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Fix weak linkage

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This removes the last sysroot patch apart from the few patches that disable tests
This commit is contained in:
bjorn3 2020-08-16 21:20:12 +02:00
parent 02b7cdc316
commit ca9fc101c0
4 changed files with 60 additions and 90 deletions
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17
example/mini_core_hello_world.rs
View file

@ -241,19 +241,22 @@ fn main() {
assert_eq!(((|()| 42u8) as fn(()) -> u8)(()), 42);
extern {
#[linkage = "extern_weak"]
static ABC: *const u8;
}
#[cfg(not(jit))]
{
extern {
#[linkage = "extern_weak"]
static ABC: *const u8;
}
}
unsafe { assert_eq!(ABC as usize, 0); }
{
extern {
#[linkage = "extern_weak"]
static ABC: *const u8;
}
}
unsafe { assert_eq!(ABC as usize, 0); }
}
&mut (|| Some(0 as *const ())) as &mut dyn FnMut() -> Option<*const ()>;

45
patches/0025-Remove-usage-of-extern_weak-in-thread_local_dtor.patch
View file

@ -1,45 +0,0 @@
From 7496bb94a2fb2bc34629c9781c3bc3a470becaee Mon Sep 17 00:00:00 2001
From: bjorn3 <bjorn3@users.noreply.github.com>
Date: Fri, 10 Apr 2020 13:47:42 +0200
Subject: [PATCH] Remove usage of extern_weak in thread_local_dtor
---
library/std/src/sys/unix/thread_local_dtor.rs | 20 --------------------
1 files changed, 0 insertions(+), 20 deletions(-)
diff --git a/library/std/src/sys/unix/thread_local_dtor.rs b/library/std/src/sys/unix/thread_local_dtor.rs
index 8730b4d..8d6e3d5 100644
--- a/library/std/src/sys/unix/thread_local_dtor.rs
+++ b/library/std/src/sys/unix/thread_local_dtor.rs
@@ -15,28 +15,8 @@
target_os = "emscripten"
))]
pub unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern "C" fn(*mut u8)) {
- use crate::mem;
use crate::sys_common::thread_local_dtor::register_dtor_fallback;
- extern "C" {
- #[linkage = "extern_weak"]
- static __dso_handle: *mut u8;
- #[linkage = "extern_weak"]
- static __cxa_thread_atexit_impl: *const libc::c_void;
- }
- if !__cxa_thread_atexit_impl.is_null() {
- type F = unsafe extern "C" fn(
- dtor: unsafe extern "C" fn(*mut u8),
- arg: *mut u8,
- dso_handle: *mut u8,
- ) -> libc::c_int;
- mem::transmute::<*const libc::c_void, F>(__cxa_thread_atexit_impl)(
- dtor,
- t,
- &__dso_handle as *const _ as *mut _,
- );
- return;
- }
register_dtor_fallback(t, dtor);
}
--
2.20.1

