Integrated: 8344171: Clone and initialize Assertion Predicates in order instead of in reverse-order

[Christian Hagedorn]

On Wed, 20 Nov 2024 12:40:58 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

> This patch changes the order in which we clone and initialize Assertion Predicates from "reverse-order" to "in-order".
> 
> #### Current State: Mostly "reverse-order" for Assertion Predicates
> We are currently cloning and initializing Assertion Predicates in reverse-order out of convenience and simplicity for most of the loop splitting optimizations - except for Loop Unswitching (see next section). This means that we do the following:
> 
>                                      old target loop entry
>                                                |
>          x                         Cloned Template Assertion
>          |                                Predicate 2
> Template Assertion                             |
>     Predicate 1                       Initialized Assertion
>          |               ==>               Predicate 2
> Template Assertion                             |
>     Predicate 2                    Cloned Template Assertion
>          |                                Predicate 1
>     source loop                                |
>                                       Initialized Assertion
>                                            Predicate 1
>                                                |
>                                           target loop
> 
> I don't think this is wrong but still kinda unexpected when trying to reason about a graph. But now with the recent refactorings, I think it's easy to change this to an in-order processing:
> 
>                                      old target loop entry
>                                                |
>          x                          Cloned Template Assertion
>          |                                Predicate 1
> Template Assertion                             |
>     Predicate 1                       Initialized Assertion
>          |               ==>               Predicate 1
> Template Assertion                             |
>     Predicate 2                     Cloned Template Assertion
>          |                                Predicate 2
>     source loop                                |
>                                       Initialized Assertion
>                                            Predicate 2
>                                                |
>                                           target loop
> 
>  This will also align all cloning/initializing of Assertion Predicates to the same order which was not the case before: Loop Unswitching already had an in-order cloning.
> 
> #### Why Does Loop Unswitching Use In-Order?
> The main reason wa...

This pull request has now been integrated.

Changeset: 3518b4bd
Author:    Christian Hagedorn <chagedorn at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/3518b4bd205f67a356bc6b531c0622ac1d97a962
Stats:     111 lines in 4 files changed: 65 ins; 33 del; 13 mod

8344171: Clone and initialize Assertion Predicates in order instead of in reverse-order

Reviewed-by: epeter, kvn

-------------

PR: https://git.openjdk.org/jdk/pull/22275