[WIP] Use weak linkage instead of compiler generated shims

compiler/rustc_ast/src/expand/allocator.rs

@@ -11,17 +11,8 @@ pub fn global_fn_name(base: Symbol) -> String {
     format!("__rust_{base}")
 }
 
-pub fn default_fn_name(base: Symbol) -> String {
-    format!("__rdl_{base}")
-}
-
-pub fn alloc_error_handler_name(alloc_error_handler_kind: AllocatorKind) -> &'static str {
-    match alloc_error_handler_kind {
-        AllocatorKind::Global => "__rg_oom",
-        AllocatorKind::Default => "__rdl_oom",
-    }
-}
-
+pub const ALLOC_ERROR_HANDLER: &str = "__rust_alloc_error_handler";
+pub const ALLOC_ERROR_HANDLER_DEFAULT: &str = "__rdl_oom";
 pub const NO_ALLOC_SHIM_IS_UNSTABLE: &str = "__rust_no_alloc_shim_is_unstable_v2";
 
 pub enum AllocatorTy {

compiler/rustc_builtin_macros/src/alloc_error_handler.rs

@@ -1,3 +1,4 @@
+use rustc_ast::expand::allocator::ALLOC_ERROR_HANDLER;
 use rustc_ast::ptr::P;
 use rustc_ast::{
     self as ast, Fn, FnHeader, FnSig, Generics, ItemKind, Safety, Stmt, StmtKind, TyKind,
@@ -56,7 +57,7 @@ pub(crate) fn expand(
 }
 
 // #[rustc_std_internal_symbol]
-// unsafe fn __rg_oom(size: usize, align: usize) -> ! {
+// unsafe fn __rust_alloc_error_handler(size: usize, align: usize) -> ! {
 //     handler(core::alloc::Layout::from_size_align_unchecked(size, align))
 // }
 fn generate_handler(cx: &ExtCtxt<'_>, handler: Ident, span: Span, sig_span: Span) -> Stmt {
@@ -85,7 +86,7 @@ fn generate_handler(cx: &ExtCtxt<'_>, handler: Ident, span: Span, sig_span: Span
     let kind = ItemKind::Fn(Box::new(Fn {
         defaultness: ast::Defaultness::Final,
         sig,
-        ident: Ident::from_str_and_span("__rg_oom", span),
+        ident: Ident::from_str_and_span(ALLOC_ERROR_HANDLER, span),
         generics: Generics::default(),
         contract: None,
         body,

compiler/rustc_codegen_cranelift/src/allocator.rs

@@ -2,96 +2,25 @@
 // Adapted from rustc
 
 use cranelift_frontend::{FunctionBuilder, FunctionBuilderContext};
-use rustc_ast::expand::allocator::{
-    ALLOCATOR_METHODS, AllocatorKind, AllocatorTy, NO_ALLOC_SHIM_IS_UNSTABLE,
-    alloc_error_handler_name, default_fn_name, global_fn_name,
-};
-use rustc_codegen_ssa::base::allocator_kind_for_codegen;
+use rustc_ast::expand::allocator::NO_ALLOC_SHIM_IS_UNSTABLE;
+use rustc_codegen_ssa::base::needs_allocator_shim;
 use rustc_session::config::OomStrategy;
 use rustc_symbol_mangling::mangle_internal_symbol;
 
 use crate::prelude::*;
 
