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Rollup merge of #52635 - yodaldevoid:issue_18804, r=oli-obk 

Fix #[linkage] propagation though generic functions

Fixes #18804

In the non-local branch of `get_static` (where the fix was implemented) `span_fatal` had to be replaced with `bug!` as we have no span in that case.
This commit is contained in:
Mark Rousskov 2018-07-26 09:18:27 -06:00 committed by GitHub
parent 2aeb76500e be5b668a2e
commit c7555cedde
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 121 additions and 47 deletions
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125
src/librustc_codegen_llvm/consts.rs
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@ -20,12 +20,14 @@ use monomorphize::MonoItem;
use common::{CodegenCx, val_ty};
use declare;
use monomorphize::Instance;
use syntax_pos::Span;
use syntax_pos::symbol::LocalInternedString;
use type_::Type;
use type_of::LayoutLlvmExt;
use rustc::ty;
use rustc::ty::{self, Ty};
use rustc::ty::layout::{Align, LayoutOf};
use rustc::hir::{self, CodegenFnAttrFlags};
use rustc::hir::{self, CodegenFnAttrs, CodegenFnAttrFlags};
use std::ffi::{CStr, CString};
@ -119,6 +121,8 @@ pub fn get_static(cx: &CodegenCx, def_id: DefId) -> ValueRef {
let ty = instance.ty(cx.tcx);
let sym = cx.tcx.symbol_name(instance).as_str();
debug!("get_static: sym={} instance={:?}", sym, instance);
let g = if let Some(id) = cx.tcx.hir.as_local_node_id(def_id) {
let llty = cx.layout_of(ty).llvm_type(cx);
@ -144,50 +148,15 @@ pub fn get_static(cx: &CodegenCx, def_id: DefId) -> ValueRef {
hir_map::NodeForeignItem(&hir::ForeignItem {
ref attrs, span, node: hir::ForeignItemKind::Static(..), ..
}) => {
let g = if let Some(linkage) = cx.tcx.codegen_fn_attrs(def_id).linkage {
// If this is a static with a linkage specified, then we need to handle
// it a little specially. The typesystem prevents things like &T and
// extern "C" fn() from being non-null, so we can't just declare a
// static and call it a day. Some linkages (like weak) will make it such
// that the static actually has a null value.
let llty2 = match ty.sty {
ty::TyRawPtr(ref mt) => cx.layout_of(mt.ty).llvm_type(cx),
_ => {
cx.sess().span_fatal(span, "must have type `*const T` or `*mut T`");
}
};
unsafe {
// Declare a symbol `foo` with the desired linkage.
let g1 = declare::declare_global(cx, &sym, llty2);
llvm::LLVMRustSetLinkage(g1, base::linkage_to_llvm(linkage));
// 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 mut real_name = "_rust_extern_with_linkage_".to_string();
real_name.push_str(&sym);
let g2 = declare::define_global(cx, &real_name, llty).unwrap_or_else(||{
cx.sess().span_fatal(span,
&format!("symbol `{}` is already defined", &sym))
});
llvm::LLVMRustSetLinkage(g2, llvm::Linkage::InternalLinkage);
llvm::LLVMSetInitializer(g2, g1);
g2
}
} else {
// Generate an external declaration.
declare::declare_global(cx, &sym, llty)
};
(g, attrs)
let fn_attrs = cx.tcx.codegen_fn_attrs(def_id);
(check_and_apply_linkage(cx, &fn_attrs, ty, sym, Some(span)), attrs)
}
item => bug!("get_static: expected static, found {:?}", item)
};
debug!("get_static: sym={} attrs={:?}", sym, attrs);
for attr in attrs {
if attr.check_name("thread_local") {
llvm::set_thread_local_mode(g, cx.tls_model);
@ -197,19 +166,21 @@ pub fn get_static(cx: &CodegenCx, def_id: DefId) -> ValueRef {
g
} else {
// FIXME(nagisa): perhaps the map of externs could be offloaded to llvm somehow?
// FIXME(nagisa): investigate whether it can be changed into define_global
let g = declare::declare_global(cx, &sym, cx.layout_of(ty).llvm_type(cx));
debug!("get_static: sym={} item_attr={:?}", sym, cx.tcx.item_attrs(def_id));
