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Auto merge of #96281 - SparrowLii:const_prop, r=wesleywiser

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Optimize `const_prop` mir-opt by accessing `local_decls` through `ecx`

From the FIXME in the impl of `ConstPropagator`. Accessing `local_decls` and `scource_scopes` from `ecx` can reduce `clone` calls and save compile time.
Besides, according to #96213 , the FIXME about writing `layouts` to `ecx` in advance can also be removed.
This commit is contained in:
bors 2022-04-24 01:09:11 +00:00
commit b21759f550
2 changed files with 11 additions and 29 deletions
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17
compiler/rustc_mir_transform/src/const_prop.rs
View file

@ -313,9 +313,7 @@ struct ConstPropagator<'mir, 'tcx> {
ecx: InterpCx<'mir, 'tcx, ConstPropMachine<'mir, 'tcx>>,
tcx: TyCtxt<'tcx>,
param_env: ParamEnv<'tcx>,
// FIXME(eddyb) avoid cloning this field more than once,
// by accessing it through `ecx` instead.
local_decls: IndexVec<Local, LocalDecl<'tcx>>,
local_decls: &'mir IndexVec<Local, LocalDecl<'tcx>>,
// Because we have `MutVisitor` we can't obtain the `SourceInfo` from a `Location`. So we store
// the last known `SourceInfo` here and just keep revisiting it.
source_info: Option<SourceInfo>,
@ -361,10 +359,6 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
let substs = &InternalSubsts::identity_for_item(tcx, def_id);
let param_env = tcx.param_env_reveal_all_normalized(def_id);
let span = tcx.def_span(def_id);
// FIXME: `CanConstProp::check` computes the layout of all locals, return those layouts
// so we can write them to `ecx.frame_mut().locals.layout, reducing the duplication in
// `layout_of` query invocations.
let can_const_prop = CanConstProp::check(tcx, param_env, body);
let mut only_propagate_inside_block_locals = BitSet::new_empty(can_const_prop.len());
for (l, mode) in can_const_prop.iter_enumerated() {
@ -374,7 +368,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
}
let mut ecx = InterpCx::new(
tcx,
span,
tcx.def_span(def_id),
param_env,
ConstPropMachine::new(only_propagate_inside_block_locals, can_const_prop),
);
@ -405,10 +399,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
ecx,
tcx,
param_env,
// FIXME(eddyb) avoid cloning this field more than once,
// by accessing it through `ecx` instead.
//FIXME(wesleywiser) we can't steal this because `Visitor::super_visit_body()` needs it
local_decls: body.local_decls.clone(),
local_decls: &dummy_body.local_decls,
source_info: None,
}
}
@ -511,7 +502,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
let r = r?;
// We need the type of the LHS. We cannot use `place_layout` as that is the type
// of the result, which for checked binops is not the same!
let left_ty = left.ty(&self.local_decls, self.tcx);
let left_ty = left.ty(self.local_decls, self.tcx);
let left_size = self.ecx.layout_of(left_ty).ok()?.size;
let right_size = r.layout.size;
let r_bits = r.to_scalar().ok();

23
compiler/rustc_mir_transform/src/const_prop_lint.rs
View file

@ -308,10 +308,8 @@ struct ConstPropagator<'mir, 'tcx> {
ecx: InterpCx<'mir, 'tcx, ConstPropMachine<'mir, 'tcx>>,
tcx: TyCtxt<'tcx>,
param_env: ParamEnv<'tcx>,
// FIXME(eddyb) avoid cloning these two fields more than once,
// by accessing them through `ecx` instead.
source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
local_decls: IndexVec<Local, LocalDecl<'tcx>>,
source_scopes: &'mir IndexVec<SourceScope, SourceScopeData<'tcx>>,
local_decls: &'mir IndexVec<Local, LocalDecl<'tcx>>,
// Because we have `MutVisitor` we can't obtain the `SourceInfo` from a `Location`. So we store
// the last known `SourceInfo` here and just keep revisiting it.
source_info: Option<SourceInfo>,
@ -357,10 +355,6 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
let substs = &InternalSubsts::identity_for_item(tcx, def_id);
let param_env = tcx.param_env_reveal_all_normalized(def_id);
let span = tcx.def_span(def_id);
// FIXME: `CanConstProp::check` computes the layout of all locals, return those layouts
// so we can write them to `ecx.frame_mut().locals.layout, reducing the duplication in
// `layout_of` query invocations.
let can_const_prop = CanConstProp::check(tcx, param_env, body);
let mut only_propagate_inside_block_locals = BitSet::new_empty(can_const_prop.len());
for (l, mode) in can_const_prop.iter_enumerated() {
@ -370,7 +364,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
}
let mut ecx = InterpCx::new(
tcx,
span,
tcx.def_span(def_id),
param_env,
ConstPropMachine::new(only_propagate_inside_block_locals, can_const_prop),
);
@ -401,11 +395,8 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
ecx,
tcx,
param_env,
// FIXME(eddyb) avoid cloning these two fields more than once,
// by accessing them through `ecx` instead.
source_scopes: body.source_scopes.clone(),
//FIXME(wesleywiser) we can't steal this because `Visitor::super_visit_body()` needs it
local_decls: body.local_decls.clone(),
source_scopes: &dummy_body.source_scopes,
local_decls: &dummy_body.local_decls,
source_info: None,
}
}
@ -435,7 +426,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
}
fn lint_root(&self, source_info: SourceInfo) -> Option<HirId> {
source_info.scope.lint_root(&self.source_scopes)
source_info.scope.lint_root(self.source_scopes)
}
fn use_ecx<F, T>(&mut self, f: F) -> Option<T>
@ -572,7 +563,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
let r = r?;
// We need the type of the LHS. We cannot use `place_layout` as that is the type
// of the result, which for checked binops is not the same!
let left_ty = left.ty(&self.local_decls, self.tcx);
let left_ty = left.ty(self.local_decls, self.tcx);
let left_size = self.ecx.layout_of(left_ty).ok()?.size;
let right_size = r.layout.size;
let r_bits = r.to_scalar().ok();