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codegen_fn_attrs.rs
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use rustc_abi::Align;
use rustc_ast::expand::autodiff_attrs::AutoDiffAttrs;
use rustc_attr_parsing::{InlineAttr, InstructionSetAttr, OptimizeAttr};
use rustc_macros::{HashStable, TyDecodable, TyEncodable};
use rustc_span::Symbol;
use rustc_target::spec::SanitizerSet;
use crate::mir::mono::Linkage;
#[derive(Clone, TyEncodable, TyDecodable, HashStable, Debug)]
pub struct CodegenFnAttrs {
pub flags: CodegenFnAttrFlags,
/// Parsed representation of the `#[inline]` attribute
pub inline: InlineAttr,
/// Parsed representation of the `#[optimize]` attribute
pub optimize: OptimizeAttr,
/// The `#[export_name = "..."]` attribute, indicating a custom symbol a
/// function should be exported under
pub export_name: Option<Symbol>,
/// The `#[link_name = "..."]` attribute, indicating a custom symbol an
/// imported function should be imported as. Note that `export_name`
/// probably isn't set when this is set, this is for foreign items while
/// `#[export_name]` is for Rust-defined functions.
pub link_name: Option<Symbol>,
/// The `#[link_ordinal = "..."]` attribute, indicating an ordinal an
/// imported function has in the dynamic library. Note that this must not
/// be set when `link_name` is set. This is for foreign items with the
/// "raw-dylib" kind.
pub link_ordinal: Option<u16>,
/// The `#[target_feature(enable = "...")]` attribute and the enabled
/// features (only enabled features are supported right now).
/// Implied target features have already been applied.
pub target_features: Vec<TargetFeature>,
/// Whether the function was declared safe, but has target features
pub safe_target_features: bool,
/// The `#[linkage = "..."]` attribute on Rust-defined items and the value we found.
pub linkage: Option<Linkage>,
/// The `#[linkage = "..."]` attribute on foreign items and the value we found.
pub import_linkage: Option<Linkage>,
/// The `#[link_section = "..."]` attribute, or what executable section this
/// should be placed in.
pub link_section: Option<Symbol>,
/// The `#[no_sanitize(...)]` attribute. Indicates sanitizers for which
/// instrumentation should be disabled inside the annotated function.
pub no_sanitize: SanitizerSet,
/// The `#[instruction_set(set)]` attribute. Indicates if the generated code should
/// be generated against a specific instruction set. Only usable on architectures which allow
/// switching between multiple instruction sets.
pub instruction_set: Option<InstructionSetAttr>,
/// The `#[repr(align(...))]` attribute. Indicates the value of which the function should be
/// aligned to.
pub alignment: Option<Align>,
/// The `#[patchable_function_entry(...)]` attribute. Indicates how many nops should be around
/// the function entry.
pub patchable_function_entry: Option<PatchableFunctionEntry>,
/// For the `#[autodiff]` macros.
pub autodiff_item: Option<AutoDiffAttrs>,
}
#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
pub struct TargetFeature {
/// The name of the target feature (e.g. "avx")
pub name: Symbol,
/// The feature is implied by another feature, rather than explicitly added by the
/// `#[target_feature]` attribute
pub implied: bool,
}
#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
pub struct PatchableFunctionEntry {
/// Nops to prepend to the function
prefix: u8,
/// Nops after entry, but before body
entry: u8,
}
impl PatchableFunctionEntry {
pub fn from_config(config: rustc_session::config::PatchableFunctionEntry) -> Self {
Self { prefix: config.prefix(), entry: config.entry() }
}
pub fn from_prefix_and_entry(prefix: u8, entry: u8) -> Self {
Self { prefix, entry }
}
pub fn prefix(&self) -> u8 {
self.prefix
}
pub fn entry(&self) -> u8 {
self.entry
}
}
#[derive(Clone, Copy, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
pub struct CodegenFnAttrFlags(u32);
bitflags::bitflags! {
impl CodegenFnAttrFlags: u32 {
/// `#[cold]`: a hint to LLVM that this function, when called, is never on
/// the hot path.
