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Move from an "asm" flag to a "no-asm" feature flag (#386)

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* Use a no-asm feature instead of an asm feature

This works better as core/alloc/std have trouble supporting default
featues in this crate.

Signed-off-by: Joe Richey <joerichey@google.com>

* Have no-asm disable arm assembly intrinsics

Signed-off-by: Joe Richey <joerichey@google.com>
This commit is contained in:
Joseph Richey 2020-11-09 07:24:25 -08:00 • committed by GitHub
parent 53daa3c593
commit 5c294cedc0
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GPG key ID: 4AEE18F83AFDEB23
10 changed files with 65 additions and 28 deletions
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8
library/compiler-builtins/Cargo.toml
View file

@ -40,14 +40,14 @@ panic-handler = { path = 'crates/panic-handler' }
[features]
default = ["compiler-builtins"]
# Some algorithms benefit from inline assembly, but some compiler backends do
# not support it, so inline assembly is only enabled when this flag is set.
asm = []
# Enable compilation of C code in compiler-rt, filling in some more optimized
# implementations and also filling in unimplemented intrinsics
c = ["cc"]
# Workaround for the Cranelift codegen backend. Disables any implementations
# which use inline assembly and fall back to pure Rust versions (if avalible).
no-asm = []
# Flag this library as the unstable compiler-builtins lib
compiler-builtins = []

8
library/compiler-builtins/ci/run.sh
View file

@ -12,16 +12,16 @@ else
$run --release
$run --features c
$run --features c --release
$run --features asm
$run --features asm --release
$run --features no-asm
$run --features no-asm --release
fi
cargo build --target $1
cargo build --target $1 --release
cargo build --target $1 --features c
cargo build --target $1 --release --features c
cargo build --target $1 --features asm
cargo build --target $1 --release --features asm
cargo build --target $1 --features no-asm
cargo build --target $1 --release --features no-asm
PREFIX=$(echo $1 | sed -e 's/unknown-//')-
case $1 in

2
library/compiler-builtins/src/arm.rs
View file

@ -1,3 +1,5 @@
#![cfg(not(feature = "no-asm"))]
use core::intrinsics;
// NOTE This function and the ones below are implemented using assembly because they using a custom

16
library/compiler-builtins/src/int/specialized_div_rem/mod.rs
View file

@ -115,7 +115,7 @@ fn u64_by_u64_div_rem(duo: u64, div: u64) -> (u64, u64) {
// microarchitecture can multiply and divide. We decide to be optimistic and assume `trifecta` is
// faster if the target pointer width is at least 64.
#[cfg(all(
not(all(feature = "asm", target_arch = "x86_64")),
not(all(not(feature = "no-asm"), target_arch = "x86_64")),
not(any(target_pointer_width = "16", target_pointer_width = "32"))
))]
impl_trifecta!(
@ -131,7 +131,7 @@ impl_trifecta!(
// If the pointer width less than 64, then the target architecture almost certainly does not have
// the fast 64 to 128 bit widening multiplication needed for `trifecta` to be faster.
#[cfg(all(
not(all(feature = "asm", target_arch = "x86_64")),
not(all(not(feature = "no-asm"), target_arch = "x86_64")),
any(target_pointer_width = "16", target_pointer_width = "32")
))]
impl_delegate!(
@ -152,7 +152,7 @@ impl_delegate!(
///
/// If the quotient does not fit in a `u64`, a floating point exception occurs.
/// If `div == 0`, then a division by zero exception occurs.
#[cfg(all(feature = "asm", target_arch = "x86_64"))]
#[cfg(all(not(feature = "no-asm"), target_arch = "x86_64"))]
#[inline]
unsafe fn u128_by_u64_div_rem(duo: u128, div: u64) -> (u64, u64) {
let duo_lo = duo as u64;
@ -174,7 +174,7 @@ unsafe fn u128_by_u64_div_rem(duo: u128, div: u64) -> (u64, u64) {
}
// use `asymmetric` instead of `trifecta` on x86_64
#[cfg(all(feature = "asm", target_arch = "x86_64"))]
#[cfg(all(not(feature = "no-asm"), target_arch = "x86_64"))]
impl_asymmetric!(
u128_div_rem,
zero_div_fn,
@ -203,7 +203,7 @@ fn u32_by_u32_div_rem(duo: u32, div: u32) -> (u32, u32) {
// When not on x86 and the pointer width is not 64, use `delegate` since the division size is larger
// than register size.
#[cfg(all(
not(all(feature = "asm", target_arch = "x86")),
not(all(not(feature = "no-asm"), target_arch = "x86")),
not(target_pointer_width = "64")
))]
impl_delegate!(
@ -220,7 +220,7 @@ impl_delegate!(
// When not on x86 and the pointer width is 64, use `binary_long`.
#[cfg(all(
not(all(feature = "asm", target_arch = "x86")),
not(all(not(feature = "no-asm"), target_arch = "x86")),
target_pointer_width = "64"
))]
impl_binary_long!(
@ -238,7 +238,7 @@ impl_binary_long!(
///
/// If the quotient does not fit in a `u32`, a floating point exception occurs.
/// If `div == 0`, then a division by zero exception occurs.
#[cfg(all(feature = "asm", target_arch = "x86"))]
#[cfg(all(not(feature = "no-asm"), target_arch = "x86"))]
#[inline]
unsafe fn u64_by_u32_div_rem(duo: u64, div: u32) -> (u32, u32) {
let duo_lo = duo as u32;
@ -260,7 +260,7 @@ unsafe fn u64_by_u32_div_rem(duo: u64, div: u32) -> (u32, u32) {
}
// use `asymmetric` instead of `delegate` on x86
#[cfg(all(feature = "asm", target_arch = "x86"))]
#[cfg(all(not(feature = "no-asm"), target_arch = "x86"))]
impl_asymmetric!(
u64_div_rem,
zero_div_fn,

