Fix LoongArch C function ABI when passing/returning structs containing floats#145709
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bors merged 1 commit intorust-lang:masterfrom Sep 5, 2025
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Fix LoongArch C function ABI when passing/returning structs containing floats#145709bors merged 1 commit intorust-lang:masterfrom
bors merged 1 commit intorust-lang:masterfrom
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a gentle ping. r? compiler |
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r? jackh726 Can you provide a bit of high-level context on the root issue and the fix here? |
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Code-wise, this looks fine. I do think (if nothing else but for posterity) some context added to the PR would be good. Though, r=me after that. @bors delegate+ |
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Fix LoongArch C function ABI when passing/returning structs containing floats Similar to RISC-V, LoongArch passes structs containing only one or two floats (or a float–integer pair) in registers, as long as each element fits into a single corresponding register. Before this PR, Rust did not check the actual offset of the second float or integer; instead, it assumed the standard offset based on the default alignment. However, since the offset can be affected by `#[repr(align(N))]` and `#[repr(packed)]`, this led to miscompilations (see rust-lang#145692). This PR fixes the issue by explicitly specifying the offset for the remainder of the cast.
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Fix LoongArch C function ABI when passing/returning structs containing floats Similar to RISC-V, LoongArch passes structs containing only one or two floats (or a float–integer pair) in registers, as long as each element fits into a single corresponding register. Before this PR, Rust did not check the actual offset of the second float or integer; instead, it assumed the standard offset based on the default alignment. However, since the offset can be affected by `#[repr(align(N))]` and `#[repr(packed)]`, this led to miscompilations (see rust-lang#145692). This PR fixes the issue by explicitly specifying the offset for the remainder of the cast.
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Fix LoongArch C function ABI when passing/returning structs containing floats Similar to RISC-V, LoongArch passes structs containing only one or two floats (or a float–integer pair) in registers, as long as each element fits into a single corresponding register. Before this PR, Rust did not check the actual offset of the second float or integer; instead, it assumed the standard offset based on the default alignment. However, since the offset can be affected by `#[repr(align(N))]` and `#[repr(packed)]`, this led to miscompilations (see rust-lang#145692). This PR fixes the issue by explicitly specifying the offset for the remainder of the cast.
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Rollup of 6 pull requests Successful merges: - #144342 (add exact bitshifts) - #145709 (Fix LoongArch C function ABI when passing/returning structs containing floats) - #146152 (Unify and deduplicate algebraic float tests) - #146186 (Update cc-rs to 1.2.33, and switch rustc_codegen_ssa to use find-msvc-tools) - #146207 (std: Implement WASIp2-specific stdio routines) - #146217 (fix ICE when suggesting `::new`) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup of 5 pull requests Successful merges: - #144342 (add exact bitshifts) - #145709 (Fix LoongArch C function ABI when passing/returning structs containing floats) - #146152 (Unify and deduplicate algebraic float tests) - #146207 (std: Implement WASIp2-specific stdio routines) - #146217 (fix ICE when suggesting `::new`) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of #145709 - heiher:issue-145692-1, r=jackh726 Fix LoongArch C function ABI when passing/returning structs containing floats Similar to RISC-V, LoongArch passes structs containing only one or two floats (or a float–integer pair) in registers, as long as each element fits into a single corresponding register. Before this PR, Rust did not check the actual offset of the second float or integer; instead, it assumed the standard offset based on the default alignment. However, since the offset can be affected by `#[repr(align(N))]` and `#[repr(packed)]`, this led to miscompilations (see #145692). This PR fixes the issue by explicitly specifying the offset for the remainder of the cast.
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Similar to RISC-V, LoongArch passes structs containing only one or two floats (or a float–integer pair) in registers, as long as each element fits into a single corresponding register. Before this PR, Rust did not check the actual offset of the second float or integer; instead, it assumed the standard offset based on the default alignment. However, since the offset can be affected by
#[repr(align(N))]and#[repr(packed)], this led to miscompilations (see #145692). This PR fixes the issue by explicitly specifying the offset for the remainder of the cast.