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. --- src/test/codegen/vec-calloc.rs | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'src/test/codegen/vec-calloc.rs') diff --git a/src/test/codegen/vec-calloc.rs b/src/test/codegen/vec-calloc.rs index 08302796c41..435a4ab5187 100644 --- a/src/test/codegen/vec-calloc.rs +++ b/src/test/codegen/vec-calloc.rs @@ -1,6 +1,7 @@ // compile-flags: -O // only-x86_64 // ignore-debug +// min-llvm-version: 15.0 #![crate_type = "lib"] @@ -142,3 +143,8 @@ pub fn vec_non_zero_tuple(n: usize) -> Vec<(i16, u8, char)> { // CHECK: ret void vec![(0, 0, 'A'); n] } + +// Ensure that __rust_alloc_zeroed gets the right attributes for LLVM to optimize it away. +// CHECK: declare noalias ptr @__rust_alloc_zeroed(i64, i64 allocalign) unnamed_addr [[RUST_ALLOC_ZEROED_ATTRS:#[0-9]+]] + +// CHECK-DAG: attributes [[RUST_ALLOC_ZEROED_ATTRS]] = { {{.*}} allockind("alloc,zeroed,aligned") allocsize(0) uwtable "alloc-family"="__rust_alloc" {{.*}} } -- cgit 1.4.1-3-g733a5