box large variants in MIR

Operand: 72 -> 24 B
Statement: 192 -> 96 B
Terminator: 256 -> 112 B
librustc translation memory usage: 1795 -> 1669 MB

next step would be interning lvalues, I suppose?

6 files changed, 11 insertions, 12 deletions

diff --git a/src/librustc_mir/transform/copy_prop.rs b/src/librustc_mir/transform/copy_prop.rs
index fbb67161bac..08a4961c6cd 100644
--- a/src/librustc_mir/transform/copy_prop.rs
+++ b/src/librustc_mir/transform/copy_prop.rs
@@ -316,7 +316,7 @@ impl<'tcx> MutVisitor<'tcx> for ConstantPropagationVisitor<'tcx> {
             _ => return,
         }
 
-        *operand = Operand::Constant(self.constant.clone());
+        *operand = Operand::Constant(box self.constant.clone());
         self.uses_replaced += 1
     }
 }
diff --git a/src/librustc_mir/transform/deaggregator.rs b/src/librustc_mir/transform/deaggregator.rs
index 4309f91c635..d21dbeafb5d 100644
--- a/src/librustc_mir/transform/deaggregator.rs
+++ b/src/librustc_mir/transform/deaggregator.rs
@@ -49,8 +49,8 @@ impl MirPass for Deaggregator {
                     &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)
+                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),
                 };
@@ -114,8 +114,8 @@ fn get_aggregate_statement_index<'a, 'tcx, 'b>(start: usize,
             &Rvalue::Aggregate(ref kind, ref operands) => (kind, operands),
             _ => continue,
         };
-        let (adt_def, variant) = match kind {
-            &AggregateKind::Adt(adt_def, variant, _, None) => (adt_def, variant),
+        let (adt_def, variant) = match **kind {
+            AggregateKind::Adt(adt_def, variant, _, None) => (adt_def, variant),
             _ => continue,
         };
         if operands.len() == 0 {
diff --git a/src/librustc_mir/transform/promote_consts.rs b/src/librustc_mir/transform/promote_consts.rs
index ed9a0d3809f..e1c4602b045 100644
--- a/src/librustc_mir/transform/promote_consts.rs
+++ b/src/librustc_mir/transform/promote_consts.rs
@@ -230,7 +230,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
                 (if self.keep_original {
                     rhs.clone()
                 } else {
-                    let unit = Rvalue::Aggregate(AggregateKind::Tuple, vec![]);
+                    let unit = Rvalue::Aggregate(box AggregateKind::Tuple, vec![]);
                     mem::replace(rhs, unit)
                 }, statement.source_info)
             };
@@ -288,7 +288,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
 
     fn promote_candidate(mut self, candidate: Candidate) {
         let span = self.promoted.span;
-        let new_operand = Operand::Constant(Constant {
+        let new_operand = Operand::Constant(box Constant {
             span: span,
             ty: self.promoted.return_ty,
             literal: Literal::Promoted {
diff --git a/src/librustc_mir/transform/qualify_consts.rs b/src/librustc_mir/transform/qualify_consts.rs
index 0d592b4d72b..df837a32133 100644
--- a/src/librustc_mir/transform/qualify_consts.rs
+++ b/src/librustc_mir/transform/qualify_consts.rs
@@ -730,7 +730,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
             }
 
             Rvalue::Aggregate(ref kind, _) => {
-                if let AggregateKind::Adt(def, ..) = *kind {
+                if let AggregateKind::Adt(def, ..) = **kind {
                     if def.has_dtor(self.tcx) {
                         self.add(Qualif::NEEDS_DROP);
                         self.deny_drop();
diff --git a/src/librustc_mir/transform/simplify_branches.rs b/src/librustc_mir/transform/simplify_branches.rs
index d21a6ddfdfb..1dcacb29c3e 100644
--- a/src/librustc_mir/transform/simplify_branches.rs
+++ b/src/librustc_mir/transform/simplify_branches.rs
@@ -37,7 +37,7 @@ impl MirPass for SimplifyBranches {
         for block in mir.basic_blocks_mut() {
             let terminator = block.terminator_mut();
             terminator.kind = match terminator.kind {
-                TerminatorKind::SwitchInt { discr: Operand::Constant(Constant {
+                TerminatorKind::SwitchInt { discr: Operand::Constant(box Constant {
                     literal: Literal::Value { ref value }, ..
                 }), ref values, ref targets, .. } => {
                     if let Some(ref constint) = value.to_const_int() {
@@ -54,7 +54,7 @@ impl MirPass for SimplifyBranches {
                         continue
                     }
                 },
-                TerminatorKind::Assert { target, cond: Operand::Constant(Constant {
+                TerminatorKind::Assert { target, cond: Operand::Constant(box Constant {
                     literal: Literal::Value {
                         value: ConstVal::Bool(cond)
                     }, ..
@@ -66,4 +66,3 @@ impl MirPass for SimplifyBranches {
         }
     }
 }
-
diff --git a/src/librustc_mir/transform/type_check.rs b/src/librustc_mir/transform/type_check.rs
index b325470ec81..be384218a41 100644
--- a/src/librustc_mir/transform/type_check.rs
+++ b/src/librustc_mir/transform/type_check.rs
@@ -534,7 +534,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
 
     fn is_box_free(&self, operand: &Operand<'tcx>) -> bool {
         match operand {
-            &Operand::Constant(Constant {
+            &Operand::Constant(box Constant {
                 literal: Literal::Value {
                     value: ConstVal::Function(def_id, _), ..
                 }, ..