566 lines
25 KiB
Rust
566 lines
25 KiB
Rust
use crate::base;
|
|
use crate::common::CodegenCx;
|
|
use crate::debuginfo;
|
|
use crate::llvm::{self, True};
|
|
use crate::llvm_util;
|
|
use crate::type_::Type;
|
|
use crate::type_of::LayoutLlvmExt;
|
|
use crate::value::Value;
|
|
use cstr::cstr;
|
|
use libc::c_uint;
|
|
use rustc_codegen_ssa::traits::*;
|
|
use rustc_hir::def_id::DefId;
|
|
use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
|
|
use rustc_middle::mir::interpret::{
|
|
read_target_uint, Allocation, ConstAllocation, ErrorHandled, GlobalAlloc, InitChunk, Pointer,
|
|
Scalar as InterpScalar,
|
|
};
|
|
use rustc_middle::mir::mono::MonoItem;
|
|
use rustc_middle::ty::layout::LayoutOf;
|
|
use rustc_middle::ty::{self, Instance, Ty};
|
|
use rustc_middle::{bug, span_bug};
|
|
use rustc_target::abi::{
|
|
AddressSpace, Align, HasDataLayout, Primitive, Scalar, Size, WrappingRange,
|
|
};
|
|
use std::ops::Range;
|
|
use tracing::debug;
|
|
|
|
pub fn const_alloc_to_llvm<'ll>(cx: &CodegenCx<'ll, '_>, alloc: ConstAllocation<'_>) -> &'ll Value {
|
|
let alloc = alloc.inner();
|
|
let mut llvals = Vec::with_capacity(alloc.relocations().len() + 1);
|
|
let dl = cx.data_layout();
|
|
let pointer_size = dl.pointer_size.bytes() as usize;
|
|
|
|
// Note: this function may call `inspect_with_uninit_and_ptr_outside_interpreter`,
|
|
// so `range` must be within the bounds of `alloc` and not contain or overlap a relocation.
|
|
fn append_chunks_of_init_and_uninit_bytes<'ll, 'a, 'b>(
|
|
llvals: &mut Vec<&'ll Value>,
|
|
cx: &'a CodegenCx<'ll, 'b>,
|
|
alloc: &'a Allocation,
|
|
range: Range<usize>,
|
|
) {
|
|
let chunks = alloc
|
|
.init_mask()
|
|
.range_as_init_chunks(Size::from_bytes(range.start), Size::from_bytes(range.end));
|
|
|
|
let chunk_to_llval = move |chunk| match chunk {
|
|
InitChunk::Init(range) => {
|
|
let range = (range.start.bytes() as usize)..(range.end.bytes() as usize);
|
|
let bytes = alloc.inspect_with_uninit_and_ptr_outside_interpreter(range);
|
|
cx.const_bytes(bytes)
|
|
}
|
|
InitChunk::Uninit(range) => {
|
|
let len = range.end.bytes() - range.start.bytes();
|
|
cx.const_undef(cx.type_array(cx.type_i8(), len))
|
|
}
|
|
};
|
|
|
|
// Generating partially-uninit consts is limited to small numbers of chunks,
|
|
// to avoid the cost of generating large complex const expressions.
|
|
// For example, `[(u32, u8); 1024 * 1024]` contains uninit padding in each element,
|
|
// and would result in `{ [5 x i8] zeroinitializer, [3 x i8] undef, ...repeat 1M times... }`.
|
|
let max = if llvm_util::get_version() < (14, 0, 0) {
|
|
// Generating partially-uninit consts inhibits optimizations in LLVM < 14.
|
|
// See https://github.com/rust-lang/rust/issues/84565.
|
|
1
|
|
} else {
|
|
cx.sess().opts.debugging_opts.uninit_const_chunk_threshold
|
|
};
|
|
let allow_uninit_chunks = chunks.clone().take(max.saturating_add(1)).count() <= max;
|
|
|
|
if allow_uninit_chunks {
|
|
llvals.extend(chunks.map(chunk_to_llval));
|
|
} else {
|
|
// If this allocation contains any uninit bytes, codegen as if it was initialized
|
|
// (using some arbitrary value for uninit bytes).
