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);

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

@@ -12,13 +12,10 @@
 
       bb0: {
           StorageLive(_3);
--         _3 = BitOr(_2, const true);
-+         _3 = const true;
+          _3 = BitOr(_2, const true);
           StorageLive(_5);
--         _5 = BitAnd(_1, const false);
--         _0 = BitAnd(move _3, move _5);
-+         _5 = const false;
-+         _0 = const false;
+          _5 = BitAnd(_1, const false);
+          _0 = BitAnd(move _3, move _5);
           StorageDead(_5);
           StorageDead(_3);
           return;

tests/mir-opt/const_prop/boolean_identities.test.ConstProp.diff

@@ -22,12 +22,9 @@
           StorageLive(_1);
           StorageLive(_2);
           StorageLive(_3);
--         _4 = SizeOf(i32);
--         _5 = AlignOf(i32);
--         _6 = alloc::alloc::exchange_malloc(move _4, move _5) -> [return: bb1, unwind unreachable];
-+         _4 = const 4_usize;
-+         _5 = const 4_usize;
-+         _6 = alloc::alloc::exchange_malloc(const 4_usize, const 4_usize) -> [return: bb1, unwind unreachable];
+          _4 = SizeOf(i32);
+          _5 = AlignOf(i32);
+          _6 = alloc::alloc::exchange_malloc(move _4, move _5) -> [return: bb1, unwind unreachable];
       }
 
       bb1: {

tests/mir-opt/const_prop/boxes.main.ConstProp.panic-abort.diff

@@ -22,12 +22,9 @@
           StorageLive(_1);
           StorageLive(_2);
           StorageLive(_3);
--         _4 = SizeOf(i32);
--         _5 = AlignOf(i32);
--         _6 = alloc::alloc::exchange_malloc(move _4, move _5) -> [return: bb1, unwind continue];
-+         _4 = const 4_usize;
-+         _5 = const 4_usize;
-+         _6 = alloc::alloc::exchange_malloc(const 4_usize, const 4_usize) -> [return: bb1, unwind continue];
+          _4 = SizeOf(i32);
+          _5 = AlignOf(i32);
+          _6 = alloc::alloc::exchange_malloc(move _4, move _5) -> [return: bb1, unwind continue];
       }
 
       bb1: {

tests/mir-opt/const_prop/boxes.main.ConstProp.panic-unwind.diff

@@ -4,11 +4,21 @@
   fn main() -> () {
       let mut _0: ();
       let _1: u32;
+      let mut _5: u8;
+      let mut _6: i32;
       scope 1 {
           debug x => _1;
           let _2: u8;
           scope 2 {
               debug y => _2;
+              let _3: i32;
+              scope 3 {
+                  debug a => _3;
+                  let _4: u8;
+                  scope 4 {
+                      debug b => _4;
+                  }
+              }
           }
       }
 
@@ -19,7 +29,22 @@
           StorageLive(_2);
 -         _2 = const 42_u32 as u8 (IntToInt);
 +         _2 = const 42_u8;
+          StorageLive(_3);
+          _3 = const 257_i32;
+          StorageLive(_4);
+          StorageLive(_5);
+          StorageLive(_6);
+-         _6 = _3;
+-         _5 = move _6 as u8 (IntToInt);
++         _6 = const 257_i32;
++         _5 = const 1_u8;
+          StorageDead(_6);
+-         _4 = Add(move _5, const 1_u8);
++         _4 = const 2_u8;
+          StorageDead(_5);
           _0 = const ();
+          StorageDead(_4);
+          StorageDead(_3);
           StorageDead(_2);
           StorageDead(_1);
           return;

tests/mir-opt/const_prop/cast.main.ConstProp.diff

@@ -3,6 +3,8 @@
 
 fn main() {
     let x = 42u8 as u32;
-
     let y = 42u32 as u8;
+
+    let a = 257;
+    let b = a as u8 + 1;
 }

tests/mir-opt/const_prop/cast.rs

@@ -1,5 +1,5 @@
-- // MIR for `main` before DataflowConstProp
-+ // MIR for `main` after DataflowConstProp
+- // MIR for `main` before ConstProp
++ // MIR for `main` after ConstProp
 
   fn main() -> () {
       let mut _0: ();

tests/mir-opt/dataflow-const-prop/checked.main.DataflowConstProp.panic-abort.diff renamed to tests/mir-opt/const_prop/checked.main.ConstProp.panic-abort.diff

@@ -1,5 +1,5 @@
-- // MIR for `main` before DataflowConstProp
-+ // MIR for `main` after DataflowConstProp
+- // MIR for `main` before ConstProp
++ // MIR for `main` after ConstProp
 
   fn main() -> () {
       let mut _0: ();

tests/mir-opt/dataflow-const-prop/checked.main.DataflowConstProp.panic-unwind.diff renamed to tests/mir-opt/const_prop/checked.main.ConstProp.panic-unwind.diff

@@ -1,8 +1,8 @@
 // EMIT_MIR_FOR_EACH_PANIC_STRATEGY
-// unit-test: DataflowConstProp
+// unit-test: ConstProp
 // compile-flags: -Coverflow-checks=on
 
-// EMIT_MIR checked.main.DataflowConstProp.diff
+// EMIT_MIR checked.main.ConstProp.diff
 #[allow(arithmetic_overflow)]
 fn main() {
     let a = 1;

tests/mir-opt/dataflow-const-prop/checked.rs renamed to tests/mir-opt/const_prop/checked.rs

