Replace ConstProp by DataflowConstProp.

Author: cjgillot

compiler/rustc_mir_transform/src/const_prop.rs

@@ -26,11 +26,11 @@ use crate::MirPass;
 const BLOCK_LIMIT: usize = 100;
 const PLACE_LIMIT: usize = 100;
 
-pub struct DataflowConstProp;
+pub struct ConstProp;
 
-impl<'tcx> MirPass<'tcx> for DataflowConstProp {
+impl<'tcx> MirPass<'tcx> for ConstProp {
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
-        sess.mir_opt_level() >= 3
+        sess.mir_opt_level() >= 2
     }
 
     #[instrument(skip_all level = "debug")]

compiler/rustc_mir_transform/src/dataflow_const_prop.rs

@@ -364,7 +364,7 @@ fn inner_mir_for_ctfe(tcx: TyCtxt<'_>, def: LocalDefId) -> Body<'_> {
             pm::run_passes(
                 tcx,
                 &mut body,
-                &[&const_prop::ConstProp],
+                &[&dataflow_const_prop::ConstProp],
                 Some(MirPhase::Runtime(RuntimePhase::Optimized)),
             );
         }
@@ -565,8 +565,7 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
             // destroy the SSA property. It should still happen before const-propagation, so the
             // latter pass will leverage the created opportunities.
             &separate_const_switch::SeparateConstSwitch,
-            &const_prop::ConstProp,
-            &dataflow_const_prop::DataflowConstProp,
+            &dataflow_const_prop::ConstProp,
             //
             // Const-prop runs unconditionally, but doesn't mutate the MIR at mir-opt-level=0.
             &const_debuginfo::ConstDebugInfo,

compiler/rustc_mir_transform/src/lib.rs

@@ -18,17 +18,15 @@
           _2 = [const 0_u32, const 1_u32, const 2_u32, const 3_u32];
           StorageLive(_3);
           _3 = const 2_usize;
--         _4 = Len(_2);
+          _4 = Len(_2);
 -         _5 = Lt(_3, _4);
 -         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind unreachable];
-+         _4 = const 4_usize;
-+         _5 = const true;
-+         assert(const true, "index out of bounds: the length is {} but the index is {}", const 4_usize, const 2_usize) -> [success: bb1, unwind unreachable];
++         _5 = Lt(const 2_usize, _4);
++         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind unreachable];
       }
 
       bb1: {
--         _1 = _2[_3];
-+         _1 = const 2_u32;
+          _1 = _2[_3];
           StorageDead(_3);
           StorageDead(_2);
           _0 = const ();

tests/mir-opt/const_prop/array_index.main.ConstProp.32bit.panic-abort.diff

@@ -18,17 +18,15 @@
           _2 = [const 0_u32, const 1_u32, const 2_u32, const 3_u32];
           StorageLive(_3);
           _3 = const 2_usize;
--         _4 = Len(_2);
+          _4 = Len(_2);
 -         _5 = Lt(_3, _4);
 -         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind continue];
-+         _4 = const 4_usize;
-+         _5 = const true;
-+         assert(const true, "index out of bounds: the length is {} but the index is {}", const 4_usize, const 2_usize) -> [success: bb1, unwind continue];
++         _5 = Lt(const 2_usize, _4);
++         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind continue];
       }
 
       bb1: {
--         _1 = _2[_3];
-+         _1 = const 2_u32;
+          _1 = _2[_3];
           StorageDead(_3);
           StorageDead(_2);
           _0 = const ();

tests/mir-opt/const_prop/array_index.main.ConstProp.32bit.panic-unwind.diff

@@ -18,17 +18,15 @@
           _2 = [const 0_u32, const 1_u32, const 2_u32, const 3_u32];
           StorageLive(_3);
           _3 = const 2_usize;
--         _4 = Len(_2);
+          _4 = Len(_2);
 -         _5 = Lt(_3, _4);
 -         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind unreachable];
-+         _4 = const 4_usize;
-+         _5 = const true;
-+         assert(const true, "index out of bounds: the length is {} but the index is {}", const 4_usize, const 2_usize) -> [success: bb1, unwind unreachable];
++         _5 = Lt(const 2_usize, _4);
++         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind unreachable];
       }
 
       bb1: {
--         _1 = _2[_3];
-+         _1 = const 2_u32;
+          _1 = _2[_3];
           StorageDead(_3);
           StorageDead(_2);
           _0 = const ();

tests/mir-opt/const_prop/array_index.main.ConstProp.64bit.panic-abort.diff

@@ -18,17 +18,15 @@
           _2 = [const 0_u32, const 1_u32, const 2_u32, const 3_u32];
           StorageLive(_3);
           _3 = const 2_usize;
--         _4 = Len(_2);
+          _4 = Len(_2);
 -         _5 = Lt(_3, _4);
 -         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind continue];
-+         _4 = const 4_usize;
-+         _5 = const true;
-+         assert(const true, "index out of bounds: the length is {} but the index is {}", const 4_usize, const 2_usize) -> [success: bb1, unwind continue];
++         _5 = Lt(const 2_usize, _4);
++         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind continue];
       }
 
       bb1: {
--         _1 = _2[_3];
-+         _1 = const 2_u32;
+          _1 = _2[_3];
           StorageDead(_3);
           StorageDead(_2);
           _0 = const ();

tests/mir-opt/const_prop/array_index.main.ConstProp.64bit.panic-unwind.diff

@@ -42,8 +42,7 @@
       }
 
       bb1: {
--         _5 = (*_1)[_6];
-+         _5 = (*_1)[3 of 4];
+          _5 = (*_1)[_6];
           StorageDead(_6);
           _0 = const ();
           StorageDead(_5);

tests/mir-opt/const_prop/bad_op_unsafe_oob_for_slices.main.ConstProp.32bit.panic-abort.diff

@@ -42,8 +42,7 @@
       }
 
       bb1: {
--         _5 = (*_1)[_6];
-+         _5 = (*_1)[3 of 4];
+          _5 = (*_1)[_6];
           StorageDead(_6);
           _0 = const ();
           StorageDead(_5);

tests/mir-opt/const_prop/bad_op_unsafe_oob_for_slices.main.ConstProp.32bit.panic-unwind.diff

@@ -42,8 +42,7 @@
       }
 
       bb1: {
--         _5 = (*_1)[_6];
-+         _5 = (*_1)[3 of 4];
+          _5 = (*_1)[_6];
           StorageDead(_6);
           _0 = const ();
           StorageDead(_5);