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Avoid a hir access inside get_static #81664

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merged 2 commits into from
Feb 6, 2021
Merged

Avoid a hir access inside get_static #81664

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fbe109a
Avoid a hir access inside get_static
bjorn3 Feb 2, 2021
da53655
Use is_local instead of as_local
bjorn3 Feb 4, 2021
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80 changes: 24 additions & 56 deletions compiler/rustc_codegen_llvm/src/consts.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,17 +8,14 @@ use crate::value::Value;
use libc::c_uint;
use rustc_codegen_ssa::traits::*;
use rustc_data_structures::const_cstr;
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_hir::Node;
use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
use rustc_middle::mir::interpret::{
read_target_uint, Allocation, ErrorHandled, GlobalAlloc, Pointer,
};
use rustc_middle::mir::mono::MonoItem;
use rustc_middle::ty::{self, Instance, Ty};
use rustc_middle::{bug, span_bug};
use rustc_span::symbol::sym;
use rustc_target::abi::{AddressSpace, Align, HasDataLayout, LayoutOf, Primitive, Scalar, Size};
use tracing::debug;

Expand Down Expand Up @@ -209,70 +206,42 @@ impl CodegenCx<'ll, 'tcx> {

let ty = instance.ty(self.tcx, ty::ParamEnv::reveal_all());
let sym = self.tcx.symbol_name(instance).name;
let fn_attrs = self.tcx.codegen_fn_attrs(def_id);

debug!("get_static: sym={} instance={:?}", sym, instance);
debug!("get_static: sym={} instance={:?} fn_attrs={:?}", sym, instance, fn_attrs);

let g = if let Some(local_def_id) = def_id.as_local() {
let id = self.tcx.hir().local_def_id_to_hir_id(local_def_id);
let g = if def_id.as_local().is_some() && !self.tcx.is_foreign_item(def_id) {
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let llty = self.layout_of(ty).llvm_type(self);
// FIXME: refactor this to work without accessing the HIR
let (g, attrs) = match self.tcx.hir().get(id) {
Node::Item(&hir::Item { attrs, kind: hir::ItemKind::Static(..), .. }) => {
if let Some(g) = self.get_declared_value(sym) {
if self.val_ty(g) != self.type_ptr_to(llty) {
span_bug!(self.tcx.def_span(def_id), "Conflicting types for static");
}
}

let g = self.declare_global(sym, llty);

if !self.tcx.is_reachable_non_generic(local_def_id) {
unsafe {
llvm::LLVMRustSetVisibility(g, llvm::Visibility::Hidden);
}
}

(g, attrs)
if let Some(g) = self.get_declared_value(sym) {
if self.val_ty(g) != self.type_ptr_to(llty) {
span_bug!(self.tcx.def_span(def_id), "Conflicting types for static");
}
}

Node::ForeignItem(&hir::ForeignItem {
ref attrs,
kind: hir::ForeignItemKind::Static(..),
..
}) => {
let fn_attrs = self.tcx.codegen_fn_attrs(local_def_id);
(check_and_apply_linkage(&self, &fn_attrs, ty, sym, def_id), &**attrs)
}

item => bug!("get_static: expected static, found {:?}", item),
};

debug!("get_static: sym={} attrs={:?}", sym, attrs);
let g = self.declare_global(sym, llty);

for attr in attrs {
if self.tcx.sess.check_name(attr, sym::thread_local) {
llvm::set_thread_local_mode(g, self.tls_model);
if !self.tcx.is_reachable_non_generic(def_id) {
unsafe {
llvm::LLVMRustSetVisibility(g, llvm::Visibility::Hidden);
}
}

g
} else {
// FIXME(nagisa): perhaps the map of externs could be offloaded to llvm somehow?
debug!("get_static: sym={} item_attr={:?}", sym, self.tcx.item_attrs(def_id));
check_and_apply_linkage(&self, &fn_attrs, ty, sym, def_id)
};

let attrs = self.tcx.codegen_fn_attrs(def_id);
let g = check_and_apply_linkage(&self, &attrs, ty, sym, def_id);

// 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.
if attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) {
llvm::set_thread_local_mode(g, self.tls_model);
}
// 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.
if fn_attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) {
llvm::set_thread_local_mode(g, self.tls_model);
}

if def_id.as_local().is_none() {
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let needs_dll_storage_attr = self.use_dll_storage_attrs && !self.tcx.is_foreign_item(def_id) &&
// ThinLTO can't handle this workaround in all cases, so we don't
// emit the attrs. Instead we make them unnecessary by disallowing
Expand Down Expand Up @@ -304,8 +273,7 @@ impl CodegenCx<'ll, 'tcx> {
}
}
}
g
};
}

if self.use_dll_storage_attrs && self.tcx.is_dllimport_foreign_item(def_id) {
// For foreign (native) libs we know the exact storage type to use.
Expand Down