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codegen: use new {re,de,}allocator annotations in llvm

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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.
This commit is contained in:
Augie Fackler 2022-03-21 15:30:54 -04:00
parent 2fdbf075cf
commit 130a1df71e
14 changed files with 356 additions and 4 deletions
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21
compiler/rustc_codegen_llvm/src/llvm/ffi.rs
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@ -193,6 +193,9 @@ pub enum AttributeKind {
SanitizeMemTag = 34,
NoCfCheck = 35,
ShadowCallStack = 36,
AllocSize = 37,
AllocatedPointer = 38,
AllocAlign = 39,
}
/// LLVMIntPredicate
@ -986,6 +989,22 @@ pub mod debuginfo {
}
}
use bitflags::bitflags;
// These values **must** match with LLVMRustAllocKindFlags
bitflags! {
#[repr(transparent)]
#[derive(Default)]
pub struct AllocKindFlags : u64 {
const Unknown = 0;
const Alloc = 1;
const Realloc = 1 << 1;
const Free = 1 << 2;
const Uninitialized = 1 << 3;
const Zeroed = 1 << 4;
const Aligned = 1 << 5;
}
}
extern "C" {
pub type ModuleBuffer;
}
@ -1193,6 +1212,8 @@ extern "C" {
pub fn LLVMRustCreateByValAttr<'a>(C: &'a Context, ty: &'a Type) -> &'a Attribute;
pub fn LLVMRustCreateStructRetAttr<'a>(C: &'a Context, ty: &'a Type) -> &'a Attribute;
pub fn LLVMRustCreateUWTableAttr(C: &Context, async_: bool) -> &Attribute;
pub fn LLVMRustCreateAllocSizeAttr(C: &Context, size_arg: u32) -> &Attribute;
pub fn LLVMRustCreateAllocKindAttr(C: &Context, size_arg: u64) -> &Attribute;
// Operations on functions
pub fn LLVMRustGetOrInsertFunction<'a>(