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Patryk Wychowaniec 73f57893aa
fix: Add #[avr_skip] for floats 
Same story as always, i.e. ABI mismatch:

- https://github.com/rust-lang/compiler-builtins/pull/462
- https://github.com/rust-lang/compiler-builtins/pull/466
- https://github.com/rust-lang/compiler-builtins/pull/513

I've made sure the changes work by rendering a Mandelbrot fractal:

```rust
#[arduino_hal::entry]
fn main() -> ! {
    let dp = arduino_hal::Peripherals::take().unwrap();
    let pins = arduino_hal::pins!(dp);
    let mut serial = arduino_hal::default_serial!(dp, pins, 57600);

    mandelbrot(&mut serial, 60, 40, -2.05, -1.12, 0.47, 1.12, 100);

    loop {
        //
    }
}

fn mandelbrot<T>(
    output: &mut T,
    viewport_width: i64,
    viewport_height: i64,
    x1: f32,
    y1: f32,
    x2: f32,
    y2: f32,
    max_iterations: i64,
) where
    T: uWrite,
{
    for viewport_y in 0..viewport_height {
        let y0 = y1 + (y2 - y1) * ((viewport_y as f32) / (viewport_height as f32));

        for viewport_x in 0..viewport_width {
            let x0 = x1 + (x2 - x1) * ((viewport_x as f32) / (viewport_width as f32));

            let mut x = 0.0;
            let mut y = 0.0;
            let mut iterations = max_iterations;

            while x * x + y * y <= 4.0 && iterations > 0 {
                let xtemp = x * x - y * y + x0;
                y = 2.0 * x * y + y0;
                x = xtemp;
                iterations -= 1;
            }

            let ch = "#%=-:,. "
                .chars()
                .nth((8.0 * ((iterations as f32) / (max_iterations as f32))) as _)
                .unwrap();

            _ = ufmt::uwrite!(output, "{}", ch);
        }

        _ = ufmt::uwriteln!(output, "");
    }
}
```

... where without avr_skips, the code printed an image full of only `#`.

Note that because libgcc doesn't provide implementations for f64, using
those (e.g. swapping f32 to f64 in the code above) will cause linking to
fail:

```
undefined reference to `__divdf3'
undefined reference to `__muldf3'
undefined reference to `__gedf2'
undefined reference to `__fixunsdfsi'
undefined reference to `__gtdf2'
```

Ideally compiler-builtins could jump right in and provide those, but f64
also require a special calling convention which hasn't been yet exposed
through LLVM.

Note that because using 64-bit floats on an 8-bit target is a pretty
niche thing to do, and because f64 floats don't work correctly anyway at
the moment (due to this ABI mismatch), we're not actually breaking
anything by skipping those functions, since any code that currently uses
f64 on AVR works by accident.

Closes https://github.com/rust-lang/rust/issues/108489.
2023-06-12 14:14:36 +02:00
..
.github/workflows Update the version of compiler-rt in CI 2021-04-30 12:24:12 -07:00
ci Fix run-docker.sh so it can be run locally 2022-02-06 09:20:19 +00:00
crates/panic-handler Fix panic-handler documentation 2021-04-02 08:58:50 -05:00
examples Remove truncdfsf2.c from sources in build.rs and add test for __truncdfsf2vfp 2021-12-12 21:12:42 -05:00
libm@1dbb9d2d47 Upgrade libm to 0.2.7 2023-05-20 10:49:41 +02:00
src fix: Add #[avr_skip] for floats 2023-06-12 14:14:36 +02:00
testcrate Disable another test on powerpc 2023-03-29 21:49:08 +01:00
.gitignore initial commit 2016-08-07 15:58:21 -05:00
.gitmodules Update the gitmodule url for libm 2019-09-25 11:19:35 -07:00
build.rs Add emutls.c for OpenHarmony 2023-03-10 19:59:23 +00:00
Cargo.toml Bump to 0.1.92 2023-05-20 10:50:12 +02:00
LICENSE.txt Use lower-case file extension for LICENSE.txt 2020-02-21 11:03:51 +01:00
PUBLISHING.md Update publishing instructions 2019-11-11 10:40:09 -08:00
README.md Remove truncdfsf2.c from sources in build.rs and add test for __truncdfsf2vfp 2021-12-12 21:12:42 -05:00
thumbv6m-linux-eabi.json Update target specs 2017-10-03 02:28:49 -07:00
thumbv7em-linux-eabi.json Update target specs 2017-10-03 02:28:49 -07:00
thumbv7em-linux-eabihf.json Update target specs 2017-10-03 02:28:49 -07:00
thumbv7m-linux-eabi.json Update target specs 2017-10-03 02:28:49 -07:00

README.md

compiler-builtins

Porting compiler-rt intrinsics to Rust

See rust-lang/rust#35437.

