From 130a1df71ea73ab9d66d3cb8fc9cdb43155d514b Mon Sep 17 00:00:00 2001 From: Augie Fackler Date: Mon, 21 Mar 2022 15:30:54 -0400 Subject: codegen: use new {re,de,}allocator annotations in llvm This obviates the patch that teaches LLVM internals about _rust_{re,de}alloc functions by putting annotations directly in the IR for the optimizer. The sole test change is required to anchor FileCheck to the body of the `box_uninitialized` method, so it doesn't see the `allocalign` on `__rust_alloc` and get mad about the string `alloca` showing up. Since I was there anyway, I added some checks on the attributes to prove the right attributes got set. While we're here, we also emit allocator attributes on __rust_alloc_zeroed. This should allow LLVM to perform more optimizations for zeroed blocks, and probably fixes #90032. [This comment](https://github.com/rust-lang/rust/issues/24194#issuecomment-308791157) mentions "weird UB-like behaviour with bitvec iterators in rustc_data_structures" so we may need to back this change out if things go wrong. The new test cases require LLVM 15, so we copy them into LLVM 14-supporting versions, which we can delete when we drop LLVM 14. --- library/alloc/src/alloc.rs | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'library/alloc') diff --git a/library/alloc/src/alloc.rs b/library/alloc/src/alloc.rs index efdc86bf57a..cc8da7bccff 100644 --- a/library/alloc/src/alloc.rs +++ b/library/alloc/src/alloc.rs @@ -25,15 +25,18 @@ extern "Rust" { // (the code expanding that attribute macro generates those functions), or to call // the default implementations in libstd (`__rdl_alloc` etc. in `library/std/src/alloc.rs`) // otherwise. - // The rustc fork of LLVM also special-cases these function names to be able to optimize them + // The rustc fork of LLVM 14 and earlier also special-cases these function names to be able to optimize them // like `malloc`, `realloc`, and `free`, respectively. #[rustc_allocator] #[rustc_allocator_nounwind] fn __rust_alloc(size: usize, align: usize) -> *mut u8; + #[cfg_attr(not(bootstrap), rustc_deallocator)] #[rustc_allocator_nounwind] fn __rust_dealloc(ptr: *mut u8, size: usize, align: usize); + #[cfg_attr(not(bootstrap), rustc_reallocator)] #[rustc_allocator_nounwind] fn __rust_realloc(ptr: *mut u8, old_size: usize, align: usize, new_size: usize) -> *mut u8; + #[cfg_attr(not(bootstrap), rustc_allocator_zeroed)] #[rustc_allocator_nounwind] fn __rust_alloc_zeroed(size: usize, align: usize) -> *mut u8; } -- cgit 1.4.1-3-g733a5