Skip to content

Commit

Permalink
Auto merge of #71911 - wesleywiser:const_prop_small_cleanups, r=oli-obk
Browse files Browse the repository at this point in the history 
[mir-opt] Small ConstProp cleanup
  • Loading branch information
@bors
bors committed Jun 21, 2020
2 parents 228a0ed + 2f49d55 commit 38bd83d
Show file tree
Hide file tree
Showing 8 changed files with 88 additions and 45 deletions.
47 changes: 21 additions & 26 deletions src/librustc_mir/transform/const_prop.rs
View file
Expand Up @@ -716,8 +716,6 @@ enum ConstPropMode {
OnlyInsideOwnBlock,
/// The `Local` can be propagated into but reads cannot be propagated.
OnlyPropagateInto,
/// No propagation is allowed at all.
NoPropagation,
}

struct CanConstProp {
Expand Down Expand Up @@ -788,7 +786,7 @@ impl<'tcx> Visitor<'tcx> for CanConstProp {
"local {:?} can't be propagated because of multiple assignments",
local,
);
*other = ConstPropMode::NoPropagation;
*other = ConstPropMode::OnlyPropagateInto;
}
}
}
Expand All @@ -815,7 +813,7 @@ impl<'tcx> Visitor<'tcx> for CanConstProp {
| MutatingUse(MutatingUseContext::Borrow)
| MutatingUse(MutatingUseContext::AddressOf) => {
trace!("local {:?} can't be propagaged because it's used: {:?}", local, context);
self.can_const_prop[local] = ConstPropMode::NoPropagation;
self.can_const_prop[local] = ConstPropMode::OnlyPropagateInto;
}
}
}
Expand Down Expand Up @@ -847,31 +845,28 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
if let Ok(place_layout) = self.tcx.layout_of(self.param_env.and(place_ty)) {
let can_const_prop = self.can_const_prop[place.local];
if let Some(()) = self.const_prop(rval, place_layout, source_info, place) {
if can_const_prop != ConstPropMode::NoPropagation {
// This will return None for variables that are from other blocks,
// so it should be okay to propagate from here on down.
if let Some(value) = self.get_const(place) {
if self.should_const_prop(value) {
trace!("replacing {:?} with {:?}", rval, value);
self.replace_with_const(rval, value, source_info);
if can_const_prop == ConstPropMode::FullConstProp
|| can_const_prop == ConstPropMode::OnlyInsideOwnBlock
{
trace!("propagated into {:?}", place);
}
}
if can_const_prop == ConstPropMode::OnlyInsideOwnBlock {
trace!(
"found local restricted to its block. Will remove it from const-prop after block is finished. Local: {:?}",
place.local
);
self.locals_of_current_block.insert(place.local);
// This will return None for variables that are from other blocks,
// so it should be okay to propagate from here on down.
if let Some(value) = self.get_const(place) {
if self.should_const_prop(value) {
trace!("replacing {:?} with {:?}", rval, value);
self.replace_with_const(rval, value, source_info);
if can_const_prop == ConstPropMode::FullConstProp
|| can_const_prop == ConstPropMode::OnlyInsideOwnBlock
{
trace!("propagated into {:?}", place);
}
}
}
if can_const_prop == ConstPropMode::OnlyPropagateInto
|| can_const_prop == ConstPropMode::NoPropagation
{
if can_const_prop == ConstPropMode::OnlyInsideOwnBlock {
trace!(
"found local restricted to its block. Will remove it from const-prop after block is finished. Local: {:?}",
place.local
);
self.locals_of_current_block.insert(place.local);
}