When and how to use this crate?

If you are working with a target that doesn't have binary releases of std available via rustup (this probably means you are building the core crate yourself) and need compiler-rt intrinsics (i.e. you are probably getting linker errors when building an executable: undefined reference to __aeabi_memcpy), you can use this crate to get those intrinsics and solve the linker errors. To do that, add this crate somewhere in the dependency graph of the crate you are building:

# Cargo.toml
[dependencies]
compiler_builtins = { git = "https://github.com/rust-lang/compiler-builtins" }

extern crate compiler_builtins;

// ...

If you still get an "undefined reference to $INTRINSIC" error after that change, that means that we haven't ported $INTRINSIC to Rust yet! Please open an issue with the name of the intrinsic and the LLVM triple (e.g. thumbv7m-none-eabi) of the target you are using. That way we can prioritize porting that particular intrinsic.

If you've got a C compiler available for your target then while we implement this intrinsic you can temporarily enable a fallback to the actual compiler-rt implementation as well for unimplemented intrinsics:

[dependencies.compiler_builtins]
git = "https://github.com/rust-lang/compiler-builtins"
features = ["c"]

Contributing

  1. Pick one or more intrinsics from the pending list.
  2. Fork this repository.
  3. Port the intrinsic(s) and their corresponding unit tests from their C implementation to Rust.
  4. Implement a test generator to compare the behavior of the ported intrinsic(s) with their implementation on the testing host. Note that randomized compiler-builtin tests should be run using cargo test --features gen-tests.
  5. Send a Pull Request (PR).
  6. Once the PR passes our extensive testing infrastructure, we'll merge it!
  7. Celebrate 🎉

Porting Reminders

  1. Rust and C have slightly different operator precedence. C evaluates comparisons (== !=) before bitwise operations (& | ^), while Rust evaluates the other way.
  2. C assumes wrapping operations everywhere. Rust panics on overflow when in debug mode. Consider using the Wrapping type or the explicit wrapping_* functions where applicable.
  3. Note C implicit casts, especially integer promotion. Rust is much more explicit about casting, so be sure that any cast which affects the output is ported to the Rust implementation.
  4. Rust has many functions for integer or floating point manipulation in the standard library. Consider using one of these functions rather than porting a new one.