|
|
let bytes = alloc.inspect_with_uninit_and_ptr_outside_interpreter(range);
|
|
llvals.push(cx.const_bytes(bytes));
|
|
}
|
|
}
|
|
|
|
let mut next_offset = 0;
|
|
for &(offset, alloc_id) in alloc.relocations().iter() {
|
|
let offset = offset.bytes();
|
|
assert_eq!(offset as usize as u64, offset);
|
|
let offset = offset as usize;
|
|
if offset > next_offset {
|
|
// This `inspect` is okay since we have checked that it is not within a relocation, it
|
|
// is within the bounds of the allocation, and it doesn't affect interpreter execution
|
|
// (we inspect the result after interpreter execution).
|
|
append_chunks_of_init_and_uninit_bytes(&mut llvals, cx, alloc, next_offset..offset);
|
|
}
|
|
let ptr_offset = read_target_uint(
|
|
dl.endian,
|
|
// This `inspect` is okay since it is within the bounds of the allocation, it doesn't
|
|
// affect interpreter execution (we inspect the result after interpreter execution),
|
|
// and we properly interpret the relocation as a relocation pointer offset.
|
|
alloc.inspect_with_uninit_and_ptr_outside_interpreter(offset..(offset + pointer_size)),
|
|
)
|
|
.expect("const_alloc_to_llvm: could not read relocation pointer")
|
|
as u64;
|
|
|
|
let address_space = match cx.tcx.global_alloc(alloc_id) {
|
|
GlobalAlloc::Function(..) => cx.data_layout().instruction_address_space,
|
|
GlobalAlloc::Static(..) | GlobalAlloc::Memory(..) => AddressSpace::DATA,
|
|
};
|
|
|
|
llvals.push(cx.scalar_to_backend(
|
|
InterpScalar::from_pointer(
|
|
Pointer::new(alloc_id, Size::from_bytes(ptr_offset)),
|
|
&cx.tcx,
|
|
),
|
|
Scalar::Initialized {
|
|
value: Primitive::Pointer,
|
|
valid_range: WrappingRange::full(dl.pointer_size),
|
|
},
|
|
cx.type_i8p_ext(address_space),
|
|
));
|
|
next_offset = offset + pointer_size;
|
|
}
|
|
if alloc.len() >= next_offset {
|
|
let range = next_offset..alloc.len();
|
|
// This `inspect` is okay since we have check that it is after all relocations, it is
|
|
// within the bounds of the allocation, and it doesn't affect interpreter execution (we
|
|
// inspect the result after interpreter execution).
|
|
append_chunks_of_init_and_uninit_bytes(&mut llvals, cx, alloc, range);
|
|
}
|
|
|
|
cx.const_struct(&llvals, true)
|
|
}
|
|
|
|
pub fn codegen_static_initializer<'ll, 'tcx>(
|
|
cx: &CodegenCx<'ll, 'tcx>,
|
|
def_id: DefId,
|
|
) -> Result<(&'ll Value, ConstAllocation<'tcx>), ErrorHandled> {
|
|
let alloc = cx.tcx.eval_static_initializer(def_id)?;
|
|
Ok((const_alloc_to_llvm(cx, alloc), alloc))
|
|
}
|
|
|
|
fn set_global_alignment<'ll>(cx: &CodegenCx<'ll, '_>, gv: &'ll Value, mut align: Align) {
|
|
// The target may require greater alignment for globals than the type does.
|
|
// Note: GCC and Clang also allow `__attribute__((aligned))` on variables,
|
|
// which can force it to be smaller. Rust doesn't support this yet.