@@ -11,9 +11,8 @@
 
       bb0: {
           StorageLive(_1);
--         _2 = CheckedAdd(const 1_u32, const 1_u32);
+          _2 = CheckedAdd(const 1_u32, const 1_u32);
 -         assert(!move (_2.1: bool), "attempt to compute `{} + {}`, which would overflow", const 1_u32, const 1_u32) -> [success: bb1, unwind unreachable];
-+         _2 = const (2_u32, false);
 +         assert(!const false, "attempt to compute `{} + {}`, which would overflow", const 1_u32, const 1_u32) -> [success: bb1, unwind unreachable];
       }
 

tests/mir-opt/const_prop/checked_add.main.ConstProp.panic-abort.diff

@@ -11,9 +11,8 @@
 
       bb0: {
           StorageLive(_1);
--         _2 = CheckedAdd(const 1_u32, const 1_u32);
+          _2 = CheckedAdd(const 1_u32, const 1_u32);
 -         assert(!move (_2.1: bool), "attempt to compute `{} + {}`, which would overflow", const 1_u32, const 1_u32) -> [success: bb1, unwind continue];
-+         _2 = const (2_u32, false);
 +         assert(!const false, "attempt to compute `{} + {}`, which would overflow", const 1_u32, const 1_u32) -> [success: bb1, unwind continue];
       }
 

tests/mir-opt/const_prop/checked_add.main.ConstProp.panic-unwind.diff

@@ -8,9 +8,8 @@
 
       bb0: {
           StorageLive(_1);
--         _1 = const _;
+          _1 = const _;
 -         switchInt(move _1) -> [0: bb2, otherwise: bb1];
-+         _1 = const false;
 +         switchInt(const false) -> [0: bb2, otherwise: bb1];
       }
 

tests/mir-opt/const_allocation.main.ConstProp.after.32bit.mir renamed to tests/mir-opt/const_prop/const_allocation.main.ConstProp.after.32bit.mir

@@ -8,9 +8,8 @@
 
       bb0: {
           StorageLive(_1);
--         _1 = const _;
+          _1 = const _;
 -         switchInt(move _1) -> [0: bb2, otherwise: bb1];
-+         _1 = const false;
 +         switchInt(const false) -> [0: bb2, otherwise: bb1];
       }
 

tests/mir-opt/const_allocation.main.ConstProp.after.64bit.mir renamed to tests/mir-opt/const_prop/const_allocation.main.ConstProp.after.64bit.mir

@@ -17,10 +17,9 @@
           StorageLive(_1);
           StorageLive(_2);
           StorageLive(_3);
--         _3 = Option::<bool>::Some(const true);
+          _3 = Option::<bool>::Some(const true);
 -         _4 = discriminant(_3);
 -         switchInt(move _4) -> [1: bb1, otherwise: bb3];
-+         _3 = const Option::<bool>::Some(true);
 +         _4 = const 1_isize;
 +         switchInt(const 1_isize) -> [1: bb1, otherwise: bb3];
       }
@@ -41,7 +40,8 @@
       }
 
       bb4: {
-          _1 = Add(move _2, const 0_i32);
+-         _1 = Add(move _2, const 0_i32);
++         _1 = const 42_i32;
           StorageDead(_2);
           StorageDead(_3);
           _0 = const ();

tests/mir-opt/const_allocation.rs renamed to tests/mir-opt/const_prop/const_allocation.rs

@@ -17,10 +17,9 @@
           StorageLive(_1);
           StorageLive(_2);
           StorageLive(_3);
--         _3 = Option::<bool>::Some(const true);
+          _3 = Option::<bool>::Some(const true);
 -         _4 = discriminant(_3);
 -         switchInt(move _4) -> [1: bb1, otherwise: bb3];
-+         _3 = const Option::<bool>::Some(true);
 +         _4 = const 1_isize;
 +         switchInt(const 1_isize) -> [1: bb1, otherwise: bb3];
       }
@@ -41,7 +40,8 @@
       }
 
       bb4: {
-          _1 = Add(move _2, const 0_i32);
+-         _1 = Add(move _2, const 0_i32);
++         _1 = const 42_i32;
           StorageDead(_2);
           StorageDead(_3);
           _0 = const ();

tests/mir-opt/const_allocation2.main.ConstProp.after.32bit.mir renamed to tests/mir-opt/const_prop/const_allocation2.main.ConstProp.after.32bit.mir

@@ -1,5 +1,5 @@
-- // MIR for `multiple` before DataflowConstProp
-+ // MIR for `multiple` after DataflowConstProp
+- // MIR for `multiple` before ConstProp
++ // MIR for `multiple` after ConstProp
 
   fn multiple(_1: bool, _2: u8) -> () {
       debug x => _1;

tests/mir-opt/const_allocation2.main.ConstProp.after.64bit.mir renamed to tests/mir-opt/const_prop/const_allocation2.main.ConstProp.after.64bit.mir

@@ -1,5 +1,5 @@
-- // MIR for `mutate_discriminant` before DataflowConstProp
-+ // MIR for `mutate_discriminant` after DataflowConstProp
+- // MIR for `mutate_discriminant` before ConstProp
++ // MIR for `mutate_discriminant` after ConstProp
 
   fn mutate_discriminant() -> u8 {
       let mut _0: u8;