Rust's i128 return ABI does not agree with Clang and GCC on Windows targets
#134288
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A-ABI
Area: Concerning the application binary interface (ABI)
A-LLVM
Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues.
C-bug
Category: This is a bug.
O-windows
Operating system: Windows
T-compiler
Relevant to the compiler team, which will review and decide on the PR/issue.
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tgross35
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Dec 14, 2024
Clang and GCC both return `i128` in xmm0 on Windows, both for MSVC and MinGW targets. Currently, Rust returns `i128` indirectly. Add a fixup for return ABI so we also return scalar `i128`s, which should make our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288 (does not fix)
tgross35
added a commit
to tgross35/rust
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this issue
Dec 14, 2024
Clang and GCC both return `i128` in xmm0 on Windows, both for MSVC and MinGW targets. Currently, Rust returns `i128` indirectly. Add a fixup for return ABI so we also return scalar `i128`s, which should make our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288 (does not fix)
tgross35
added a commit
to tgross35/rust
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this issue
Dec 14, 2024
Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288 (does not fix)
tgross35
added a commit
to tgross35/rust
that referenced
this issue
Dec 14, 2024
Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288 (does not fix)
bors
added a commit
to rust-lang-ci/rust
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Dec 14, 2024
Windows x86: Change i128 to return via the vector ABI Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288 (does not fix) try-job: x86_64-msvc try-job: x86_64-msvc-ext1 try-job: x86_64-mingw-1 try-job: x86_64-mingw-2
tgross35
added a commit
to tgross35/rust
that referenced
this issue
Dec 15, 2024
Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288
tgross35
added a commit
to tgross35/rust
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this issue
Dec 15, 2024
Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu but Rust returns the type on the stack. The LLVM backend was changed to use the same convention as the C compilers; change Cranelift to do the same. Link: rust-lang#134288
bors
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Dec 15, 2024
Windows x86: Change i128 to return via the vector ABI Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288 (does not fix) try-job: x86_64-msvc try-job: x86_64-msvc-ext1 try-job: x86_64-mingw-1 try-job: x86_64-mingw-2
tgross35
added a commit
to tgross35/rust
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this issue
Dec 17, 2024
Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288
tgross35
added a commit
to tgross35/rust
that referenced
this issue
Dec 17, 2024
Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu but Rust returns the type on the stack. The LLVM backend was changed to use the same convention as the C compilers; change Cranelift libcalls to do the same. Link: rust-lang#134288
tgross35
added a commit
to tgross35/rust
that referenced
this issue
Dec 17, 2024
Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288
tgross35
added a commit
to tgross35/rust
that referenced
this issue
Dec 17, 2024
Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu but Rust returns the type on the stack. The LLVM backend was changed to use the same convention as the C compilers; change Cranelift libcalls to do the same. Link: rust-lang#134288
bors
added a commit
to rust-lang-ci/rust
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Dec 17, 2024
Windows x86: Change i128 to return via the vector ABI Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288 (does not fix) try-job: x86_64-msvc try-job: x86_64-msvc-ext1 try-job: x86_64-mingw-1 try-job: x86_64-mingw-2
tgross35
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Dec 22, 2024
Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288
tgross35
added a commit
to tgross35/rust
that referenced
this issue
Dec 22, 2024
Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu but Rust returns the type on the stack. The LLVM backend was changed to use the same convention as the C compilers; change Cranelift libcalls to do the same. Link: rust-lang#134288
bors
added a commit
to rust-lang-ci/rust
that referenced
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Dec 22, 2024
Windows x86: Change i128 to return via the vector ABI Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288 (does not fix) [1] try-job: x86_64-msvc try-job: x86_64-msvc-ext1 try-job: x86_64-mingw-1 try-job: x86_64-mingw-2
tgross35
added a commit
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Jan 15, 2025
Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288
bors
added a commit
to rust-lang-ci/rust
that referenced
this issue
Jan 15, 2025
Windows x86: Change i128 to return via the vector ABI Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288 (does not fix) [1] try-job: x86_64-msvc try-job: x86_64-msvc-ext1 try-job: x86_64-mingw-1 try-job: x86_64-mingw-2
tgross35
added a commit
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Jan 16, 2025
Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288
matthiaskrgr
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Jan 17, 2025
…bjorn3,wesleywiser Windows x86: Change i128 to return via the vector ABI Clang and GCC both return `i128` in xmm0 on windows-msvc and windows-gnu. Currently, Rust returns the type on the stack. Add a calling convention adjustment so we also return scalar `i128`s using the vector ABI, which makes our `i128` compatible with C. In the future, Clang may change to return `i128` on the stack for its `-msvc` targets (more at [1]). If this happens, the change here will need to be adjusted to only affect MinGW. Link: rust-lang#134288 (does not fix) [1] try-job: x86_64-msvc try-job: x86_64-msvc-ext1 try-job: x86_64-mingw-1 try-job: x86_64-mingw-2
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Originally reported at rust-lang/lang-team#255 (comment), Clang and GCC-MinGW return
__int128in xmm0. Rust currently returns it on the stack.@wesleywiser has a proposed patch to make Clang return on the stack for
-msvctargets, while keeping the behavior for MinGW wesleywiser/llvm-project@b2f8b83.Rustc could probably just change the Windows ABI to always return in xmm0 for now, and then if the Clang patch lands we can change this to apply only to MinGW.
Demo: https://godbolt.org/z/o9h8We69o
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