let attrs = cx.tcx.codegen_fn_attrs(def_id);
let g = check_and_apply_linkage(cx, &attrs, ty, sym, None);
// Thread-local statics in some other crate need to *always* be linked
// against in a thread-local fashion, so we need to be sure to apply the
// thread-local attribute locally if it was present remotely. If we
// don't do this then linker errors can be generated where the linker
// complains that one object files has a thread local version of the
// symbol and another one doesn't.
for attr in cx.tcx.get_attrs(def_id).iter() {
if attr.check_name("thread_local") {
llvm::set_thread_local_mode(g, cx.tls_model);
}
if attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) {
llvm::set_thread_local_mode(g, cx.tls_model);
}
if cx.use_dll_storage_attrs && !cx.tcx.is_foreign_item(def_id) {
// This item is external but not foreign, i.e. it originates from an external Rust
// crate. Since we don't know whether this crate will be linked dynamically or
@ -242,6 +213,66 @@ pub fn get_static(cx: &CodegenCx, def_id: DefId) -> ValueRef {
g
}
fn check_and_apply_linkage<'tcx>(
cx: &CodegenCx<'_, 'tcx>,
attrs: &CodegenFnAttrs,
ty: Ty<'tcx>,
sym: LocalInternedString,
span: Option<Span>
) -> ValueRef {
let llty = cx.layout_of(ty).llvm_type(cx);
if let Some(linkage) = attrs.linkage {
debug!("get_static: sym={} linkage={:?}", sym, linkage);
// If this is a static with a linkage specified, then we need to handle
// it a little specially. The typesystem prevents things like &T and
// extern "C" fn() from being non-null, so we can't just declare a
// static and call it a day. Some linkages (like weak) will make it such
// that the static actually has a null value.
let llty2 = match ty.sty {
ty::TyRawPtr(ref mt) => cx.layout_of(mt.ty).llvm_type(cx),
_ => {
if span.is_some() {
cx.sess().span_fatal(span.unwrap(), "must have type `*const T` or `*mut T`")
} else {
bug!("must have type `*const T` or `*mut T`")
}
}
};
unsafe {
// Declare a symbol `foo` with the desired linkage.
let g1 = declare::declare_global(cx, &sym, llty2);
llvm::LLVMRustSetLinkage(g1, base::linkage_to_llvm(linkage));
// 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 mut real_name = "_rust_extern_with_linkage_".to_string();
real_name.push_str(&sym);
let g2 = declare::define_global(cx, &real_name, llty).unwrap_or_else(||{
if span.is_some() {
cx.sess().span_fatal(
span.unwrap(),
&format!("symbol `{}` is already defined", &sym)
)
} else {
bug!("symbol `{}` is already defined", &sym)
}
});
llvm::LLVMRustSetLinkage(g2, llvm::Linkage::InternalLinkage);
llvm::LLVMSetInitializer(g2, g1);
g2
}
} else {
// Generate an external declaration.
// FIXME(nagisa): investigate whether it can be changed into define_global
declare::declare_global(cx, &sym, llty)
}
}
pub fn codegen_static<'a, 'tcx>(
cx: &CodegenCx<'a, 'tcx>,
def_id: DefId,

20
src/test/run-pass/issue-18804/auxiliary/lib.rs Normal file
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@ -0,0 +1,20 @@
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#![crate_type = "rlib"]
#![feature(linkage)]
pub fn foo<T>() -> *const() {
extern {
#[linkage = "extern_weak"]
static FOO: *const();
}
unsafe { FOO }
}

23
src/test/run-pass/issue-18804/main.rs Normal file
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@ -0,0 +1,23 @@
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// Test for issue #18804, #[linkage] does not propagate thorugh generic
// functions. Failure results in a linker error.
// ignore-asmjs no weak symbol support
// ignore-emscripten no weak symbol support
// aux-build:lib.rs
extern crate lib;
fn main() {
lib::foo::<i32>();
}