Improve the support for SIMD vectors in FFI #21233
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This seems to work on x86-64, but I am not able to test on other platforms. cc rust-lang#20043
Unlike the intrinics in C, this types the SSE values base on integer size. This matches the LLVM intrinsics which have concrete vector types (`<4 x i32>` etc.), and is no loss of expressivity: if one is using a C function that really takes an untyped integral SSE value, just give it whatever Rust type makes most sense.
This seems to match what clang does on arm, but I cannot do any experimentation with mips, but it matches how the LLVM intrinsics are defined in any case...
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This just compiles a test using SIMD in FFI (mostly importing LLVM intrinsics) for almost all rustc's supported platforms, but not linking it or running it, so there's absolutely no guarantee that this is correct.
I don't know if this handling of SIMD types is correct for the C ABI on all platforms, so lets add an even finer feature gate than just the `simd` one. The `simd` one can be used with (relatively) little risk of complete nonsense, the reason for it is that it is likely that things will change. Using the types in FFI with an incorrect ABI will at best give absolute nonsense results, but possibly cause serious breakage too, so this is a step up in badness, hence a new feature gate.
bors
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This stops the compiler ICEing on the use of SIMD types in FFI signatures. It emits correct code for LLVM intrinsics, but I am quite unsure about the ABI handling in general so I've added a new feature gate `simd_ffi` to try to ensure people don't use it without realising there's a non-trivial risk of codegen brokenness. Closes #20043.
This was referenced Apr 20, 2015
steveklabnik
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As part of the audit for rust-lang#22820 the following duplicate feature gate tests were removed: * `box_patterns` * `simd_ffi` These tests for `box_patterns` and `simd_ffi` were added in rust-lang#23578, however there were existing tests in rust-lang#20723 and rust-lang#21233 respectively. r? @nrc
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As part of the audit for rust-lang#22820 the following duplicate feature gate tests were removed: * `box_patterns` * `simd_ffi` These tests for `box_patterns` and `simd_ffi` were added in rust-lang#23578, however there were existing tests in rust-lang#20723 and rust-lang#21233 respectively. r? @nrc
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Apr 25, 2015
As part of the audit for rust-lang#22820 the following duplicate feature gate tests were removed: * `box_patterns` * `simd_ffi` These tests for `box_patterns` and `simd_ffi` were added in rust-lang#23578, however there were existing tests in rust-lang#20723 and rust-lang#21233 respectively. r? @nrc
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This stops the compiler ICEing on the use of SIMD types in FFI signatures. It emits correct code for LLVM intrinsics, but I am quite unsure about the ABI handling in general so I've added a new feature gate
simd_ffito try to ensure people don't use it without realising there's a non-trivial risk of codegen brokenness.Closes #20043.