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ensure JSON-defined targets are consistent
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RalfJung committed Nov 24, 2024
1 parent c49a687 commit 1628e60
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Showing 5 changed files with 305 additions and 187 deletions.
304 changes: 301 additions & 3 deletions compiler/rustc_target/src/spec/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,9 @@
//! the target's settings, though `target-feature` and `link-args` will *add*
//! to the list specified by the target, rather than replace.
// ignore-tidy-filelength

use std::assert_matches::assert_matches;
use std::borrow::Cow;
use std::collections::BTreeMap;
use std::hash::{Hash, Hasher};
Expand Down Expand Up @@ -1605,13 +1608,11 @@ macro_rules! supported_targets {

#[cfg(test)]
mod tests {
mod tests_impl;

// Cannot put this into a separate file without duplication, make an exception.
$(
#[test] // `#[test]`
fn $module() {
tests_impl::test_target(crate::spec::targets::$module::target());
crate::spec::targets::$module::target().test_target()
}
)+
}
Expand Down Expand Up @@ -2849,6 +2850,302 @@ impl Target {
self.max_atomic_width.unwrap_or_else(|| self.pointer_width.into())
}

fn check_consistency(&self) -> Result<(), String> {
macro_rules! check {
($b:expr, $($msg:tt)*) => {
if !$b {
return Err(format!($($msg)*));
}
}
}
macro_rules! check_eq {
($left:expr, $right:expr, $($msg:tt)*) => {
if ($left) != ($right) {
return Err(format!($($msg)*));
}
}
}
macro_rules! check_ne {
($left:expr, $right:expr, $($msg:tt)*) => {
if ($left) == ($right) {
return Err(format!($($msg)*));
}
}
}
macro_rules! check_matches {
($left:expr, $right:pat, $($msg:tt)*) => {
if !matches!($left, $right) {
return Err(format!($($msg)*));
}
}
}

check_eq!(
self.is_like_osx,
self.vendor == "apple",
"`is_like_osx` must be set if and only if `vendor` is `apple`"
);
check_eq!(
self.is_like_solaris,
self.os == "solaris" || self.os == "illumos",
"`is_like_solaris` must be set if and only if `os` is `solaris` or `illumos`"
);
check_eq!(
self.is_like_windows,
self.os == "windows" || self.os == "uefi",
"`is_like_windows` must be set if and only if `os` is `windows` or `uefi`"
);
check_eq!(
self.is_like_wasm,
self.arch == "wasm32" || self.arch == "wasm64",
"`is_like_wasm` must be set if and only if `arch` is `wasm32` or `wasm64`"
);
if self.is_like_msvc {
check!(self.is_like_windows, "if `is_like_msvc` is set, `is_like_windows` must be set");
}

// Check that default linker flavor is compatible with some other key properties.
check_eq!(
self.is_like_osx,
matches!(self.linker_flavor, LinkerFlavor::Darwin(..)),
"`linker_flavor` must be `darwin` if and only if `is_like_osx` is set"
);
check_eq!(
self.is_like_msvc,
matches!(self.linker_flavor, LinkerFlavor::Msvc(..)),
"`linker_flavor` must be `mscv` if and only if `is_like_msvc` is set"
);
check_eq!(
self.is_like_wasm && self.os != "emscripten",
matches!(self.linker_flavor, LinkerFlavor::WasmLld(..)),
"`linker_flavor` must be `wasm-lld` if and only if `is_like_wasm` is set and the `os` is not `emscripten`",
);
check_eq!(
self.os == "emscripten",
matches!(self.linker_flavor, LinkerFlavor::EmCc),
"`linker_flavor` must be `em-cc` if and only if `os` is `emscripten`"
);
check_eq!(
self.arch == "bpf",
matches!(self.linker_flavor, LinkerFlavor::Bpf),
"`linker_flavor` must be `bpf` if and only if `arch` is `bpf`"
);
check_eq!(
self.arch == "nvptx64",
matches!(self.linker_flavor, LinkerFlavor::Ptx),
"`linker_flavor` must be `ptc` if and only if `arch` is `nvptx64`"
);

