bjoernager/rust
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Auto merge of #109025 - cjgillot:refprop-dbg, r=JakobDegen

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Enable MIR reference propagation by default
This commit is contained in:
bors 2023-07-14 17:32:59 +00:00
commit 079e544174
43 changed files with 707 additions and 905 deletions
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2
compiler/rustc_mir_transform/src/lib.rs
View file

@ -553,6 +553,7 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
&normalize_array_len::NormalizeArrayLen, // has to run after `slice::len` lowering
&const_goto::ConstGoto,
&remove_unneeded_drops::RemoveUnneededDrops,
&ref_prop::ReferencePropagation,
&sroa::ScalarReplacementOfAggregates,
&match_branches::MatchBranchSimplification,
// inst combine is after MatchBranchSimplification to clean up Ne(_1, false)
@ -560,7 +561,6 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
&instsimplify::InstSimplify,
&simplify::SimplifyLocals::BeforeConstProp,
&copy_prop::CopyProp,
&ref_prop::ReferencePropagation,
// Perform `SeparateConstSwitch` after SSA-based analyses, as cloning blocks may
// destroy the SSA property. It should still happen before const-propagation, so the
// latter pass will leverage the created opportunities.

44
compiler/rustc_mir_transform/src/ref_prop.rs
View file

@ -71,7 +71,7 @@ pub struct ReferencePropagation;
impl<'tcx> MirPass<'tcx> for ReferencePropagation {
fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
sess.mir_opt_level() >= 4
sess.mir_opt_level() >= 2
}
#[instrument(level = "trace", skip(self, tcx, body))]
@ -355,7 +355,10 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'tcx> {
}
fn visit_var_debug_info(&mut self, debuginfo: &mut VarDebugInfo<'tcx>) {
if let VarDebugInfoContents::Place(ref mut place) = debuginfo.value
// If the debuginfo is a pointer to another place:
// - if it's a reborrow, see through it;
// - if it's a direct borrow, increase `debuginfo.references`.
while let VarDebugInfoContents::Place(ref mut place) = debuginfo.value
&& place.projection.is_empty()
&& let Value::Pointer(target, _) = self.targets[place.local]
&& target.projection.iter().all(|p| p.can_use_in_debuginfo())
@ -369,28 +372,37 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'tcx> {
debuginfo.references = references;
*place = target;
self.any_replacement = true;
} else {
break
}
}
// Simplify eventual projections left inside `debuginfo`.
self.super_var_debug_info(debuginfo);
}
fn visit_place(&mut self, place: &mut Place<'tcx>, ctxt: PlaceContext, loc: Location) {
if place.projection.first() != Some(&PlaceElem::Deref) {
return;
}
loop {
if let Value::Pointer(target, _) = self.targets[place.local] {
let perform_opt = matches!(ctxt, PlaceContext::NonUse(_))
|| self.allowed_replacements.contains(&(target.local, loc));
if perform_opt {
*place = target.project_deeper(&place.projection[1..], self.tcx);
self.any_replacement = true;
continue;
}
if place.projection.first() != Some(&PlaceElem::Deref) {
return;
}
break;
let Value::Pointer(target, _) = self.targets[place.local] else { return };
let perform_opt = match ctxt {
PlaceContext::NonUse(NonUseContext::VarDebugInfo) => {
target.projection.iter().all(|p| p.can_use_in_debuginfo())
}
PlaceContext::NonUse(_) => true,
_ => self.allowed_replacements.contains(&(target.local, loc)),
};
if !perform_opt {
return;
}
*place = target.project_deeper(&place.projection[1..], self.tcx);
self.any_replacement = true;
}
}