Progress

  • adddf3.c
  • addsf3.c
  • arm/adddf3vfp.S
  • arm/addsf3vfp.S
  • arm/aeabi_dcmp.S
  • arm/aeabi_fcmp.S
  • arm/aeabi_idivmod.S
  • arm/aeabi_ldivmod.S
  • arm/aeabi_memcpy.S
  • arm/aeabi_memmove.S
  • arm/aeabi_memset.S
  • arm/aeabi_uidivmod.S
  • arm/aeabi_uldivmod.S
  • arm/divdf3vfp.S
  • arm/divmodsi4.S (generic version is done)
  • arm/divsf3vfp.S
  • arm/divsi3.S (generic version is done)
  • arm/eqdf2vfp.S
  • arm/eqsf2vfp.S
  • arm/extendsfdf2vfp.S
  • arm/fixdfsivfp.S
  • arm/fixsfsivfp.S
  • arm/fixunsdfsivfp.S
  • arm/fixunssfsivfp.S
  • arm/floatsidfvfp.S
  • arm/floatsisfvfp.S
  • arm/floatunssidfvfp.S
  • arm/floatunssisfvfp.S
  • arm/gedf2vfp.S
  • arm/gesf2vfp.S
  • arm/gtdf2vfp.S
  • arm/gtsf2vfp.S
  • arm/ledf2vfp.S
  • arm/lesf2vfp.S
  • arm/ltdf2vfp.S
  • arm/ltsf2vfp.S
  • arm/modsi3.S (generic version is done)
  • arm/muldf3vfp.S
  • arm/mulsf3vfp.S
  • arm/nedf2vfp.S
  • arm/negdf2vfp.S
  • arm/negsf2vfp.S
  • arm/nesf2vfp.S
  • arm/softfloat-alias.list
  • arm/subdf3vfp.S
  • arm/subsf3vfp.S
  • arm/truncdfsf2vfp.S
  • arm/udivmodsi4.S (generic version is done)
  • arm/udivsi3.S (generic version is done)
  • arm/umodsi3.S (generic version is done)
  • arm/unorddf2vfp.S
  • arm/unordsf2vfp.S
  • ashldi3.c
  • ashrdi3.c
  • comparedf2.c
  • comparesf2.c
  • divdf3.c
  • divdi3.c
  • divmoddi4.c
  • divmodsi4.c
  • divsf3.c
  • divsi3.c
  • extendhfsf2.c
  • extendsfdf2.c
  • fixdfdi.c
  • fixdfsi.c
  • fixsfdi.c
  • fixsfsi.c
  • fixunsdfdi.c
  • fixunsdfsi.c
  • fixunssfdi.c
  • fixunssfsi.c
  • floatdidf.c
  • floatdisf.c
  • floatsidf.c
  • floatsisf.c
  • floatundidf.c
  • floatundisf.c
  • floatunsidf.c
  • floatunsisf.c
  • i386/ashldi3.S
  • i386/ashrdi3.S
  • i386/chkstk.S
  • i386/chkstk2.S
  • i386/divdi3.S
  • i386/lshrdi3.S
  • i386/moddi3.S
  • i386/muldi3.S
  • i386/udivdi3.S
  • i386/umoddi3.S
  • lshrdi3.c
  • moddi3.c
  • modsi3.c
  • muldf3.c
  • muldi3.c
  • mulodi4.c
  • mulosi4.c
  • mulsf3.c
  • powidf2.c
  • powisf2.c
  • subdf3.c
  • subsf3.c
  • truncdfhf2.c
  • truncdfsf2.c
  • truncsfhf2.c
  • udivdi3.c
  • udivmoddi4.c
  • udivmodsi4.c
  • udivsi3.c
  • umoddi3.c
  • umodsi3.c
  • x86_64/chkstk.S
  • x86_64/chkstk2.S

These builtins are needed to support 128-bit integers, which are in the process of being added to Rust.

  • ashlti3.c
  • ashrti3.c
  • divti3.c
  • fixdfti.c
  • fixsfti.c
  • fixunsdfti.c
  • fixunssfti.c
  • floattidf.c
  • floattisf.c
  • floatuntidf.c
  • floatuntisf.c
  • lshrti3.c
  • modti3.c
  • muloti4.c
  • multi3.c
  • udivmodti4.c
  • udivti3.c
  • umodti3.c

Unimplemented functions

These builtins involve floating-point types ("f128", "f80" and complex numbers) that are not supported by Rust.

  • addtf3.c
  • comparetf2.c
  • divdc3.c
  • divsc3.c
  • divtc3.c
  • divtf3.c
  • divxc3.c
  • extenddftf2.c
  • extendsftf2.c
  • fixtfdi.c
  • fixtfsi.c
  • fixtfti.c
  • fixunstfdi.c
  • fixunstfsi.c
  • fixunstfti.c
  • fixunsxfdi.c
  • fixunsxfsi.c
  • fixunsxfti.c
  • fixxfdi.c
  • fixxfti.c
  • floatditf.c
  • floatdixf.c
  • floatsitf.c
  • floattixf.c
  • floatunditf.c
  • floatundixf.c
  • floatunsitf.c
  • floatuntixf.c
  • i386/floatdixf.S
  • i386/floatundixf.S
  • muldc3.c
  • mulsc3.c
  • multc3.c
  • multf3.c
  • mulxc3.c
  • powitf2.c
  • powixf2.c
  • ppc/divtc3.c
  • ppc/fixtfdi.c
  • ppc/fixunstfdi.c
  • ppc/floatditf.c
  • ppc/floatunditf.c
  • ppc/gcc_qadd.c
  • ppc/gcc_qdiv.c
  • ppc/gcc_qmul.c
  • ppc/gcc_qsub.c
  • ppc/multc3.c
  • subtf3.c
  • trunctfdf2.c
  • trunctfsf2.c
  • x86_64/floatdixf.c
  • x86_64/floatundixf.S

These builtins are never called by LLVM.

