RFR: 8369002: Extract the loop->is_member(get_loop(get_ctrl(node))) pattern in a new function

[Benoît Maillard]

On Wed, 12 Nov 2025 08:49:49 GMT, Anton Seoane Ampudia <aseoane at openjdk.org> wrote:

> This PR adds a "shorthand" for the common `loop->is_member(get_loop(get_ctrl(node)))` pattern in loop optimizations.
> 
> In PhaseIdealLoop, there is already an `is_member` function that checks if a node is a (nested) member of an IdealLoopTree. In a similar fashion, this changeset adds a `ctrl_is_member` that aims to simplify the common pattern of:
> 
> Node* node_ctrl = get_ctrl(node);
> if (loop->is_member(get_loop(node))) { ... }
> 
> 
> This hopes to provide a bit more readability and code conciseness in such a common operation.
> 
> **Testing:** passes tiers 1-3

Looks good to me, thanks for making the change @anton-seoane! I would just change the return type, see my comments.

src/hotspot/share/opto/loopnode.hpp line 1389:

> 1387: 
> 1388:   // Is 'n' a (nested) member of 'loop'?
> 1389:   int is_member( const IdealLoopTree *loop, Node *n ) const {

Let's change this one as well while we're at it
Suggestion:

  bool is_member( const IdealLoopTree *loop, Node *n ) const {

src/hotspot/share/opto/loopnode.hpp line 1394:

> 1392: 
> 1393:   // is the control for 'n' a (nested) member of 'loop'?
> 1394:   int ctrl_is_member(const IdealLoopTree *loop, Node *n) {

We should take advantage of the opportunity to make the return type consistent with the other variation (`bool is_member(const IdealLoopTree *l)`)
Suggestion:

  bool ctrl_is_member(const IdealLoopTree *loop, Node *n) {

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PR Review: https://git.openjdk.org/jdk/pull/28259#pullrequestreview-3452473070
PR Review Comment: https://git.openjdk.org/jdk/pull/28259#discussion_r2517579412
PR Review Comment: https://git.openjdk.org/jdk/pull/28259#discussion_r2517578812