Rollup merge of #70259 - wesleywiser:use_reveal_all, r=eddyb

Use Reveal::All in MIR optimizations

Resolves some code review feedback in #67662.

Fixes #68855

r? @eddyb
This commit is contained in:
Mazdak Farrokhzad 2020-03-24 07:13:38 +01:00 committed by GitHub
commit 0d5b83df26
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3 changed files with 68 additions and 18 deletions

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@ -337,14 +337,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
) -> ConstPropagator<'mir, 'tcx> {
let def_id = source.def_id();
let substs = &InternalSubsts::identity_for_item(tcx, def_id);
let mut param_env = tcx.param_env(def_id);
// If we're evaluating inside a monomorphic function, then use `Reveal::All` because
// we want to see the same instances that codegen will see. This allows us to `resolve()`
// specializations.
if !substs.needs_subst() {
param_env = param_env.with_reveal_all();
}
let param_env = tcx.param_env(def_id).with_reveal_all();
let span = tcx.def_span(def_id);
let mut ecx = InterpCx::new(tcx.at(span), param_env, ConstPropMachine, ());

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@ -3,8 +3,8 @@
use rustc::middle::codegen_fn_attrs::CodegenFnAttrFlags;
use rustc::mir::visit::*;
use rustc::mir::*;
use rustc::ty::subst::{InternalSubsts, Subst, SubstsRef};
use rustc::ty::{self, Instance, InstanceDef, ParamEnv, Ty, TyCtxt, TypeFoldable};
use rustc::ty::subst::{Subst, SubstsRef};
use rustc::ty::{self, Instance, InstanceDef, ParamEnv, Ty, TyCtxt};
use rustc_attr as attr;
use rustc_hir::def_id::DefId;
use rustc_index::bit_set::BitSet;
@ -66,14 +66,7 @@ impl Inliner<'tcx> {
let mut callsites = VecDeque::new();
let mut param_env = self.tcx.param_env(self.source.def_id());
let substs = &InternalSubsts::identity_for_item(self.tcx, self.source.def_id());
// For monomorphic functions, we can use `Reveal::All` to resolve specialized instances.
if !substs.needs_subst() {
param_env = param_env.with_reveal_all();
}
let param_env = self.tcx.param_env(self.source.def_id()).with_reveal_all();
// Only do inlining into fn bodies.
let id = self.tcx.hir().as_local_hir_id(self.source.def_id()).unwrap();

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@ -0,0 +1,64 @@
// compile-flags: -Zmir-opt-level=1
trait NeedsDrop:Sized{
const NEEDS:bool=std::mem::needs_drop::<Self>();
}
impl<This> NeedsDrop for This{}
fn hello<T>(){
if <bool>::NEEDS {
panic!()
}
}
pub fn main() {
hello::<()>();
hello::<Vec<()>>();
}
// END RUST SOURCE
// START rustc.hello.ConstProp.before.mir
// let mut _0: ();
// let mut _1: bool;
// let mut _2: !;
// bb0: {
// StorageLive(_1);
// _1 = const <bool as NeedsDrop>::NEEDS;
// switchInt(_1) -> [false: bb1, otherwise: bb2];
// }
// bb1: {
// _0 = ();
// StorageDead(_1);
// return;
// }
// bb2: {
// StorageLive(_2);
// const std::rt::begin_panic::<&str>(const "explicit panic");
// }
// END rustc.hello.ConstProp.before.mir
// START rustc.hello.ConstProp.after.mir
// let mut _0: ();
// let mut _1: bool;
// let mut _2: !;
// bb0: {
// StorageLive(_1);
// _1 = const false;
// switchInt(const false) -> [false: bb1, otherwise: bb2];
// }
// bb1: {
// _0 = ();
// StorageDead(_1);
// return;
// }
// bb2: {
// StorageLive(_2);
// const std::rt::begin_panic::<&str>(const "explicit panic");
// }
// END rustc.hello.ConstProp.after.mir
// START rustc.hello.PreCodegen.before.mir
// let mut _0: ();
// bb0: {
// return;
// }
// END rustc.hello.PreCodegen.before.mir