From markro at cs.washington.edu  Wed May  7 17:43:46 2025
From: markro at cs.washington.edu (Mark Roberts)
Date: Wed, 7 May 2025 10:43:46 -0700
Subject: are CodeElements unique?
Message-ID: <38c4f632a1700c758245c52273f24070@mail.gmail.com>

Are the members of a CodeModel.elementList() unique?  Specifically, is it
safe to use a CodeElement as the key value in a Map?



Thank you,

Mark
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From paul.sandoz at oracle.com  Wed May  7 17:59:49 2025
From: paul.sandoz at oracle.com (Paul Sandoz)
Date: Wed, 7 May 2025 17:59:49 +0000
Subject: are CodeElements unique?
In-Reply-To: <38c4f632a1700c758245c52273f24070@mail.gmail.com>
References: <38c4f632a1700c758245c52273f24070@mail.gmail.com>
Message-ID: <507610BE-7D8B-49FA-852A-7DDD798E5872@oracle.com>

Yes. All code items have identity, and their equals/hashCode is defined in terms of that identity i.e., same implementation as for Object.

A reflected method body or lambda body must have only one code model instance associated with it. (We have been fixing some a bugs to ensure this is guaranteed.)

Paul.

On May 7, 2025, at 10:43?AM, Mark Roberts <markro at cs.washington.edu> wrote:

Are the members of a CodeModel.elementList() unique?  Specifically, is it safe to use a CodeElement as the key value in a Map?

Thank you,
Mark

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From paul.sandoz at oracle.com  Wed May  7 18:00:23 2025
From: paul.sandoz at oracle.com (Paul Sandoz)
Date: Wed, 7 May 2025 18:00:23 +0000
Subject: are CodeElements unique?
In-Reply-To: <507610BE-7D8B-49FA-852A-7DDD798E5872@oracle.com>
References: <38c4f632a1700c758245c52273f24070@mail.gmail.com>
 <507610BE-7D8B-49FA-852A-7DDD798E5872@oracle.com>
Message-ID: <D12789F1-1FC0-46BD-B3D3-BA46F5F36475@oracle.com>

Oops apologies, I thought this was a Babylon code model question, please ignore!

Paul.

On May 7, 2025, at 10:59?AM, paul.sandoz at oracle.com wrote:

Yes. All code items have identity, and their equals/hashCode is defined in terms of that identity i.e., same implementation as for Object.

A reflected method body or lambda body must have only one code model instance associated with it. (We have been fixing some a bugs to ensure this is guaranteed.)

Paul.

On May 7, 2025, at 10:43?AM, Mark Roberts <markro at cs.washington.edu> wrote:

Are the members of a CodeModel.elementList() unique?  Specifically, is it safe to use a CodeElement as the key value in a Map?

Thank you,
Mark


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From chen.l.liang at oracle.com  Wed May  7 18:02:45 2025
From: chen.l.liang at oracle.com (Chen Liang)
Date: Wed, 7 May 2025 18:02:45 +0000
Subject: [External] : are CodeElements unique?
In-Reply-To: <38c4f632a1700c758245c52273f24070@mail.gmail.com>
References: <38c4f632a1700c758245c52273f24070@mail.gmail.com>
Message-ID: <SJ2PR10MB7669FD9F1DA46E94CB0F1908A288A@SJ2PR10MB7669.namprd10.prod.outlook.com>

Hi Mark,
Very good question - and the answer is unfortunately, no. Transforms are allowed to reuse code models, and I think the bound Code attribute expansion also returns duplicate load or store instructions.
To ensure identity, I think tracking a pair of (index, element) is better.

Regards,
Chen Liang
________________________________
From: Mark Roberts <markro at cs.washington.edu>
Sent: Wednesday, May 7, 2025 12:43 PM
To: classfile-api-dev at openjdk.org <classfile-api-dev at openjdk.org>
Cc: Chen Liang <chen.l.liang at oracle.com>
Subject: [External] : are CodeElements unique?


Are the members of a CodeModel.elementList() unique?  Specifically, is it safe to use a CodeElement as the key value in a Map?



Thank you,

Mark


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From chen.l.liang at oracle.com  Wed May  7 19:00:36 2025
From: chen.l.liang at oracle.com (Chen Liang)
Date: Wed, 7 May 2025 19:00:36 +0000
Subject: are CodeElements unique?
In-Reply-To: <D12789F1-1FC0-46BD-B3D3-BA46F5F36475@oracle.com>
References: <38c4f632a1700c758245c52273f24070@mail.gmail.com>
 <507610BE-7D8B-49FA-852A-7DDD798E5872@oracle.com>
 <D12789F1-1FC0-46BD-B3D3-BA46F5F36475@oracle.com>
Message-ID: <SJ2PR10MB76693992024E98FB9E37B436A288A@SJ2PR10MB7669.namprd10.prod.outlook.com>

No worries - this actually reminds me of Adam's complaints about ClassFile API's parsed instructions having no identity and thus complicated to handle for the low code model in Babylon.

Identity is important for control flow and transforms like SSA transform. Unfortunately, since transforms are free to pass in any element or duplicate them, we probably can't do that for ClassFile API, and have to resort to such an external mechanism at the terminals.

Regards,
Chen
________________________________
From: Paul Sandoz <paul.sandoz at oracle.com>
Sent: Wednesday, May 7, 2025 1:00 PM
Cc: Mark Roberts <markro at cs.washington.edu>; classfile-api-dev at openjdk.org <classfile-api-dev at openjdk.org>; Chen Liang <chen.l.liang at oracle.com>
Subject: Re: are CodeElements unique?

Oops apologies, I thought this was a Babylon code model question, please ignore!

Paul.

