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Simplify assignments.

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This commit is contained in:
Camille GILLOT 2025-06-23 16:08:01 +00:00
parent 706f244db5
commit fba4177d0f
1 changed files with 32 additions and 27 deletions
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59
compiler/rustc_mir_transform/src/gvn.rs
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@ -1755,7 +1755,7 @@ impl<'tcx> MutVisitor<'tcx> for VnState<'_, 'tcx> {
fn visit_place(&mut self, place: &mut Place<'tcx>, context: PlaceContext, location: Location) {
self.simplify_place_projection(place, location);
if context.is_mutating_use() && !place.projection.is_empty() {
if context.is_mutating_use() && place.is_indirect() {
// Non-local mutation maybe invalidate deref.
self.invalidate_derefs();
}
@ -1767,36 +1767,41 @@ impl<'tcx> MutVisitor<'tcx> for VnState<'_, 'tcx> {
self.super_operand(operand, location);
}
fn visit_statement(&mut self, stmt: &mut Statement<'tcx>, location: Location) {
if let StatementKind::Assign(box (ref mut lhs, ref mut rvalue)) = stmt.kind {
self.simplify_place_projection(lhs, location);
fn visit_assign(
&mut self,
lhs: &mut Place<'tcx>,
rvalue: &mut Rvalue<'tcx>,
location: Location,
) {
self.simplify_place_projection(lhs, location);
let value = self.simplify_rvalue(lhs, rvalue, location);
let value = if let Some(local) = lhs.as_local()
&& self.ssa.is_ssa(local)
// FIXME(#112651) `rvalue` may have a subtype to `local`. We can only mark
// `local` as reusable if we have an exact type match.
&& self.local_decls[local].ty == rvalue.ty(self.local_decls, self.tcx)
let value = self.simplify_rvalue(lhs, rvalue, location);
if let Some(value) = value {
if let Some(const_) = self.try_as_constant(value) {
*rvalue = Rvalue::Use(Operand::Constant(Box::new(const_)));
} else if let Some(place) = self.try_as_place(value, location, false)
&& *rvalue != Rvalue::Use(Operand::Move(place))
&& *rvalue != Rvalue::Use(Operand::Copy(place))
{
let value = value.unwrap_or_else(|| self.new_opaque());
self.assign(local, value);
Some(value)
} else {
value
};
if let Some(value) = value {
if let Some(const_) = self.try_as_constant(value) {
*rvalue = Rvalue::Use(Operand::Constant(Box::new(const_)));
} else if let Some(place) = self.try_as_place(value, location, false)
&& *rvalue != Rvalue::Use(Operand::Move(place))
&& *rvalue != Rvalue::Use(Operand::Copy(place))
{
*rvalue = Rvalue::Use(Operand::Copy(place));
self.reused_locals.insert(place.local);
}
*rvalue = Rvalue::Use(Operand::Copy(place));
self.reused_locals.insert(place.local);
}
}
self.super_statement(stmt, location);
if lhs.is_indirect() {
// Non-local mutation maybe invalidate deref.
self.invalidate_derefs();
}
if let Some(local) = lhs.as_local()
&& self.ssa.is_ssa(local)
// FIXME(#112651) `rvalue` may have a subtype to `local`. We can only mark
// `local` as reusable if we have an exact type match.
&& self.local_decls[local].ty == rvalue.ty(self.local_decls, self.tcx)
{
let value = value.unwrap_or_else(|| self.new_opaque());
self.assign(local, value);
}
}
fn visit_terminator(&mut self, terminator: &mut Terminator<'tcx>, location: Location) {