diff --git a/library/core/src/iter/range.rs b/library/core/src/iter/range.rs
index 9f34aee1947cd..4365c436fe494 100644
--- a/library/core/src/iter/range.rs
+++ b/library/core/src/iter/range.rs
@@ -1,7 +1,7 @@
use crate::char;
use crate::convert::TryFrom;
use crate::mem;
-use crate::ops::{self, Add, Sub, Try};
+use crate::ops::{self, Try};
use super::{FusedIterator, TrustedLen};
@@ -201,24 +201,12 @@ macro_rules! step_identical_methods {
#[inline]
fn forward(start: Self, n: usize) -> Self {
- // In debug builds, trigger a panic on overflow.
- // This should optimize completely out in release builds.
- if Self::forward_checked(start, n).is_none() {
- let _ = Add::add(Self::MAX, 1);
- }
- // Do wrapping math to allow e.g. `Step::forward(-128i8, 255)`.
- start.wrapping_add(n as Self)
+ start + (n as Self)
}
#[inline]
fn backward(start: Self, n: usize) -> Self {
- // In debug builds, trigger a panic on overflow.
- // This should optimize completely out in release builds.
- if Self::backward_checked(start, n).is_none() {
- let _ = Sub::sub(Self::MIN, 1);
- }
- // Do wrapping math to allow e.g. `Step::backward(127i8, 255)`.
- start.wrapping_sub(n as Self)
+ start - (n as Self)
}
};
}
diff --git a/src/librustc_metadata/rmeta/decoder.rs b/src/librustc_metadata/rmeta/decoder.rs
index 8aea9a9f58850..43657be481396 100644
--- a/src/librustc_metadata/rmeta/decoder.rs
+++ b/src/librustc_metadata/rmeta/decoder.rs
@@ -1139,6 +1139,15 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
}
}
+ fn get_is_trivial_mir(&self, tcx: TyCtxt<'tcx>, id: DefIndex) -> bool {
+ self.root
+ .tables
+ .is_trivial_mir
+ .get(self, id)
+ .filter(|_| !self.is_proc_macro(id))
+ .map_or(false, |v| v.decode((self, tcx)))
+ }
+
fn get_optimized_mir(&self, tcx: TyCtxt<'tcx>, id: DefIndex) -> Body<'tcx> {
self.root
.tables
diff --git a/src/librustc_metadata/rmeta/decoder/cstore_impl.rs b/src/librustc_metadata/rmeta/decoder/cstore_impl.rs
index 10b89cdd15a52..20ae2dcbde336 100644
--- a/src/librustc_metadata/rmeta/decoder/cstore_impl.rs
+++ b/src/librustc_metadata/rmeta/decoder/cstore_impl.rs
@@ -111,6 +111,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
bug!("coerce_unsized_info: `{:?}` is missing its info", def_id);
})
}
+ is_trivial_mir => { *tcx.arena.alloc(cdata.get_is_trivial_mir(tcx, def_id.index)) }
optimized_mir => { tcx.arena.alloc(cdata.get_optimized_mir(tcx, def_id.index)) }
promoted_mir => { tcx.arena.alloc(cdata.get_promoted_mir(tcx, def_id.index)) }
unused_generic_params => { cdata.get_unused_generic_params(def_id.index) }
diff --git a/src/librustc_metadata/rmeta/encoder.rs b/src/librustc_metadata/rmeta/encoder.rs
index 6723e236a1fe9..62cbea8d74d1f 100644
--- a/src/librustc_metadata/rmeta/encoder.rs
+++ b/src/librustc_metadata/rmeta/encoder.rs
@@ -1125,6 +1125,7 @@ impl EncodeContext<'a, 'tcx> {
fn encode_optimized_mir(&mut self, def_id: LocalDefId) {
debug!("EntryBuilder::encode_mir({:?})", def_id);
if self.tcx.mir_keys(LOCAL_CRATE).contains(&def_id) {
+ record!(self.tables.is_trivial_mir[def_id.to_def_id()] <- self.tcx.is_trivial_mir(def_id));
record!(self.tables.mir[def_id.to_def_id()] <- self.tcx.optimized_mir(def_id));
let unused = self.tcx.unused_generic_params(def_id);
diff --git a/src/librustc_metadata/rmeta/mod.rs b/src/librustc_metadata/rmeta/mod.rs
index 1c287be9f6bbc..935d24e50eaa1 100644
--- a/src/librustc_metadata/rmeta/mod.rs
+++ b/src/librustc_metadata/rmeta/mod.rs
@@ -283,6 +283,7 @@ define_tables! {
// Also, as an optimization, a missing entry indicates an empty `&[]`.
