Undefined symbol _fltused when compiling to x86_64-unknown-uefi #62785
Comments
jonas-schievink
added
A-linkage
nikomatsakis
added
the
E-needs-bisection
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Update from compiler-team: Marking as high priority but the most obvious next step would be to bisect this and validate which PR caused the problem. The cargo-bisect-rustc tool could be very helpful here. cc @varkor, since the commit cited above was from them, though it's not clear to me if that is the true cause |
jonas-schievink
added
regression-from-stable-to-beta
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triage: Assigning to self to at least handle the bisection, since this seems like it fell off our radar over past month+ |
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I'll bisect tomorrow. I need to learn the bisection ropes anyway for sth else. |
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It seems like the first step is to reproduce the problem at all! I guess maybe I need to do some research into how this works, but I was not able to install the I was also not able to build a project, even a |
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At the moment, the uefi target requires @jyao1, can you take a look at this? |
#![no_std]
#![no_main]
#[no_mangle]
pub extern "C" fn efi_main() -> f32 {
2.0*3.0
}
#[panic_handler]
fn panic(_info: &core::panic::PanicInfo) -> ! {
loop{}
}This isn't a valid UEFI application, but it will triger this link error. |
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modify Run: Result: The problem is in #62592 |
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All commits related to symbol _fltused is // Define _fltused, since we're not linking against the MS C runtime, but use
// floats.
extern "C" int _fltused = 0;If I understand correctly, rust with target |
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@12101111 Thanks for the analysis! It sounds like |
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This code don't use floating point and build successfully. #![no_std]
#![no_main]
#[no_mangle]
pub extern "C" fn efi_main() -> i32 {
0
}
#[panic_handler]
fn panic(_info: &core::panic::PanicInfo) -> ! {
loop{}
}But #![no_std]
#![no_main]
use core::fmt::{Write,Error};
struct Dummy;
impl Write for Dummy {
fn write_str(&mut self, _s: &str) -> Result<(), Error>{
Ok(())
}
}
#[no_mangle]
pub extern "C" fn efi_main() -> i32 {
write!(Dummy,"Hello, world!").unwrap();
0
}
#[panic_handler]
fn panic(_info: &core::panic::PanicInfo) -> ! {
loop{}
}Edit: with In another big project, without with |
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It is caused by LLVM fixing emission of _fltused for MSVC. The current UEFI BIOS (EDKII - written in C) meets similar issue when it is built with LLVM10. |
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https://reviews.llvm.org/D56548 changed the policy to generate _fltused symbol - "It should be emitted when any floating-point operations (including calls) are present in the object, not just when calls to printf/scanf with floating point args are made." To resolve the x86_64-unknown-uefi issue, we may have below possible options:
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Ah, it seems unfortunate that using a format function triggers this even if not trying to format floats. (Though the LTO results seem encouraging.) In that case, yeah, I would suggest adding the LLVM option long-term, and until then, I think it makes sense to just define this in core internally.
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I opened #64990 with the |
Pkgsrc changes: * Adapt to the move of the implementation of random numbers. * Remove patch which is no longer relevant (Signals.inc) * Cross-build currently fails due to the still unresolved rust-lang/rust#62558, so bootstrap kits for 1.38.0 have to be built natively, and will follow shortly. * Bump bootstrap requirements to 1.37.0 except for armv7-unknown-netbsd-eabihf which I've neither managed to cross-build nor build natively. Upstream changes: Version 1.38.0 (2019-09-26) ========================== Language -------- - [The `#[global_allocator]` attribute can now be used in submodules.][62735] - [The `#[deprecated]` attribute can now be used on macros.][62042] Compiler -------- - [Added pipelined compilation support to `rustc`.][62766] This will improve compilation times in some cases. For further information please refer to the [_"Evaluating pipelined rustc compilation"_][pipeline-internals] thread. - [Added tier 3\* support for the `aarch64-uwp-windows-msvc`, `i686-uwp-windows-gnu`, `i686-uwp-windows-msvc`, `x86_64-uwp-windows-gnu`, and `x86_64-uwp-windows-msvc` targets.][60260] - [Added tier 3 support for the `armv7-unknown-linux-gnueabi` and `armv7-unknown-linux-musleabi` targets.][63107] - [Added tier 3 support for the `hexagon-unknown-linux-musl` target.][62814] - [Added tier 3 support for the `riscv32i-unknown-none-elf` target.][62784] \* Refer to Rust's [platform support page][forge-platform-support] for more information on Rust's tiered platform support. Libraries --------- - [`ascii::EscapeDefault` now implements `Clone` and `Display`.][63421] - [Derive macros for prelude traits (e.g. `Clone`, `Debug`, `Hash`) are now available at the same path as the trait.][63056] (e.g. The `Clone` derive macro is available at `std::clone::Clone`). This also makes all built-in macros available in `std`/`core` root. e.g. `std::include_bytes!