|
|
if let Some(min) = cx.sess().target.min_global_align {
|
|
match Align::from_bits(min) {
|
|
Ok(min) => align = align.max(min),
|
|
Err(err) => {
|
|
cx.sess().err(&format!("invalid minimum global alignment: {}", err));
|
|
}
|
|
}
|
|
}
|
|
unsafe {
|
|
llvm::LLVMSetAlignment(gv, align.bytes() as u32);
|
|
}
|
|
}
|
|
|
|
fn check_and_apply_linkage<'ll, 'tcx>(
|
|
cx: &CodegenCx<'ll, 'tcx>,
|
|
attrs: &CodegenFnAttrs,
|
|
ty: Ty<'tcx>,
|
|
sym: &str,
|
|
span_def_id: DefId,
|
|
) -> &'ll Value {
|
|
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 = if let ty::RawPtr(ref mt) = ty.kind() {
|
|
cx.layout_of(mt.ty).llvm_type(cx)
|
|
} else {
|
|
cx.sess().span_fatal(
|
|
cx.tcx.def_span(span_def_id),
|
|
"must have type `*const T` or `*mut T` due to `#[linkage]` attribute",
|
|
)
|
|
};
|
|
unsafe {
|
|
// Declare a symbol `foo` with the desired linkage.
|
|
let g1 = cx.declare_global(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 = cx.define_global(&real_name, llty).unwrap_or_else(|| {
|
|
cx.sess().span_fatal(
|
|
cx.tcx.def_span(span_def_id),
|
|
&format!("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
|
|
cx.declare_global(sym, llty)
|
|
}
|
|
}
|
|
|
|
pub fn ptrcast<'ll>(val: &'ll Value, ty: &'ll Type) -> &'ll Value {
|
|
unsafe { llvm::LLVMConstPointerCast(val, ty) }
|
|
}
|
|
|
|
impl<'ll> CodegenCx<'ll, '_> {
|
|
pub(crate) fn const_bitcast(&self, val: &'ll Value, ty: &'ll Type) -> &'ll Value {
|
|
unsafe { llvm::LLVMConstBitCast(val, ty) }
|
|
}
|
|
|
|
pub(crate) fn static_addr_of_mut(
|
|
&self,
|
|
cv: &'ll Value,
|
|
align: Align,
|
|
kind: Option<&str>,
|
|
) -> &'ll Value {
|
|
unsafe {
|
|
let gv = match kind {
|
|
Some(kind) if !self.tcx.sess.fewer_names() => {
|
|
let name = self.generate_local_symbol_name(kind);
|
|
let gv = self.define_global(&name, self.val_ty(cv)).unwrap_or_else(|| {
|
|
bug!("symbol `{}` is already defined", name);
|
|
});
|
|
llvm::LLVMRustSetLinkage(gv, llvm::Linkage::PrivateLinkage);
|
|
gv
|
|
}
|
|
_ => self.define_private_global(self.val_ty(cv)),
|
|
};
|
|
llvm::LLVMSetInitializer(gv, cv);
|
|
set_global_alignment(self, gv, align);
|
|
llvm::SetUnnamedAddress(gv, llvm::UnnamedAddr::Global);
|
|
gv
|
|
}
|
|
}
|
|
|
|
pub(crate) fn get_static(&self, def_id: DefId) -> &'ll Value {
|
|
let instance = Instance::mono(self.tcx, def_id);
|
|
if let Some(&g) = self.instances.borrow().get(&instance) {
|
|
return g;
|
|
}
|
|
|
|
let defined_in_current_codegen_unit =
|
|
self.codegen_unit.items().contains_key(&MonoItem::Static(def_id));
|
|
assert!(
|
|
!defined_in_current_codegen_unit,
|
|
"consts::get_static() should always hit the cache for \
|
|
statics defined in the same CGU, but did not for `{:?}`",
|
|
def_id
|
|
);
|
|
|
|
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={:?} fn_attrs={:?}", sym, instance, fn_attrs);
|
|
|
|
let g = if def_id.is_local() && !self.tcx.is_foreign_item(def_id) {
|
|
let llty = self.layout_of(ty).llvm_type(self);
|
|
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(def_id) {
|
|
unsafe {
|
|
llvm::LLVMRustSetVisibility(g, llvm::Visibility::Hidden);
|
|
}
|
|
}
|
|
|
|
g
|
|
} else {
|
|
check_and_apply_linkage(self, fn_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 fn_attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) {
|
|
llvm::set_thread_local_mode(g, self.tls_model);
|
|
}
|
|
|
|
if !def_id.is_local() {
|
|
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
|
|
// dynamic linking when linker plugin based LTO is enabled.
