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Auto merge of #48052 - eddyb:deggregate, r=nikomatsakis

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rustc_mir: handle all aggregate kinds in, and always run, the deaggregator.

This helps with removing`Rvalue::Aggregate` from the MIR, and with enabling more optimizations.
r? @nikomatsakis
This commit is contained in:
bors 2018-02-23 02:21:06 +00:00
commit 928435305a
12 changed files with 181 additions and 130 deletions
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1
src/librustc/lib.rs
View File

@ -69,6 +69,7 @@
#![feature(underscore_lifetimes)]
#![feature(universal_impl_trait)]
#![feature(trace_macros)]
#![feature(trusted_len)]
#![feature(catch_expr)]
#![feature(test)]

65
src/librustc/mir/mod.rs
View File

@ -34,13 +34,13 @@ use std::ascii;
use std::borrow::{Cow};
use std::cell::Ref;
use std::fmt::{self, Debug, Formatter, Write};
use std::{iter, u32};
use std::{iter, mem, u32};
use std::ops::{Index, IndexMut};
use std::rc::Rc;
use std::vec::IntoIter;
use syntax::ast::{self, Name};
use syntax::symbol::InternedString;
use syntax_pos::Span;
use syntax_pos::{Span, DUMMY_SP};
mod cache;
pub mod tcx;
@ -984,11 +984,62 @@ impl<'tcx> BasicBlockData<'tcx> {
pub fn retain_statements<F>(&mut self, mut f: F) where F: FnMut(&mut Statement) -> bool {
for s in &mut self.statements {
if !f(s) {
s.kind = StatementKind::Nop;
s.make_nop();
}
}
}
pub fn expand_statements<F, I>(&mut self, mut f: F)
where F: FnMut(&mut Statement<'tcx>) -> Option<I>,
I: iter::TrustedLen<Item = Statement<'tcx>>
{
// Gather all the iterators we'll need to splice in, and their positions.
let mut splices: Vec<(usize, I)> = vec![];
let mut extra_stmts = 0;
for (i, s) in self.statements.iter_mut().enumerate() {
if let Some(mut new_stmts) = f(s) {
if let Some(first) = new_stmts.next() {
// We can already store the first new statement.
*s = first;
// Save the other statements for optimized splicing.
let remaining = new_stmts.size_hint().0;
if remaining > 0 {
splices.push((i + 1 + extra_stmts, new_stmts));
extra_stmts += remaining;
}
} else {
s.make_nop();
}
}
}
// Splice in the new statements, from the end of the block.
// FIXME(eddyb) This could be more efficient with a "gap buffer"
// where a range of elements ("gap") is left uninitialized, with
// splicing adding new elements to the end of that gap and moving
// existing elements from before the gap to the end of the gap.
// For now, this is safe code, emulating a gap but initializing it.
let mut gap = self.statements.len()..self.statements.len()+extra_stmts;
self.statements.resize(gap.end, Statement {
source_info: SourceInfo {
span: DUMMY_SP,
scope: ARGUMENT_VISIBILITY_SCOPE
},
kind: StatementKind::Nop
});
for (splice_start, new_stmts) in splices.into_iter().rev() {
let splice_end = splice_start + new_stmts.size_hint().0;
while gap.end > splice_end {
gap.start -= 1;
gap.end -= 1;
self.statements.swap(gap.start, gap.end);
}
self.statements.splice(splice_start..splice_end, new_stmts);
gap.end = splice_start;
}
}
pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> {
if index < self.statements.len() {
&self.statements[index]
@ -1157,6 +1208,14 @@ impl<'tcx> Statement<'tcx> {
pub fn make_nop(&mut self) {
self.kind = StatementKind::Nop
}
/// Changes a statement to a nop and returns the original statement.
pub fn replace_nop(&mut self) -> Self {
Statement {
source_info: self.source_info,
kind: mem::replace(&mut self.kind, StatementKind::Nop)
}
}
}
#[derive(Clone, Debug, RustcEncodable, RustcDecodable)]