 /// Returns whether an allocator shim was created
 pub(crate) fn codegen(tcx: TyCtxt<'_>, module: &mut dyn Module) -> bool {
-    let Some(kind) = allocator_kind_for_codegen(tcx) else { return false };
-    codegen_inner(
-        tcx,
-        module,
-        kind,
-        tcx.alloc_error_handler_kind(()).unwrap(),
-        tcx.sess.opts.unstable_opts.oom,
-    );
-    true
-}
-
-fn codegen_inner(
-    tcx: TyCtxt<'_>,
-    module: &mut dyn Module,
-    kind: AllocatorKind,
-    alloc_error_handler_kind: AllocatorKind,
-    oom_strategy: OomStrategy,
-) {
-    let usize_ty = module.target_config().pointer_type();
-
-    if kind == AllocatorKind::Default {
-        for method in ALLOCATOR_METHODS {
-            let mut arg_tys = Vec::with_capacity(method.inputs.len());
-            for input in method.inputs.iter() {
-                match input.ty {
-                    AllocatorTy::Layout => {
-                        arg_tys.push(usize_ty); // size
-                        arg_tys.push(usize_ty); // align
-                    }
-                    AllocatorTy::Ptr => arg_tys.push(usize_ty),
-                    AllocatorTy::Usize => arg_tys.push(usize_ty),
-
-                    AllocatorTy::ResultPtr | AllocatorTy::Unit => panic!("invalid allocator arg"),
-                }
-            }
-            let output = match method.output {
-                AllocatorTy::ResultPtr => Some(usize_ty),
-                AllocatorTy::Unit => None,
-
-                AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
-                    panic!("invalid allocator output")
-                }
-            };
-
-            let sig = Signature {
-                call_conv: module.target_config().default_call_conv,
-                params: arg_tys.iter().cloned().map(AbiParam::new).collect(),
-                returns: output.into_iter().map(AbiParam::new).collect(),
-            };
-            crate::common::create_wrapper_function(
-                module,
-                sig,
-                &mangle_internal_symbol(tcx, &global_fn_name(method.name)),
-                &mangle_internal_symbol(tcx, &default_fn_name(method.name)),
-            );
-        }
+    if needs_allocator_shim(tcx) {
+        codegen_inner(tcx, module, tcx.sess.opts.unstable_opts.oom);
+        true
+    } else {
+        false
     }
+}
 
-    let sig = Signature {
-        call_conv: module.target_config().default_call_conv,
-        params: vec![AbiParam::new(usize_ty), AbiParam::new(usize_ty)],
-        returns: vec![],
-    };
-    crate::common::create_wrapper_function(
-        module,
-        sig,
-        &mangle_internal_symbol(tcx, "__rust_alloc_error_handler"),
-        &mangle_internal_symbol(tcx, alloc_error_handler_name(alloc_error_handler_kind)),
-    );
-
-    let data_id = module
-        .declare_data(
-            &mangle_internal_symbol(tcx, OomStrategy::SYMBOL),
-            Linkage::Export,
-            false,
-            false,
-        )
-        .unwrap();
+fn codegen_inner(tcx: TyCtxt<'_>, module: &mut dyn Module, oom_strategy: OomStrategy) {
+    let data_id = module.declare_data(OomStrategy::SYMBOL, Linkage::Export, false, false).unwrap();
     let mut data = DataDescription::new();
     data.set_align(1);
     let val = oom_strategy.should_panic();

compiler/rustc_codegen_gcc/src/allocator.rs

@@ -1,11 +1,7 @@
 use gccjit::{Context, FunctionType, GlobalKind, ToRValue, Type};
 #[cfg(feature = "master")]
 use gccjit::{FnAttribute, VarAttribute};
-use rustc_ast::expand::allocator::{
-    ALLOCATOR_METHODS, AllocatorKind, AllocatorTy, NO_ALLOC_SHIM_IS_UNSTABLE,
-    alloc_error_handler_name, default_fn_name, global_fn_name,
-};
-use rustc_middle::bug;
+use rustc_ast::expand::allocator::NO_ALLOC_SHIM_IS_UNSTABLE;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::OomStrategy;
 use rustc_symbol_mangling::mangle_internal_symbol;
@@ -14,62 +10,9 @@ use crate::GccContext;
 #[cfg(feature = "master")]
 use crate::base::symbol_visibility_to_gcc;
 
