Auto merge of #128657 - clubby789:optimize-none, r=fee1-dead,WaffleLa…

…pkin

Add `#[optimize(none)]`

cc #54882

This extends the `optimize` attribute to add `none`, which corresponds to the LLVM `OptimizeNone` attribute.

Not sure if an MCP is required for this, happy to file one if so.

compiler/rustc_attr_data_structures/src/attributes.rs

@@ -35,13 +35,25 @@ pub enum InstructionSetAttr {
     ArmT32,
 }
 
-#[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
+#[derive(Clone, Encodable, Decodable, Debug, PartialEq, Eq, HashStable_Generic, Default)]
 pub enum OptimizeAttr {
-    None,
+    /// No `#[optimize(..)]` attribute
+    #[default]
+    Default,
+    /// `#[optimize(none)]`
+    DoNotOptimize,
+    /// `#[optimize(speed)]`
     Speed,
+    /// `#[optimize(size)]`
     Size,
 }
 
+impl OptimizeAttr {
+    pub fn do_not_optimize(&self) -> bool {
+        matches!(self, Self::DoNotOptimize)
+    }
+}
+
 #[derive(Clone, Debug, Encodable, Decodable)]
 pub enum DiagnosticAttribute {
     // tidy-alphabetical-start

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -333,22 +333,25 @@ pub(crate) fn llfn_attrs_from_instance<'ll, 'tcx>(
     let mut to_add = SmallVec::<[_; 16]>::new();
 
     match codegen_fn_attrs.optimize {
-        OptimizeAttr::None => {
+        OptimizeAttr::Default => {
             to_add.extend(default_optimisation_attrs(cx));
         }
+        OptimizeAttr::DoNotOptimize => {
+            to_add.push(llvm::AttributeKind::OptimizeNone.create_attr(cx.llcx));
+        }
         OptimizeAttr::Size => {
             to_add.push(llvm::AttributeKind::MinSize.create_attr(cx.llcx));
             to_add.push(llvm::AttributeKind::OptimizeForSize.create_attr(cx.llcx));
         }
         OptimizeAttr::Speed => {}
     }
 
-    let inline =
-        if codegen_fn_attrs.inline == InlineAttr::None && instance.def.requires_inline(cx.tcx) {
-            InlineAttr::Hint
-        } else {
-            codegen_fn_attrs.inline
-        };
+    // `optnone` requires `noinline`
+    let inline = match (codegen_fn_attrs.inline, &codegen_fn_attrs.optimize) {
+        (_, OptimizeAttr::DoNotOptimize) => InlineAttr::Never,
+        (InlineAttr::None, _) if instance.def.requires_inline(cx.tcx) => InlineAttr::Hint,
+        (inline, _) => inline,
+    };
     to_add.extend(inline_attr(cx, inline));
 
     // The `uwtable` attribute according to LLVM is:

compiler/rustc_codegen_ssa/src/base.rs

@@ -1053,10 +1053,7 @@ pub(crate) fn provide(providers: &mut Providers) {
 
         let any_for_speed = defids.items().any(|id| {
             let CodegenFnAttrs { optimize, .. } = tcx.codegen_fn_attrs(*id);
-            match optimize {
-                attr::OptimizeAttr::None | attr::OptimizeAttr::Size => false,
-                attr::OptimizeAttr::Speed => true,
-            }
+            matches!(optimize, attr::OptimizeAttr::Speed)
         });
 
         if any_for_speed {

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -575,7 +575,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
         codegen_fn_attrs.inline = InlineAttr::Never;
     }
 
-    codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
+    codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::Default, |ia, attr| {
         if !attr.has_name(sym::optimize) {
             return ia;
         }
@@ -587,17 +587,19 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
             inline_span = Some(attr.span);
             if items.len() != 1 {
                 err(attr.span, "expected one argument");
-                OptimizeAttr::None
+                OptimizeAttr::Default
             } else if list_contains_name(items, sym::size) {
                 OptimizeAttr::Size
             } else if list_contains_name(items, sym::speed) {
                 OptimizeAttr::Speed
+            } else if list_contains_name(items, sym::none) {
+                OptimizeAttr::DoNotOptimize
             } else {
                 err(items[0].span(), "invalid argument");
-                OptimizeAttr::None
+                OptimizeAttr::Default
             }
         } else {
-            OptimizeAttr::None
+            OptimizeAttr::Default
         }
     });
 

compiler/rustc_feature/src/builtin_attrs.rs

@@ -532,7 +532,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     ),
     // RFC 2412
     gated!(
-        optimize, Normal, template!(List: "size|speed"), ErrorPreceding,
+        optimize, Normal, template!(List: "none|size|speed"), ErrorPreceding,
         EncodeCrossCrate::No, optimize_attribute, experimental!(optimize)
     ),
 

