From 9366ba31668af3575ecadb3b35d2b67e138c3605 Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <nnethercote@mozilla.com>
Date: Thu, 3 Nov 2016 14:58:32 +1100
Subject: [PATCH 1/2] Reorder `hir::Expr` fields.

On 64-bit platforms this reduces the size of `Expr` from 96 bytes to 88
bytes.
---
 src/librustc/hir/mod.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/librustc/hir/mod.rs b/src/librustc/hir/mod.rs
index c451a789193aa..5ff69a789ed59 100644
--- a/src/librustc/hir/mod.rs
+++ b/src/librustc/hir/mod.rs
@@ -840,8 +840,8 @@ pub enum UnsafeSource {
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 pub struct Expr {
     pub id: NodeId,
-    pub node: Expr_,
     pub span: Span,
+    pub node: Expr_,
     pub attrs: ThinVec<Attribute>,
 }
 

From 43452a36efae22492ffef157ce44f05346bde1b0 Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <nnethercote@mozilla.com>
Date: Fri, 4 Nov 2016 15:04:16 +1100
Subject: [PATCH 2/2] Shrink `Expr_::ExprStruct`.

On 64-bit platforms this reduces the size of `Expr_` from  64 bytes to
56 bytes, and reduces the size of `Expr` from 88 bytes to 80 bytes.
---
 src/librustc/hir/lowering.rs    | 4 ++--
 src/librustc/hir/mod.rs         | 2 +-
 src/librustc_const_eval/eval.rs | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
index 620ee30c95628..7567c405bcaec 100644
--- a/src/librustc/hir/lowering.rs
+++ b/src/librustc/hir/lowering.rs
@@ -1239,7 +1239,7 @@ impl<'a> LoweringContext<'a> {
                 }), outputs.iter().map(|out| self.lower_expr(&out.expr)).collect(),
                    inputs.iter().map(|&(_, ref input)| self.lower_expr(input)).collect()),
                 ExprKind::Struct(ref path, ref fields, ref maybe_expr) => {
-                    hir::ExprStruct(self.lower_path(path),
+                    hir::ExprStruct(P(self.lower_path(path)),
                                     fields.iter().map(|x| self.lower_field(x)).collect(),
                                     maybe_expr.as_ref().map(|x| self.lower_expr(x)))
                 }
@@ -1743,7 +1743,7 @@ impl<'a> LoweringContext<'a> {
                    e: Option<P<hir::Expr>>,
                    attrs: ThinVec<Attribute>) -> P<hir::Expr> {
         let def = self.resolver.resolve_generated_global_path(&path, false);
-        let expr = self.expr(sp, hir::ExprStruct(path, fields, e), attrs);
+        let expr = self.expr(sp, hir::ExprStruct(P(path), fields, e), attrs);
         self.resolver.record_resolution(expr.id, def);
         expr
     }
diff --git a/src/librustc/hir/mod.rs b/src/librustc/hir/mod.rs
index 5ff69a789ed59..5f57ceac353cc 100644
--- a/src/librustc/hir/mod.rs
+++ b/src/librustc/hir/mod.rs
@@ -946,7 +946,7 @@ pub enum Expr_ {
     ///
     /// For example, `Foo {x: 1, y: 2}`, or
     /// `Foo {x: 1, .. base}`, where `base` is the `Option<Expr>`.
-    ExprStruct(Path, HirVec<Field>, Option<P<Expr>>),
+    ExprStruct(P<Path>, HirVec<Field>, Option<P<Expr>>),
 
     /// An array literal constructed from one repeated element.
     ///
diff --git a/src/librustc_const_eval/eval.rs b/src/librustc_const_eval/eval.rs
index c02cca0da7225..ad9e718617a52 100644
--- a/src/librustc_const_eval/eval.rs
+++ b/src/librustc_const_eval/eval.rs
@@ -314,7 +314,7 @@ pub fn const_expr_to_pat<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                           },
                       }))
                       .collect::<Result<_, _>>()?;
-            PatKind::Struct(path.clone(), field_pats, false)
+            PatKind::Struct((**path).clone(), field_pats, false)
         }
 
         hir::ExprArray(ref exprs) => {