Auto merge of #50282 - fitzgen:run-more-passes-on-constant-mir, r=nik…

…omatsakis

Run more passes on constant mir

Not very familiar with this code, but everything seems to be working!

r? @eddyb

src/librustc_mir/transform/copy_prop.rs

@@ -29,7 +29,6 @@
 //! (non-mutating) use of `SRC`. These restrictions are conservative and may be relaxed in the
 //! future.
 
-use rustc::hir;
 use rustc::mir::{Constant, Local, LocalKind, Location, Place, Mir, Operand, Rvalue, StatementKind};
 use rustc::mir::visit::MutVisitor;
 use rustc::ty::TyCtxt;
@@ -41,26 +40,8 @@ pub struct CopyPropagation;
 impl MirPass for CopyPropagation {
     fn run_pass<'a, 'tcx>(&self,
                           tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                          source: MirSource,
+                          _source: MirSource,
                           mir: &mut Mir<'tcx>) {
-        // 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) {
-            (_, 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
-                }
-            }
-        }
-
         // We only run when the MIR optimization level is > 1.
         // This avoids a slow pass, and messing up debug info.
         if tcx.sess.opts.debugging_opts.mir_opt_level <= 1 {

src/librustc_mir/transform/deaggregator.rs

@@ -8,7 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use rustc::hir;
 use rustc::ty::TyCtxt;
 use rustc::mir::*;
 use rustc_data_structures::indexed_vec::Idx;
@@ -19,26 +18,8 @@ pub struct Deaggregator;
 impl MirPass for Deaggregator {
     fn run_pass<'a, 'tcx>(&self,
                           tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                          source: MirSource,
+                          _source: MirSource,
                           mir: &mut Mir<'tcx>) {
-        // 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) {
-            (_, 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
-                }
-            }
-        }
-
         let (basic_blocks, local_decls) = mir.basic_blocks_and_local_decls_mut();
         let local_decls = &*local_decls;
         for bb in basic_blocks {

src/librustc_mir/transform/elaborate_drops.rs

@@ -15,7 +15,6 @@ use dataflow::{on_all_children_bits, on_all_drop_children_bits};
 use dataflow::{drop_flag_effects_for_location, on_lookup_result_bits};
 use dataflow::MoveDataParamEnv;
 use dataflow::{self, do_dataflow, DebugFormatted};
-use rustc::hir;
 use rustc::ty::{self, TyCtxt};
 use rustc::mir::*;
 use rustc::middle::const_val::ConstVal;
@@ -42,14 +41,7 @@ impl MirPass for ElaborateDrops {
     {
         debug!("elaborate_drops({:?} @ {:?})", src, mir.span);
 
-        // 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(src.def_id).unwrap();
-        match (tcx.hir.body_owner_kind(id), src.promoted) {
-            (hir::BodyOwnerKind::Fn, None) => {},
-            _ => return
-        }
         let param_env = tcx.param_env(src.def_id).with_reveal_all();
         let move_data = MoveData::gather_moves(mir, tcx).unwrap();
         let elaborate_patch = {