  • absvdi2.c
  • absvsi2.c
  • absvti2.c
  • addvdi3.c
  • addvsi3.c
  • addvti3.c
  • arm/aeabi_cdcmp.S
  • arm/aeabi_cdcmpeq_check_nan.c
  • arm/aeabi_cfcmp.S
  • arm/aeabi_cfcmpeq_check_nan.c
  • arm/aeabi_div0.c
  • arm/aeabi_drsub.c
  • arm/aeabi_frsub.c
  • arm/aeabi_memcmp.S
  • arm/bswapdi2.S
  • arm/bswapsi2.S
  • arm/clzdi2.S
  • arm/clzsi2.S
  • arm/comparesf2.S
  • arm/restore_vfp_d8_d15_regs.S
  • arm/save_vfp_d8_d15_regs.S
  • arm/switch16.S
  • arm/switch32.S
  • arm/switch8.S
  • arm/switchu8.S
  • clzdi2.c
  • clzsi2.c
  • clzti2.c
  • cmpdi2.c
  • cmpti2.c
  • ctzdi2.c
  • ctzsi2.c
  • ctzti2.c
  • ffsdi2.c - this is called by gcc though!
  • ffsti2.c
  • mulvdi3.c
  • mulvsi3.c
  • mulvti3.c
  • negdf2.c
  • negdi2.c
  • negsf2.c
  • negti2.c
  • negvdi2.c
  • negvsi2.c
  • negvti2.c
  • paritydi2.c
  • paritysi2.c
  • parityti2.c
  • popcountdi2.c
  • popcountsi2.c
  • popcountti2.c
  • ppc/restFP.S
  • ppc/saveFP.S
  • subvdi3.c
  • subvsi3.c
  • subvti3.c
  • ucmpdi2.c
  • ucmpti2.c
  • udivmodti4.c

Rust only exposes atomic types on platforms that support them, and therefore does not need to fall back to software implementations.

  • arm/sync_fetch_and_add_4.S
  • arm/sync_fetch_and_add_8.S
  • arm/sync_fetch_and_and_4.S
  • arm/sync_fetch_and_and_8.S
  • arm/sync_fetch_and_max_4.S
  • arm/sync_fetch_and_max_8.S
  • arm/sync_fetch_and_min_4.S
  • arm/sync_fetch_and_min_8.S
  • arm/sync_fetch_and_nand_4.S
  • arm/sync_fetch_and_nand_8.S
  • arm/sync_fetch_and_or_4.S
  • arm/sync_fetch_and_or_8.S
  • arm/sync_fetch_and_sub_4.S
  • arm/sync_fetch_and_sub_8.S
  • arm/sync_fetch_and_umax_4.S
  • arm/sync_fetch_and_umax_8.S
  • arm/sync_fetch_and_umin_4.S
  • arm/sync_fetch_and_umin_8.S
  • arm/sync_fetch_and_xor_4.S
  • arm/sync_fetch_and_xor_8.S
  • arm/sync_synchronize.S
  • atomic.c
  • atomic_flag_clear.c
  • atomic_flag_clear_explicit.c
  • atomic_flag_test_and_set.c
  • atomic_flag_test_and_set_explicit.c
  • atomic_signal_fence.c
  • atomic_thread_fence.c

Miscellaneous functionality that is not used by Rust.

  • apple_versioning.c
  • clear_cache.c
  • emutls.c
  • enable_execute_stack.c
  • eprintf.c
  • gcc_personality_v0.c
  • trampoline_setup.c

Floating-point implementations of builtins that are only called from soft-float code. It would be better to simply use the generic soft-float versions in this case.

  • i386/floatdidf.S
  • i386/floatdisf.S
  • i386/floatundidf.S
  • i386/floatundisf.S
  • x86_64/floatundidf.S
  • x86_64/floatundisf.S
  • x86_64/floatdidf.c
  • x86_64/floatdisf.c

License

The compiler-builtins crate is dual licensed under both the University of Illinois "BSD-Like" license and the MIT license. As a user of this code you may choose to use it under either license. As a contributor, you agree to allow your code to be used under both.

Full text of the relevant licenses is in LICENSE.TXT.