80
src/constant.rs
View file

@ -43,8 +43,7 @@ pub(crate) fn codegen_tls_ref<'tcx>(
def_id: DefId,
layout: TyAndLayout<'tcx>,
) -> CValue<'tcx> {
let linkage = crate::linkage::get_static_ref_linkage(fx.tcx, def_id);
let data_id = data_id_for_static(fx.tcx, fx.module, def_id, linkage);
let data_id = data_id_for_static(fx.tcx, fx.module, def_id, false);
let local_data_id = fx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
#[cfg(debug_assertions)]
fx.add_comment(local_data_id, format!("tls {:?}", def_id));
@ -57,8 +56,7 @@ fn codegen_static_ref<'tcx>(
def_id: DefId,
layout: TyAndLayout<'tcx>,
) -> CPlace<'tcx> {
let linkage = crate::linkage::get_static_ref_linkage(fx.tcx, def_id);
let data_id = data_id_for_static(fx.tcx, fx.module, def_id, linkage);
let data_id = data_id_for_static(fx.tcx, fx.module, def_id, false);
let local_data_id = fx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
#[cfg(debug_assertions)]
fx.add_comment(local_data_id, format!("{:?}", def_id));
@ -159,8 +157,7 @@ pub(crate) fn trans_const_value<'tcx>(
}
Some(GlobalAlloc::Static(def_id)) => {
assert!(fx.tcx.is_static(def_id));
let linkage = crate::linkage::get_static_ref_linkage(fx.tcx, def_id);
let data_id = data_id_for_static(fx.tcx, fx.module, def_id, linkage);
let data_id = data_id_for_static(fx.tcx, fx.module, def_id, false);
let local_data_id = fx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
#[cfg(debug_assertions)]
fx.add_comment(local_data_id, format!("{:?}", def_id));
@ -226,8 +223,20 @@ fn data_id_for_static(
tcx: TyCtxt<'_>,
module: &mut Module<impl Backend>,
def_id: DefId,
linkage: Linkage,
definition: bool,
) -> DataId {
let rlinkage = tcx.codegen_fn_attrs(def_id).linkage;
let linkage = if definition {
crate::linkage::get_static_linkage(tcx, def_id)
} else {
if rlinkage == Some(rustc_middle::mir::mono::Linkage::ExternalWeak)
|| rlinkage == Some(rustc_middle::mir::mono::Linkage::WeakAny) {
Linkage::Preemptible
} else {
Linkage::Import
}
};
let instance = Instance::mono(tcx, def_id).polymorphize(tcx);
let symbol_name = tcx.symbol_name(instance).name;
let ty = instance.ty(tcx, ParamEnv::reveal_all());
@ -255,26 +264,39 @@ fn data_id_for_static(
)
.unwrap();
if linkage == Linkage::Preemptible {
if let ty::RawPtr(_) = ty.kind {
} else {
tcx.sess.span_fatal(
tcx.def_span(def_id),
"must have type `*const T` or `*mut T` due to `#[linkage]` attribute",
)
}
if rlinkage.is_some() {
// Comment copied from https://github.com/rust-lang/rust/blob/45060c2a66dfd667f88bd8b94261b28a58d85bd5/src/librustc_codegen_llvm/consts.rs#L141
// Declare an internal global `extern_with_linkage_foo` which
// is initialized with the address of `foo`. If `foo` is
// discarded during linking (for example, if `foo` has weak
// linkage and there are no definitions), then
// `extern_with_linkage_foo` will instead be initialized to
// zero.
let ref_name = format!("_rust_extern_with_linkage_{}", symbol_name);
let ref_data_id = module
.declare_data(
&ref_name,
Linkage::Local,
true,
false,
Some(align.try_into().unwrap()),
)
.unwrap();
let mut data_ctx = DataContext::new();
data_ctx.define_zeroinit(pointer_ty(tcx).bytes() as usize);
match module.define_data(data_id, &data_ctx) {
// Everytime a weak static is referenced, there will be a zero pointer definition,
let data = module.declare_data_in_data(data_id, &mut data_ctx);
data_ctx.define(std::iter::repeat(0).take(pointer_ty(tcx).bytes() as usize).collect());
data_ctx.write_data_addr(0, data, 0);
match module.define_data(ref_data_id, &data_ctx) {
// Every time the static is referenced there will be another definition of this global,
// so duplicate definitions are expected and allowed.
Err(ModuleError::DuplicateDefinition(_)) => {}
res => res.unwrap(),
}
ref_data_id
} else {
data_id
}
data_id
}
fn define_all_allocs(tcx: TyCtxt<'_>, module: &mut Module<impl Backend>, cx: &mut ConstantCx) {
@ -301,16 +323,7 @@ fn define_all_allocs(tcx: TyCtxt<'_>, module: &mut Module<impl Backend>, cx: &mu
_ => bug!("static const eval returned {:#?}", const_),
};
let data_id = data_id_for_static(
tcx,
module,
def_id,
if tcx.is_reachable_non_generic(def_id) {
Linkage::Export
} else {
Linkage::Export // FIXME Set hidden visibility
},
);
let data_id = data_id_for_static(tcx, module, def_id, true);
(data_id, alloc, section_name)
}
};
@ -360,12 +373,7 @@ fn define_all_allocs(tcx: TyCtxt<'_>, module: &mut Module<impl Backend>, cx: &mu
// Don't push a `TodoItem::Static` here, as it will cause statics used by
// multiple crates to be duplicated between them. It isn't necessary anyway,
// as it will get pushed by `codegen_static` when necessary.
data_id_for_static(
tcx,
module,
def_id,
crate::linkage::get_static_ref_linkage(tcx, def_id),
)
data_id_for_static(tcx, module, def_id, false)
}
};

8
src/linkage.rs
View file

@ -11,7 +11,7 @@ pub(crate) fn get_clif_linkage(mono_item: MonoItem<'_>, linkage: RLinkage, visib
}
}
pub(crate) fn get_static_ref_linkage(tcx: TyCtxt<'_>, def_id: DefId) -> Linkage {
pub(crate) fn get_static_linkage(tcx: TyCtxt<'_>, def_id: DefId) -> Linkage {
let fn_attrs = tcx.codegen_fn_attrs(def_id);
if let Some(linkage) = fn_attrs.linkage {
@ -22,6 +22,10 @@ pub(crate) fn get_static_ref_linkage(tcx: TyCtxt<'_>, def_id: DefId) -> Linkage
_ => panic!("{:?}", linkage),
}
} else {
Linkage::Import
if tcx.is_reachable_non_generic(def_id) {
Linkage::Export
} else {
Linkage::Export // FIXME use Linkage::Hidden
}
}
}