|
|
!self.tcx.sess.opts.cg.linker_plugin_lto.enabled();
|
|
|
|
// If this assertion triggers, there's something wrong with commandline
|
|
// argument validation.
|
|
debug_assert!(
|
|
!(self.tcx.sess.opts.cg.linker_plugin_lto.enabled()
|
|
&& self.tcx.sess.target.is_like_windows
|
|
&& self.tcx.sess.opts.cg.prefer_dynamic)
|
|
);
|
|
|
|
if needs_dll_storage_attr {
|
|
// 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
|
|
// statically in the final application, we always mark such symbols as 'dllimport'.
|
|
// If final linkage happens to be static, we rely on compiler-emitted __imp_ stubs
|
|
// to make things work.
|
|
//
|
|
// However, in some scenarios we defer emission of statics to downstream
|
|
// crates, so there are cases where a static with an upstream DefId
|
|
// is actually present in the current crate. We can find out via the
|
|
// is_codegened_item query.
|
|
if !self.tcx.is_codegened_item(def_id) {
|
|
unsafe {
|
|
llvm::LLVMSetDLLStorageClass(g, llvm::DLLStorageClass::DllImport);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
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.
|
|
unsafe {
|
|
llvm::LLVMSetDLLStorageClass(g, llvm::DLLStorageClass::DllImport);
|
|
}
|
|
}
|
|
|
|
unsafe {
|
|
if self.should_assume_dso_local(g, true) {
|
|
llvm::LLVMRustSetDSOLocal(g, true);
|
|
}
|
|
}
|
|
|
|
self.instances.borrow_mut().insert(instance, g);
|
|
g
|
|
}
|
|
}
|
|
|
|
impl<'ll> StaticMethods for CodegenCx<'ll, '_> {
|
|
fn static_addr_of(&self, cv: &'ll Value, align: Align, kind: Option<&str>) -> &'ll Value {
|
|
if let Some(&gv) = self.const_globals.borrow().get(&cv) {
|
|
unsafe {
|
|
// Upgrade the alignment in cases where the same constant is used with different
|
|
// alignment requirements
|
|
let llalign = align.bytes() as u32;
|
|
if llalign > llvm::LLVMGetAlignment(gv) {
|
|
llvm::LLVMSetAlignment(gv, llalign);
|
|
}
|
|
}
|
|
return gv;
|
|
}
|
|
let gv = self.static_addr_of_mut(cv, align, kind);
|
|
unsafe {
|
|
llvm::LLVMSetGlobalConstant(gv, True);
|
|
}
|
|
self.const_globals.borrow_mut().insert(cv, gv);
|
|
gv
|
|
}
|
|
|
|
fn codegen_static(&self, def_id: DefId, is_mutable: bool) {
|
|
unsafe {
|
|
let attrs = self.tcx.codegen_fn_attrs(def_id);
|
|
|
|
let Ok((v, alloc)) = codegen_static_initializer(self, def_id) else {
|
|
// Error has already been reported
|
|
return;
|
|
};
|
|
let alloc = alloc.inner();
|
|
|
|
let g = self.get_static(def_id);
|
|
|
|
// boolean SSA values are i1, but they have to be stored in i8 slots,
|
|
// otherwise some LLVM optimization passes don't work as expected
|
|
let mut val_llty = self.val_ty(v);
|
|
let v = if val_llty == self.type_i1() {
|
|
val_llty = self.type_i8();
|
|
llvm::LLVMConstZExt(v, val_llty)
|
|
} else {
|
|
v
|
|
};
|
|
|
|
let instance = Instance::mono(self.tcx, def_id);
|
|
let ty = instance.ty(self.tcx, ty::ParamEnv::reveal_all());
|
|
let llty = self.layout_of(ty).llvm_type(self);
|
|
let g = if val_llty == llty {
|
|
g
|
|
} else {
|
|
// If we created the global with the wrong type,
|
|
// correct the type.
