Add more simplify passes.

Author: cjgillot

compiler/rustc_mir_transform/src/lib.rs

@@ -596,18 +596,19 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
             &match_branches::MatchBranchSimplification,
             // inst combine is after MatchBranchSimplification to clean up Ne(_1, false)
             &instsimplify::InstSimplify,
+            &o1(simplify::SimplifyCfg::AfterGVN),
             // Turn non-aliasing places into locals.
             // Helps `DeadStoreElimination` to remove them and `CopyProp` to merge them.
             &simplify::SimplifyLocals::BeforeSROA,
             &sroa::ScalarReplacementOfAggregates,
             // Compute `Len` when it comes from an unsizing cast.
             &normalize_array_len::NormalizeArrayLen,
             // Perform a first round of constant propagation.
-            &o1(simplify::SimplifyCfg::BeforeConstProp),
             &simplify::SimplifyLocals::BeforeConstProp,
             // Turn `SwitchInt(Eq(x, constant))` into `SwitchInt(x)`.
             // Runs after ConstProp to increase probability to have constants.
             &simplify_comparison_integral::SimplifyComparisonIntegral,
+            &o1(simplify::SimplifyCfg::AfterConstProp),
             &early_otherwise_branch::EarlyOtherwiseBranch,
             // Merge locals that just copy each another.
             &copy_prop::CopyProp,
@@ -623,7 +624,7 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
             &gvn::GVN::Final,
             &o1(remove_noop_landing_pads::RemoveNoopLandingPads),
             &o1(simplify::SimplifyCfg::Final),
-            &simplify::SimplifyLocals::AfterGVN,
+            &simplify::SimplifyLocals::BeforeDestProp,
             &dest_prop::DestinationPropagation,
             // Attempt to promote call operands from copies to moves.
             &dead_store_elimination::DeadStoreElimination::Final,

compiler/rustc_mir_transform/src/simplify.rs

@@ -39,6 +39,8 @@ pub enum SimplifyCfg {
     RemoveFalseEdges,
     EarlyOpt,
     ElaborateDrops,
+    AfterGVN,
+    AfterConstProp,
     Final,
     MakeShim,
     AfterUninhabitedEnumBranching,
@@ -53,6 +55,8 @@ impl SimplifyCfg {
             SimplifyCfg::RemoveFalseEdges => "SimplifyCfg-remove-false-edges",
             SimplifyCfg::EarlyOpt => "SimplifyCfg-early-opt",
             SimplifyCfg::ElaborateDrops => "SimplifyCfg-elaborate-drops",
+            SimplifyCfg::AfterGVN => "SimplifyCfg-after-gvn",
+            SimplifyCfg::AfterConstProp => "SimplifyCfg-after-const-prop",
             SimplifyCfg::Final => "SimplifyCfg-final",
             SimplifyCfg::MakeShim => "SimplifyCfg-make_shim",
             SimplifyCfg::AfterUninhabitedEnumBranching => {
@@ -350,6 +354,7 @@ pub(crate) fn remove_dead_blocks(body: &mut Body<'_>) {
 pub enum SimplifyLocals {
     BeforeSROA,
     BeforeConstProp,
+    BeforeDestProp,
     AfterGVN,
     Final,
 }
@@ -359,6 +364,7 @@ impl<'tcx> MirPass<'tcx> for SimplifyLocals {
         match &self {
             SimplifyLocals::BeforeSROA => "SimplifyLocals-before-sroa",
             SimplifyLocals::BeforeConstProp => "SimplifyLocals-before-const-prop",
+            SimplifyLocals::BeforeDestProp => "SimplifyLocals-before-dest-prop",
             SimplifyLocals::AfterGVN => "SimplifyLocals-after-value-numbering",
             SimplifyLocals::Final => "SimplifyLocals-final",
         }

tests/mir-opt/pre-codegen/optimizes_into_variable.main.ScalarReplacementOfAggregates.32bit.panic-abort.diff

@@ -14,14 +14,6 @@
       }
 
       bb0: {
-          goto -> bb1;
-      }
-  
-      bb1: {
-          goto -> bb2;
-      }
-  
-      bb2: {
           return;
       }
   }

tests/mir-opt/pre-codegen/optimizes_into_variable.main.ScalarReplacementOfAggregates.32bit.panic-unwind.diff

@@ -14,14 +14,6 @@
       }
 
       bb0: {
-          goto -> bb1;
-      }
-  
-      bb1: {
-          goto -> bb2;
-      }
-  
-      bb2: {
           return;
       }
   }

tests/mir-opt/pre-codegen/optimizes_into_variable.main.ScalarReplacementOfAggregates.64bit.panic-abort.diff

@@ -14,14 +14,6 @@
       }
 
       bb0: {
-          goto -> bb1;
-      }
-  
-      bb1: {
-          goto -> bb2;
-      }
-  
-      bb2: {
           return;
       }
   }

tests/mir-opt/pre-codegen/optimizes_into_variable.main.ScalarReplacementOfAggregates.64bit.panic-unwind.diff

@@ -14,14 +14,6 @@
       }
 
       bb0: {
-          goto -> bb1;
-      }
-  
-      bb1: {
-          goto -> bb2;
-      }
-  
-      bb2: {
           return;
       }
   }