for args in [
&self.pre_link_args,
&self.late_link_args,
&self.late_link_args_dynamic,
&self.late_link_args_static,
&self.post_link_args,
] {
for (&flavor, flavor_args) in args {
check!(!flavor_args.is_empty(), "linker flavor args must not be empty");
// Check that flavors mentioned in link args are compatible with the default flavor.
match self.linker_flavor {
LinkerFlavor::Gnu(..) => {
check_matches!(
flavor,
LinkerFlavor::Gnu(..),
"mixing GNU and non-GNU linker flavors"
);
}
LinkerFlavor::Darwin(..) => {
check_matches!(
flavor,
LinkerFlavor::Darwin(..),
"mixing Darwin and non-Darwin linker flavors"
)
}
LinkerFlavor::WasmLld(..) => {
check_matches!(
flavor,
LinkerFlavor::WasmLld(..),
"mixing wasm and non-wasm linker flavors"
)
}
LinkerFlavor::Unix(..) => {
check_matches!(
flavor,
LinkerFlavor::Unix(..),
"mixing unix and non-unix linker flavors"
);
}
LinkerFlavor::Msvc(..) => {
check_matches!(
flavor,
LinkerFlavor::Msvc(..),
"mixing MSVC and non-MSVC linker flavors"
);
}
LinkerFlavor::EmCc
| LinkerFlavor::Bpf
| LinkerFlavor::Ptx
| LinkerFlavor::Llbc => {
check_eq!(flavor, self.linker_flavor, "mixing different linker flavors")
}
}

// Check that link args for cc and non-cc versions of flavors are consistent.
let check_noncc = |noncc_flavor| -> Result<(), String> {
if let Some(noncc_args) = args.get(&noncc_flavor) {
for arg in flavor_args {
if let Some(suffix) = arg.strip_prefix("-Wl,") {
check!(
noncc_args.iter().any(|a| a == suffix),
" link args for cc and non-cc versions of flavors are not consistent"
);
}
}
}
Ok(())
};

match self.linker_flavor {
LinkerFlavor::Gnu(Cc::Yes, lld) => check_noncc(LinkerFlavor::Gnu(Cc::No, lld))?,
LinkerFlavor::WasmLld(Cc::Yes) => check_noncc(LinkerFlavor::WasmLld(Cc::No))?,
LinkerFlavor::Unix(Cc::Yes) => check_noncc(LinkerFlavor::Unix(Cc::No))?,
_ => {}
}
}

// Check that link args for lld and non-lld versions of flavors are consistent.
for cc in [Cc::No, Cc::Yes] {
check_eq!(
args.get(&LinkerFlavor::Gnu(cc, Lld::No)),
args.get(&LinkerFlavor::Gnu(cc, Lld::Yes)),
"link args for lld and non-lld versions of flavors are not consistent",
);
check_eq!(
args.get(&LinkerFlavor::Darwin(cc, Lld::No)),
args.get(&LinkerFlavor::Darwin(cc, Lld::Yes)),
"link args for lld and non-lld versions of flavors are not consistent",
);
}
check_eq!(
args.get(&LinkerFlavor::Msvc(Lld::No)),
args.get(&LinkerFlavor::Msvc(Lld::Yes)),
"link args for lld and non-lld versions of flavors are not consistent",
);
}

if self.link_self_contained.is_disabled() {
check!(
self.pre_link_objects_self_contained.is_empty()
&& self.post_link_objects_self_contained.is_empty(),
"if `link_self_contained` is disabled, then `pre_link_objects_self_contained` and `post_link_objects_self_contained` must be empty",
);
}