|
|
let name = llvm::get_value_name(g).to_vec();
|
|
llvm::set_value_name(g, b"");
|
|
|
|
let linkage = llvm::LLVMRustGetLinkage(g);
|
|
let visibility = llvm::LLVMRustGetVisibility(g);
|
|
|
|
let new_g = llvm::LLVMRustGetOrInsertGlobal(
|
|
self.llmod,
|
|
name.as_ptr().cast(),
|
|
name.len(),
|
|
val_llty,
|
|
);
|
|
|
|
llvm::LLVMRustSetLinkage(new_g, linkage);
|
|
llvm::LLVMRustSetVisibility(new_g, visibility);
|
|
|
|
// The old global has had its name removed but is returned by
|
|
// get_static since it is in the instance cache. Provide an
|
|
// alternative lookup that points to the new global so that
|
|
// global_asm! can compute the correct mangled symbol name
|
|
// for the global.
|
|
self.renamed_statics.borrow_mut().insert(def_id, new_g);
|
|
|
|
// To avoid breaking any invariants, we leave around the old
|
|
// global for the moment; we'll replace all references to it
|
|
// with the new global later. (See base::codegen_backend.)
|
|
self.statics_to_rauw.borrow_mut().push((g, new_g));
|
|
new_g
|
|
};
|
|
set_global_alignment(self, g, self.align_of(ty));
|
|
llvm::LLVMSetInitializer(g, v);
|
|
|
|
if self.should_assume_dso_local(g, true) {
|
|
llvm::LLVMRustSetDSOLocal(g, true);
|
|
}
|
|
|
|
// As an optimization, all shared statics which do not have interior
|
|
// mutability are placed into read-only memory.
|
|
if !is_mutable && self.type_is_freeze(ty) {
|
|
llvm::LLVMSetGlobalConstant(g, llvm::True);
|
|
}
|
|
|
|
debuginfo::build_global_var_di_node(self, def_id, g);
|
|
|
|
if attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) {
|
|
llvm::set_thread_local_mode(g, self.tls_model);
|
|
|
|
// Do not allow LLVM to change the alignment of a TLS on macOS.
|
|
//
|
|
// By default a global's alignment can be freely increased.
|
|
// This allows LLVM to generate more performant instructions
|
|
// e.g., using load-aligned into a SIMD register.
|
|
//
|
|
// However, on macOS 10.10 or below, the dynamic linker does not
|
|
// respect any alignment given on the TLS (radar 24221680).
|
|
// This will violate the alignment assumption, and causing segfault at runtime.
|
|
//
|
|
// This bug is very easy to trigger. In `println!` and `panic!`,
|
|
// the `LOCAL_STDOUT`/`LOCAL_STDERR` handles are stored in a TLS,
|
|
// which the values would be `mem::replace`d on initialization.
|
|
// The implementation of `mem::replace` will use SIMD
|
|
// whenever the size is 32 bytes or higher. LLVM notices SIMD is used
|
|
// and tries to align `LOCAL_STDOUT`/`LOCAL_STDERR` to a 32-byte boundary,
|
|
// which macOS's dyld disregarded and causing crashes
|
|
// (see issues #51794, #51758, #50867, #48866 and #44056).
|
|
//
|
|
// To workaround the bug, we trick LLVM into not increasing
|
|
// the global's alignment by explicitly assigning a section to it
|
|
// (equivalent to automatically generating a `#[link_section]` attribute).
|
|
// See the comment in the `GlobalValue::canIncreaseAlignment()` function
|
|
// of `lib/IR/Globals.cpp` for why this works.
|
|
//
|
|
// When the alignment is not increased, the optimized `mem::replace`
|
|
// will use load-unaligned instructions instead, and thus avoiding the crash.
|
|
//
|
|
// We could remove this hack whenever we decide to drop macOS 10.10 support.
|
|
if self.tcx.sess.target.is_like_osx {
|
|
// The `inspect` method is okay here because we checked relocations, and
|
|
// because we are doing this access to inspect the final interpreter state
|
|
// (not as part of the interpreter execution).