170
src/librustc_mir/transform/deaggregator.rs
View File

@ -21,116 +21,90 @@ impl MirPass for Deaggregator {
tcx: TyCtxt<'a, 'tcx, 'tcx>,
source: MirSource,
mir: &mut Mir<'tcx>) {
let node_path = tcx.item_path_str(source.def_id);
debug!("running on: {:?}", node_path);
// we only run when mir_opt_level > 2
if tcx.sess.opts.debugging_opts.mir_opt_level <= 2 {
return;
}
// Don't run on constant MIR, because trans might not be able to
// evaluate the modified MIR.
// FIXME(eddyb) Remove check after miri is merged.
let id = tcx.hir.as_local_node_id(source.def_id).unwrap();
match (tcx.hir.body_owner_kind(id), source.promoted) {
(hir::BodyOwnerKind::Fn, None) => {},
_ => return
(_, Some(_)) |
(hir::BodyOwnerKind::Const, _) |
(hir::BodyOwnerKind::Static(_), _) => return,
(hir::BodyOwnerKind::Fn, _) => {
if tcx.is_const_fn(source.def_id) {
// Don't run on const functions, as, again, trans might not be able to evaluate
// the optimized IR.
return
}
}
}
// In fact, we might not want to trigger in other cases.
// Ex: when we could use SROA. See issue #35259
for bb in mir.basic_blocks_mut() {
let mut curr: usize = 0;
while let Some(idx) = get_aggregate_statement_index(curr, &bb.statements) {
// do the replacement
debug!("removing statement {:?}", idx);
let src_info = bb.statements[idx].source_info;
let suffix_stmts = bb.statements.split_off(idx+1);
let orig_stmt = bb.statements.pop().unwrap();
let (lhs, rhs) = match orig_stmt.kind {
StatementKind::Assign(ref lhs, ref rhs) => (lhs, rhs),
_ => span_bug!(src_info.span, "expected assign, not {:?}", orig_stmt),
};
let (agg_kind, operands) = match rhs {
&Rvalue::Aggregate(ref agg_kind, ref operands) => (agg_kind, operands),
_ => span_bug!(src_info.span, "expected aggregate, not {:?}", rhs),
};
let (adt_def, variant, substs) = match **agg_kind {
AggregateKind::Adt(adt_def, variant, substs, None)
=> (adt_def, variant, substs),
_ => span_bug!(src_info.span, "expected struct, not {:?}", rhs),
};
let n = bb.statements.len();
bb.statements.reserve(n + operands.len() + suffix_stmts.len());
for (i, op) in operands.iter().enumerate() {
let ref variant_def = adt_def.variants[variant];
let ty = variant_def.fields[i].ty(tcx, substs);
let rhs = Rvalue::Use(op.clone());
let lhs_cast = if adt_def.is_enum() {
Place::Projection(Box::new(PlaceProjection {
base: lhs.clone(),
elem: ProjectionElem::Downcast(adt_def, variant),
}))
let (basic_blocks, local_decls) = mir.basic_blocks_and_local_decls_mut();
let local_decls = &*local_decls;
for bb in basic_blocks {
bb.expand_statements(|stmt| {
// FIXME(eddyb) don't match twice on `stmt.kind` (post-NLL).
if let StatementKind::Assign(_, ref rhs) = stmt.kind {
if let Rvalue::Aggregate(ref kind, _) = *rhs {
// FIXME(#48193) Deaggregate arrays when it's cheaper to do so.
if let AggregateKind::Array(_) = **kind {
return None;
}
} else {
lhs.clone()
};
let lhs_proj = Place::Projection(Box::new(PlaceProjection {
base: lhs_cast,
elem: ProjectionElem::Field(Field::new(i), ty),
}));
let new_statement = Statement {
source_info: src_info,
kind: StatementKind::Assign(lhs_proj, rhs),
};
debug!("inserting: {:?} @ {:?}", new_statement, idx + i);
bb.statements.push(new_statement);
return None;
}
} else {
return None;
}
// if the aggregate was an enum, we need to set the discriminant
if adt_def.is_enum() {
let set_discriminant = Statement {
kind: StatementKind::SetDiscriminant {
place: lhs.clone(),
variant_index: variant,
},
source_info: src_info,
};
bb.statements.push(set_discriminant);
let stmt = stmt.replace_nop();
let source_info = stmt.source_info;
let (mut lhs, kind, operands) = match stmt.kind {
StatementKind::Assign(lhs, Rvalue::Aggregate(kind, operands))
=> (lhs, kind, operands),
_ => bug!()
};
curr = bb.statements.len();
bb.statements.extend(suffix_stmts);
}
let mut set_discriminant = None;
let active_field_index = match *kind {
AggregateKind::Adt(adt_def, variant_index, _, active_field_index) => {
if adt_def.is_enum() {
set_discriminant = Some(Statement {
kind: StatementKind::SetDiscriminant {
place: lhs.clone(),
variant_index,
},
source_info,
});
lhs = lhs.downcast(adt_def, variant_index);
}
active_field_index
}
_ => None
};
Some(operands.into_iter().enumerate().map(move |(i, op)| {
let lhs_field = if let AggregateKind::Array(_) = *kind {
// FIXME(eddyb) `offset` should be u64.
let offset = i as u32;
assert_eq!(offset as usize, i);
lhs.clone().elem(ProjectionElem::ConstantIndex {
offset,
// FIXME(eddyb) `min_length` doesn't appear to be used.
min_length: offset + 1,
from_end: false
})
} else {
let ty = op.ty(local_decls, tcx);
let field = Field::new(active_field_index.unwrap_or(i));
lhs.clone().field(field, ty)
};
Statement {
source_info,
kind: StatementKind::Assign(lhs_field, Rvalue::Use(op)),
}
}).chain(set_discriminant))
});
}
}
}
fn get_aggregate_statement_index<'a, 'tcx, 'b>(start: usize,
statements: &Vec<Statement<'tcx>>)
-> Option<usize> {
for i in start..statements.len() {
let ref statement = statements[i];
let rhs = match statement.kind {
StatementKind::Assign(_, ref rhs) => rhs,
_ => continue,
};
let (kind, operands) = match rhs {
&Rvalue::Aggregate(ref kind, ref operands) => (kind, operands),
_ => continue,
};
let (adt_def, variant) = match **kind {
AggregateKind::Adt(adt_def, variant, _, None) => (adt_def, variant),
_ => continue,
};
if operands.len() == 0 {
// don't deaggregate ()
continue;
}
debug!("getting variant {:?}", variant);
debug!("for adt_def {:?}", adt_def);
return Some(i);
};
None
}

