mirror of https://github.com/rust-lang/rust.git
Rollup merge of #128388 - beetrees:f16-f128-slightly-improve-windows-abi, r=tgross35
Match LLVM ABI in `extern "C"` functions for `f128` on Windows As MSVC doesn't support `_Float128`, x86-64 Windows doesn't have a defined ABI for `f128`. Currently, Rust will pass and return `f128` indirectly for `extern "C"` functions. This is inconsistent with LLVM, which passes and returns `f128` in XMM registers, meaning that e.g. the ABI of `extern "C"` compiler builtins won't match. This PR fixes this discrepancy by making the x86-64 Windows `extern "C"` ABI pass `f128` directly through to LLVM, so that Rust will follow whatever LLVM does. This still leaves the difference between LLVM and GCC (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115054) but this PR is still an improvement as at least Rust is now consistent with it's primary codegen backend and compiler builtins from `compiler-builtins` will now work. I've also fixed the x86-64 Windows `has_reliable_f16` match arm in `std` `build.rs` to refer to the correct target, and added an equivalent match arm to `has_reliable_f128` as the LLVM-GCC ABI difference affects both `f16` and `f128`. Tracking issue: #116909 try-job: x86_64-msvc try-job: x86_64-mingw
This commit is contained in:
commit
5c63363284
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@ -1,5 +1,5 @@
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use crate::abi::call::{ArgAbi, FnAbi, Reg};
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use crate::abi::Abi;
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use crate::abi::{Abi, Float, Primitive};
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// Win64 ABI: https://docs.microsoft.com/en-us/cpp/build/parameter-passing
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@ -18,8 +18,12 @@ pub fn compute_abi_info<Ty>(fn_abi: &mut FnAbi<'_, Ty>) {
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// FIXME(eddyb) there should be a size cap here
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// (probably what clang calls "illegal vectors").
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}
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Abi::Scalar(_) => {
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if a.layout.size.bytes() > 8 {
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Abi::Scalar(scalar) => {
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// Match what LLVM does for `f128` so that `compiler-builtins` builtins match up
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// with what LLVM expects.
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if a.layout.size.bytes() > 8
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&& !matches!(scalar.primitive(), Primitive::Float(Float::F128))
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{
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a.make_indirect();
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} else {
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a.extend_integer_width_to(32);
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@ -94,7 +94,7 @@ fn main() {
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// Unsupported <https://github.com/llvm/llvm-project/issues/94434>
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("arm64ec", _) => false,
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// MinGW ABI bugs <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115054>
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("x86", "windows") => false,
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("x86_64", "windows") => false,
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// x86 has ABI bugs that show up with optimizations. This should be partially fixed with
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// the compiler-builtins update. <https://github.com/rust-lang/rust/issues/123885>
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("x86" | "x86_64", _) => false,
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@ -122,6 +122,8 @@ fn main() {
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("nvptx64", _) => false,
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// ABI unsupported <https://github.com/llvm/llvm-project/issues/41838>
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("sparc", _) => false,
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// MinGW ABI bugs <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115054>
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("x86_64", "windows") => false,
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// 64-bit Linux is about the only platform to have f128 symbols by default
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(_, "linux") if target_pointer_width == 64 => true,
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// Same as for f16, except MacOS is also missing f128 symbols.
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@ -0,0 +1,39 @@
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//@ assembly-output: emit-asm
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//@ compile-flags: -O
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//@ only-windows
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//@ only-x86_64
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#![feature(f16, f128)]
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#![crate_type = "lib"]
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// CHECK-LABEL: second_f16
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// CHECK: movaps %xmm1, %xmm0
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// CHECK-NEXT: retq
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#[no_mangle]
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pub extern "C" fn second_f16(_: f16, x: f16) -> f16 {
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x
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}
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// CHECK-LABEL: second_f32
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// CHECK: movaps %xmm1, %xmm0
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// CHECK-NEXT: retq
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#[no_mangle]
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pub extern "C" fn second_f32(_: f32, x: f32) -> f32 {
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x
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}
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// CHECK-LABEL: second_f64
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// CHECK: movaps %xmm1, %xmm0
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// CHECK-NEXT: retq
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#[no_mangle]
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pub extern "C" fn second_f64(_: f64, x: f64) -> f64 {
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x
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}
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// CHECK-LABEL: second_f128
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// CHECK: movaps %xmm1, %xmm0
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// CHECK-NEXT: retq
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#[no_mangle]
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pub extern "C" fn second_f128(_: f128, x: f128) -> f128 {
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x
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}
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