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Rollup merge of #137603 - davidtwco:extern-types-no-deref, r=lcnr

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codegen_llvm: avoid `Deref` impls w/ extern type

`rustc_codegen_llvm` relied on `Deref` impls where `Deref::Target` was or contained an extern type - in my experimental implementation of rust-lang/rfcs#3729, this isn't possible as the `Target` associated type's `?Sized` bound cannot be relaxed backwards compatibly (unless we come up with some way of doing this).

In later pull requests with the rust-lang/rfcs#3729 implementation, breakage like this could only occur for nightly users relying on the `extern_types` feature.

Upstreaming this to avoid needing to keep carrying this patch locally, and I think it'll necessarily need to change eventually.
This commit is contained in:
León Orell Valerian Liehr 2025-02-26 04:15:06 +01:00 • committed by GitHub
commit a579a23a73
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GPG key ID: B5690EEEBB952194
8 changed files with 31 additions and 30 deletions
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6
compiler/rustc_codegen_llvm/src/back/lto.rs
View file

@ -793,7 +793,9 @@ pub(crate) unsafe fn optimize_thin_module(
{
let _timer =
cgcx.prof.generic_activity_with_arg("LLVM_thin_lto_rename", thin_module.name());
unsafe { llvm::LLVMRustPrepareThinLTORename(thin_module.shared.data.0, llmod, target) };
unsafe {
llvm::LLVMRustPrepareThinLTORename(thin_module.shared.data.0, llmod, target.raw())
};
save_temp_bitcode(cgcx, &module, "thin-lto-after-rename");
}
@ -823,7 +825,7 @@ pub(crate) unsafe fn optimize_thin_module(
let _timer =
cgcx.prof.generic_activity_with_arg("LLVM_thin_lto_import", thin_module.name());
if unsafe {
!llvm::LLVMRustPrepareThinLTOImport(thin_module.shared.data.0, llmod, target)
!llvm::LLVMRustPrepareThinLTOImport(thin_module.shared.data.0, llmod, target.raw())
} {
return Err(write::llvm_err(dcx, LlvmError::PrepareThinLtoModule));
}

11
compiler/rustc_codegen_llvm/src/back/owned_target_machine.rs
View file

@ -1,6 +1,5 @@
use std::ffi::{CStr, c_char};
use std::marker::PhantomData;
use std::ops::Deref;
use std::ptr::NonNull;
use rustc_data_structures::small_c_str::SmallCStr;
@ -80,12 +79,12 @@ impl OwnedTargetMachine {
.map(|tm_unique| Self { tm_unique, phantom: PhantomData })
.ok_or_else(|| LlvmError::CreateTargetMachine { triple: SmallCStr::from(triple) })
}
}
impl Deref for OwnedTargetMachine {
type Target = llvm::TargetMachine;
fn deref(&self) -> &Self::Target {
/// Returns inner `llvm::TargetMachine` type.
///
/// This could be a `Deref` implementation, but `llvm::TargetMachine` is an extern type and
/// `Deref::Target: ?Sized`.
pub fn raw(&self) -> &llvm::TargetMachine {
// SAFETY: constructing ensures we have a valid pointer created by
// llvm::LLVMRustCreateTargetMachine.
unsafe { self.tm_unique.as_ref() }

6
compiler/rustc_codegen_llvm/src/back/write.rs
View file

@ -637,7 +637,7 @@ pub(crate) unsafe fn llvm_optimize(
let result = unsafe {
llvm::LLVMRustOptimize(
module.module_llvm.llmod(),
&*module.module_llvm.tm,
&*module.module_llvm.tm.raw(),
to_pass_builder_opt_level(opt_level),
opt_stage,
cgcx.opts.cg.linker_plugin_lto.enabled(),
@ -875,7 +875,7 @@ pub(crate) unsafe fn codegen(
};
write_output_file(
dcx,
tm,
tm.raw(),
config.no_builtins,
llmod,
&path,
@ -909,7 +909,7 @@ pub(crate) unsafe fn codegen(
write_output_file(
dcx,
tm,
tm.raw(),
config.no_builtins,
llmod,
&obj_out,