-pub(crate) unsafe fn codegen(
-    tcx: TyCtxt<'_>,
-    mods: &mut GccContext,
-    _module_name: &str,
-    kind: AllocatorKind,
-    alloc_error_handler_kind: AllocatorKind,
-) {
+pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut GccContext, _module_name: &str) {
     let context = &mods.context;
-    let usize = match tcx.sess.target.pointer_width {
-        16 => context.new_type::<u16>(),
-        32 => context.new_type::<u32>(),
-        64 => context.new_type::<u64>(),
-        tws => bug!("Unsupported target word size for int: {}", tws),
-    };
     let i8 = context.new_type::<i8>();
-    let i8p = i8.make_pointer();
-
-    if kind == AllocatorKind::Default {
-        for method in ALLOCATOR_METHODS {
-            let mut types = Vec::with_capacity(method.inputs.len());
-            for input in method.inputs.iter() {
-                match input.ty {
-                    AllocatorTy::Layout => {
-                        types.push(usize);
-                        types.push(usize);
-                    }
-                    AllocatorTy::Ptr => types.push(i8p),
-                    AllocatorTy::Usize => types.push(usize),
-
-                    AllocatorTy::ResultPtr | AllocatorTy::Unit => panic!("invalid allocator arg"),
-                }
-            }
-            let output = match method.output {
-                AllocatorTy::ResultPtr => Some(i8p),
-                AllocatorTy::Unit => None,
-
-                AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
-                    panic!("invalid allocator output")
-                }
-            };
-            let from_name = mangle_internal_symbol(tcx, &global_fn_name(method.name));
-            let to_name = mangle_internal_symbol(tcx, &default_fn_name(method.name));
-
-            create_wrapper_function(tcx, context, &from_name, Some(&to_name), &types, output);
-        }
-    }
-
-    // FIXME(bjorn3): Add noreturn attribute
-    create_wrapper_function(
-        tcx,
-        context,
-        &mangle_internal_symbol(tcx, "__rust_alloc_error_handler"),
-        Some(&mangle_internal_symbol(tcx, alloc_error_handler_name(alloc_error_handler_kind))),
-        &[usize, usize],
-        None,
-    );
 
     let name = mangle_internal_symbol(tcx, OomStrategy::SYMBOL);
     let global = context.new_global(None, GlobalKind::Exported, i8, name);

compiler/rustc_codegen_gcc/src/lib.rs

@@ -95,7 +95,6 @@ use back::lto::{ThinBuffer, ThinData};
 use gccjit::{CType, Context, OptimizationLevel};
 #[cfg(feature = "master")]
 use gccjit::{TargetInfo, Version};
-use rustc_ast::expand::allocator::AllocatorKind;
 use rustc_ast::expand::autodiff_attrs::AutoDiffItem;
 use rustc_codegen_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule};
 use rustc_codegen_ssa::back::write::{
@@ -277,13 +276,7 @@ fn new_context<'gcc, 'tcx>(tcx: TyCtxt<'tcx>) -> Context<'gcc> {
 }
 
 impl ExtraBackendMethods for GccCodegenBackend {
-    fn codegen_allocator(
-        &self,
-        tcx: TyCtxt<'_>,
-        module_name: &str,
-        kind: AllocatorKind,
-        alloc_error_handler_kind: AllocatorKind,
-    ) -> Self::Module {
+    fn codegen_allocator(&self, tcx: TyCtxt<'_>, module_name: &str) -> Self::Module {
         let mut mods = GccContext {
             context: Arc::new(SyncContext::new(new_context(tcx))),
             relocation_model: tcx.sess.relocation_model(),
@@ -292,7 +285,7 @@ impl ExtraBackendMethods for GccCodegenBackend {
         };
 
         unsafe {
-            allocator::codegen(tcx, &mut mods, module_name, kind, alloc_error_handler_kind);
+            allocator::codegen(tcx, &mut mods, module_name);
         }
         mods
     }

compiler/rustc_codegen_llvm/src/allocator.rs

@@ -1,10 +1,6 @@
 use libc::c_uint;
-use rustc_ast::expand::allocator::{
-    ALLOCATOR_METHODS, AllocatorKind, AllocatorTy, NO_ALLOC_SHIM_IS_UNSTABLE,
-    alloc_error_handler_name, default_fn_name, global_fn_name,
-};
+use rustc_ast::expand::allocator::NO_ALLOC_SHIM_IS_UNSTABLE;
 use rustc_codegen_ssa::traits::BaseTypeCodegenMethods as _;
-use rustc_middle::bug;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::{DebugInfo, OomStrategy};
 use rustc_symbol_mangling::mangle_internal_symbol;
@@ -14,63 +10,8 @@ use crate::declare::declare_simple_fn;
 use crate::llvm::{self, False, True, Type};
 use crate::{SimpleCx, attributes, debuginfo};
 