if can_const_prop == ConstPropMode::OnlyPropagateInto {
trace!("can't propagate into {:?}", place);
if place.local != RETURN_PLACE {
Self::remove_const(&mut self.ecx, place.local);
Expand Down
6 changes: 4 additions & 2 deletions src/test/mir-opt/const_prop/mutable_variable_aggregate_mut_ref/rustc.main.ConstProp.diff
View file
Expand Up @@ -23,13 +23,15 @@
// + ty: i32
// + val: Value(Scalar(0x0000002a))
// mir::Constant
// + span: $DIR/mutable_variable_aggregate_mut_ref.rs:5:18: 5:20
- // + span: $DIR/mutable_variable_aggregate_mut_ref.rs:5:18: 5:20
+ // + span: $DIR/mutable_variable_aggregate_mut_ref.rs:5:17: 5:25
// + literal: Const { ty: i32, val: Value(Scalar(0x0000002a)) }
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x0000002b))
// mir::Constant
// + span: $DIR/mutable_variable_aggregate_mut_ref.rs:5:22: 5:24
- // + span: $DIR/mutable_variable_aggregate_mut_ref.rs:5:22: 5:24
+ // + span: $DIR/mutable_variable_aggregate_mut_ref.rs:5:17: 5:25
// + literal: Const { ty: i32, val: Value(Scalar(0x0000002b)) }
StorageLive(_2); // scope 1 at $DIR/mutable_variable_aggregate_mut_ref.rs:6:9: 6:10
_2 = &mut _1; // scope 1 at $DIR/mutable_variable_aggregate_mut_ref.rs:6:13: 6:19
Expand Down
9 changes: 4 additions & 5 deletions src/test/mir-opt/simplify-arm-identity/32bit/rustc.main.SimplifyArmIdentity.diff
View file
Expand Up @@ -39,14 +39,13 @@
}

bb1: {
((_2 as Foo).0: u8) = const 0u8; // scope 1 at $DIR/simplify-arm-identity.rs:21:21: 21:32
_2 = const Dst::Foo(0u8); // scope 1 at $DIR/simplify-arm-identity.rs:21:21: 21:32
// ty::Const
// + ty: u8
// + ty: Dst
// + val: Value(Scalar(0x00))
// mir::Constant
// + span: $DIR/simplify-arm-identity.rs:21:30: 21:31
// + literal: Const { ty: u8, val: Value(Scalar(0x00)) }
discriminant(_2) = 0; // scope 1 at $DIR/simplify-arm-identity.rs:21:21: 21:32
// + span: $DIR/simplify-arm-identity.rs:21:21: 21:32
// + literal: Const { ty: Dst, val: Value(Scalar(0x00)) }
goto -> bb4; // scope 1 at $DIR/simplify-arm-identity.rs:19:18: 22:6
}

Expand Down
9 changes: 4 additions & 5 deletions src/test/mir-opt/simplify-arm-identity/64bit/rustc.main.SimplifyArmIdentity.diff
View file
Expand Up @@ -39,14 +39,13 @@
}

bb1: {
((_2 as Foo).0: u8) = const 0u8; // scope 1 at $DIR/simplify-arm-identity.rs:21:21: 21:32
_2 = const Dst::Foo(0u8); // scope 1 at $DIR/simplify-arm-identity.rs:21:21: 21:32
// ty::Const
// + ty: u8
// + ty: Dst
// + val: Value(Scalar(0x00))
// mir::Constant
// + span: $DIR/simplify-arm-identity.rs:21:30: 21:31
// + literal: Const { ty: u8, val: Value(Scalar(0x00)) }
discriminant(_2) = 0; // scope 1 at $DIR/simplify-arm-identity.rs:21:21: 21:32
// + span: $DIR/simplify-arm-identity.rs:21:21: 21:32
// + literal: Const { ty: Dst, val: Value(Scalar(0x00)) }
goto -> bb4; // scope 1 at $DIR/simplify-arm-identity.rs:19:18: 22:6
}

Expand Down
11 changes: 5 additions & 6 deletions src/test/mir-opt/simplify-arm-identity/rustc.main.SimplifyArmIdentity.diff
View file
Expand Up @@ -33,15 +33,14 @@
}

bb1: {
((_2 as Foo).0: u8) = const 0u8; // scope 1 at $DIR/simplify-arm-identity.rs:20:21: 20:32
_2 = const Dst::Foo(0u8); // bb1[0]: scope 1 at $DIR/simplify-arm-identity.rs:20:21: 20:32
// ty::Const
// + ty: u8
// + ty: Dst
// + val: Value(Scalar(0x00))
// mir::Constant
// + span: $DIR/simplify-arm-identity.rs:20:30: 20:31
// + literal: Const { ty: u8, val: Value(Scalar(0x00)) }
discriminant(_2) = 0; // scope 1 at $DIR/simplify-arm-identity.rs:20:21: 20:32
goto -> bb4; // scope 1 at $DIR/simplify-arm-identity.rs:18:18: 21:6
// + span: $DIR/simplify-arm-identity.rs:20:21: 20:32
// + literal: Const { ty: Dst, val: Value(Scalar(0x00)) }
goto -> bb4; // bb1[1]: scope 1 at $DIR/simplify-arm-identity.rs:18:18: 21:6
}

bb2: {
Expand Down
1 change: 1 addition & 0 deletions src/test/mir-opt/simplify-locals-removes-unused-discriminant-reads.rs
View file
Expand Up @@ -9,4 +9,5 @@ fn main() {
map(None);
}

// EMIT_MIR_FOR_EACH_BIT_WIDTH
// EMIT_MIR rustc.map.SimplifyLocals.diff
8 changes: 7 additions & 1 deletion ...inant-reads/rustc.map.SimplifyLocals.diff → ...reads/32bit/rustc.map.SimplifyLocals.diff
View file
Expand Up @@ -24,7 +24,13 @@
}

bb2: {
discriminant(_0) = 0; // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:17: 3:21
_0 = const std::option::Option::<std::boxed::Box<()>>::None; // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:17: 3:21
// ty::Const
// + ty: std::option::Option<std::boxed::Box<()>>
// + val: Value(Scalar(0x00000000))
// mir::Constant
// + span: $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:17: 3:21
// + literal: Const { ty: std::option::Option<std::boxed::Box<()>>, val: Value(Scalar(0x00000000)) }
goto -> bb3; // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:2:5: 5:6
}

Expand Down
42 changes: 42 additions & 0 deletions ...opt/simplify-locals-removes-unused-discriminant-reads/64bit/rustc.map.SimplifyLocals.diff
View file
@@ -0,0 +1,42 @@
- // MIR for `map` before SimplifyLocals
+ // MIR for `map` after SimplifyLocals

fn map(_1: std::option::Option<std::boxed::Box<()>>) -> std::option::Option<std::boxed::Box<()>> {
debug x => _1; // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:1:8: 1:9
let mut _0: std::option::Option<std::boxed::Box<()>>; // return place in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:1:31: 1:46
let mut _2: isize; // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:9: 3:13
let _3: std::boxed::Box<()>; // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
- let mut _4: std::boxed::Box<()>; // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:25: 4:26
- let mut _5: isize; // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:1: 6:2
- let mut _6: isize; // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:1: 6:2
scope 1 {
debug x => _3; // in scope 1 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
}

bb0: {
_2 = discriminant(_1); // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:9: 3:13
switchInt(move _2) -> [0isize: bb2, otherwise: bb1]; // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:9: 3:13
}

bb1: {
_0 = move _1; // scope 1 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:20: 4:27
goto -> bb3; // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:2:5: 5:6
}

bb2: {
_0 = const std::option::Option::<std::boxed::Box<()>>::None; // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:17: 3:21
// ty::Const
// + ty: std::option::Option<std::boxed::Box<()>>
// + val: Value(Scalar(0x0000000000000000))
// mir::Constant
// + span: $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:17: 3:21
// + literal: Const { ty: std::option::Option<std::boxed::Box<()>>, val: Value(Scalar(0x0000000000000000)) }
goto -> bb3; // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:2:5: 5:6
}

bb3: {
- _5 = discriminant(_1); // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:1: 6:2
return; // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:2: 6:2
}
}

0 comments on commit 38bd83d

Please sign in to comment.