compiler/rustc_middle/src/middle/codegen_fn_attrs.rs

@@ -147,7 +147,7 @@ impl CodegenFnAttrs {
         CodegenFnAttrs {
             flags: CodegenFnAttrFlags::empty(),
             inline: InlineAttr::None,
-            optimize: OptimizeAttr::None,
+            optimize: OptimizeAttr::Default,
             export_name: None,
             link_name: None,
             link_ordinal: None,

compiler/rustc_mir_transform/src/abort_unwinding_calls.rs

@@ -116,4 +116,8 @@ impl<'tcx> crate::MirPass<'tcx> for AbortUnwindingCalls {
         // We may have invalidated some `cleanup` blocks so clean those up now.
         super::simplify::remove_dead_blocks(body);
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }

compiler/rustc_mir_transform/src/add_call_guards.rs

@@ -75,4 +75,8 @@ impl<'tcx> crate::MirPass<'tcx> for AddCallGuards {
 
         body.basic_blocks_mut().extend(new_blocks);
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }

compiler/rustc_mir_transform/src/add_moves_for_packed_drops.rs

@@ -68,6 +68,10 @@ impl<'tcx> crate::MirPass<'tcx> for AddMovesForPackedDrops {
 
         patch.apply(body);
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }
 
 fn add_move_for_packed_drop<'tcx>(

compiler/rustc_mir_transform/src/add_retag.rs

@@ -176,4 +176,8 @@ impl<'tcx> crate::MirPass<'tcx> for AddRetag {
             }
         }
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }

compiler/rustc_mir_transform/src/add_subtyping_projections.rs

@@ -61,4 +61,8 @@ impl<'tcx> crate::MirPass<'tcx> for Subtyper {
         }
         checker.patcher.apply(body);
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }

compiler/rustc_mir_transform/src/check_alignment.rs

@@ -60,6 +60,10 @@ impl<'tcx> crate::MirPass<'tcx> for CheckAlignment {
             }
         }
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }
 
 struct PointerFinder<'a, 'tcx> {

compiler/rustc_mir_transform/src/cleanup_post_borrowck.rs

@@ -72,4 +72,8 @@ impl<'tcx> crate::MirPass<'tcx> for CleanupPostBorrowck {
             decl.user_ty = None;
         }
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }

compiler/rustc_mir_transform/src/copy_prop.rs

@@ -56,6 +56,10 @@ impl<'tcx> crate::MirPass<'tcx> for CopyProp {
             crate::simplify::remove_unused_definitions(body);
         }
     }
+
+    fn is_required(&self) -> bool {
+        false
+    }
 }
 
 /// `SsaLocals` computed equivalence classes between locals considering copy/move assignments.

compiler/rustc_mir_transform/src/coroutine.rs

@@ -1688,6 +1688,10 @@ impl<'tcx> crate::MirPass<'tcx> for StateTransform {
         // Run derefer to fix Derefs that are not in the first place
         deref_finder(tcx, body);
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }
 
 /// Looks for any assignments between locals (e.g., `_4 = _5`) that will both be converted to fields

compiler/rustc_mir_transform/src/coverage/mod.rs

@@ -61,6 +61,10 @@ impl<'tcx> crate::MirPass<'tcx> for InstrumentCoverage {
 
         instrument_function_for_coverage(tcx, mir_body);
     }
+
+    fn is_required(&self) -> bool {
+        false
+    }
 }
 
 fn instrument_function_for_coverage<'tcx>(tcx: TyCtxt<'tcx>, mir_body: &mut mir::Body<'tcx>) {

compiler/rustc_mir_transform/src/cross_crate_inline.rs

@@ -69,7 +69,7 @@ fn cross_crate_inlinable(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
     // Don't do any inference if codegen optimizations are disabled and also MIR inlining is not
     // enabled. This ensures that we do inference even if someone only passes -Zinline-mir,
     // which is less confusing than having to also enable -Copt-level=1.
-    let inliner_will_run = pm::should_run_pass(tcx, &inline::Inline)
+    let inliner_will_run = pm::should_run_pass(tcx, &inline::Inline, pm::Optimizations::Allowed)
         || inline::ForceInline::should_run_pass_for_callee(tcx, def_id.to_def_id());
     if matches!(tcx.sess.opts.optimize, OptLevel::No) && !inliner_will_run {
         return false;

compiler/rustc_mir_transform/src/ctfe_limit.rs

@@ -36,6 +36,10 @@ impl<'tcx> crate::MirPass<'tcx> for CtfeLimit {
             );
         }
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }
 
 fn has_back_edge(

compiler/rustc_mir_transform/src/dataflow_const_prop.rs

@@ -71,6 +71,10 @@ impl<'tcx> crate::MirPass<'tcx> for DataflowConstProp {
         let mut patch = visitor.patch;
         debug_span!("patch").in_scope(|| patch.visit_body_preserves_cfg(body));
     }
+
+    fn is_required(&self) -> bool {
+        false
+    }
 }
 
