Disable some MIR opts with #[optimize(none)]

Author: clubby789

compiler/rustc_attr/src/builtin.rs

@@ -55,7 +55,7 @@ pub enum InstructionSetAttr {
 
 #[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic, PartialEq, Eq)]
 pub enum OptimizeAttr {
-    /// `#[optimize(none)]`
+    /// `#[optimize(none)]`. This implies `#[inline(never)]`, required by LLVM
     None,
     /// `#[optimize(speed)]`
     Speed,
@@ -64,7 +64,7 @@ pub enum OptimizeAttr {
 }
 
 impl OptimizeAttr {
-    pub fn is_none(&self) -> bool {
+    pub fn do_not_optimize(&self) -> bool {
         matches!(*self, OptimizeAttr::None)
     }
 }

compiler/rustc_middle/src/mir/mod.rs

@@ -153,6 +153,10 @@ pub trait MirPass<'tcx> {
         to_profiler_name(self.name())
     }
 
+    fn min_mir_opt_level(&self) -> usize {
+        0
+    }
+
     /// Returns `true` if this pass is enabled with the current combination of compiler flags.
     fn is_enabled(&self, _sess: &Session) -> bool {
         true
@@ -443,9 +447,8 @@ pub struct Body<'tcx> {
     /// If `-Cinstrument-coverage` is not active, or if an individual function
     /// is not eligible for coverage, then this should always be `None`.
     pub function_coverage_info: Option<Box<coverage::FunctionCoverageInfo>>,
-
-    /// Whether optimization is disabled by `#[optimize(none)]`
-    pub optimization_disabled: bool,
+    // /// Whether optimization is disabled by `#[optimize(none)]`
+    // pub optimization_disabled: bool,
 }
 
 impl<'tcx> Body<'tcx> {
@@ -460,7 +463,6 @@ impl<'tcx> Body<'tcx> {
         span: Span,
         coroutine: Option<Box<CoroutineInfo<'tcx>>>,
         tainted_by_errors: Option<ErrorGuaranteed>,
-        optimization_disabled: bool,
     ) -> Self {
         // We need `arg_count` locals, and one for the return place.
         assert!(
@@ -490,7 +492,6 @@ impl<'tcx> Body<'tcx> {
             tainted_by_errors,
             coverage_info_hi: None,
             function_coverage_info: None,
-            optimization_disabled,
         };
         body.is_polymorphic = body.has_non_region_param();
         body
@@ -522,7 +523,6 @@ impl<'tcx> Body<'tcx> {
             tainted_by_errors: None,
             coverage_info_hi: None,
             function_coverage_info: None,
-            optimization_disabled: false,
         };
         body.is_polymorphic = body.has_non_region_param();
         body

compiler/rustc_mir_build/src/build/custom/mod.rs

@@ -62,7 +62,6 @@ pub(super) fn build_custom_mir<'tcx>(
         pass_count: 0,
         coverage_info_hi: None,
         function_coverage_info: None,
-        optimization_disabled: false,
     };
 
     body.local_decls.push(LocalDecl::new(return_ty, return_ty_span));

compiler/rustc_mir_build/src/build/mod.rs

@@ -718,7 +718,6 @@ fn construct_error(tcx: TyCtxt<'_>, def_id: LocalDefId, guar: ErrorGuaranteed) -
         span,
         coroutine,
         Some(guar),
-        false,
     )
 }
 
@@ -795,13 +794,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             }
         }
 
-        let def_id = self.def_id.to_def_id();
-        let optimization_disabled = if self.tcx.def_kind(def_id).has_codegen_attrs() {
-            self.tcx.codegen_fn_attrs(def_id).optimize.as_ref().is_some_and(|o| o.is_none())
-        } else {
-            false
-        };
-
         let mut body = Body::new(
             MirSource::item(self.def_id.to_def_id()),
             self.cfg.basic_blocks,
@@ -813,7 +805,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             self.fn_span,
             self.coroutine,
             None,
-            optimization_disabled,
         );
         body.coverage_info_hi = self.coverage_info.map(|b| b.into_done());
         body

compiler/rustc_mir_transform/src/copy_prop.rs

@@ -19,6 +19,10 @@ use crate::ssa::SsaLocals;
 pub struct CopyProp;
 
 impl<'tcx> MirPass<'tcx> for CopyProp {
+    fn min_mir_opt_level(&self) -> usize {
+        1
+    }
+
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
         sess.mir_opt_level() >= 1
     }

compiler/rustc_mir_transform/src/dataflow_const_prop.rs

@@ -28,6 +28,10 @@ const PLACE_LIMIT: usize = 100;
 pub struct DataflowConstProp;
 
 impl<'tcx> MirPass<'tcx> for DataflowConstProp {
+    fn min_mir_opt_level(&self) -> usize {
+        3
+    }
+
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
         sess.mir_opt_level() >= 3
     }

compiler/rustc_mir_transform/src/dead_store_elimination.rs

@@ -140,6 +140,10 @@ impl<'tcx> MirPass<'tcx> for DeadStoreElimination {
         }
     }
 
+    fn min_mir_opt_level(&self) -> usize {
+        2
+    }
+
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
         sess.mir_opt_level() >= 2
     }

compiler/rustc_mir_transform/src/deduplicate_blocks.rs

@@ -15,6 +15,10 @@ use super::simplify::simplify_cfg;
 pub struct DeduplicateBlocks;
 
 impl<'tcx> MirPass<'tcx> for DeduplicateBlocks {
+    fn min_mir_opt_level(&self) -> usize {
+        4
+    }
+
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
         sess.mir_opt_level() >= 4
     }

compiler/rustc_mir_transform/src/dest_prop.rs

@@ -150,6 +150,10 @@ use crate::MirPass;
 pub struct DestinationPropagation;
 
 impl<'tcx> MirPass<'tcx> for DestinationPropagation {
+    fn min_mir_opt_level(&self) -> usize {
+        3
+    }
+
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
         // For now, only run at MIR opt level 3. Two things need to be changed before this can be
         // turned on by default:

compiler/rustc_mir_transform/src/early_otherwise_branch.rs

@@ -92,6 +92,10 @@ use super::simplify::simplify_cfg;
 pub struct EarlyOtherwiseBranch;
 
 impl<'tcx> MirPass<'tcx> for EarlyOtherwiseBranch {
+    fn min_mir_opt_level(&self) -> usize {
+        2
+    }
+
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
         sess.mir_opt_level() >= 2
     }