Do not run the DA+ConstProp before DropElab

Also fix some more tests.

Author: nagisa

src/librustc_borrowck/borrowck/mir/gather_moves.rs

@@ -614,14 +614,10 @@ fn gather_moves<'a, 'tcx>(mir: &Mir<'tcx>, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> MoveD
                         Rvalue::InlineAsm { .. } => {}
                     }
                 }
-                StatementKind::SetDiscriminant{ ref lvalue, .. } => {
-                    // not a move, is assignment like.
-                    bb_ctxt.builder.create_move_path(lvalue);
-                    let assigned_path = bb_ctxt.builder.move_path_for(lvalue);
-                    bb_ctxt.path_map.fill_to(assigned_path.index());
-                }
                 StatementKind::StorageLive(_) |
                 StatementKind::StorageDead(_) => {}
+                StatementKind::SetDiscriminant{ .. } =>
+                    bug!("SetDiscriminant and drop elaboration are incompatible")
             }
         }
 

src/librustc_borrowck/borrowck/mir/mod.rs

@@ -369,7 +369,6 @@ fn drop_flag_effects_for_location<'a, 'tcx, F>(
     let block = &mir[loc.block];
     match block.statements.get(loc.index) {
         Some(stmt) => match stmt.kind {
-            repr::StatementKind::SetDiscriminant{ ref lvalue, .. } |
             repr::StatementKind::Assign(ref lvalue, _) => {
                 debug!("drop_flag_effects: assignment {:?}", stmt);
                  on_all_children_bits(tcx, mir, move_data,
@@ -378,6 +377,8 @@ fn drop_flag_effects_for_location<'a, 'tcx, F>(
             }
             repr::StatementKind::StorageLive(_) |
             repr::StatementKind::StorageDead(_) => {}
+            repr::StatementKind::SetDiscriminant{ .. } =>
+                bug!("SetDiscriminant and drop elaboration are incompatible")
         },
         None => {
             debug!("drop_flag_effects: replace {:?}", block.terminator());

src/librustc_driver/driver.rs

@@ -991,16 +991,15 @@ pub fn phase_4_translate_to_llvm<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 
         passes.push_pass(box mir::transform::erase_regions::EraseRegions);
 
-        passes.push_pass(box mir::transform::deaggregator::Deaggregator);
-        passes.push_pass(box mir::transform::const_propagate::ConstPropagate);
-        passes.push_pass(box mir::transform::simplify::SimplifyCfg::new("const-propagate"));
-        passes.push_pass(box mir::transform::deadcode::DeadCode);
-
         passes.push_pass(box mir::transform::add_call_guards::AddCallGuards);
         passes.push_pass(box borrowck::ElaborateDrops);
         passes.push_pass(box mir::transform::no_landing_pads::NoLandingPads);
         passes.push_pass(box mir::transform::simplify::SimplifyCfg::new("elaborate-drops"));
 
+        passes.push_pass(box mir::transform::deaggregator::Deaggregator);
+        passes.push_pass(box mir::transform::const_propagate::ConstPropagate);
+        passes.push_pass(box mir::transform::simplify::SimplifyCfg::new("const-propagate"));
+        passes.push_pass(box mir::transform::deadcode::DeadCode);
 
         passes.push_pass(box mir::transform::simplify::SimplifyLocals);
         passes.push_pass(box mir::transform::add_call_guards::AddCallGuards);

src/test/compile-fail/huge-array.rs

@@ -12,6 +12,7 @@
 
 fn generic<T: Copy>(t: T) {
     let s: [T; 1518600000] = [t; 1518600000];
+    drop(s);
 }
 
 fn main() {

src/test/compile-fail/huge-enum.rs

@@ -15,9 +15,11 @@
 #[cfg(target_pointer_width = "32")]
 fn main() {
     let big: Option<[u32; (1<<29)-1]> = None;
+    drop(big);
 }
 
 #[cfg(target_pointer_width = "64")]
 fn main() {
     let big: Option<[u32; (1<<45)-1]> = None;
+    drop(big);
 }

src/test/compile-fail/huge-struct.rs

@@ -51,4 +51,5 @@ struct S1M<T> { val: S1k<S1k<T>> }
 
 fn main() {
     let fat: Option<S1M<S1M<S1M<u32>>>> = None;
+    drop(fat);
 }

src/test/compile-fail/issue-15919.rs

@@ -13,9 +13,11 @@
 #[cfg(target_pointer_width = "32")]
 fn main() {
     let x = [0usize; 0xffff_ffff];
+    drop(x);
 }
 
 #[cfg(target_pointer_width = "64")]
 fn main() {
     let x = [0usize; 0xffff_ffff_ffff_ffff];
+    drop(x);
 }

src/test/mir-opt/storage_ranges.rs

@@ -19,7 +19,29 @@ fn main() {
 }
 
 // END RUST SOURCE
-// START rustc.node4.PreTrans.after.mir
+// START rustc.node4.SimplifyCfg.initial-after.mir
+// bb0: {
+//     StorageLive(var0);
+//     var0 = const 0i32;
+//     StorageLive(var1);
+//     StorageLive(tmp1);
+//     StorageLive(tmp2);
+//     tmp2 = var0;
+//     tmp1 = std::prelude::v1::Some<i32>(tmp2,);
+//     var1 = &tmp1;
+//     StorageDead(tmp2);
+//     tmp0 = ();
+//     StorageDead(tmp1);
+//     StorageDead(var1);
+//     StorageLive(var2);
+//     var2 = const 1i32;
+//     return = ();
+//     StorageDead(var2);
+//     StorageDead(var0);
+//     goto -> bb1;
+// }
+// END rustc.node4.SimplifyCfg.initial-after.mir
+// START rustc.node4.DeadCode.after.mir
 // bb0: {
 //     StorageLive(var0);
 //     StorageLive(var1);
@@ -34,4 +56,10 @@ fn main() {
 //     StorageDead(var0);
 //     goto -> bb1;
 // }
+// END rustc.node4.DeadCode.after.mir
+// START rustc.node4.PreTrans.after.mir
+// bb0: {
+//     return = ();
+//     goto -> bb1;
+// }
 // END rustc.node4.PreTrans.after.mir