Rollup merge of #147150 - nikic:alloc-shim-attributes, r=bjorn3

Emit allocator attributes for allocator shim

This emits the same attributes we place on allocator declarations on the definitions in the allocator shim as well. This complements https://github.com/rust-lang/rust/pull/146766, which added the attribute for `#[global_allocator]` definitions. Emitting the attributes on the definitions ensures that they cannot be lost of the allocator shim participates in LTO.

See https://github.com/rust-lang/rust/issues/145995 for context, though that one was about `#[global_allocator]`. I'm not sure whether this can occur with the allocator shim as well or not, but better safe than sorry.

I'm not sure whether there is any good way to test this, as the allocator shim is not part of `--emit=llvm-ir`. I've verified this locally by inspecting the bitcode produced by `-C save-temps`.

r? ``@bjorn3``

1 files changed, 26 insertions, 4 deletions

diff --git a/compiler/rustc_codegen_llvm/src/allocator.rs b/compiler/rustc_codegen_llvm/src/allocator.rs
index abd63120397..896d6755c75 100644
--- a/compiler/rustc_codegen_llvm/src/allocator.rs
+++ b/compiler/rustc_codegen_llvm/src/allocator.rs
@@ -5,9 +5,10 @@ use rustc_ast::expand::allocator::{
 };
 use rustc_codegen_ssa::traits::BaseTypeCodegenMethods as _;
 use rustc_middle::bug;
-use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
+use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::{DebugInfo, OomStrategy};
+use rustc_span::sym;
 use rustc_symbol_mangling::mangle_internal_symbol;
 
 use crate::attributes::llfn_attrs_from_instance;
@@ -59,7 +60,26 @@ pub(crate) unsafe fn codegen(
             let from_name = mangle_internal_symbol(tcx, &global_fn_name(method.name));
             let to_name = mangle_internal_symbol(tcx, &default_fn_name(method.name));
 
-            create_wrapper_function(tcx, &cx, &from_name, Some(&to_name), &args, output, false);
+            let alloc_attr_flag = match method.name {
+                sym::alloc => CodegenFnAttrFlags::ALLOCATOR,
+                sym::dealloc => CodegenFnAttrFlags::DEALLOCATOR,
+                sym::realloc => CodegenFnAttrFlags::REALLOCATOR,
+                sym::alloc_zeroed => CodegenFnAttrFlags::ALLOCATOR_ZEROED,
+                _ => unreachable!("Unknown allocator method!"),
+            };
+
+            let mut attrs = CodegenFnAttrs::new();
+            attrs.flags |= alloc_attr_flag;
+            create_wrapper_function(
+                tcx,
+                &cx,
+                &from_name,
+                Some(&to_name),
+                &args,
+                output,
+                false,
+                &attrs,
+            );
         }
     }
 
@@ -72,6 +92,7 @@ pub(crate) unsafe fn codegen(
         &[usize, usize], // size, align
         None,
         true,
+        &CodegenFnAttrs::new(),
     );
 
     unsafe {
@@ -93,6 +114,7 @@ pub(crate) unsafe fn codegen(
             &[],
             None,
             false,
+            &CodegenFnAttrs::new(),
         );
     }
 
@@ -139,6 +161,7 @@ fn create_wrapper_function(
     args: &[&Type],
     output: Option<&Type>,
     no_return: bool,
+    attrs: &CodegenFnAttrs,
 ) {
     let ty = cx.type_func(args, output.unwrap_or_else(|| cx.type_void()));
     let llfn = declare_simple_fn(
@@ -150,8 +173,7 @@ fn create_wrapper_function(
         ty,
     );
 
-    let attrs = CodegenFnAttrs::new();
-    llfn_attrs_from_instance(cx, tcx, llfn, &attrs, None);
+    llfn_attrs_from_instance(cx, tcx, llfn, attrs, None);
 
     let no_return = if no_return {
         // -> ! DIFlagNoReturn