 // Note: Currently, places that have their reference taken cannot be tracked. Although this would

compiler/rustc_mir_transform/src/dead_store_elimination.rs

@@ -147,4 +147,8 @@ impl<'tcx> crate::MirPass<'tcx> for DeadStoreElimination {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         eliminate(tcx, body);
     }
+
+    fn is_required(&self) -> bool {
+        false
+    }
 }

compiler/rustc_mir_transform/src/deduplicate_blocks.rs

@@ -31,6 +31,10 @@ impl<'tcx> crate::MirPass<'tcx> for DeduplicateBlocks {
             simplify_cfg(body);
         }
     }
+
+    fn is_required(&self) -> bool {
+        false
+    }
 }
 
 struct OptApplier<'tcx> {

compiler/rustc_mir_transform/src/deref_separator.rs

@@ -81,4 +81,8 @@ impl<'tcx> crate::MirPass<'tcx> for Derefer {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         deref_finder(tcx, body);
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }

compiler/rustc_mir_transform/src/dest_prop.rs

@@ -240,6 +240,10 @@ impl<'tcx> crate::MirPass<'tcx> for DestinationPropagation {
 
         trace!(round_count);
     }
+
+    fn is_required(&self) -> bool {
+        false
+    }
 }
 
 #[derive(Debug, Default)]

compiler/rustc_mir_transform/src/dump_mir.rs

@@ -15,6 +15,10 @@ impl<'tcx> crate::MirPass<'tcx> for Marker {
     }
 
     fn run_pass(&self, _tcx: TyCtxt<'tcx>, _body: &mut Body<'tcx>) {}
+
+    fn is_required(&self) -> bool {
+        false
+    }
 }
 
 pub fn emit_mir(tcx: TyCtxt<'_>) -> io::Result<()> {

compiler/rustc_mir_transform/src/early_otherwise_branch.rs

@@ -227,6 +227,10 @@ impl<'tcx> crate::MirPass<'tcx> for EarlyOtherwiseBranch {
             simplify_cfg(body);
         }
     }
+
+    fn is_required(&self) -> bool {
+        false
+    }
 }
 
 #[derive(Debug)]

compiler/rustc_mir_transform/src/elaborate_box_derefs.rs

@@ -150,4 +150,8 @@ impl<'tcx> crate::MirPass<'tcx> for ElaborateBoxDerefs {
             }
         }
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }

compiler/rustc_mir_transform/src/elaborate_drops.rs

@@ -88,6 +88,10 @@ impl<'tcx> crate::MirPass<'tcx> for ElaborateDrops {
         elaborate_patch.apply(body);
         deref_finder(tcx, body);
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }
 
 /// Records unwind edges which are known to be unreachable, because they are in `drop` terminators

compiler/rustc_mir_transform/src/gvn.rs

@@ -163,6 +163,10 @@ impl<'tcx> crate::MirPass<'tcx> for GVN {
         // statements.
         StorageRemover { tcx, reused_locals: state.reused_locals }.visit_body_preserves_cfg(body);
     }
+
+    fn is_required(&self) -> bool {
+        false
+    }
 }
 
 newtype_index! {

compiler/rustc_mir_transform/src/impossible_predicates.rs

@@ -53,4 +53,8 @@ impl<'tcx> MirPass<'tcx> for ImpossiblePredicates {
             body.local_decls.raw.truncate(body.arg_count + 1);
         }
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }

compiler/rustc_mir_transform/src/inline.rs

@@ -66,6 +66,10 @@ impl<'tcx> crate::MirPass<'tcx> for Inline {
             deref_finder(tcx, body);
         }
     }
+
+    fn is_required(&self) -> bool {
+        false
+    }
 }
 
 pub struct ForceInline;
@@ -85,6 +89,10 @@ impl<'tcx> crate::MirPass<'tcx> for ForceInline {
         false
     }
 
+    fn is_required(&self) -> bool {
+        true
+    }
+
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         let span = trace_span!("force_inline", body = %tcx.def_path_str(body.source.def_id()));
         let _guard = span.enter();

compiler/rustc_mir_transform/src/instsimplify.rs

@@ -62,6 +62,10 @@ impl<'tcx> crate::MirPass<'tcx> for InstSimplify {
             simplify_duplicate_switch_targets(block.terminator.as_mut().unwrap());
         }
     }
+
+    fn is_required(&self) -> bool {
+        false
+    }
 }
 
 struct InstSimplifyContext<'a, 'tcx> {

compiler/rustc_mir_transform/src/jump_threading.rs

@@ -105,6 +105,10 @@ impl<'tcx> crate::MirPass<'tcx> for JumpThreading {
         }
         OpportunitySet::new(body, opportunities).apply(body);
     }
+
+    fn is_required(&self) -> bool {
+        false
+    }
 }
 
 #[derive(Debug)]