`. - [`str::Chars` now implements `Debug`.][63000] - [`slice::{concat, connect, join}` now accepts `&[T]` in addition to `&T`.][62528] - [`*const T` and `*mut T` now implement `marker::Unpin`.][62583] - [`Arc<[T]>` and `Rc<[T]>` now implement `FromIterator<T>`.][61953] - [Added euclidean remainder and division operations (`div_euclid`, `rem_euclid`) to all numeric primitives.][61884] Additionally `checked`, `overflowing`, and `wrapping` versions are available for all integer primitives. - [`thread::AccessError` now implements `Clone`, `Copy`, `Eq`, `Error`, and `PartialEq`.][61491] - [`iter::{StepBy, Peekable, Take}` now implement `DoubleEndedIterator`.][61457] Stabilized APIs --------------- - [`<*const T>::cast`] - [`<*mut T>::cast`] - [`Duration::as_secs_f32`] - [`Duration::as_secs_f64`] - [`Duration::div_duration_f32`] - [`Duration::div_duration_f64`] - [`Duration::div_f32`] - [`Duration::div_f64`] - [`Duration::from_secs_f32`] - [`Duration::from_secs_f64`] - [`Duration::mul_f32`] - [`Duration::mul_f64`] - [`any::type_name`] Cargo ----- - [Added pipelined compilation support to `cargo`.][cargo/7143] - [You can now pass the `--features` option multiple times to enable multiple features.][cargo/7084] Misc ---- - [`rustc` will now warn about some incorrect uses of `mem::{uninitialized, zeroed}` that are known to cause undefined behaviour.][63346] Compatibility Notes ------------------- - Unfortunately the [`x86_64-unknown-uefi` platform can not be built][62785] with rustc 1.39.0. - The [`armv7-unknown-linux-gnueabihf` platform is also known to have issues][62896] for certain crates such as libc. [60260]: rust-lang/rust#60260 [61457]: rust-lang/rust#61457 [61491]: rust-lang/rust#61491 [61884]: rust-lang/rust#61884 [61953]: rust-lang/rust#61953 [62042]: rust-lang/rust#62042 [62528]: rust-lang/rust#62528 [62583]: rust-lang/rust#62583 [62735]: rust-lang/rust#62735 [62766]: rust-lang/rust#62766 [62784]: rust-lang/rust#62784 [62785]: rust-lang/rust#62785 [62814]: rust-lang/rust#62814 [62896]: rust-lang/rust#62896 [63000]: rust-lang/rust#63000 [63056]: rust-lang/rust#63056 [63107]: rust-lang/rust#63107 [63346]: rust-lang/rust#63346 [63421]: rust-lang/rust#63421 [cargo/7084]: rust-lang/cargo#7084 [cargo/7143]: rust-lang/cargo#7143 [`<*const T>::cast`]: https://doc.rust-lang.org/std/primitive.pointer.html#method.cast [`<*mut T>::cast`]: https://doc.rust-lang.org/std/primitive.pointer.html#method.cast [`Duration::as_secs_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.as_secs_f32 [`Duration::as_secs_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.as_secs_f64 [`Duration::div_duration_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.div_duration_f32 [`Duration::div_duration_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.div_duration_f64 [`Duration::div_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.div_f32 [`Duration::div_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.div_f64 [`Duration::from_secs_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.from_secs_f32 [`Duration::from_secs_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.from_secs_f64 [`Duration::mul_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.mul_f32 [`Duration::mul_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.mul_f64 [`any::type_name`]: https://doc.rust-lang.org/std/any/fn.type_name.html [forge-platform-support]: https://forge.rust-lang.org/platform-support.html [pipeline-internals]: https://internals.rust-lang.org/t/evaluating-pipelined-rustc-compilation/10199
Pkgsrc changes: * Adapt to the move of the implementation of random numbers. * Remove patch which is no longer relevant (Signals.inc) * Cross-build currently fails due to the still unresolved rust-lang/rust#62558, so bootstrap kits for 1.38.0 have to be built natively, and will follow shortly. * Bump bootstrap requirements to 1.37.0 except for armv7-unknown-netbsd-eabihf which I've neither managed to cross-build nor build natively. Upstream changes: Version 1.38.0 (2019-09-26) ========================== Language -------- - [The `#[global_allocator]` attribute can now be used in submodules.][62735] - [The `#[deprecated]` attribute can now be used on macros.][62042] Compiler -------- - [Added pipelined compilation support to `rustc`.][62766] This will improve compilation times in some cases. For further information please refer to the [_"Evaluating pipelined rustc compilation"_][pipeline-internals] thread. - [Added tier 3\* support for the `aarch64-uwp-windows-msvc`, `i686-uwp-windows-gnu`, `i686-uwp-windows-msvc`, `x86_64-uwp-windows-gnu`, and `x86_64-uwp-windows-msvc` targets.][60260] - [Added tier 3 support for the `armv7-unknown-linux-gnueabi` and `armv7-unknown-linux-musleabi` targets.][63107] - [Added tier 3 support for the `hexagon-unknown-linux-musl` target.][62814] - [Added tier 3 support for the `riscv32i-unknown-none-elf` target.][62784] \* Refer to Rust's [platform support page][forge-platform-support] for more information on Rust's tiered platform support. Libraries --------- - [`ascii::EscapeDefault` now implements `Clone` and `Display`.][63421] - [Derive macros for prelude traits (e.g. `Clone`, `Debug`, `Hash`) are now available at the same path as the trait.][63056] (e.g. The `Clone` derive macro is available at `std::clone::Clone`). This also makes all built-in macros available in `std`/`core` root. e.g. `std::include_bytes!