Improve V3Split (#8385)

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Various cleanups, simplifications and improvements:
- Build the output bottom up, eliminating AstSplitPlaceholder
- Replace the 'ignore step' pruning with removing the vertices and edges
- Treat an NBA written variable as a block input, enabling more splits
- Move instead of clone leaf statements

Overall V3Split is faster, uses less memory, can do more splits, is
simpler algorithmically, and has half the lines of code in V3Split

Most notably this can now be split, which could not be before:

```systemverilog
always @(posedge clk) begin
    a <= !a;
    if (a) b <= c;
end
```

t_x_rand_mt_stability* pin $random values, but there is one random seed
per C thread, so they depend on which thread runs the block. More
splitting moved that block onto a different thread, so force a single
MTask in those tests to keep them stable.

Some property/assert test changed hit counts due to races, but are now
closer to what might be expected.

...

This commit is contained in:

Geza Lore

2026-09-17 23:11:26 +02:00

committed by GitHub

parent 2d0eaab5df

commit 1c4c6c9e9d

33 changed files with 533 additions and 751 deletions

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src/V3Split.cpp

+327 -686

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