Cleanup CodegenFnAttrFlags

- Rename `USED` to `USED_COMPILER` to better reflect its behavior.
- Reorder some items to group the used and allocator flags together
- Renumber them without gaps

9 files changed, 31 insertions, 34 deletions

diff --git a/compiler/rustc_codegen_gcc/src/consts.rs b/compiler/rustc_codegen_gcc/src/consts.rs
index 033afc0f8fb..8aed04c836a 100644
--- a/compiler/rustc_codegen_gcc/src/consts.rs
+++ b/compiler/rustc_codegen_gcc/src/consts.rs
@@ -154,7 +154,7 @@ impl<'gcc, 'tcx> StaticCodegenMethods for CodegenCx<'gcc, 'tcx> {
             // TODO(antoyo): set link section.
         }
 
-        if attrs.flags.contains(CodegenFnAttrFlags::USED)
+        if attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER)
             || attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)
         {
             self.add_used_global(global.to_rvalue());
diff --git a/compiler/rustc_codegen_llvm/src/consts.rs b/compiler/rustc_codegen_llvm/src/consts.rs
index bf81eb648f8..fe2f2027327 100644
--- a/compiler/rustc_codegen_llvm/src/consts.rs
+++ b/compiler/rustc_codegen_llvm/src/consts.rs
@@ -527,7 +527,7 @@ impl<'ll> CodegenCx<'ll, '_> {
 
             base::set_variable_sanitizer_attrs(g, attrs);
 
-            if attrs.flags.contains(CodegenFnAttrFlags::USED) {
+            if attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER) {
                 // `USED` and `USED_LINKER` can't be used together.
                 assert!(!attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER));
 
@@ -551,7 +551,7 @@ impl<'ll> CodegenCx<'ll, '_> {
             }
             if attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER) {
                 // `USED` and `USED_LINKER` can't be used together.
-                assert!(!attrs.flags.contains(CodegenFnAttrFlags::USED));
+                assert!(!attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER));
 
