diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src/ssa.rs')
| -rw-r--r-- | compiler/rustc_mir_transform/src/ssa.rs | 77 |
1 files changed, 49 insertions, 28 deletions
diff --git a/compiler/rustc_mir_transform/src/ssa.rs b/compiler/rustc_mir_transform/src/ssa.rs index fad58930e3a..8dc7b60c4e5 100644 --- a/compiler/rustc_mir_transform/src/ssa.rs +++ b/compiler/rustc_mir_transform/src/ssa.rs @@ -5,7 +5,6 @@ //! As a consequence of rule 2, we consider that borrowed locals are not SSA, even if they are //! `Freeze`, as we do not track that the assignment dominates all uses of the borrow. -use either::Either; use rustc_data_structures::graph::dominators::Dominators; use rustc_index::bit_set::BitSet; use rustc_index::{IndexSlice, IndexVec}; @@ -27,6 +26,12 @@ pub struct SsaLocals { direct_uses: IndexVec<Local, u32>, } +pub enum AssignedValue<'a, 'tcx> { + Arg, + Rvalue(&'a mut Rvalue<'tcx>), + Terminator(&'a mut TerminatorKind<'tcx>), +} + impl SsaLocals { pub fn new<'tcx>(body: &Body<'tcx>) -> SsaLocals { let assignment_order = Vec::with_capacity(body.local_decls.len()); @@ -39,6 +44,7 @@ impl SsaLocals { for local in body.args_iter() { visitor.assignments[local] = Set1::One(DefLocation::Argument); + visitor.assignment_order.push(local); } // For SSA assignments, a RPO visit will see the assignment before it sees any use. @@ -105,8 +111,8 @@ impl SsaLocals { ) -> impl Iterator<Item = (Local, &'a Rvalue<'tcx>, Location)> + 'a { self.assignment_order.iter().filter_map(|&local| { if let Set1::One(DefLocation::Body(loc)) = self.assignments[local] { + let stmt = body.stmt_at(loc).left()?; // `loc` must point to a direct assignment to `local`. - let Either::Left(stmt) = body.stmt_at(loc) else { bug!() }; let Some((target, rvalue)) = stmt.kind.as_assign() else { bug!() }; assert_eq!(target.as_local(), Some(local)); Some((local, rvalue, loc)) @@ -118,18 +124,33 @@ impl SsaLocals { pub fn for_each_assignment_mut<'tcx>( &self, - basic_blocks: &mut BasicBlocks<'tcx>, - mut f: impl FnMut(Local, &mut Rvalue<'tcx>, Location), + basic_blocks: &mut IndexSlice<BasicBlock, BasicBlockData<'tcx>>, + mut f: impl FnMut(Local, AssignedValue<'_, 'tcx>, Location), ) { for &local in &self.assignment_order { - if let Set1::One(DefLocation::Body(loc)) = self.assignments[local] { - // `loc` must point to a direct assignment to `local`. - let bbs = basic_blocks.as_mut_preserves_cfg(); - let bb = &mut bbs[loc.block]; - let stmt = &mut bb.statements[loc.statement_index]; - let StatementKind::Assign(box (target, ref mut rvalue)) = stmt.kind else { bug!() }; - assert_eq!(target.as_local(), Some(local)); - f(local, rvalue, loc) + match self.assignments[local] { + Set1::One(DefLocation::Argument) => f( + local, + AssignedValue::Arg, + Location { block: START_BLOCK, statement_index: 0 }, + ), + Set1::One(DefLocation::Body(loc)) => { + let bb = &mut basic_blocks[loc.block]; + let value = if loc.statement_index < bb.statements.len() { + // `loc` must point to a direct assignment to `local`. + let stmt = &mut bb.statements[loc.statement_index]; + let StatementKind::Assign(box (target, ref mut rvalue)) = stmt.kind else { + bug!() + }; + assert_eq!(target.as_local(), Some(local)); + AssignedValue::Rvalue(rvalue) + } else { + let term = bb.terminator_mut(); + AssignedValue::Terminator(&mut term.kind) + }; + f(local, value, loc) + } + _ => {} } } } @@ -228,8 +249,22 @@ impl<'tcx> Visitor<'tcx> for SsaVisitor<'_> { } 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. + let location = match ctxt { + PlaceContext::MutatingUse( + MutatingUseContext::Store | MutatingUseContext::Call | MutatingUseContext::Yield, + ) => Some(DefLocation::Body(loc)), + _ => None, + }; + if let Some(location) = location + && let Some(local) = place.as_local() + { + self.assignments[local].insert(location); + if let Set1::One(_) = self.assignments[local] { + // Only record if SSA-like, to avoid growing the vector needlessly. + self.assignment_order.push(local); + } + } else if place.projection.first() == Some(&PlaceElem::Deref) { + // Do not do anything for debuginfo. if ctxt.is_use() { // Only change the context if it is a real use, not a "use" in debuginfo. let new_ctxt = PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy); @@ -237,25 +272,11 @@ impl<'tcx> Visitor<'tcx> for SsaVisitor<'_> { self.visit_projection(place.as_ref(), new_ctxt, loc); self.check_dominates(place.local, loc); } - return; } else { self.visit_projection(place.as_ref(), ctxt, loc); self.visit_local(place.local, ctxt, loc); } } - - fn visit_assign(&mut self, place: &Place<'tcx>, rvalue: &Rvalue<'tcx>, loc: Location) { - if let Some(local) = place.as_local() { - self.assignments[local].insert(DefLocation::Body(loc)); - if let Set1::One(_) = self.assignments[local] { - // Only record if SSA-like, to avoid growing the vector needlessly. - self.assignment_order.push(local); - } - } else { - self.visit_place(place, PlaceContext::MutatingUse(MutatingUseContext::Store), loc); - } - self.visit_rvalue(rvalue, loc); - } } #[instrument(level = "trace", skip(ssa, body))] |