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Netlist hierarchy explorer

The netlist table holds one flat module; the design hierarchy survives only in the names of its instances. The explorer rebuilds a tree of scopes from these names, counts what each level holds, and searches the names.

Levels of a name

The core naming rules (CORE-REQ-0111, CORE-REQ-0112) make a hierarchical name of segments separated by unescaped /, where \/ and \\ escape a slash and a backslash inside a segment. Netlists that come from flattening often carry their hierarchy inside one segment instead: the synthesis tool of the suite joins the RTL instance path with . in the names it keeps (its state nets, such as u_fifo.mem[2][7]), and netlists from other flows write it as escaped identifiers with /, which the structural reader stores as \/ (VERILOG-REQ-0318). Instance names that the synthesis tool generates carry no hierarchy at all, so its netlists show a flat tree.

STUDIO-REQ-0030 A name is split into levels in one of two modes. In mode core, levels are the segments of the core rules: split at unescaped /. In mode flattened, the default, a name is also split at . and at the escaped slash \/, both only outside brackets, so that u_core.gen_lane[2].u_add/g7 has the levels u_core, gen_lane[2], u_add and g7, and mem[1.5] stays one level. A separator at the start or the end of the name, or right after another separator, is kept as text, so that no level is empty. A level is shown with its escapes undone (CORE-REQ-0112). The last level is the leaf; the levels before it are scopes.

The tree

STUDIO-REQ-0031 The hierarchy is a tree of scopes rooted at the module (scope 0, named after the module). Each instance belongs to the scope of its levels before the leaf, created on first use; each scope lists its child scopes and its instances in natural order (digit runs compared as numbers, u2 before u10, then by bytes and by row) and the number of instances in it and below it. The tree is built in time linear in the total length of the names.

STUDIO-REQ-0032 Counts are shown per scope (its instances in total and its child scopes) and per level: for each depth below the module, the scopes at that depth and the instances directly in scopes one level above.

STUDIO-REQ-0033 The tree panel lists rows for the scopes the user opened: at depth 0 the module's child scopes, then its instances; an open scope is followed by its child scopes and then its instances, one level deeper. Rows are computed for open scopes only, and the panel draws only its visible rows (STUDIO-REQ-0165), so a scope with a million instances is listed without building a million row widgets. Focusing an instance opens the scopes that enclose it.

STUDIO-REQ-0034 A search lists the instances and the scopes whose names contain the query, ignoring the case of ASCII letters, at most max_search_results of each, with the number of all matches and whether some were left out (U0061 when the budget cut the list); an empty or blank query matches nothing.

STUDIO-REQ-0035 A name with more levels than max_hierarchy_depth keeps its first max_hierarchy_depth - 1 levels as scopes and its remaining levels together as its leaf; the number of such names is reported once as U0060.