RFR: 8349479: C2: when a Type node becomes dead, make CFG path that uses it unreachable [v7]

[Roland Westrelin]

On Tue, 1 Apr 2025 07:09:46 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   review
>
> src/hotspot/share/opto/node.cpp line 3096:
> 
>> 3094: // paths. The dead paths are then replaced by a Halt node.
>> 3095: void TypeNode::make_paths_from_here_dead(PhaseIterGVN* igvn, PhaseIdealLoop* loop, const char* phase_str) {
>> 3096:   Unique_Node_List wq;
> 
> Should there be a `ResourceMark` here?

The callers have the `ResourceMark`. This is because it's code I extracted from 8275202: I think it used to not be safe to call `PhaseIdealLoop::register_new_node` from within the `ResourceMark` but I see there were changes in that area (data structures used by `PhaseIdealLoop` no longer allocated in the resource area). So it looks like it could be changed now.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23468#discussion_r2022357322