compiler/rustc_middle/src/middle/codegen_fn_attrs.rs

   1 use crate::mir::mono::Linkage;
   2 use rustc_attr::{InlineAttr, InstructionSetAttr, OptimizeAttr};
   3 use rustc_span::symbol::Symbol;
   4 use rustc_target::spec::SanitizerSet;
   5
   6 #[derive(Clone, TyEncodable, TyDecodable, HashStable, Debug)]
   7 pub struct CodegenFnAttrs {
   8     pub flags: CodegenFnAttrFlags,
   9     /// Parsed representation of the `#[inline]` attribute
  10     pub inline: InlineAttr,
  11     /// Parsed representation of the `#[optimize]` attribute
  12     pub optimize: OptimizeAttr,
  13     /// The `#[export_name = "..."]` attribute, indicating a custom symbol a
  14     /// function should be exported under
  15     pub export_name: Option<Symbol>,
  16     /// The `#[link_name = "..."]` attribute, indicating a custom symbol an
  17     /// imported function should be imported as. Note that `export_name`
  18     /// probably isn't set when this is set, this is for foreign items while
  19     /// `#[export_name]` is for Rust-defined functions.
  20     pub link_name: Option<Symbol>,
  21     /// The `#[link_ordinal = "..."]` attribute, indicating an ordinal an
  22     /// imported function has in the dynamic library. Note that this must not
  23     /// be set when `link_name` is set. This is for foreign items with the
  24     /// "raw-dylib" kind.
  25     pub link_ordinal: Option<usize>,
  26     /// The `#[target_feature(enable = "...")]` attribute and the enabled
  27     /// features (only enabled features are supported right now).
  28     pub target_features: Vec<Symbol>,
  29     /// The `#[linkage = "..."]` attribute and the value we found.
  30     pub linkage: Option<Linkage>,
  31     /// The `#[link_section = "..."]` attribute, or what executable section this
  32     /// should be placed in.
  33     pub link_section: Option<Symbol>,
  34     /// The `#[no_sanitize(...)]` attribute. Indicates sanitizers for which
  35     /// instrumentation should be disabled inside the annotated function.
  36     pub no_sanitize: SanitizerSet,
  37     /// The `#[instruction_set(set)]` attribute. Indicates if the generated code should
  38     /// be generated against a specific instruction set. Only usable on architectures which allow
  39     /// switching between multiple instruction sets.
  40     pub instruction_set: Option<InstructionSetAttr>,
  41     /// The `#[repr(align(...))]` attribute. Indicates the value of which the function should be
  42     /// aligned to.
  43     pub alignment: Option<u32>,
  44 }
  45
  46 bitflags! {
  47     #[derive(TyEncodable, TyDecodable, HashStable)]
  48     pub struct CodegenFnAttrFlags: u32 {
  49         /// `#[cold]`: a hint to LLVM that this function, when called, is never on
  50         /// the hot path.
  51         const COLD                      = 1 << 0;
  52         /// `#[rustc_allocator]`: a hint to LLVM that the pointer returned from this
  53         /// function is never null.
  54         const ALLOCATOR                 = 1 << 1;
  55         /// `#[unwind]`: an indicator that this function may unwind despite what
  56         /// its ABI signature may otherwise imply.
  57         const UNWIND                    = 1 << 2;
  58         /// `#[rust_allocator_nounwind]`, an indicator that an imported FFI
  59         /// function will never unwind. Probably obsolete by recent changes with
  60         /// #[unwind], but hasn't been removed/migrated yet
  61         const RUSTC_ALLOCATOR_NOUNWIND  = 1 << 3;
  62         /// `#[naked]`: an indicator to LLVM that no function prologue/epilogue
  63         /// should be generated.
  64         const NAKED                     = 1 << 4;
  65         /// `#[no_mangle]`: an indicator that the function's name should be the same
  66         /// as its symbol.
  67         const NO_MANGLE                 = 1 << 5;
  68         /// `#[rustc_std_internal_symbol]`: an indicator that this symbol is a
  69         /// "weird symbol" for the standard library in that it has slightly
  70         /// different linkage, visibility, and reachability rules.
  71         const RUSTC_STD_INTERNAL_SYMBOL = 1 << 6;
  72         /// `#[thread_local]`: indicates a static is actually a thread local
  73         /// piece of memory
  74         const THREAD_LOCAL              = 1 << 8;
  75         /// `#[used]`: indicates that LLVM can't eliminate this function (but the
  76         /// linker can!).
  77         const USED                      = 1 << 9;
  78         /// `#[ffi_returns_twice]`, indicates that an extern function can return
  79         /// multiple times
  80         const FFI_RETURNS_TWICE         = 1 << 10;
  81         /// `#[track_caller]`: allow access to the caller location
  82         const TRACK_CALLER              = 1 << 11;
  83         /// #[ffi_pure]: applies clang's `pure` attribute to a foreign function
  84         /// declaration.
  85         const FFI_PURE                  = 1 << 12;
  86         /// #[ffi_const]: applies clang's `const` attribute to a foreign function
  87         /// declaration.
  88         const FFI_CONST                 = 1 << 13;
  89         /// #[cmse_nonsecure_entry]: with a TrustZone-M extension, declare a
  90         /// function as an entry function from Non-Secure code.
  91         const CMSE_NONSECURE_ENTRY      = 1 << 14;
  92         /// `#[no_coverage]`: indicates that the function should be ignored by
  93         /// the MIR `InstrumentCoverage` pass and not added to the coverage map
  94         /// during codegen.
  95         const NO_COVERAGE               = 1 << 15;
  96     }
  97 }
  98
  99 impl CodegenFnAttrs {
 100     pub fn new() -> CodegenFnAttrs {
 101         CodegenFnAttrs {
 102             flags: CodegenFnAttrFlags::empty(),
 103             inline: InlineAttr::None,
 104             optimize: OptimizeAttr::None,
 105             export_name: None,
 106             link_name: None,
 107             link_ordinal: None,
 108             target_features: vec![],
 109             linkage: None,
 110             link_section: None,
 111             no_sanitize: SanitizerSet::empty(),
 112             instruction_set: None,
 113             alignment: None,
 114         }
 115     }
 116
 117     /// Returns `true` if `#[inline]` or `#[inline(always)]` is present.
 118     pub fn requests_inline(&self) -> bool {
 119         match self.inline {
 120             InlineAttr::Hint | InlineAttr::Always => true,
 121             InlineAttr::None | InlineAttr::Never => false,
 122         }
 123     }
 124
 125     /// Returns `true` if it looks like this symbol needs to be exported, for example:
 126     ///
 127     /// * `#[no_mangle]` is present
 128     /// * `#[export_name(...)]` is present
 129     /// * `#[linkage]` is present
 130     pub fn contains_extern_indicator(&self) -> bool {
 131         self.flags.contains(CodegenFnAttrFlags::NO_MANGLE)
 132             || self.export_name.is_some()
 133             || match self.linkage {
 134                 // These are private, so make sure we don't try to consider
 135                 // them external.
 136                 None | Some(Linkage::Internal | Linkage::Private) => false,
 137                 Some(_) => true,
 138             }
 139     }
 140 }