Do partial SsaLocals analysis in unoptimized builds

Author: saethlin

compiler/rustc_mir_transform/src/copy_prop.rs

@@ -5,7 +5,7 @@ use rustc_middle::mir::*;
 use rustc_middle::ty::TyCtxt;
 use tracing::{debug, instrument};
 
-use crate::ssa::SsaLocals;
+use crate::ssa::{SsaAnalysis, SsaLocals};
 
 /// Unify locals that copy each other.
 ///
@@ -29,7 +29,11 @@ impl<'tcx> crate::MirPass<'tcx> for CopyProp {
         debug!(def_id = ?body.source.def_id());
 
         let typing_env = body.typing_env(tcx);
-        let ssa = SsaLocals::new(tcx, body, typing_env);
+        let ssa_analysis = match tcx.sess.mir_opt_level() {
+            0 | 1 => SsaAnalysis::Partial,
+            _ => SsaAnalysis::Full,
+        };
+        let ssa = SsaLocals::new(tcx, body, typing_env, ssa_analysis);
 
         let fully_moved = fully_moved_locals(&ssa, body);
         debug!(?fully_moved);

compiler/rustc_mir_transform/src/gvn.rs

@@ -107,21 +107,25 @@ use rustc_span::def_id::DefId;
 use smallvec::SmallVec;
 use tracing::{debug, instrument, trace};
 
-use crate::ssa::{AssignedValue, SsaLocals};
+use crate::ssa::{AssignedValue, SsaAnalysis, SsaLocals};
 
 pub(super) struct GVN;
 
 impl<'tcx> crate::MirPass<'tcx> for GVN {
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
-        sess.mir_opt_level() >= 2
+        sess.mir_opt_level() >= 1
     }
 
     #[instrument(level = "trace", skip(self, tcx, body))]
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         debug!(def_id = ?body.source.def_id());
 
         let typing_env = body.typing_env(tcx);
-        let ssa = SsaLocals::new(tcx, body, typing_env);
+        let ssa_analysis = match tcx.sess.mir_opt_level() {
+            0 | 1 => SsaAnalysis::Partial,
+            _ => SsaAnalysis::Full,
+        };
+        let ssa = SsaLocals::new(tcx, body, typing_env, ssa_analysis);
         // Clone dominators because we need them while mutating the body.
         let dominators = body.basic_blocks.dominators().clone();
 

compiler/rustc_mir_transform/src/ref_prop.rs

@@ -11,7 +11,7 @@ use rustc_mir_dataflow::Analysis;
 use rustc_mir_dataflow::impls::{MaybeStorageDead, always_storage_live_locals};
 use tracing::{debug, instrument};
 
-use crate::ssa::{SsaLocals, StorageLiveLocals};
+use crate::ssa::{SsaAnalysis, SsaLocals, StorageLiveLocals};
 
 /// Propagate references using SSA analysis.
 ///
@@ -85,7 +85,7 @@ impl<'tcx> crate::MirPass<'tcx> for ReferencePropagation {
 
 fn propagate_ssa<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) -> bool {
     let typing_env = body.typing_env(tcx);
-    let ssa = SsaLocals::new(tcx, body, typing_env);
+    let ssa = SsaLocals::new(tcx, body, typing_env, SsaAnalysis::Full);
 
     let mut replacer = compute_replacement(tcx, body, &ssa);
     debug!(?replacer.targets);

compiler/rustc_mir_transform/src/ssa.rs

@@ -38,11 +38,17 @@ pub(super) enum AssignedValue<'a, 'tcx> {
     Terminator,
 }
 
+pub(super) enum SsaAnalysis {
+    Full,
+    Partial,
+}
+
 impl SsaLocals {
     pub(super) fn new<'tcx>(
         tcx: TyCtxt<'tcx>,
         body: &Body<'tcx>,
         typing_env: ty::TypingEnv<'tcx>,
+        analysis: SsaAnalysis,
     ) -> SsaLocals {
         let assignment_order = Vec::with_capacity(body.local_decls.len());
 
@@ -79,9 +85,15 @@ impl SsaLocals {
         // borrows, we need to check the types. For raw pointers and mutable borrows, the locals
         // have already been marked as non-SSA.
         debug!(?visitor.borrowed_locals);
+
         for local in visitor.borrowed_locals.iter() {
-            if !body.local_decls[local].ty.is_freeze(tcx, typing_env) {
-                visitor.assignments[local] = Set1::Many;
+            match analysis {
+                SsaAnalysis::Full => {
+                    if !body.local_decls[local].ty.is_freeze(tcx, typing_env) {
+                        visitor.assignments[local] = Set1::Many;
+                    }
+                }
+                SsaAnalysis::Partial => visitor.assignments[local] = Set1::Many,
             }
         }
 

tests/mir-opt/gvn.arithmetic.GVN.panic-unwind.diff

@@ -79,7 +79,6 @@
       let mut _74: u64;
 
       bb0: {
-          StorageLive(_2);
           StorageLive(_3);
           StorageLive(_4);
           _4 = copy _1;
@@ -92,8 +91,6 @@
 
       bb1: {
           StorageDead(_3);
-          StorageDead(_2);
-          StorageLive(_5);
           StorageLive(_6);
           StorageLive(_7);
           _7 = copy _1;
@@ -106,8 +103,6 @@
 
       bb2: {
           StorageDead(_6);
-          StorageDead(_5);
-          StorageLive(_8);
 -         StorageLive(_9);
 +         nop;
           StorageLive(_10);
@@ -125,8 +120,6 @@
       bb3: {
 -         StorageDead(_9);
 +         nop;
-          StorageDead(_8);
-          StorageLive(_12);
           StorageLive(_13);
           StorageLive(_14);
           _14 = copy _1;
@@ -139,8 +132,6 @@
 