On May 7, 2025, at 10:59?AM, paul.sandoz at oracle.com wrote:

Yes. All code items have identity, and their equals/hashCode is defined in terms of that identity i.e., same implementation as for Object.

A reflected method body or lambda body must have only one code model instance associated with it. (We have been fixing some a bugs to ensure this is guaranteed.)

Paul.

On May 7, 2025, at 10:43?AM, Mark Roberts <markro at cs.washington.edu> wrote:

Are the members of a CodeModel.elementList() unique?  Specifically, is it safe to use a CodeElement as the key value in a Map?



Thank you,
Mark


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From markro at cs.washington.edu  Wed May  7 19:06:44 2025
From: markro at cs.washington.edu (Mark Roberts)
Date: Wed, 7 May 2025 12:06:44 -0700
Subject: [External] : are CodeElements unique?
In-Reply-To: <SJ2PR10MB7669FD9F1DA46E94CB0F1908A288A@SJ2PR10MB7669.namprd10.prod.outlook.com>
References: <38c4f632a1700c758245c52273f24070@mail.gmail.com>
 <SJ2PR10MB7669FD9F1DA46E94CB0F1908A288A@SJ2PR10MB7669.namprd10.prod.outlook.com>
Message-ID: <7762eed170be88c6e3368caef2f9a1e0@mail.gmail.com>

How about only for the original, immutable elementlist prior to any
transforms?



Also, not sure what you meant by a (index, element) pair.



Thanks, Mark



*From:* Chen Liang <chen.l.liang at oracle.com>
*Sent:* Wednesday, May 7, 2025 11:03 AM
*To:* Mark Roberts <markro at cs.washington.edu>; classfile-api-dev at openjdk.org
*Subject:* Re: [External] : are CodeElements unique?



Hi Mark,

Very good question - and the answer is unfortunately, no. Transforms are
allowed to reuse code models, and I think the bound Code attribute
expansion also returns duplicate load or store instructions.

To ensure identity, I think tracking a pair of (index, element) is better.



Regards,

Chen Liang
------------------------------

*From:* Mark Roberts <markro at cs.washington.edu>
*Sent:* Wednesday, May 7, 2025 12:43 PM
*To:* classfile-api-dev at openjdk.org <classfile-api-dev at openjdk.org>
*Cc:* Chen Liang <chen.l.liang at oracle.com>
*Subject:* [External] : are CodeElements unique?



Are the members of a CodeModel.elementList() unique?  Specifically, is it
safe to use a CodeElement as the key value in a Map?



Thank you,

Mark
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From adam.sotona at oracle.com  Mon May 12 09:56:26 2025
From: adam.sotona at oracle.com (Adam Sotona)
Date: Mon, 12 May 2025 09:56:26 +0000
Subject: [External] : are CodeElements unique?
In-Reply-To: <7762eed170be88c6e3368caef2f9a1e0@mail.gmail.com>
References: <38c4f632a1700c758245c52273f24070@mail.gmail.com>
 <SJ2PR10MB7669FD9F1DA46E94CB0F1908A288A@SJ2PR10MB7669.namprd10.prod.outlook.com>
 <7762eed170be88c6e3368caef2f9a1e0@mail.gmail.com>
Message-ID: <DS0PR10MB684757DD7D7D23F2FDE50DC88C97A@DS0PR10MB6847.namprd10.prod.outlook.com>

Hi Mark,
Code elements are generally not unique, so they cannot be used as keys in maps.

However, there are several approaches to work around it (based on the use case):

  *   If you need to iterate over a list of elements multiple times and then transform it ? you can use the index of the element as a key.
  *   Or if you have a complex set of chained and nested transformations and need to mark a code element for later identification, you can bind a label (CodeBuilder::newBoundLabel) to a position before, after, or instead of the element. Labels are unique, and your subsequent transformations will receive a LabelTarget pseudo-instruction at the marked point, and LabelTarget::label will match the label you bound earlier.

Adam

From: classfile-api-dev <classfile-api-dev-retn at openjdk.org> on behalf of Mark Roberts <markro at cs.washington.edu>
Date: Wednesday, 7 May 2025 at 21:06
To: Chen Liang <chen.l.liang at oracle.com>, classfile-api-dev at openjdk.org <classfile-api-dev at openjdk.org>
Subject: RE: [External] : are CodeElements unique?
How about only for the original, immutable elementlist prior to any transforms?

Also, not sure what you meant by a (index, element) pair.

Thanks, Mark

From: Chen Liang <chen.l.liang at oracle.com<mailto:chen.l.liang at oracle.com>>
Sent: Wednesday, May 7, 2025 11:03 AM
To: Mark Roberts <markro at cs.washington.edu<mailto:markro at cs.washington.edu>>; classfile-api-dev at openjdk.org<mailto:classfile-api-dev at openjdk.org>
Subject: Re: [External] : are CodeElements unique?

Hi Mark,
Very good question - and the answer is unfortunately, no. Transforms are allowed to reuse code models, and I think the bound Code attribute expansion also returns duplicate load or store instructions.
To ensure identity, I think tracking a pair of (index, element) is better.

Regards,
Chen Liang
________________________________
From: Mark Roberts <markro at cs.washington.edu<mailto:markro at cs.washington.edu>>
Sent: Wednesday, May 7, 2025 12:43 PM
To: classfile-api-dev at openjdk.org<mailto:classfile-api-dev at openjdk.org> <classfile-api-dev at openjdk.org<mailto:classfile-api-dev at openjdk.org>>
Cc: Chen Liang <chen.l.liang at oracle.com<mailto:chen.l.liang at oracle.com>>
Subject: [External] : are CodeElements unique?


Are the members of a CodeModel.elementList() unique?  Specifically, is it safe to use a CodeElement as the key value in a Map?



Thank you,

Mark


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