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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/rust#145692). This PR fixes the issue by explicitly specifying the offset for the remainder of the cast.
The files here use the LLVM FileCheck framework, documented at https://llvm.org/docs/CommandGuide/FileCheck.html.
One extension worth noting is the use of revisions as custom prefixes for FileCheck. If your codegen test has different behavior based on the chosen target or different compiler flags that you want to exercise, you can use a revisions annotation, like so:
// revisions: aaa bbb
// [bbb] compile-flags: --flags-for-bbb
After specifying those variations, you can write different expected, or
explicitly unexpected output by using <prefix>-SAME: and <prefix>-NOT:,
like so:
// CHECK: expected code
// aaa-SAME: emitted-only-for-aaa
// aaa-NOT: emitted-only-for-bbb
// bbb-NOT: emitted-only-for-aaa
// bbb-SAME: emitted-only-for-bbb