Rollup merge of #103977 - TimNN:memory-effects, r=nikic

LLVM 16: Switch to using MemoryEffects

This adapts the compiler to the changes required by https://github.com/llvm/llvm-project/commit/304f1d59ca41872c094def3aee0a8689df6aa398.

AFAICT, `WriteOnly` isn't used by the compiler, all `ReadNone` uses were migrated and the remaining use of `ReadOnly` is only for function parameters.

To simplify the FFI, this PR uses an enum to represent `MemoryEffects` across the FFI boundary, which then gets mapped to the matching static factory method when constructing the attribute.

Fixes #103961.

`@rustbot` label +llvm-main

r? `@nikic`

1 files changed, 3 insertions, 3 deletions

diff --git a/compiler/rustc_codegen_llvm/src/attributes.rs b/compiler/rustc_codegen_llvm/src/attributes.rs
index eff2436d41c..d96da5cc11d 100644
--- a/compiler/rustc_codegen_llvm/src/attributes.rs
+++ b/compiler/rustc_codegen_llvm/src/attributes.rs
@@ -13,7 +13,7 @@ use smallvec::SmallVec;
 
 use crate::attributes;
 use crate::llvm::AttributePlace::Function;
-use crate::llvm::{self, AllocKindFlags, Attribute, AttributeKind, AttributePlace};
+use crate::llvm::{self, AllocKindFlags, Attribute, AttributeKind, AttributePlace, MemoryEffects};
 use crate::llvm_util;
 pub use rustc_attr::{InlineAttr, InstructionSetAttr, OptimizeAttr};
 
@@ -303,10 +303,10 @@ pub fn from_fn_attrs<'ll, 'tcx>(
         to_add.push(AttributeKind::ReturnsTwice.create_attr(cx.llcx));
     }
     if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::FFI_PURE) {
-        to_add.push(AttributeKind::ReadOnly.create_attr(cx.llcx));
+        to_add.push(MemoryEffects::ReadOnly.create_attr(cx.llcx));
     }
     if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::FFI_CONST) {
-        to_add.push(AttributeKind::ReadNone.create_attr(cx.llcx));
+        to_add.push(MemoryEffects::None.create_attr(cx.llcx));
     }
     if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NAKED) {
         to_add.push(AttributeKind::Naked.create_attr(cx.llcx));