bjoernager/rust
bjoernager/rust
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remove unnecessary and ineffective caching

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This commit is contained in:
Erik Desjardins 2021-03-17 20:24:29 -04:00
parent b6d5b728b3
commit 1205e82578
1 changed files with 9 additions and 22 deletions
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31
compiler/rustc_mir/src/transform/remove_zsts.rs
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@ -1,7 +1,6 @@
//! Removes assignments to ZST places. //! Removes assignments to ZST places.
use crate::transform::MirPass; use crate::transform::MirPass;
use rustc_data_structures::fx::FxHashMap;
use rustc_middle::mir::{Body, StatementKind}; use rustc_middle::mir::{Body, StatementKind};
use rustc_middle::ty::TyCtxt; use rustc_middle::ty::TyCtxt;
@ -10,35 +9,23 @@ pub struct RemoveZsts;
impl<'tcx> MirPass<'tcx> for RemoveZsts { impl<'tcx> MirPass<'tcx> for RemoveZsts {
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let param_env = tcx.param_env(body.source.def_id()); let param_env = tcx.param_env(body.source.def_id());
let (basic_blocks, local_decls) = body.basic_blocks_and_local_decls_mut(); let (basic_blocks, local_decls) = body.basic_blocks_and_local_decls_mut();
let mut is_zst_cache = FxHashMap::default();
for block in basic_blocks.iter_mut() { for block in basic_blocks.iter_mut() {
for statement in block.statements.iter_mut() { for statement in block.statements.iter_mut() {
match statement.kind { match statement.kind {
StatementKind::Assign(box (place, _)) => { StatementKind::Assign(box (place, _)) => {
let place_ty = place.ty(local_decls, tcx).ty; let place_ty = place.ty(local_decls, tcx).ty;
if let Ok(layout) = tcx.layout_of(param_env.and(place_ty)) {
let is_inhabited_zst = *is_zst_cache.entry(place_ty).or_insert_with(|| { if layout.is_zst() && !layout.abi.is_uninhabited() {
if let Ok(layout) = tcx.layout_of(param_env.and(place_ty)) { if tcx.consider_optimizing(|| {
if layout.is_zst() && !layout.abi.is_uninhabited() { format!(
return true; "RemoveZsts - Place: {:?} SourceInfo: {:?}",
place, statement.source_info
)
}) {
statement.make_nop();
} }
} }
false
});
if is_inhabited_zst {
if tcx.consider_optimizing(|| {
format!(
"RemoveZsts - Place: {:?} SourceInfo: {:?}",
place, statement.source_info
)
}) {
statement.make_nop();
}
} }
} }
_ => {} _ => {}