, the answer of this post says it is a hard thing to use multithread with IcarusVerilog, but it does not say that it is impossible. Would you have any comment or advice on how to make C++ multithreading work with IcarusVerilog please?
Thanks you a lot!

[martinwhitaker]

The hard thing about making a Verilog simulator multi-threaded is preventing the inter-thread communication dominating the overall execution time. Verilog models generally consist of many parallel tasks, but they are normally highly inter-dependent. To make a viable multi-threaded simulator, you would need to assign highly-related tasks to the same CPU thread and ensure the CPU threads rarely needed to communicate.

Your tgt-cmp may be different, and more easily mapped to multiple threads.

The iverilog targets are DLLs that are loaded by the main compiler. Maybe you need to add the -pthread flag in the top level Makefile as well.

[esther-78]

Thank you a lot for your answer. My tgt-cmp is only composed of C++ source codes and the main program in tgt-cmp can completely be multithreaded. My issue is that I do not manage to find how to place the right flag in the Makefile of tgt-cmp and / or in the top level Makefile.