Fix setting inline hint based on `InstanceDef::requires_inline`

For instances where `InstanceDef::requires_inline` is true, an attempt
is made to set an inline hint though a call to the `inline` function.
The attempt is ineffective, since all attributes will be usually removed
by the second call.

Fix the issue by applying the attributes only once, with user provided
attributes having a priority when provided.

1 files changed, 4 insertions, 12 deletions

diff --git a/compiler/rustc_codegen_llvm/src/attributes.rs b/compiler/rustc_codegen_llvm/src/attributes.rs
index e06e2d45665..9a2fbf359ea 100644
--- a/compiler/rustc_codegen_llvm/src/attributes.rs
+++ b/compiler/rustc_codegen_llvm/src/attributes.rs
@@ -25,7 +25,7 @@ use crate::value::Value;
 
 /// Mark LLVM function to use provided inline heuristic.
 #[inline]
-fn inline(cx: &CodegenCx<'ll, '_>, val: &'ll Value, inline: InlineAttr) {
+fn inline(cx: &CodegenCx<'ll, '_>, val: &'ll Value, inline: InlineAttr, requires_inline: bool) {
     use self::InlineAttr::*;
     match inline {
         Hint => Attribute::InlineHint.apply_llfn(Function, val),
@@ -35,11 +35,8 @@ fn inline(cx: &CodegenCx<'ll, '_>, val: &'ll Value, inline: InlineAttr) {
                 Attribute::NoInline.apply_llfn(Function, val);
             }
         }
-        None => {
-            Attribute::InlineHint.unapply_llfn(Function, val);
-            Attribute::AlwaysInline.unapply_llfn(Function, val);
-            Attribute::NoInline.unapply_llfn(Function, val);
-        }
+        None if requires_inline => Attribute::InlineHint.apply_llfn(Function, val),
+        None => {}
     };
 }
 
@@ -229,12 +226,7 @@ pub fn from_fn_attrs(cx: &CodegenCx<'ll, 'tcx>, llfn: &'ll Value, instance: ty::
         }
     }
 
-    // FIXME(eddyb) consolidate these two `inline` calls (and avoid overwrites).
-    if instance.def.requires_inline(cx.tcx) {
-        inline(cx, llfn, attributes::InlineAttr::Hint);
-    }
-
-    inline(cx, llfn, codegen_fn_attrs.inline.clone());
+    inline(cx, llfn, codegen_fn_attrs.inline.clone(), instance.def.requires_inline(cx.tcx));
 
     // The `uwtable` attribute according to LLVM is:
     //