6
compiler/rustc_codegen_llvm/src/builder.rs
View file

@ -405,7 +405,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
// Emit KCFI operand bundle
let kcfi_bundle = self.kcfi_operand_bundle(fn_attrs, fn_abi, instance, llfn);
if let Some(kcfi_bundle) = kcfi_bundle.as_deref() {
if let Some(kcfi_bundle) = kcfi_bundle.as_ref().map(|b| b.raw()) {
bundles.push(kcfi_bundle);
}
@ -1433,7 +1433,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
// Emit KCFI operand bundle
let kcfi_bundle = self.kcfi_operand_bundle(fn_attrs, fn_abi, instance, llfn);
if let Some(kcfi_bundle) = kcfi_bundle.as_deref() {
if let Some(kcfi_bundle) = kcfi_bundle.as_ref().map(|b| b.raw()) {
bundles.push(kcfi_bundle);
}
@ -1782,7 +1782,7 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
// Emit KCFI operand bundle
let kcfi_bundle = self.kcfi_operand_bundle(fn_attrs, fn_abi, instance, llfn);
if let Some(kcfi_bundle) = kcfi_bundle.as_deref() {
if let Some(kcfi_bundle) = kcfi_bundle.as_ref().map(|b| b.raw()) {
bundles.push(kcfi_bundle);
}

2
compiler/rustc_codegen_llvm/src/common.rs
View file

@ -77,7 +77,7 @@ impl<'ll> Funclet<'ll> {
}
pub(crate) fn bundle(&self) -> &llvm::OperandBundle<'ll> {
&self.operand
self.operand.raw()
}
}

2
compiler/rustc_codegen_llvm/src/context.rs
View file

@ -205,7 +205,7 @@ pub(crate) unsafe fn create_module<'ll>(
{
let tm = crate::back::write::create_informational_target_machine(tcx.sess, false);
unsafe {
llvm::LLVMRustSetDataLayoutFromTargetMachine(llmod, &tm);
llvm::LLVMRustSetDataLayoutFromTargetMachine(llmod, tm.raw());
}
let llvm_data_layout = unsafe { llvm::LLVMGetDataLayoutStr(llmod) };

21
compiler/rustc_codegen_llvm/src/llvm/mod.rs
View file

@ -1,7 +1,6 @@
#![allow(non_snake_case)]
use std::ffi::{CStr, CString};
use std::ops::Deref;
use std::ptr;
use std::str::FromStr;
use std::string::FromUtf8Error;
@ -355,6 +354,16 @@ impl<'a> OperandBundleOwned<'a> {
};
OperandBundleOwned { raw: ptr::NonNull::new(raw).unwrap() }
}
/// Returns inner `OperandBundle` type.
///
/// This could be a `Deref` implementation, but `OperandBundle` contains an extern type and
/// `Deref::Target: ?Sized`.
pub(crate) fn raw(&self) -> &OperandBundle<'a> {
// SAFETY: The returned reference is opaque and can only used for FFI.
// It is valid for as long as `&self` is.
unsafe { self.raw.as_ref() }
}
}
impl Drop for OperandBundleOwned<'_> {
@ -365,16 +374,6 @@ impl Drop for OperandBundleOwned<'_> {
}
}
impl<'a> Deref for OperandBundleOwned<'a> {
type Target = OperandBundle<'a>;
fn deref(&self) -> &Self::Target {
// SAFETY: The returned reference is opaque and can only used for FFI.
// It is valid for as long as `&self` is.
unsafe { self.raw.as_ref() }
}
}
pub(crate) fn add_module_flag_u32(
module: &Module,
merge_behavior: ModuleFlagMergeBehavior,

7
compiler/rustc_codegen_llvm/src/llvm_util.rs
View file

@ -331,7 +331,8 @@ pub(crate) fn target_features_cfg(sess: &Session, allow_unstable: bool) -> Vec<S
if let Some(feat) = to_llvm_features(sess, feature) {
for llvm_feature in feat {
let cstr = SmallCStr::new(llvm_feature);
if !unsafe { llvm::LLVMRustHasFeature(&target_machine, cstr.as_ptr()) } {
if !unsafe { llvm::LLVMRustHasFeature(target_machine.raw(), cstr.as_ptr()) }
{
return false;
}
}
@ -453,8 +454,8 @@ pub(crate) fn print(req: &PrintRequest, out: &mut String, sess: &Session) {
require_inited();
let tm = create_informational_target_machine(sess, false);
match req.kind {
PrintKind::TargetCPUs => print_target_cpus(sess, &tm, out),
PrintKind::TargetFeatures => print_target_features(sess, &tm, out),
PrintKind::TargetCPUs => print_target_cpus(sess, tm.raw(), out),
PrintKind::TargetFeatures => print_target_features(sess, tm.raw(), out),
_ => bug!("rustc_codegen_llvm can't handle print request: {:?}", req),
}
}