inferred_outlives: Table<DefIndex, Lazy!(&'tcx [(ty::Predicate<'tcx>, Span)])>,
super_predicates: Table<DefIndex, Lazy!(ty::GenericPredicates<'tcx>)>,
+ is_trivial_mir: Table<DefIndex, Lazy<bool>>,
mir: Table<DefIndex, Lazy!(mir::Body<'tcx>)>,
promoted_mir: Table<DefIndex, Lazy!(IndexVec<mir::Promoted, mir::Body<'tcx>>)>,
unused_generic_params: Table<DefIndex, Lazy<FiniteBitSet<u32>>>,
diff --git a/src/librustc_middle/query/mod.rs b/src/librustc_middle/query/mod.rs
index a8f6723a35605..ae61093199fc5 100644
--- a/src/librustc_middle/query/mod.rs
+++ b/src/librustc_middle/query/mod.rs
@@ -260,6 +260,10 @@ rustc_queries! {
}
}
+ query is_trivial_mir(key: DefId) -> bool {
+ desc { |tcx| "checking if MIR for `{}` is trivial", tcx.def_path_str(key) }
+ }
+
/// MIR after our optimization passes have run. This is MIR that is ready
/// for codegen. This is also the only query that can fetch non-local MIR, at present.
query optimized_mir(key: DefId) -> &'tcx mir::Body<'tcx> {
diff --git a/src/librustc_mir/transform/inline.rs b/src/librustc_mir/transform/inline.rs
index 92ea162e419db..881eec0c2d69a 100644
--- a/src/librustc_mir/transform/inline.rs
+++ b/src/librustc_mir/transform/inline.rs
@@ -38,7 +38,7 @@ struct CallSite<'tcx> {
impl<'tcx> MirPass<'tcx> for Inline {
fn run_pass(&self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut Body<'tcx>) {
- if tcx.sess.opts.debugging_opts.mir_opt_level >= 2 {
+ if tcx.sess.opts.debugging_opts.mir_opt_level >= 1 {
if tcx.sess.opts.debugging_opts.instrument_coverage {
// The current implementation of source code coverage injects code region counters
// into the MIR, and assumes a 1-to-1 correspondence between MIR and source-code-
@@ -100,7 +100,12 @@ impl Inliner<'tcx> {
continue;
}
- let callee_body = if let Some(callee_def_id) = callsite.callee.as_local() {
+ let callee_body = if self.tcx.is_trivial_mir(callsite.callee) {
+ self.tcx.optimized_mir(callsite.callee)
+ } else if self.tcx.sess.opts.debugging_opts.mir_opt_level < 2 {
+ // Only inline trivial functions by default.
+ continue;
+ } else if let Some(callee_def_id) = callsite.callee.as_local() {
let callee_hir_id = self.tcx.hir().as_local_hir_id(callee_def_id);
let self_hir_id =
self.tcx.hir().as_local_hir_id(self.source.def_id().expect_local());
@@ -802,3 +807,44 @@ impl<'a, 'tcx> MutVisitor<'tcx> for Integrator<'a, 'tcx> {
*scope = self.scope_map[*scope];
}
}
+
+struct FunctionCallFinder {
+ found: bool,
+}
+
+impl FunctionCallFinder {
+ fn new() -> Self {
+ FunctionCallFinder { found: false }
+ }
+}
+
+impl<'tcx> Visitor<'tcx> for FunctionCallFinder {
+ fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, _location: Location) {
+ if let TerminatorKind::Call { .. } = terminator.kind {
+ self.found = true;
+ }
+ }
+}
+
+pub fn is_trivial_mir(tcx: TyCtxt<'tcx>, did: DefId) -> bool {
+ debug!("is_trivial_mir({:?})", did);
+ if tcx.is_constructor(did) {
+ debug!("is_trivial_mir = true (constructor)");
+ return true;
+ }
+
+ if let Some(did) = did.as_local() {
+ let body = tcx
+ .mir_drops_elaborated_and_const_checked(ty::WithOptConstParam::unknown(did))
+ .borrow();
+ let mut finder = FunctionCallFinder::new();
+ finder.visit_body(&body);
+ debug!("is_trivial_mir = {}", !finder.found);
+ !finder.found
+ } else {
+ // This branch is only taken if no `optimized_mir` is available for
+ // an extern crate, as `is_trivial_mir` has otherwise been encoded.
+ debug!("is_trivial_mir = false (no MIR available)");
+ false
+ }
+}
diff --git a/src/librustc_mir/transform/mod.rs b/src/librustc_mir/transform/mod.rs
index 3803ee78fd4d9..aec1b9e952321 100644
--- a/src/librustc_mir/transform/mod.rs
+++ b/src/librustc_mir/transform/mod.rs
@@ -61,6 +61,7 @@ pub(crate) fn provide(providers: &mut Providers) {
},
mir_validated,
mir_drops_elaborated_and_const_checked,
+ is_trivial_mir: inline::is_trivial_mir,
optimized_mir,
optimized_mir_of_const_arg,
is_mir_available,
@@ -510,6 +511,8 @@ fn inner_optimized_mir(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>)
return shim::build_adt_ctor(tcx, def.did.to_def_id());
}
+ // `is_trivial_mir` uses `mir_drops_elaborated_and_const_checked` so run that first.
+ tcx.ensure().is_trivial_mir(def.did.to_def_id());
let mut body = tcx.mir_drops_elaborated_and_const_checked(def).steal();
run_optimization_passes(tcx, &mut body, def.did, None);