const COLD = 1 << 0;
/// `#[rustc_allocator]`: a hint to LLVM that the pointer returned from this
/// function is never null and the function has no side effects other than allocating.
const ALLOCATOR = 1 << 1;
/// An indicator that function will never unwind. Will become obsolete
/// once C-unwind is fully stabilized.
const NEVER_UNWIND = 1 << 3;
/// `#[naked]`: an indicator to LLVM that no function prologue/epilogue
/// should be generated.
const NAKED = 1 << 4;
/// `#[no_mangle]`: an indicator that the function's name should be the same
/// as its symbol.
const NO_MANGLE = 1 << 5;
/// `#[rustc_std_internal_symbol]`: an indicator that this symbol is a
/// "weird symbol" for the standard library in that it has slightly
/// different linkage, visibility, and reachability rules.
const RUSTC_STD_INTERNAL_SYMBOL = 1 << 6;
/// `#[thread_local]`: indicates a static is actually a thread local
/// piece of memory
const THREAD_LOCAL = 1 << 8;
/// `#[used]`: indicates that LLVM can't eliminate this function (but the
/// linker can!).
const USED = 1 << 9;
/// `#[track_caller]`: allow access to the caller location
const TRACK_CALLER = 1 << 10;
/// #[ffi_pure]: applies clang's `pure` attribute to a foreign function
/// declaration.
const FFI_PURE = 1 << 11;
/// #[ffi_const]: applies clang's `const` attribute to a foreign function
/// declaration.
const FFI_CONST = 1 << 12;
// (Bit 13 was used for `#[cmse_nonsecure_entry]`, but is now unused.)
// (Bit 14 was used for `#[coverage(off)]`, but is now unused.)
/// `#[used(linker)]`:
/// indicates that neither LLVM nor the linker will eliminate this function.
const USED_LINKER = 1 << 15;
/// `#[rustc_deallocator]`: a hint to LLVM that the function only deallocates memory.
const DEALLOCATOR = 1 << 16;
/// `#[rustc_reallocator]`: a hint to LLVM that the function only reallocates memory.
const REALLOCATOR = 1 << 17;
/// `#[rustc_allocator_zeroed]`: a hint to LLVM that the function only allocates zeroed memory.
const ALLOCATOR_ZEROED = 1 << 18;
/// `#[no_builtins]`: indicates that disable implicit builtin knowledge of functions for the function.
const NO_BUILTINS = 1 << 19;
}
}
rustc_data_structures::external_bitflags_debug! { CodegenFnAttrFlags }
impl CodegenFnAttrs {
pub const EMPTY: &'static Self = &Self::new();
pub const fn new() -> CodegenFnAttrs {
CodegenFnAttrs {
flags: CodegenFnAttrFlags::empty(),
inline: InlineAttr::None,
optimize: OptimizeAttr::Default,
export_name: None,
link_name: None,
link_ordinal: None,
target_features: vec![],
safe_target_features: false,
linkage: None,
import_linkage: None,
link_section: None,
no_sanitize: SanitizerSet::empty(),
instruction_set: None,
alignment: None,
patchable_function_entry: None,
autodiff_item: None,
}
}
/// Returns `true` if it looks like this symbol needs to be exported, for example:
///
/// * `#[no_mangle]` is present
/// * `#[export_name(...)]` is present
/// * `#[linkage]` is present
///
/// Keep this in sync with the logic for the unused_attributes for `#[inline]` lint.
pub fn contains_extern_indicator(&self) -> bool {
self.flags.contains(CodegenFnAttrFlags::NO_MANGLE)
|| self.export_name.is_some()
|| match self.linkage {
// These are private, so make sure we don't try to consider
// them external.
None | Some(Linkage::Internal) => false,
Some(_) => true,
}
}
}