core: Use __jcvt() intrinsic on AArch64 for f64→i32 conversion #22138
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In ruffle-rs#21780, an optimisation has been added to use the fjcvtzs ARMv8.3 instruction when available, to convert a f64 into an i32. This made me wonder why core::arch::aarch64 didn’t have an intrinsic for this instruction, so I implemented it in stdarch[1], which got pulled in Rust yesterday[2] (see the tracking issue[3]). This PR makes use of this new intrinsic to remove the unsafe asm!() block, and simplify the code. [1] rust-lang/stdarch#1938 [2] rust-lang/rust#148402 [3] rust-lang/rust#147555
Member
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Thanks for taking care of it! Ruffle uses stable Rust, so we have to wait until this feature is stabilized. |
Author
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I’ll try to move forward with the stabilization, in the meantime should I close this PR and reopen it when the intrinsic got stabilized, or should I keep it open as a draft? I originally thought it would be better for stabilization if projects using it were actually using the intrinsic. |
Member
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It's fine to leave it as a draft. |
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In #21780, an optimisation has been added to use the
fjcvtzsARMv8.3 instruction when available, to convert af64into ani32. This made me wonder whycore::arch::aarch64didn’t have an intrinsic for this instruction, so I implemented it in stdarch, which got pulled in Rust yesterday (see the tracking issue).This PR makes use of this new intrinsic to remove the unsafe
asm!()block, and simplify the code.