-pub(crate) unsafe fn codegen(
-    tcx: TyCtxt<'_>,
-    cx: SimpleCx<'_>,
-    module_name: &str,
-    kind: AllocatorKind,
-    alloc_error_handler_kind: AllocatorKind,
-) {
-    let usize = match tcx.sess.target.pointer_width {
-        16 => cx.type_i16(),
-        32 => cx.type_i32(),
-        64 => cx.type_i64(),
-        tws => bug!("Unsupported target word size for int: {}", tws),
-    };
+pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, cx: SimpleCx<'_>, module_name: &str) {
     let i8 = cx.type_i8();
-    let i8p = cx.type_ptr();
-
-    if kind == AllocatorKind::Default {
-        for method in ALLOCATOR_METHODS {
-            let mut args = Vec::with_capacity(method.inputs.len());
-            for input in method.inputs.iter() {
-                match input.ty {
-                    AllocatorTy::Layout => {
-                        args.push(usize); // size
-                        args.push(usize); // align
-                    }
-                    AllocatorTy::Ptr => args.push(i8p),
-                    AllocatorTy::Usize => args.push(usize),
-
-                    AllocatorTy::ResultPtr | AllocatorTy::Unit => panic!("invalid allocator arg"),
-                }
-            }
-            let output = match method.output {
-                AllocatorTy::ResultPtr => Some(i8p),
-                AllocatorTy::Unit => None,
-
-                AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
-                    panic!("invalid allocator output")
-                }
-            };
-
-            let from_name = mangle_internal_symbol(tcx, &global_fn_name(method.name));
-            let to_name = mangle_internal_symbol(tcx, &default_fn_name(method.name));
-
-            create_wrapper_function(tcx, &cx, &from_name, Some(&to_name), &args, output, false);
-        }
-    }
-
-    // rust alloc error handler
-    create_wrapper_function(
-        tcx,
-        &cx,
-        &mangle_internal_symbol(tcx, "__rust_alloc_error_handler"),
-        Some(&mangle_internal_symbol(tcx, alloc_error_handler_name(alloc_error_handler_kind))),
-        &[usize, usize], // size, align
-        None,
-        true,
-    );
 
     unsafe {
         // __rust_alloc_error_handler_should_panic

compiler/rustc_codegen_llvm/src/lib.rs

@@ -28,7 +28,6 @@ use back::write::{create_informational_target_machine, create_target_machine};
 use context::SimpleCx;
 use errors::{AutoDiffWithoutLTO, ParseTargetMachineConfig};
 use llvm_util::target_config;
-use rustc_ast::expand::allocator::AllocatorKind;
 use rustc_ast::expand::autodiff_attrs::AutoDiffItem;
 use rustc_codegen_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule};
 use rustc_codegen_ssa::back::write::{
@@ -104,18 +103,12 @@ impl Drop for TimeTraceProfiler {
 }
 
 impl ExtraBackendMethods for LlvmCodegenBackend {
-    fn codegen_allocator<'tcx>(
-        &self,
-        tcx: TyCtxt<'tcx>,
-        module_name: &str,
-        kind: AllocatorKind,
-        alloc_error_handler_kind: AllocatorKind,
-    ) -> ModuleLlvm {
+    fn codegen_allocator<'tcx>(&self, tcx: TyCtxt<'tcx>, module_name: &str) -> ModuleLlvm {
         let module_llvm = ModuleLlvm::new_metadata(tcx, module_name);
         let cx =
             SimpleCx::new(module_llvm.llmod(), &module_llvm.llcx, tcx.data_layout.pointer_size);
         unsafe {
-            allocator::codegen(tcx, cx, module_name, kind, alloc_error_handler_kind);
+            allocator::codegen(tcx, cx, module_name);
         }
         module_llvm
     }