RFR: 8287647: VM debug support: find node by pattern in name or dump

[Roberto Castañeda Lozano]

On Thu, 2 Jun 2022 09:16:28 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

> **Goal**
> Refactor `Node::find`, allow not just searching for `node->_idx`, but also matching for `node->Name()` and even `node->dump()`.
> 
> **Proposal**
> Refactor `Node::find` into `visit_nodes`, which visits all nodes and calls a `callback` on them. This callback can be used to filter by `idx` (`find_node_by_idx`, `Node::find`, `find_node` etc.). It can also be used to match node names (`find_node_by_name`) and even node dump (`find_node_by_dump`).
> 
> Thus, I present these additional functions:
> `Node* find_node_by_name(const char* name)`: find all nodes matching the `name` pattern.
> `Node* find_node_by_dump(const char* pattern)`: find all nodes matching the `pattern`.
> The nodes are sorted by node idx, and then dumped.
> 
> Patterns can contain `*` characters to match any characters (eg. `Con*L` matches both `ConL` and `ConvI2L`)
> 
> **Usecase**
> Find all `CastII` nodes. Find all `Loop` nodes. Use `find_node_by_name`.
> 
> Find all all `CastII` nodes that depend on a rangecheck. Use `find_node_by_dump("CastII*range check dependency")`.
> Find all `Bool` nodes that perform a `[ne]` check. Use `find_node_by_dump("Bool*[ne]")`.
> Find all `Phi` nodes that are `tripcount`. Use `find_node_by_dump("Phi*tripcount")`.
> 
> Find all `Load` nodes that are associated with line 301 in some file. Use `find_node_by_dump("Load*line 301")`.
> 
> You can probably find more usecases yourself ;)

Thanks for adding this functionality, I tested it and works well!

src/hotspot/share/opto/node.cpp line 1692:

> 1690:   }
> 1691:   return nullptr; // no i was a match
> 1692: }

Suggesting: move this code to `src/hotspot/share/utilities/stringUtils.cpp`.

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Marked as reviewed by rcastanedalo (Committer).

PR: https://git.openjdk.org/jdk/pull/8988