From 56074b5231ceef266a1097ea355f62c951e1b468 Mon Sep 17 00:00:00 2001 From: Amanieu d'Antras Date: Fri, 14 Oct 2022 02:24:58 +0100 Subject: Rewrite implementation of `#[alloc_error_handler]` The new implementation doesn't use weak lang items and instead changes `#[alloc_error_handler]` to an attribute macro just like `#[global_allocator]`. The attribute will generate the `__rg_oom` function which is called by the compiler-generated `__rust_alloc_error_handler`. If no `__rg_oom` function is defined in any crate then the compiler shim will call `__rdl_oom` in the alloc crate which will simply panic. This also fixes link errors with `-C link-dead-code` with `default_alloc_error_handler`: `__rg_oom` was previously defined in the alloc crate and would attempt to reference the `oom` lang item, even if it didn't exist. This worked as long as `__rg_oom` was excluded from linking since it was not called. This is a prerequisite for the stabilization of `default_alloc_error_handler` (#102318). --- compiler/rustc_codegen_llvm/src/allocator.rs | 5 ++--- compiler/rustc_codegen_llvm/src/lib.rs | 4 ++-- 2 files changed, 4 insertions(+), 5 deletions(-) (limited to 'compiler/rustc_codegen_llvm/src') diff --git a/compiler/rustc_codegen_llvm/src/allocator.rs b/compiler/rustc_codegen_llvm/src/allocator.rs index 72961ae888e..fed56cdd438 100644 --- a/compiler/rustc_codegen_llvm/src/allocator.rs +++ b/compiler/rustc_codegen_llvm/src/allocator.rs @@ -15,7 +15,7 @@ pub(crate) unsafe fn codegen( module_llvm: &mut ModuleLlvm, module_name: &str, kind: AllocatorKind, - has_alloc_error_handler: bool, + alloc_error_handler_kind: AllocatorKind, ) { let llcx = &*module_llvm.llcx; let llmod = module_llvm.llmod(); @@ -117,8 +117,7 @@ pub(crate) unsafe fn codegen( attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &[uwtable]); } - let kind = if has_alloc_error_handler { AllocatorKind::Global } else { AllocatorKind::Default }; - let callee = kind.fn_name(sym::oom); + let callee = alloc_error_handler_kind.fn_name(sym::oom); let callee = llvm::LLVMRustGetOrInsertFunction(llmod, callee.as_ptr().cast(), callee.len(), ty); // -> ! DIFlagNoReturn attributes::apply_to_llfn(callee, llvm::AttributePlace::Function, &[no_return]); diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs index 89c7e51d09e..d51aced85df 100644 --- a/compiler/rustc_codegen_llvm/src/lib.rs +++ b/compiler/rustc_codegen_llvm/src/lib.rs @@ -108,11 +108,11 @@ impl ExtraBackendMethods for LlvmCodegenBackend { tcx: TyCtxt<'tcx>, module_name: &str, kind: AllocatorKind, - has_alloc_error_handler: bool, + alloc_error_handler_kind: AllocatorKind, ) -> ModuleLlvm { let mut module_llvm = ModuleLlvm::new_metadata(tcx, module_name); unsafe { - allocator::codegen(tcx, &mut module_llvm, module_name, kind, has_alloc_error_handler); + allocator::codegen(tcx, &mut module_llvm, module_name, kind, alloc_error_handler_kind); } module_llvm } -- cgit 1.4.1-3-g733a5