                 self.add_used_global(g);
             }
diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
index 96aec9769d2..e26f999773d 100644
--- a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
+++ b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
@@ -128,7 +128,7 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, _: LocalCrate) -> DefIdMap<S
                 } else {
                     SymbolExportKind::Text
                 },
-                used: codegen_attrs.flags.contains(CodegenFnAttrFlags::USED)
+                used: codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER)
                     || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)
                     || used,
             };
diff --git a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
index b3bda784d43..4bcafa3be36 100644
--- a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
+++ b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
@@ -189,7 +189,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                             )
                             .emit();
                         }
-                        codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
+                        codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_COMPILER;
                     }
                     Some(_) => {
                         tcx.dcx().emit_err(errors::ExpectedUsedSymbol { span: attr.span() });
@@ -220,7 +220,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                             || tcx.sess.target.is_like_windows
                             || tcx.sess.target.is_like_wasm);
                         codegen_fn_attrs.flags |= if is_like_elf {
-                            CodegenFnAttrFlags::USED
+                            CodegenFnAttrFlags::USED_COMPILER
                         } else {
                             CodegenFnAttrFlags::USED_LINKER
                         };
diff --git a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
index 00da1a6aeec..f21cf5fa45e 100644
--- a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
+++ b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
@@ -96,49 +96,46 @@ bitflags::bitflags! {
         /// `#[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;
+        /// `#[rustc_nounwind]`: An indicator that function will never unwind.
+        const NEVER_UNWIND              = 1 << 1;
         /// `#[naked]`: an indicator to LLVM that no function prologue/epilogue
         /// should be generated.
-        const NAKED                     = 1 << 4;
+        const NAKED                     = 1 << 2;
         /// `#[no_mangle]`: an indicator that the function's name should be the same
         /// as its symbol.
-        const NO_MANGLE                 = 1 << 5;
+        const NO_MANGLE                 = 1 << 3;
         /// `#[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;
+        const RUSTC_STD_INTERNAL_SYMBOL = 1 << 4;
         /// `#[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
+        const THREAD_LOCAL              = 1 << 5;
+        /// `#[used(compiler)]`: indicates that LLVM can't eliminate this function (but the
         /// linker can!).
-        const USED                      = 1 << 9;
+        const USED_COMPILER             = 1 << 6;
+        /// `#[used(linker)]`:
+        /// indicates that neither LLVM nor the linker will eliminate this function.
+        const USED_LINKER               = 1 << 7;
         /// `#[track_caller]`: allow access to the caller location
-        const TRACK_CALLER              = 1 << 10;
+        const TRACK_CALLER              = 1 << 8;
         /// #[ffi_pure]: applies clang's `pure` attribute to a foreign function
         /// declaration.
-        const FFI_PURE                  = 1 << 11;
+        const FFI_PURE                  = 1 << 9;
         /// #[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;
+        const FFI_CONST                 = 1 << 10;
+        /// `#[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 << 11;
         /// `#[rustc_deallocator]`: a hint to LLVM that the function only deallocates memory.
-        const DEALLOCATOR               = 1 << 16;
+        const DEALLOCATOR               = 1 << 12;
         /// `#[rustc_reallocator]`: a hint to LLVM that the function only reallocates memory.
-        const REALLOCATOR               = 1 << 17;
+        const REALLOCATOR               = 1 << 13;
         /// `#[rustc_allocator_zeroed]`: a hint to LLVM that the function only allocates zeroed memory.
-        const ALLOCATOR_ZEROED          = 1 << 18;
+        const ALLOCATOR_ZEROED          = 1 << 14;
         /// `#[no_builtins]`: indicates that disable implicit builtin knowledge of functions for the function.
-        const NO_BUILTINS               = 1 << 19;
+        const NO_BUILTINS               = 1 << 15;
     }
 }
 rustc_data_structures::external_bitflags_debug! { CodegenFnAttrFlags }
diff --git a/compiler/rustc_passes/src/dead.rs b/compiler/rustc_passes/src/dead.rs
index 0060e726a8e..6e5357d8007 100644
--- a/compiler/rustc_passes/src/dead.rs
+++ b/compiler/rustc_passes/src/dead.rs
@@ -707,7 +707,7 @@ fn has_allow_dead_code_or_lang_attr(
             // #[used], #[no_mangle], #[export_name], etc also keeps the item alive
             // forcefully, e.g., for placing it in a specific section.
             cg_attrs.contains_extern_indicator()
-                || cg_attrs.flags.contains(CodegenFnAttrFlags::USED)
+                || cg_attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER)
                 || cg_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)
         }
     }
diff --git a/compiler/rustc_passes/src/reachable.rs b/compiler/rustc_passes/src/reachable.rs
index f0e8fa986fe..7e15267a953 100644
--- a/compiler/rustc_passes/src/reachable.rs
+++ b/compiler/rustc_passes/src/reachable.rs
@@ -427,7 +427,7 @@ fn has_custom_linkage(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
         // FIXME(nbdd0121): `#[used]` are marked as reachable here so it's picked up by
         // `linked_symbols` in cg_ssa. They won't be exported in binary or cdylib due to their
         // `SymbolExportLevel::Rust` export level but may end up being exported in dylibs.
-        || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED)
+        || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER)
         || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)
 }
 
diff --git a/src/tools/miri/src/bin/miri.rs b/src/tools/miri/src/bin/miri.rs
index 469fc264970..7098ef5130d 100644
--- a/src/tools/miri/src/bin/miri.rs
+++ b/src/tools/miri/src/bin/miri.rs
@@ -281,7 +281,7 @@ impl rustc_driver::Callbacks for MiriBeRustCompilerCalls {
                             }
                             let codegen_fn_attrs = tcx.codegen_fn_attrs(local_def_id);
                             if codegen_fn_attrs.contains_extern_indicator()
-                                || codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::USED)
+                                || codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER)
                                 || codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)
                             {
                                 Some((
diff --git a/src/tools/miri/src/helpers.rs b/src/tools/miri/src/helpers.rs
index ff2ec1b3e60..6a6adc966a8 100644
--- a/src/tools/miri/src/helpers.rs
+++ b/src/tools/miri/src/helpers.rs
@@ -135,7 +135,7 @@ pub fn iter_exported_symbols<'tcx>(
             let codegen_attrs = tcx.codegen_fn_attrs(def_id);
             codegen_attrs.contains_extern_indicator()
                 || codegen_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL)
-                || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED)
+                || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER)
                 || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)
         };
         if exported {