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Change the return type of can_simplify to Option<()>
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@DianQK
DianQK committed Apr 8, 2024
1 parent 032bb74 commit f440737
Showing 1 changed file with 26 additions and 28 deletions.
54 changes: 26 additions & 28 deletions compiler/rustc_mir_transform/src/match_branches.rs
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Expand Up @@ -37,11 +37,11 @@ impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
_ => continue,
};

if SimplifyToIf.simplify(tcx, body, bb_idx, param_env) {
if SimplifyToIf.simplify(tcx, body, bb_idx, param_env).is_some() {
should_cleanup = true;
continue;
}
if SimplifyToExp::default().simplify(tcx, body, bb_idx, param_env) {
if SimplifyToExp::default().simplify(tcx, body, bb_idx, param_env).is_some() {
should_cleanup = true;
continue;
}
Expand All @@ -62,17 +62,15 @@ trait SimplifyMatch<'tcx> {
body: &mut Body<'tcx>,
switch_bb_idx: BasicBlock,
param_env: ParamEnv<'tcx>,
) -> bool {
) -> Option<()> {
let bbs = &body.basic_blocks;
let (discr, targets) = match bbs[switch_bb_idx].terminator().kind {
TerminatorKind::SwitchInt { ref discr, ref targets, .. } => (discr, targets),
_ => unreachable!(),
};

let discr_ty = discr.ty(body.local_decls(), tcx);
if !self.can_simplify(tcx, targets, param_env, bbs, discr_ty) {
return false;
}
self.can_simplify(tcx, targets, param_env, bbs, discr_ty)?;

let mut patch = MirPatch::new(body);

Expand All @@ -92,7 +90,7 @@ trait SimplifyMatch<'tcx> {
patch.add_statement(parent_end, StatementKind::StorageDead(discr_local));
patch.patch_terminator(switch_bb_idx, bbs[first].terminator().kind.clone());
patch.apply(body);
true
Some(())
}

/// Check that the BBs to be simplified satisfies all distinct and
Expand All @@ -105,7 +103,7 @@ trait SimplifyMatch<'tcx> {
param_env: ParamEnv<'tcx>,
bbs: &IndexSlice<BasicBlock, BasicBlockData<'tcx>>,
discr_ty: Ty<'tcx>,
) -> bool;
) -> Option<()>;

fn new_stmts(
&self,
Expand Down Expand Up @@ -161,27 +159,27 @@ impl<'tcx> SimplifyMatch<'tcx> for SimplifyToIf {
param_env: ParamEnv<'tcx>,
bbs: &IndexSlice<BasicBlock, BasicBlockData<'tcx>>,
_discr_ty: Ty<'tcx>,
) -> bool {
) -> Option<()> {
if targets.iter().len() != 1 {
return false;
return None;
}
// We require that the possible target blocks all be distinct.
let (_, first) = targets.iter().next().unwrap();
let second = targets.otherwise();
if first == second {
return false;
return None;
}
// Check that destinations are identical, and if not, then don't optimize this block
if bbs[first].terminator().kind != bbs[second].terminator().kind {
return false;
return None;
}

// Check that blocks are assignments of consts to the same place or same statement,
// and match up 1-1, if not don't optimize this block.
let first_stmts = &bbs[first].statements;
let second_stmts = &bbs[second].statements;
if first_stmts.len() != second_stmts.len() {
return false;
return None;
}
for (f, s) in iter::zip(first_stmts, second_stmts) {
match (&f.kind, &s.kind) {
Expand All @@ -199,10 +197,10 @@ impl<'tcx> SimplifyMatch<'tcx> for SimplifyToIf {
&& s_c.const_.try_eval_bool(tcx, param_env).is_some() => {}

// Otherwise we cannot optimize. Try another block.
_ => return false,
_ => return None,
}
}
true
Some(())
}

fn new_stmts(
Expand Down Expand Up @@ -340,16 +338,16 @@ impl<'tcx> SimplifyMatch<'tcx> for SimplifyToExp {
param_env: ParamEnv<'tcx>,
bbs: &IndexSlice<BasicBlock, BasicBlockData<'tcx>>,
discr_ty: Ty<'tcx>,
) -> bool {
) -> Option<()> {
if targets.iter().len() < 2 || targets.iter().len() > 64 {
return false;
return None;
}
// We require that the possible target blocks all be distinct.
if !targets.is_distinct() {
return false;
return None;
}
if !bbs[targets.otherwise()].is_empty_unreachable() {
return false;
return None;
}
let mut target_iter = targets.iter();
let (first_val, first_target) = target_iter.next().unwrap();
Expand All @@ -359,15 +357,15 @@ impl<'tcx> SimplifyMatch<'tcx> for SimplifyToExp {
.iter()
.all(|(_, other_target)| first_terminator_kind == &bbs[other_target].terminator().kind)
{
return false;
return None;
}

let discr_size = tcx.layout_of(param_env.and(discr_ty)).unwrap().size;
let first_stmts = &bbs[first_target].statements;
let (second_val, second_target) = target_iter.next().unwrap();
let second_stmts = &bbs[second_target].statements;
if first_stmts.len() != second_stmts.len() {
return false;
return None;
}

fn int_equal(l: ScalarInt, r: impl Into<u128>, size: Size) -> bool {
Expand Down Expand Up @@ -412,13 +410,13 @@ impl<'tcx> SimplifyMatch<'tcx> for SimplifyToExp {
}
}
_ => {
return false;
return None;
}
}
}

// Otherwise we cannot optimize. Try another block.
_ => return false,
_ => return None,
};
compare_types.push(compare_type);
}
Expand All @@ -427,7 +425,7 @@ impl<'tcx> SimplifyMatch<'tcx> for SimplifyToExp {
for (other_val, other_target) in target_iter {
let other_stmts = &bbs[other_target].statements;
if compare_types.len() != other_stmts.len() {
return false;
return None;
}
for (f, s) in iter::zip(&compare_types, other_stmts) {
match (*f, &s.kind) {
Expand All @@ -443,7 +441,7 @@ impl<'tcx> SimplifyMatch<'tcx> for SimplifyToExp {
StatementKind::Assign(box (lhs_s, Rvalue::Use(Operand::Constant(s_c)))),
) if lhs_f == lhs_s && s_c.const_.ty() == f_ty => {
let Some(f) = s_c.const_.try_eval_scalar_int(tcx, param_env) else {
return false;
return None;
};
if is_signed
&& s_c.const_.ty().is_signed()
Expand All @@ -454,14 +452,14 @@ impl<'tcx> SimplifyMatch<'tcx> for SimplifyToExp {
if Some(f) == ScalarInt::try_from_uint(other_val, f.size()) {
continue;
}
return false;
return None;
}
_ => return false,
_ => return None,
}
}
}
self.transfrom_types = compare_types.into_iter().map(|c| c.into()).collect();
true
Some(())
}

fn new_stmts(
Expand Down

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