// If your target really needs to deviate from the rules below,
// except it and document the reasons.
// Keep the default "unknown" vendor instead.
check_ne!(self.vendor, "", "`vendor` cannot be empty");
check_ne!(self.os, "", "`os` cannot be empty");
if !self.can_use_os_unknown() {
// Keep the default "none" for bare metal targets instead.
check_ne!(
self.os,
"unknown",
"`unknown` os can only be used on particular targets; use `none` for bare-metal targets"
);
}

// Check dynamic linking stuff
// BPF: when targeting user space vms (like rbpf), those can load dynamic libraries.
// hexagon: when targeting QuRT, that OS can load dynamic libraries.
// wasm{32,64}: dynamic linking is inherent in the definition of the VM.
if self.os == "none"
&& (self.arch != "bpf"
&& self.arch != "hexagon"
&& self.arch != "wasm32"
&& self.arch != "wasm64")
{
check!(
!self.dynamic_linking,
"dynamic linking is not supported on this OS/architecture"
);
}
if self.only_cdylib
|| self.crt_static_allows_dylibs
|| !self.late_link_args_dynamic.is_empty()
{
check!(
self.dynamic_linking,
"dynamic linking must be allowed when `only_cdylib` or `crt_static_allows_dylibs` or `late_link_args_dynamic` are set"
);
}
// Apparently PIC was slow on wasm at some point, see comments in wasm_base.rs
if self.dynamic_linking && !(self.is_like_wasm && self.os != "emscripten") {
check_eq!(
self.relocation_model,
RelocModel::Pic,
"targets that support dynamic linking must use the `pic` relocation model"
);
}
if self.position_independent_executables {
check_eq!(
self.relocation_model,
RelocModel::Pic,
"targets that support position-independent executables must use the `pic` relocation model"
);
}
// The UEFI targets do not support dynamic linking but still require PIC (#101377).
if self.relocation_model == RelocModel::Pic && self.os != "uefi" {
check!(
self.dynamic_linking || self.position_independent_executables,
"when the relocation model is `pic`, the target must support dynamic linking or use position-independent executables. \
Set the relocation model to `static` to avoid this requirement"
);
}
if self.static_position_independent_executables {
assert!(self.position_independent_executables);
}
if self.position_independent_executables {
assert!(self.executables);
}

// Check crt static stuff
if self.crt_static_default || self.crt_static_allows_dylibs {
assert!(self.crt_static_respected);
}

// Check that RISC-V targets always specify which ABI they use.
match &*self.arch {
"riscv32" => {
assert_matches!(&*self.llvm_abiname, "ilp32" | "ilp32f" | "ilp32d" | "ilp32e")
}
"riscv64" => {
// Note that the `lp64e` is still unstable as it's not (yet) part of the ELF psABI.
assert_matches!(&*self.llvm_abiname, "lp64" | "lp64f" | "lp64d" | "lp64q" | "lp64e")
}
_ => {}
}

Ok(())
}

/// Test target self-consistency and JSON encoding/decoding roundtrip.
#[cfg(test)]
fn test_target(mut self) {
let recycled_target = Target::from_json(self.to_json()).map(|(j, _)| j);
self.update_to_cli();
self.check_consistency().unwrap();
assert_eq!(recycled_target, Ok(self));
}

// Add your target to the whitelist if it has `std` library
// and you certainly want "unknown" for the OS name.
fn can_use_os_unknown(&self) -> bool {
self.llvm_target == "wasm32-unknown-unknown"
|| self.llvm_target == "wasm64-unknown-unknown"
|| (self.env == "sgx" && self.vendor == "fortanix")
}

/// Loads a target descriptor from a JSON object.
pub fn from_json(obj: Json) -> Result<(Target, TargetWarnings), String> {
// While ugly, this code must remain this way to retain
Expand Down Expand Up @@ -3456,6 +3753,7 @@ impl Target {
key!(supports_xray, bool);

base.update_from_cli();
base.check_consistency()?;

// Each field should have been read using `Json::remove` so any keys remaining are unused.
let remaining_keys = obj.keys();
Expand Down
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