Rollup merge of rust-lang#146778 - nikic:allocator-shim-attributes, r=jackh726

Use standard attribute logic for allocator shim

Use llfn_attrs_from_instance() to generate the attributes for the allocator shim. This ensures that we generate all the usual attributes (and don't get to find out one-by-one that a certain attribute is important for a certain target). Additionally this will enable emitting the allocator-specific attributes (not included here).

This change is quite awkward because the allocator shim uses SimpleCx, while llfn_attrs_from_instance uses CodegenCx. I've switched it to use SimpleCx plus tcx/sess arguments where necessary. If there's a simpler way to do this, I'd love to know about it...

Author: matthiaskrgr

compiler/rustc_codegen_llvm/src/abi.rs

@@ -538,7 +538,13 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
 
         // If the declaration has an associated instance, compute extra attributes based on that.
         if let Some(instance) = instance {
-            llfn_attrs_from_instance(cx, llfn, instance);
+            llfn_attrs_from_instance(
+                cx,
+                cx.tcx,
+                llfn,
+                &cx.tcx.codegen_instance_attrs(instance.def),
+                Some(instance),
+            );
         }
     }
 

compiler/rustc_codegen_llvm/src/allocator.rs

@@ -5,15 +5,16 @@ 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::ty::TyCtxt;
 use rustc_session::config::{DebugInfo, OomStrategy};
 use rustc_symbol_mangling::mangle_internal_symbol;
-use smallvec::SmallVec;
 
+use crate::attributes::llfn_attrs_from_instance;
 use crate::builder::SBuilder;
 use crate::declare::declare_simple_fn;
 use crate::llvm::{self, FALSE, TRUE, Type, Value};
-use crate::{SimpleCx, attributes, debuginfo, llvm_util};
+use crate::{SimpleCx, attributes, debuginfo};
 
 pub(crate) unsafe fn codegen(
     tcx: TyCtxt<'_>,
@@ -149,18 +150,8 @@ fn create_wrapper_function(
         ty,
     );
 
-    let mut attrs = SmallVec::<[_; 2]>::new();
-
-    let target_cpu = llvm_util::target_cpu(tcx.sess);
-    let target_cpu_attr = llvm::CreateAttrStringValue(cx.llcx, "target-cpu", target_cpu);
-
-    let tune_cpu_attr = llvm_util::tune_cpu(tcx.sess)
-        .map(|tune_cpu| llvm::CreateAttrStringValue(cx.llcx, "tune-cpu", tune_cpu));
-
-    attrs.push(target_cpu_attr);
-    attrs.extend(tune_cpu_attr);
-
-    attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &attrs);
+    let attrs = CodegenFnAttrs::new();
+    llfn_attrs_from_instance(cx, tcx, llfn, &attrs, None);
 
     let no_return = if no_return {
         // -> ! DIFlagNoReturn
@@ -171,12 +162,6 @@ fn create_wrapper_function(
         None
     };
 
-    if tcx.sess.must_emit_unwind_tables() {
-        let uwtable =
-            attributes::uwtable_attr(cx.llcx, tcx.sess.opts.unstable_opts.use_sync_unwind);
-        attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &[uwtable]);
-    }
-
     let llbb = unsafe { llvm::LLVMAppendBasicBlockInContext(cx.llcx, llfn, c"entry".as_ptr()) };
     let mut bx = SBuilder::build(&cx, llbb);