`. - [`str::Chars` now implements `Debug`.][63000] - [`slice::{concat, connect, join}` now accepts `&[T]` in addition to `&T`.][62528] - [`*const T` and `*mut T` now implement `marker::Unpin`.][62583] - [`Arc<[T]>` and `Rc<[T]>` now implement `FromIterator<T>`.][61953] - [Added euclidean remainder and division operations (`div_euclid`, `rem_euclid`) to all numeric primitives.][61884] Additionally `checked`, `overflowing`, and `wrapping` versions are available for all integer primitives. - [`thread::AccessError` now implements `Clone`, `Copy`, `Eq`, `Error`, and `PartialEq`.][61491] - [`iter::{StepBy, Peekable, Take}` now implement `DoubleEndedIterator`.][61457] Stabilized APIs --------------- - [`<*const T>::cast`] - [`<*mut T>::cast`] - [`Duration::as_secs_f32`] - [`Duration::as_secs_f64`] - [`Duration::div_duration_f32`] - [`Duration::div_duration_f64`] - [`Duration::div_f32`] - [`Duration::div_f64`] - [`Duration::from_secs_f32`] - [`Duration::from_secs_f64`] - [`Duration::mul_f32`] - [`Duration::mul_f64`] - [`any::type_name`] Cargo ----- - [Added pipelined compilation support to `cargo`.][cargo/7143] - [You can now pass the `--features` option multiple times to enable multiple features.][cargo/7084] Misc ---- - [`rustc` will now warn about some incorrect uses of `mem::{uninitialized, zeroed}` that are known to cause undefined behaviour.][63346] Compatibility Notes ------------------- - Unfortunately the [`x86_64-unknown-uefi` platform can not be built][62785] with rustc 1.39.0. - The [`armv7-unknown-linux-gnueabihf` platform is also known to have issues][62896] for certain crates such as libc. [60260]: rust-lang/rust#60260 [61457]: rust-lang/rust#61457 [61491]: rust-lang/rust#61491 [61884]: rust-lang/rust#61884 [61953]: rust-lang/rust#61953 [62042]: rust-lang/rust#62042 [62528]: rust-lang/rust#62528 [62583]: rust-lang/rust#62583 [62735]: rust-lang/rust#62735 [62766]: rust-lang/rust#62766 [62784]: rust-lang/rust#62784 [62785]: rust-lang/rust#62785 [62814]: rust-lang/rust#62814 [62896]: rust-lang/rust#62896 [63000]: rust-lang/rust#63000 [63056]: rust-lang/rust#63056 [63107]: rust-lang/rust#63107 [63346]: rust-lang/rust#63346 [63421]: rust-lang/rust#63421 [cargo/7084]: rust-lang/cargo#7084 [cargo/7143]: rust-lang/cargo#7143 [`<*const T>::cast`]: https://doc.rust-lang.org/std/primitive.pointer.html#method.cast [`<*mut T>::cast`]: https://doc.rust-lang.org/std/primitive.pointer.html#method.cast [`Duration::as_secs_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.as_secs_f32 [`Duration::as_secs_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.as_secs_f64 [`Duration::div_duration_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.div_duration_f32 [`Duration::div_duration_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.div_duration_f64 [`Duration::div_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.div_f32 [`Duration::div_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.div_f64 [`Duration::from_secs_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.from_secs_f32 [`Duration::from_secs_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.from_secs_f64 [`Duration::mul_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.mul_f32 [`Duration::mul_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.mul_f64 [`any::type_name`]: https://doc.rust-lang.org/std/any/fn.type_name.html [forge-platform-support]: https://forge.rust-lang.org/platform-support.html [pipeline-internals]: https://internals.rust-lang.org/t/evaluating-pipelined-rustc-compilation/10199
- Makes the binary smaller - Prevents size regression when updating to new toolchain - Avoids bugs like: rust-lang/rust#62785 Signed-off-by: Joe Richey <joerichey@google.com>
- Makes the binary smaller - Prevents size regression when updating to new toolchain - Avoids bugs like: rust-lang/rust#62785 Signed-off-by: Joe Richey <joerichey@google.com>
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Hello! This issue seems to have reappeared. See, for example, this GitHub Actions job: We've made no changes to the code, the CI simply downloaded the latest nightly. The errors seem to have started with |
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I have encountered this issue when compiling on |
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Please open a new issue, ideally with a reproducible example if you're able. |
Recent nightlies give the following linker error when trying to compile with the
x86_64-unknown-uefitarget:My guess at likely causes is this commit to
compiler-builtins. The project itself does not use any floating-point operations so I'm surprised that any code that refers to this symbol is included in the final executable.I'm not sure what the best fix for this would be (assuming this isn't intended behaviour), but adding this somewhere in the project works in the meantime:
The text was updated successfully, but these errors were encountered: