diff options
| -rw-r--r-- | compiler/rustc_mir_transform/src/ssa.rs | 49 | ||||
| -rw-r--r-- | tests/mir-opt/copy-prop/reborrow.demiraw.CopyProp.diff | 41 | ||||
| -rw-r--r-- | tests/mir-opt/copy-prop/reborrow.miraw.CopyProp.diff | 37 | ||||
| -rw-r--r-- | tests/mir-opt/copy-prop/reborrow.remut.CopyProp.diff | 35 | ||||
| -rw-r--r-- | tests/mir-opt/copy-prop/reborrow.reraw.CopyProp.diff | 35 | ||||
| -rw-r--r-- | tests/mir-opt/copy-prop/reborrow.rs | 39 |
6 files changed, 222 insertions, 14 deletions
diff --git a/compiler/rustc_mir_transform/src/ssa.rs b/compiler/rustc_mir_transform/src/ssa.rs index c1e7f62dea5..0bb97c4fc09 100644 --- a/compiler/rustc_mir_transform/src/ssa.rs +++ b/compiler/rustc_mir_transform/src/ssa.rs @@ -179,6 +179,25 @@ struct SsaVisitor { assignment_order: Vec<Local>, } +impl SsaVisitor { + fn check_assignment_dominates(&mut self, local: Local, loc: Location) { + let set = &mut self.assignments[local]; + let assign_dominates = match *set { + Set1::Empty | Set1::Many => false, + Set1::One(LocationExtended::Arg) => true, + Set1::One(LocationExtended::Plain(assign)) => { + assign.successor_within_block().dominates(loc, &self.dominators) + } + }; + // We are visiting a use that is not dominated by an assignment. + // Either there is a cycle involved, or we are reading for uninitialized local. + // Bail out. + if !assign_dominates { + *set = Set1::Many; + } + } +} + impl<'tcx> Visitor<'tcx> for SsaVisitor { fn visit_local(&mut self, local: Local, ctxt: PlaceContext, loc: Location) { match ctxt { @@ -192,24 +211,26 @@ impl<'tcx> Visitor<'tcx> for SsaVisitor { // Immutable borrows are taken into account in `SsaLocals::new` by // removing non-freeze locals. PlaceContext::NonMutatingUse(_) => { - let set = &mut self.assignments[local]; - let assign_dominates = match *set { - Set1::Empty | Set1::Many => false, - Set1::One(LocationExtended::Arg) => true, - Set1::One(LocationExtended::Plain(assign)) => { - assign.successor_within_block().dominates(loc, &self.dominators) - } - }; - // We are visiting a use that is not dominated by an assignment. - // Either there is a cycle involved, or we are reading for uninitialized local. - // Bail out. - if !assign_dominates { - *set = Set1::Many; - } + self.check_assignment_dominates(local, loc); } PlaceContext::NonUse(_) => {} } } + + fn visit_place(&mut self, place: &Place<'tcx>, ctxt: PlaceContext, loc: Location) { + if place.projection.first() == Some(&PlaceElem::Deref) { + // Do not do anything for storage statements and debuginfo. + if ctxt.is_use() { + // A use through a `deref` only reads from the local, and cannot write to it. + let new_ctxt = PlaceContext::NonMutatingUse(NonMutatingUseContext::Projection); + + self.visit_projection(place.as_ref(), new_ctxt, loc); + self.check_assignment_dominates(place.local, loc); + } + return; + } + self.super_place(place, ctxt, loc); + } } #[instrument(level = "trace", skip(ssa, body))] diff --git a/tests/mir-opt/copy-prop/reborrow.demiraw.CopyProp.diff b/tests/mir-opt/copy-prop/reborrow.demiraw.CopyProp.diff new file mode 100644 index 00000000000..62ef6ca86c6 --- /dev/null +++ b/tests/mir-opt/copy-prop/reborrow.demiraw.CopyProp.diff @@ -0,0 +1,41 @@ +- // MIR for `demiraw` before CopyProp ++ // MIR for `demiraw` after CopyProp + + fn demiraw(_1: u8) -> () { + debug x => _1; // in scope 0 at $DIR/reborrow.rs:+0:12: +0:17 + let mut _0: (); // return place in scope 0 at $DIR/reborrow.rs:+0:23: +0:23 + let _2: *mut u8; // in scope 0 at $DIR/reborrow.rs:+1:9: +1:10 + let mut _4: &mut u8; // in scope 0 at $DIR/reborrow.rs:+2:22: +2:29 + scope 1 { + debug a => _2; // in scope 1 at $DIR/reborrow.rs:+1:9: +1:10 + let _3: &mut u8; // in scope 1 at $DIR/reborrow.rs:+2:9: +2:10 + scope 2 { + debug b => _3; // in scope 2 at $DIR/reborrow.rs:+2:9: +2:10 + let _5: *mut u8; // in scope 2 at $DIR/reborrow.rs:+3:9: +3:10 + scope 4 { +- debug c => _5; // in scope 4 at $DIR/reborrow.rs:+3:9: +3:10 ++ debug c => _2; // in scope 4 at $DIR/reborrow.rs:+3:9: +3:10 + } + } + scope 3 { + } + } + + bb0: { +- StorageLive(_2); // scope 0 at $DIR/reborrow.rs:+1:9: +1:10 + _2 = &raw mut _1; // scope 0 at $DIR/reborrow.rs:+1:13: +1:23 + StorageLive(_3); // scope 1 at $DIR/reborrow.rs:+2:9: +2:10 + StorageLive(_4); // scope 1 at $DIR/reborrow.rs:+2:22: +2:29 + _4 = &mut (*_2); // scope 3 at $DIR/reborrow.rs:+2:22: +2:29 + _3 = &mut (*_4); // scope 1 at $DIR/reborrow.rs:+2:22: +2:29 + StorageDead(_4); // scope 1 at $DIR/reborrow.rs:+2:31: +2:32 +- StorageLive(_5); // scope 2 at $DIR/reborrow.rs:+3:9: +3:10 +- _5 = _2; // scope 2 at $DIR/reborrow.rs:+3:13: +3:14 + _0 = const (); // scope 0 at $DIR/reborrow.rs:+0:23: +4:2 +- StorageDead(_5); // scope 2 at $DIR/reborrow.rs:+4:1: +4:2 + StorageDead(_3); // scope 1 at $DIR/reborrow.rs:+4:1: +4:2 +- StorageDead(_2); // scope 0 at $DIR/reborrow.rs:+4:1: +4:2 + return; // scope 0 at $DIR/reborrow.rs:+4:2: +4:2 + } + } + diff --git a/tests/mir-opt/copy-prop/reborrow.miraw.CopyProp.diff b/tests/mir-opt/copy-prop/reborrow.miraw.CopyProp.diff new file mode 100644 index 00000000000..5d620402eaa --- /dev/null +++ b/tests/mir-opt/copy-prop/reborrow.miraw.CopyProp.diff @@ -0,0 +1,37 @@ +- // MIR for `miraw` before CopyProp ++ // MIR for `miraw` after CopyProp + + fn miraw(_1: u8) -> () { + debug x => _1; // in scope 0 at $DIR/reborrow.rs:+0:10: +0:15 + let mut _0: (); // return place in scope 0 at $DIR/reborrow.rs:+0:21: +0:21 + let _2: *mut u8; // in scope 0 at $DIR/reborrow.rs:+1:9: +1:10 + scope 1 { + debug a => _2; // in scope 1 at $DIR/reborrow.rs:+1:9: +1:10 + let _3: *mut u8; // in scope 1 at $DIR/reborrow.rs:+2:9: +2:10 + scope 2 { + debug b => _3; // in scope 2 at $DIR/reborrow.rs:+2:9: +2:10 + let _4: *mut u8; // in scope 2 at $DIR/reborrow.rs:+3:9: +3:10 + scope 4 { +- debug c => _4; // in scope 4 at $DIR/reborrow.rs:+3:9: +3:10 ++ debug c => _2; // in scope 4 at $DIR/reborrow.rs:+3:9: +3:10 + } + } + scope 3 { + } + } + + bb0: { +- StorageLive(_2); // scope 0 at $DIR/reborrow.rs:+1:9: +1:10 + _2 = &raw mut _1; // scope 0 at $DIR/reborrow.rs:+1:13: +1:23 + StorageLive(_3); // scope 1 at $DIR/reborrow.rs:+2:9: +2:10 + _3 = &raw mut (*_2); // scope 3 at $DIR/reborrow.rs:+2:22: +2:33 +- StorageLive(_4); // scope 2 at $DIR/reborrow.rs:+3:9: +3:10 +- _4 = _2; // scope 2 at $DIR/reborrow.rs:+3:13: +3:14 + _0 = const (); // scope 0 at $DIR/reborrow.rs:+0:21: +4:2 +- StorageDead(_4); // scope 2 at $DIR/reborrow.rs:+4:1: +4:2 + StorageDead(_3); // scope 1 at $DIR/reborrow.rs:+4:1: +4:2 +- StorageDead(_2); // scope 0 at $DIR/reborrow.rs:+4:1: +4:2 + return; // scope 0 at $DIR/reborrow.rs:+4:2: +4:2 + } + } + diff --git a/tests/mir-opt/copy-prop/reborrow.remut.CopyProp.diff b/tests/mir-opt/copy-prop/reborrow.remut.CopyProp.diff new file mode 100644 index 00000000000..2c00c06ffea --- /dev/null +++ b/tests/mir-opt/copy-prop/reborrow.remut.CopyProp.diff @@ -0,0 +1,35 @@ +- // MIR for `remut` before CopyProp ++ // MIR for `remut` after CopyProp + + fn remut(_1: u8) -> () { + debug x => _1; // in scope 0 at $DIR/reborrow.rs:+0:10: +0:15 + let mut _0: (); // return place in scope 0 at $DIR/reborrow.rs:+0:21: +0:21 + let _2: &mut u8; // in scope 0 at $DIR/reborrow.rs:+1:9: +1:10 + scope 1 { + debug a => _2; // in scope 1 at $DIR/reborrow.rs:+1:9: +1:10 + let _3: &mut u8; // in scope 1 at $DIR/reborrow.rs:+2:9: +2:10 + scope 2 { + debug b => _3; // in scope 2 at $DIR/reborrow.rs:+2:9: +2:10 + let _4: &mut u8; // in scope 2 at $DIR/reborrow.rs:+3:9: +3:10 + scope 3 { +- debug c => _4; // in scope 3 at $DIR/reborrow.rs:+3:9: +3:10 ++ debug c => _2; // in scope 3 at $DIR/reborrow.rs:+3:9: +3:10 + } + } + } + + bb0: { +- StorageLive(_2); // scope 0 at $DIR/reborrow.rs:+1:9: +1:10 + _2 = &mut _1; // scope 0 at $DIR/reborrow.rs:+1:13: +1:19 + StorageLive(_3); // scope 1 at $DIR/reborrow.rs:+2:9: +2:10 + _3 = &mut (*_2); // scope 1 at $DIR/reborrow.rs:+2:13: +2:20 +- StorageLive(_4); // scope 2 at $DIR/reborrow.rs:+3:9: +3:10 +- _4 = move _2; // scope 2 at $DIR/reborrow.rs:+3:13: +3:14 + _0 = const (); // scope 0 at $DIR/reborrow.rs:+0:21: +4:2 +- StorageDead(_4); // scope 2 at $DIR/reborrow.rs:+4:1: +4:2 + StorageDead(_3); // scope 1 at $DIR/reborrow.rs:+4:1: +4:2 +- StorageDead(_2); // scope 0 at $DIR/reborrow.rs:+4:1: +4:2 + return; // scope 0 at $DIR/reborrow.rs:+4:2: +4:2 + } + } + diff --git a/tests/mir-opt/copy-prop/reborrow.reraw.CopyProp.diff b/tests/mir-opt/copy-prop/reborrow.reraw.CopyProp.diff new file mode 100644 index 00000000000..bc74ae05ce2 --- /dev/null +++ b/tests/mir-opt/copy-prop/reborrow.reraw.CopyProp.diff @@ -0,0 +1,35 @@ +- // MIR for `reraw` before CopyProp ++ // MIR for `reraw` after CopyProp + + fn reraw(_1: u8) -> () { + debug x => _1; // in scope 0 at $DIR/reborrow.rs:+0:10: +0:15 + let mut _0: (); // return place in scope 0 at $DIR/reborrow.rs:+0:21: +0:21 + let _2: &mut u8; // in scope 0 at $DIR/reborrow.rs:+1:9: +1:10 + scope 1 { + debug a => _2; // in scope 1 at $DIR/reborrow.rs:+1:9: +1:10 + let _3: *mut u8; // in scope 1 at $DIR/reborrow.rs:+2:9: +2:10 + scope 2 { + debug b => _3; // in scope 2 at $DIR/reborrow.rs:+2:9: +2:10 + let _4: &mut u8; // in scope 2 at $DIR/reborrow.rs:+3:9: +3:10 + scope 3 { +- debug c => _4; // in scope 3 at $DIR/reborrow.rs:+3:9: +3:10 ++ debug c => _2; // in scope 3 at $DIR/reborrow.rs:+3:9: +3:10 + } + } + } + + bb0: { +- StorageLive(_2); // scope 0 at $DIR/reborrow.rs:+1:9: +1:10 + _2 = &mut _1; // scope 0 at $DIR/reborrow.rs:+1:13: +1:19 + StorageLive(_3); // scope 1 at $DIR/reborrow.rs:+2:9: +2:10 + _3 = &raw mut (*_2); // scope 1 at $DIR/reborrow.rs:+2:13: +2:24 +- StorageLive(_4); // scope 2 at $DIR/reborrow.rs:+3:9: +3:10 +- _4 = move _2; // scope 2 at $DIR/reborrow.rs:+3:13: +3:14 + _0 = const (); // scope 0 at $DIR/reborrow.rs:+0:21: +4:2 +- StorageDead(_4); // scope 2 at $DIR/reborrow.rs:+4:1: +4:2 + StorageDead(_3); // scope 1 at $DIR/reborrow.rs:+4:1: +4:2 +- StorageDead(_2); // scope 0 at $DIR/reborrow.rs:+4:1: +4:2 + return; // scope 0 at $DIR/reborrow.rs:+4:2: +4:2 + } + } + diff --git a/tests/mir-opt/copy-prop/reborrow.rs b/tests/mir-opt/copy-prop/reborrow.rs new file mode 100644 index 00000000000..a1624215feb --- /dev/null +++ b/tests/mir-opt/copy-prop/reborrow.rs @@ -0,0 +1,39 @@ +// Check that CopyProp considers reborrows as not mutating the pointer. +// unit-test: CopyProp + +#![feature(raw_ref_op)] + +// EMIT_MIR reborrow.remut.CopyProp.diff +fn remut(mut x: u8) { + let a = &mut x; + let b = &mut *a; //< this cannot mutate a. + let c = a; //< so `c` and `a` can be merged. +} + +// EMIT_MIR reborrow.reraw.CopyProp.diff +fn reraw(mut x: u8) { + let a = &mut x; + let b = &raw mut *a; //< this cannot mutate a. + let c = a; //< so `c` and `a` can be merged. +} + +// EMIT_MIR reborrow.miraw.CopyProp.diff +fn miraw(mut x: u8) { + let a = &raw mut x; + let b = unsafe { &raw mut *a }; //< this cannot mutate a. + let c = a; //< so `c` and `a` can be merged. +} + +// EMIT_MIR reborrow.demiraw.CopyProp.diff +fn demiraw(mut x: u8) { + let a = &raw mut x; + let b = unsafe { &mut *a }; //< this cannot mutate a. + let c = a; //< so `c` and `a` can be merged. +} + +fn main() { + remut(0); + reraw(0); + miraw(0); + demiraw(0); +} |