6
src/librustc_mir/transform/mod.rs
View File

@ -258,6 +258,11 @@ fn optimized_mir<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx
// Optimizations begin.
inline::Inline,
// Lowering generator control-flow and variables
// has to happen before we do anything else to them.
generator::StateTransform,
instcombine::InstCombine,
deaggregator::Deaggregator,
copy_prop::CopyPropagation,
@ -265,7 +270,6 @@ fn optimized_mir<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx
simplify::SimplifyCfg::new("final"),
simplify::SimplifyLocals,
generator::StateTransform,
add_call_guards::CriticalCallEdges,
dump_mir::Marker("PreTrans"),
];

17
src/librustc_mir/transform/simplify.rs
View File

@ -42,6 +42,7 @@ use rustc_data_structures::indexed_vec::{Idx, IndexVec};
use rustc::ty::TyCtxt;
use rustc::mir::*;
use rustc::mir::visit::{MutVisitor, Visitor, PlaceContext};
use rustc::session::config::FullDebugInfo;
use std::borrow::Cow;
use transform::{MirPass, MirSource};
@ -281,16 +282,24 @@ pub struct SimplifyLocals;
impl MirPass for SimplifyLocals {
fn run_pass<'a, 'tcx>(&self,
_: TyCtxt<'a, 'tcx, 'tcx>,
tcx: TyCtxt<'a, 'tcx, 'tcx>,
_: MirSource,
mir: &mut Mir<'tcx>) {
let mut marker = DeclMarker { locals: BitVector::new(mir.local_decls.len()) };
marker.visit_mir(mir);
// Return pointer and arguments are always live
marker.locals.insert(0);
for idx in mir.args_iter() {
marker.locals.insert(idx.index());
marker.locals.insert(RETURN_PLACE.index());
for arg in mir.args_iter() {
marker.locals.insert(arg.index());
}
// We may need to keep dead user variables live for debuginfo.
if tcx.sess.opts.debuginfo == FullDebugInfo {
for local in mir.vars_iter() {
marker.locals.insert(local.index());
}
}
let map = make_local_map(&mut mir.local_decls, marker.locals);
// Update references to all vars and tmps now
LocalUpdater { map: map }.visit_mir(mir);

8
src/test/codegen/lifetime_start_end.rs
View File

@ -28,14 +28,14 @@ pub fn test() {
// CHECK: [[S_b:%[0-9]+]] = bitcast %"core::option::Option<i32>"** %b to i8*
// CHECK: call void @llvm.lifetime.start{{.*}}(i{{[0-9 ]+}}, i8* [[S_b]])
// CHECK: [[S__5:%[0-9]+]] = bitcast %"core::option::Option<i32>"* %_5 to i8*
// CHECK: call void @llvm.lifetime.start{{.*}}(i{{[0-9 ]+}}, i8* [[S__5]])
// CHECK: [[S__4:%[0-9]+]] = bitcast %"core::option::Option<i32>"* %_4 to i8*
// CHECK: call void @llvm.lifetime.start{{.*}}(i{{[0-9 ]+}}, i8* [[S__4]])
// CHECK: [[E_b:%[0-9]+]] = bitcast %"core::option::Option<i32>"** %b to i8*
// CHECK: call void @llvm.lifetime.end{{.*}}(i{{[0-9 ]+}}, i8* [[E_b]])
// CHECK: [[E__5:%[0-9]+]] = bitcast %"core::option::Option<i32>"* %_5 to i8*
// CHECK: call void @llvm.lifetime.end{{.*}}(i{{[0-9 ]+}}, i8* [[E__5]])
// CHECK: [[E__4:%[0-9]+]] = bitcast %"core::option::Option<i32>"* %_4 to i8*
// CHECK: call void @llvm.lifetime.end{{.*}}(i{{[0-9 ]+}}, i8* [[E__4]])
}
let c = 1;