6
library/compiler-builtins/src/lib.rs
View file

@ -1,8 +1,8 @@
#![cfg_attr(feature = "compiler-builtins", compiler_builtins)]
#![cfg_attr(feature = "asm", feature(asm))]
#![cfg_attr(not(feature = "no-asm"), feature(asm))]
#![feature(abi_unadjusted)]
#![feature(llvm_asm)]
#![feature(global_asm)]
#![cfg_attr(not(feature = "no-asm"), feature(llvm_asm))]
#![cfg_attr(not(feature = "no-asm"), feature(global_asm))]
#![feature(cfg_target_has_atomic)]
#![feature(compiler_builtins)]
#![feature(core_intrinsics)]

5
library/compiler-builtins/src/mem/mod.rs
View file

@ -10,7 +10,10 @@ use core::mem;
use core::ops::{BitOr, Shl};
// memcpy/memmove/memset have optimized implementations on some architectures
#[cfg_attr(all(feature = "asm", target_arch = "x86_64"), path = "x86_64.rs")]
#[cfg_attr(
all(not(feature = "no-asm"), target_arch = "x86_64"),
path = "x86_64.rs"
)]
mod impls;
#[cfg_attr(all(feature = "mem", not(feature = "mangled-names")), no_mangle)]

2
library/compiler-builtins/src/probestack.rs
View file

@ -44,6 +44,8 @@
#![cfg(not(feature = "mangled-names"))]
// Windows already has builtins to do this.
#![cfg(not(windows))]
// All these builtins require assembly
#![cfg(not(feature = "no-asm"))]
// We only define stack probing for these architectures today.
#![cfg(any(target_arch = "x86_64", target_arch = "x86"))]

21
library/compiler-builtins/src/x86.rs
View file

@ -8,7 +8,12 @@ use core::intrinsics;
// NOTE These functions are never mangled as they are not tested against compiler-rt
// and mangling ___chkstk would break the `jmp ___chkstk` instruction in __alloca
#[cfg(all(windows, target_env = "gnu", not(feature = "mangled-names")))]
#[cfg(all(
windows,
target_env = "gnu",
not(feature = "no-asm"),
not(feature = "mangled-names")
))]
#[naked]
#[no_mangle]
pub unsafe fn ___chkstk_ms() {
@ -34,7 +39,12 @@ pub unsafe fn ___chkstk_ms() {
}
// FIXME: __alloca should be an alias to __chkstk
#[cfg(all(windows, target_env = "gnu", not(feature = "mangled-names")))]
#[cfg(all(
windows,
target_env = "gnu",
not(feature = "no-asm"),
not(feature = "mangled-names")
))]
#[naked]
#[no_mangle]
pub unsafe fn __alloca() {
@ -43,7 +53,12 @@ pub unsafe fn __alloca() {
intrinsics::unreachable();
}
#[cfg(all(windows, target_env = "gnu", not(feature = "mangled-names")))]
#[cfg(all(
windows,
target_env = "gnu",
not(feature = "no-asm"),
not(feature = "mangled-names")
))]
#[naked]
#[no_mangle]
pub unsafe fn ___chkstk() {

21
library/compiler-builtins/src/x86_64.rs
View file

@ -8,7 +8,12 @@ use core::intrinsics;
// NOTE These functions are never mangled as they are not tested against compiler-rt
// and mangling ___chkstk would break the `jmp ___chkstk` instruction in __alloca
#[cfg(all(windows, target_env = "gnu", not(feature = "mangled-names")))]
#[cfg(all(
windows,
target_env = "gnu",
not(feature = "no-asm"),
not(feature = "mangled-names")
))]
#[naked]
#[no_mangle]
pub unsafe fn ___chkstk_ms() {
@ -33,7 +38,12 @@ pub unsafe fn ___chkstk_ms() {
intrinsics::unreachable();
}
#[cfg(all(windows, target_env = "gnu", not(feature = "mangled-names")))]
#[cfg(all(
windows,
target_env = "gnu",
not(feature = "no-asm"),
not(feature = "mangled-names")
))]
#[naked]
#[no_mangle]
pub unsafe fn __alloca() {
@ -43,7 +53,12 @@ pub unsafe fn __alloca() {
intrinsics::unreachable();
}
#[cfg(all(windows, target_env = "gnu", not(feature = "mangled-names")))]
#[cfg(all(
windows,
target_env = "gnu",
not(feature = "no-asm"),
not(feature = "mangled-names")
))]
#[naked]
#[no_mangle]
pub unsafe fn ___chkstk() {

4
library/compiler-builtins/testcrate/Cargo.toml
View file

@ -28,8 +28,8 @@ utest-cortex-m-qemu = { default-features = false, git = "https://github.com/japa
utest-macros = { git = "https://github.com/japaric/utest" }
[features]
default = ["asm", "mangled-names"]
asm = ["compiler_builtins/asm"]
default = ["mangled-names"]
c = ["compiler_builtins/c"]
no-asm = ["compiler_builtins/no-asm"]
mem = ["compiler_builtins/mem"]
mangled-names = ["compiler_builtins/mangled-names"]