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s390x-z17: Implement load indexed address instruction#12707

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s390x-z17: Implement load indexed address instruction#12707
theotherjimmy wants to merge 1 commit intobytecodealliance:mainfrom
theotherjimmy:z17-lxa

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@theotherjimmy
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Starting with Z17, s390x includes some specialized indexed address computation instruction that allow for computing addresses in a way that could map to finding an element within an array, skipping over a structure header of a constant size. While this does not also load the address, it is usually more efficient, at least in terms of code size, to use this newer load indexed address (lxa, llxa) instruction instead of expanded address computations using add instructions.

This is currently created as a draft, as I'm figuring out how to test this. I think testing is needed, as it's a specific sequence of IR instructions, and while I'm confident that I have them correct, it's better to be certain with testing.

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cc @uweigand

@github-actions github-actions bot added cranelift Issues related to the Cranelift code generator isle Related to the ISLE domain-specific language labels Mar 3, 2026
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github-actions bot commented Mar 3, 2026

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@theotherjimmy theotherjimmy force-pushed the z17-lxa branch 2 times, most recently from b7410c0 to ee70f7f Compare March 5, 2026 13:16
@theotherjimmy
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Big refactor to avoid expanding the Inst enum. Still needs some runtests, and running said tests.

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I added rustfmt check to my auto-test script. Sorry I missed that earlier.

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