Read Initial Placement #2666
Read Initial Placement #2666
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| } | ||
| if(!placer_opts.read_initial_place_file.empty()) { | ||
| const auto& grid = g_vpr_ctx.device().grid; | ||
| read_place(nullptr, placer_opts.read_initial_place_file.c_str(), false, grid); |
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What happens if both constraint and initial placement files are specified?
I think read_constraints() initializes the location of some blocks and mark them as fixed. The location in the initial placement would override the location in the constraint file. We probably need to handle this case
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I think it is better to print something to show that the initial placement is read from a file.
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You are right. The locations in the initial placement file will override the assigned locations in the constraint file. However, at the end of the initial placement, we call a function to check the legality of the placement, and any issues can be caught there.
Regarding printing that the initial placement is read from a file, the read_place function prints a message indicating that the placement is read from a file, along with the file name.
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Are you referring to check_initial_placement_legality() or another function?
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Yes, I meant this function. I thought it would check whether the location of the fixed blocks matched the one specified in the constraint file, but upon reviewing the implementation, I realized that's not the case.
To avoid slowing down set_block_location, which is on the critical path of the placement code, I added the check when the placement file is read in the read_place.cpp file.
In this PR, I have added an option to the CLI to read the initial placement. It was tested on the Titan Murax circuit, and the results from reading the initial placement from a file were the same as those from running the initial placement during the flow.