6
src/test/codegen/match.rs
View File

@ -19,7 +19,7 @@ pub enum E {
// CHECK-LABEL: @exhaustive_match
#[no_mangle]
pub fn exhaustive_match(e: E) {
pub fn exhaustive_match(e: E, unit: ()) {
// CHECK: switch{{.*}}, label %[[OTHERWISE:[a-zA-Z0-9_]+]] [
// CHECK-NEXT: i[[TY:[0-9]+]] [[DISCR:[0-9]+]], label %[[A:[a-zA-Z0-9_]+]]
// CHECK-NEXT: i[[TY:[0-9]+]] [[DISCR:[0-9]+]], label %[[B:[a-zA-Z0-9_]+]]
@ -31,7 +31,7 @@ pub fn exhaustive_match(e: E) {
// CHECK: [[OTHERWISE]]:
// CHECK-NEXT: unreachable
match e {
E::A => (),
E::B => (),
E::A => unit,
E::B => unit,
}
}

2
src/test/incremental/hashes/closure_expressions.rs
View File

@ -64,7 +64,7 @@ pub fn change_parameter_pattern() {
}
#[cfg(not(cfail1))]
#[rustc_clean(cfg="cfail2", except="HirBody, MirValidated, MirOptimized, TypeckTables")]
#[rustc_clean(cfg="cfail2", except="HirBody, MirValidated, TypeckTables")]
#[rustc_clean(cfg="cfail3")]
pub fn change_parameter_pattern() {
let _ = |&x: &u32| x;

2
src/test/incremental/issue-38222.rs
View File

@ -18,7 +18,7 @@
#![feature(rustc_attrs)]
#![rustc_partition_translated(module="issue_38222-mod1", cfg="rpass2")]
#![rustc_partition_reused(module="issue_38222-mod1", cfg="rpass2")]
// If trans had added a dependency edge to the Krate dep-node, nothing would
// be re-used, so checking that this module was re-used is sufficient.

28
src/test/mir-opt/copy_propagation_arg.rs
View File

@ -78,7 +78,7 @@ fn main() {
// bb1: {
// StorageDead(_3);
// _1 = const 5u8;
// _0 = ();
// ...
// return;
// }
// END rustc.bar.CopyPropagation.before.mir
@ -92,6 +92,7 @@ fn main() {
// ...
// _1 = const 5u8;
// ...
// return;
// }
// END rustc.bar.CopyPropagation.after.mir
// START rustc.baz.CopyPropagation.before.mir
@ -100,7 +101,7 @@ fn main() {
// _2 = _1;
// _1 = move _2;
// StorageDead(_2);
// _0 = ();
// ...
// return;
// }
// END rustc.baz.CopyPropagation.before.mir
@ -110,21 +111,22 @@ fn main() {
// _2 = _1;
// _1 = move _2;
// ...
// return;
// }
// END rustc.baz.CopyPropagation.after.mir
// START rustc.arg_src.CopyPropagation.before.mir
// bb0: {
// ...
// _3 = _1;
// _2 = move _3;
// ...
// _1 = const 123i32;
// ...
// _4 = _2;
// _0 = move _4;
// ...
// return;
// }
// ...
// _3 = _1;
// _2 = move _3;
// ...
// _1 = const 123i32;
// ...
// _4 = _2;
// _0 = move _4;
// ...
// return;
// }
// END rustc.arg_src.CopyPropagation.before.mir
// START rustc.arg_src.CopyPropagation.after.mir
// bb0: {

4
src/test/run-make/sepcomp-cci-copies/Makefile
View File

@ -2,9 +2,11 @@
# Check that cross-crate inlined items are inlined in all compilation units
# that refer to them, and not in any other compilation units.
# Note that we have to pass `-C codegen-units=6` because up to two CGUs may be
# created for each source module (see `rustc_mir::monomorphize::partitioning`).
all:
$(RUSTC) cci_lib.rs
$(RUSTC) foo.rs --emit=llvm-ir -C codegen-units=3 \
$(RUSTC) foo.rs --emit=llvm-ir -C codegen-units=6 \
-Z inline-in-all-cgus
[ "$$(cat "$(TMPDIR)"/foo.*.ll | grep -c define\ .*cci_fn)" -eq "2" ]

2
src/test/ui/print_type_sizes/generics.rs
View File

@ -72,7 +72,7 @@ pub fn f1<T:Copy>(x: T) {
fn start(_: isize, _: *const *const u8) -> isize {
let _b: Pair<u8> = Pair::new(0, 0);
let _s: Pair<SevenBytes> = Pair::new(SevenBytes::new(), SevenBytes::new());
let _z: ZeroSized = ZeroSized;
let ref _z: ZeroSized = ZeroSized;
f1::<SevenBytes>(SevenBytes::new());
0
}