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_cranelift/src/allocator.rs | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'compiler/rustc_codegen_cranelift/src') diff --git a/compiler/rustc_codegen_cranelift/src/allocator.rs b/compiler/rustc_codegen_cranelift/src/allocator.rs index bad8a87b9be..12bb00d346d 100644 --- a/compiler/rustc_codegen_cranelift/src/allocator.rs +++ b/compiler/rustc_codegen_cranelift/src/allocator.rs @@ -5,6 +5,7 @@ use crate::prelude::*; use rustc_ast::expand::allocator::{AllocatorKind, AllocatorTy, ALLOCATOR_METHODS}; use rustc_session::config::OomStrategy; +use rustc_span::symbol::sym; /// Returns whether an allocator shim was created pub(crate) fn codegen( @@ -23,7 +24,7 @@ pub(crate) fn codegen( module, unwind_context, kind, - tcx.lang_items().oom().is_some(), + tcx.alloc_error_handler_kind(()).unwrap(), tcx.sess.opts.unstable_opts.oom, ); true @@ -36,7 +37,7 @@ fn codegen_inner( module: &mut impl Module, unwind_context: &mut UnwindContext, kind: AllocatorKind, - has_alloc_error_handler: bool, + alloc_error_handler_kind: AllocatorKind, oom_strategy: OomStrategy, ) { let usize_ty = module.target_config().pointer_type(); @@ -108,12 +109,12 @@ fn codegen_inner( returns: vec![], }; - let callee_name = if has_alloc_error_handler { "__rg_oom" } else { "__rdl_oom" }; + let callee_name = alloc_error_handler_kind.fn_name(sym::oom); let func_id = module.declare_function("__rust_alloc_error_handler", Linkage::Export, &sig).unwrap(); - let callee_func_id = module.declare_function(callee_name, Linkage::Import, &sig).unwrap(); + let callee_func_id = module.declare_function(&callee_name, Linkage::Import, &sig).unwrap(); let mut ctx = Context::new(); ctx.func.signature = sig; -- cgit 1.4.1-3-g733a5