|
|
//
|
|
// FIXME: This check requires that the (arbitrary) value of undefined bytes
|
|
// happens to be zero. Instead, we should only check the value of defined bytes
|
|
// and set all undefined bytes to zero if this allocation is headed for the
|
|
// BSS.
|
|
let all_bytes_are_zero = alloc.relocations().is_empty()
|
|
&& alloc
|
|
.inspect_with_uninit_and_ptr_outside_interpreter(0..alloc.len())
|
|
.iter()
|
|
.all(|&byte| byte == 0);
|
|
|
|
let sect_name = if all_bytes_are_zero {
|
|
cstr!("__DATA,__thread_bss")
|
|
} else {
|
|
cstr!("__DATA,__thread_data")
|
|
};
|
|
llvm::LLVMSetSection(g, sect_name.as_ptr());
|
|
}
|
|
}
|
|
|
|
// Wasm statics with custom link sections get special treatment as they
|
|
// go into custom sections of the wasm executable.
|
|
if self.tcx.sess.target.is_like_wasm {
|
|
if let Some(section) = attrs.link_section {
|
|
let section = llvm::LLVMMDStringInContext(
|
|
self.llcx,
|
|
section.as_str().as_ptr().cast(),
|
|
section.as_str().len() as c_uint,
|
|
);
|
|
assert!(alloc.relocations().is_empty());
|
|
|
|
// The `inspect` method is okay here because we checked relocations, and
|
|
// because we are doing this access to inspect the final interpreter state (not
|
|
// as part of the interpreter execution).
|
|
let bytes =
|
|
alloc.inspect_with_uninit_and_ptr_outside_interpreter(0..alloc.len());
|
|
let alloc = llvm::LLVMMDStringInContext(
|
|
self.llcx,
|
|
bytes.as_ptr().cast(),
|
|
bytes.len() as c_uint,
|
|
);
|
|
let data = [section, alloc];
|
|
let meta = llvm::LLVMMDNodeInContext(self.llcx, data.as_ptr(), 2);
|
|
llvm::LLVMAddNamedMetadataOperand(
|
|
self.llmod,
|
|
"wasm.custom_sections\0".as_ptr().cast(),
|
|
meta,
|
|
);
|
|
}
|
|
} else {
|
|
base::set_link_section(g, attrs);
|
|
}
|
|
|
|
if attrs.flags.contains(CodegenFnAttrFlags::USED) {
|
|
// `USED` and `USED_LINKER` can't be used together.
|
|
assert!(!attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER));
|
|
|
|
// The semantics of #[used] in Rust only require the symbol to make it into the
|
|
// object file. It is explicitly allowed for the linker to strip the symbol if it
|
|
// is dead. As such, use llvm.compiler.used instead of llvm.used.
|
|
// Additionally, https://reviews.llvm.org/D97448 in LLVM 13 started emitting unique
|
|
// sections with SHF_GNU_RETAIN flag for llvm.used symbols, which may trigger bugs
|
|
// in some versions of the gold linker.
|
|
self.add_compiler_used_global(g);
|
|
}
|
|
if attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER) {
|
|
// `USED` and `USED_LINKER` can't be used together.
|
|
assert!(!attrs.flags.contains(CodegenFnAttrFlags::USED));
|
|
|
|
self.add_used_global(g);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Add a global value to a list to be stored in the `llvm.used` variable, an array of i8*.
|
|
fn add_used_global(&self, global: &'ll Value) {
|
|
let cast = unsafe { llvm::LLVMConstPointerCast(global, self.type_i8p()) };
|
|
self.used_statics.borrow_mut().push(cast);
|
|
}
|
|
|
|
/// Add a global value to a list to be stored in the `llvm.compiler.used` variable,
|
|
/// an array of i8*.
|
|
fn add_compiler_used_global(&self, global: &'ll Value) {
|
|
let cast = unsafe { llvm::LLVMConstPointerCast(global, self.type_i8p()) };
|
|
self.compiler_used_statics.borrow_mut().push(cast);
|
|
}
|
|
}
|