       bb4: {
           StorageDead(_13);
-          StorageDead(_12);
-          StorageLive(_15);
           StorageLive(_16);
           StorageLive(_17);
           _17 = copy _1;
@@ -153,8 +144,6 @@
 
       bb5: {
           StorageDead(_16);
-          StorageDead(_15);
-          StorageLive(_18);
           StorageLive(_19);
           StorageLive(_20);
           _20 = copy _1;
@@ -173,8 +162,6 @@
 
       bb7: {
           StorageDead(_19);
-          StorageDead(_18);
-          StorageLive(_22);
           StorageLive(_23);
           StorageLive(_24);
           _24 = copy _1;
@@ -194,8 +181,6 @@
 
       bb9: {
           StorageDead(_23);
-          StorageDead(_22);
-          StorageLive(_26);
           StorageLive(_27);
           StorageLive(_28);
           _28 = copy _1;
@@ -215,8 +200,6 @@
 
       bb11: {
           StorageDead(_27);
-          StorageDead(_26);
-          StorageLive(_30);
           StorageLive(_31);
           StorageLive(_32);
           _32 = copy _1;
@@ -235,8 +218,6 @@
 
       bb13: {
           StorageDead(_31);
-          StorageDead(_30);
-          StorageLive(_34);
           StorageLive(_35);
           StorageLive(_36);
           _36 = copy _1;
@@ -255,8 +236,6 @@
 
       bb15: {
           StorageDead(_35);
-          StorageDead(_34);
-          StorageLive(_38);
           StorageLive(_39);
           StorageLive(_40);
           _40 = copy _1;
@@ -276,8 +255,6 @@
 
       bb17: {
           StorageDead(_39);
-          StorageDead(_38);
-          StorageLive(_42);
           StorageLive(_43);
           StorageLive(_44);
           _44 = copy _1;
@@ -297,8 +274,6 @@
 
       bb19: {
           StorageDead(_43);
-          StorageDead(_42);
-          StorageLive(_46);
           StorageLive(_47);
           StorageLive(_48);
           _48 = copy _1;
@@ -317,8 +292,6 @@
 
       bb21: {
           StorageDead(_47);
-          StorageDead(_46);
-          StorageLive(_50);
           StorageLive(_51);
           StorageLive(_52);
           _52 = copy _1;
@@ -331,8 +304,6 @@
 
       bb22: {
           StorageDead(_51);
-          StorageDead(_50);
-          StorageLive(_53);
           StorageLive(_54);
           StorageLive(_55);
           _55 = copy _1;
@@ -345,8 +316,6 @@
 
       bb23: {
           StorageDead(_54);
-          StorageDead(_53);
-          StorageLive(_56);
           StorageLive(_57);
           StorageLive(_58);
           _58 = copy _1;
@@ -359,8 +328,6 @@
 
       bb24: {
           StorageDead(_57);
-          StorageDead(_56);
-          StorageLive(_59);
           StorageLive(_60);
           StorageLive(_61);
           _61 = copy _1;
@@ -373,8 +340,6 @@
 
       bb25: {
           StorageDead(_60);
-          StorageDead(_59);
-          StorageLive(_62);
           StorageLive(_63);
           StorageLive(_64);
           _64 = copy _1;
@@ -387,8 +352,6 @@
 
       bb26: {
           StorageDead(_63);
-          StorageDead(_62);
-          StorageLive(_65);
           StorageLive(_66);
           StorageLive(_67);
           _67 = copy _1;
@@ -404,8 +367,6 @@
 
       bb27: {
           StorageDead(_66);
-          StorageDead(_65);
-          StorageLive(_69);
           StorageLive(_70);
           StorageLive(_71);
           _71 = copy _1;
@@ -418,8 +379,6 @@
 
       bb28: {
           StorageDead(_70);
-          StorageDead(_69);
-          StorageLive(_72);
           StorageLive(_73);
           StorageLive(_74);
           _74 = copy _1;
@@ -432,8 +391,6 @@
 
       bb29: {
           StorageDead(_73);
-          StorageDead(_72);
-          _0 = const ();
           return;
       }
   }

tests/mir-opt/gvn.arithmetic_checked.GVN.panic-unwind.diff

@@ -27,7 +27,6 @@
       let mut _22: (u64, bool);
 
       bb0: {
-          StorageLive(_2);
           StorageLive(_3);
           StorageLive(_4);
           _4 = copy _1;
@@ -47,8 +46,6 @@
 
       bb2: {
           StorageDead(_3);
-          StorageDead(_2);
-          StorageLive(_6);
           StorageLive(_7);
           StorageLive(_8);
           _8 = copy _1;
@@ -68,8 +65,6 @@
 
       bb4: {
           StorageDead(_7);
-          StorageDead(_6);
-          StorageLive(_10);
 -         StorageLive(_11);
 +         nop;
           StorageLive(_12);
@@ -94,8 +89,6 @@
       bb6: {
 -         StorageDead(_11);
 +         nop;
-          StorageDead(_10);
-          StorageLive(_15);
           StorageLive(_16);
           StorageLive(_17);
           _17 = copy _1;
@@ -115,8 +108,6 @@
 
       bb8: {
           StorageDead(_16);
-          StorageDead(_15);
-          StorageLive(_19);
           StorageLive(_20);
           StorageLive(_21);
           _21 = copy _1;
@@ -136,8 +127,6 @@
 
       bb10: {
           StorageDead(_20);
-          StorageDead(_19);
-          _0 = const ();
           return;
       }
   }