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mir-opt: Use one MirPatch in MatchBranchSimplification #140080

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mir-opt: Use one MirPatch in MatchBranchSimplification #140080

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37 changes: 14 additions & 23 deletions compiler/rustc_mir_transform/src/match_branches.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,30 +19,32 @@ impl<'tcx> crate::MirPass<'tcx> for MatchBranchSimplification {

fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let typing_env = body.typing_env(tcx);
let mut should_cleanup = false;
for bb_idx in body.basic_blocks.indices() {
match &body.basic_blocks[bb_idx].terminator().kind {
let mut apply_patch = false;
let mut patch = MirPatch::new(body);
for (bb, bb_data) in body.basic_blocks.iter_enumerated() {
match &bb_data.terminator().kind {
TerminatorKind::SwitchInt {
discr: Operand::Copy(_) | Operand::Move(_),
targets,
..
// We require that the possible target blocks don't contain this block.
} if !targets.all_targets().contains(&bb_idx) => {}
} if !targets.all_targets().contains(&bb) => {}
// Only optimize switch int statements
_ => continue,
};

if SimplifyToIf.simplify(tcx, body, bb_idx, typing_env).is_some() {
should_cleanup = true;
if SimplifyToIf.simplify(tcx, body, &mut patch, bb, typing_env).is_some() {
apply_patch = true;
continue;
}
if SimplifyToExp::default().simplify(tcx, body, bb_idx, typing_env).is_some() {
should_cleanup = true;
if SimplifyToExp::default().simplify(tcx, body, &mut patch, bb, typing_env).is_some() {
apply_patch = true;
continue;
}
}

if should_cleanup {
if apply_patch {
patch.apply(body);
simplify_cfg(tcx, body);
}
}
Expand All @@ -59,7 +61,8 @@ trait SimplifyMatch<'tcx> {
fn simplify(
&mut self,
tcx: TyCtxt<'tcx>,
body: &mut Body<'tcx>,
body: &Body<'tcx>,
patch: &mut MirPatch<'tcx>,
switch_bb_idx: BasicBlock,
typing_env: ty::TypingEnv<'tcx>,
) -> Option<()> {
Expand All @@ -73,8 +76,6 @@ trait SimplifyMatch<'tcx> {
let discr_ty = discr.ty(body.local_decls(), tcx);
self.can_simplify(tcx, targets, typing_env, bbs, discr_ty)?;

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

// Take ownership of items now that we know we can optimize.
let discr = discr.clone();

Expand All @@ -87,19 +88,9 @@ trait SimplifyMatch<'tcx> {
let parent_end = Location { block: switch_bb_idx, statement_index };
patch.add_statement(parent_end, StatementKind::StorageLive(discr_local));
patch.add_assign(parent_end, Place::from(discr_local), Rvalue::Use(discr));
self.new_stmts(
tcx,
targets,
typing_env,
&mut patch,
parent_end,
bbs,
discr_local,
discr_ty,
);
self.new_stmts(tcx, targets, typing_env, patch, parent_end, bbs, discr_local, discr_ty);
patch.add_statement(parent_end, StatementKind::StorageDead(discr_local));
patch.patch_terminator(switch_bb_idx, bbs[first].terminator().kind.clone());
patch.apply(body);
Some(())
}

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