codegen: Use target pointer size consistently for layout calculations.

Closes #1284

Author: emilio

src/codegen/mod.rs

@@ -45,7 +45,6 @@ use std::collections::{HashSet, VecDeque};
 use std::collections::hash_map::{Entry, HashMap};
 use std::fmt::Write;
 use std::iter;
-use std::mem;
 use std::ops;
 
 // Name of type defined in constified enum module
@@ -1777,7 +1776,7 @@ impl CodeGenerator for CompInfo {
                     let align = layout.align;
 
                     let check_struct_align =
-                        if align > mem::size_of::<*mut ()>() {
+                        if align > ctx.target_pointer_size() {
                             // FIXME when [RFC 1358](https://github.com/rust-lang/rust/issues/33626) ready
                             None
                         } else {
@@ -2720,9 +2719,8 @@ trait TryToOpaque {
 /// leverage the blanket impl for this trait.
 trait ToOpaque: TryToOpaque {
     fn get_layout(&self, ctx: &BindgenContext, extra: &Self::Extra) -> Layout {
-        self.try_get_layout(ctx, extra).unwrap_or_else(
-            |_| Layout::for_size(1),
-        )
+        self.try_get_layout(ctx, extra)
+            .unwrap_or_else(|_| Layout::for_size(ctx, 1))
     }
 
     fn to_opaque(

src/codegen/struct_layout.rs

@@ -8,7 +8,6 @@ use ir::layout::Layout;
 use ir::ty::{Type, TypeKind};
 use quote;
 use std::cmp;
-use std::mem;
 
 /// Trace the layout of struct.
 #[derive(Debug)]
@@ -101,7 +100,7 @@ impl<'a> StructLayoutTracker<'a> {
     pub fn saw_vtable(&mut self) {
         debug!("saw vtable for {}", self.name);
 
-        let ptr_size = mem::size_of::<*mut ()>();
+        let ptr_size = self.ctx.target_pointer_size();
         self.latest_offset += ptr_size;
         self.latest_field_layout = Some(Layout::new(ptr_size, ptr_size));
         self.max_field_align = ptr_size;
@@ -165,15 +164,13 @@ impl<'a> StructLayoutTracker<'a> {
             // can support.
             //
             // This means that the structs in the array are super-unsafe to
-            // access, since they won't be properly aligned, but *shrug*.
-            if let Some(layout) = self.ctx.resolve_type(inner).layout(
-                self.ctx,
-            )
-            {
-                if layout.align > mem::size_of::<*mut ()>() {
-                    field_layout.size = align_to(layout.size, layout.align) *
-                        len;
-                    field_layout.align = mem::size_of::<*mut ()>();
+            // access, since they won't be properly aligned, but there's not too
+            // much we can do about it.
+            if let Some(layout) = self.ctx.resolve_type(inner).layout(self.ctx) {
+                if layout.align > self.ctx.target_pointer_size() {
+                    field_layout.size =
+                        align_to(layout.size, layout.align) * len;
+                    field_layout.align = self.ctx.target_pointer_size();
                 }
             }
         }
@@ -193,7 +190,7 @@ impl<'a> StructLayoutTracker<'a> {
 
             // Otherwise the padding is useless.
             let need_padding = padding_bytes >= field_layout.align ||
-                field_layout.align > mem::size_of::<*mut ()>();
+                field_layout.align > self.ctx.target_pointer_size();
 
             self.latest_offset += padding_bytes;
 
@@ -215,7 +212,7 @@ impl<'a> StructLayoutTracker<'a> {
             if need_padding && padding_bytes != 0 {
                 Some(Layout::new(
                     padding_bytes,
-                    cmp::min(field_layout.align, mem::size_of::<*mut ()>()),
+                    cmp::min(field_layout.align, self.ctx.target_pointer_size())
                 ))
             } else {
                 None
@@ -267,15 +264,15 @@ impl<'a> StructLayoutTracker<'a> {
                  (self.last_field_was_bitfield &&
                       padding_bytes >=
                           self.latest_field_layout.unwrap().align) ||
-                 layout.align > mem::size_of::<*mut ()>())
+                 layout.align > self.ctx.target_pointer_size())
         {
             let layout = if self.is_packed {
                 Layout::new(padding_bytes, 1)
             } else if self.last_field_was_bitfield ||
-                       layout.align > mem::size_of::<*mut ()>()
+                       layout.align > self.ctx.target_pointer_size()
             {
                 // We've already given up on alignment here.
-                Layout::for_size(padding_bytes)
+                Layout::for_size(self.ctx, padding_bytes)
             } else {
                 Layout::new(padding_bytes, layout.align)
             };
@@ -290,7 +287,7 @@ impl<'a> StructLayoutTracker<'a> {
 
     pub fn requires_explicit_align(&self, layout: Layout) -> bool {
         self.max_field_align < layout.align &&
-            layout.align <= mem::size_of::<*mut ()>()
+            layout.align <= self.ctx.target_pointer_size()
     }
 
     fn padding_bytes(&self, layout: Layout) -> usize {

src/ir/layout.rs

@@ -4,8 +4,9 @@ use super::derive::{CanTriviallyDeriveCopy, CanTriviallyDeriveDebug,
                     CanTriviallyDeriveDefault, CanTriviallyDeriveHash,
                     CanTriviallyDerivePartialEqOrPartialOrd, CanDerive};
 use super::ty::{RUST_DERIVE_IN_ARRAY_LIMIT, Type, TypeKind};
+use ir::context::BindgenContext;
 use clang;
-use std::{cmp, mem};
+use std::cmp;
 
 /// A type that represents the struct layout of a type.
 #[derive(Debug, Clone, Copy, PartialEq)]
@@ -20,10 +21,15 @@ pub struct Layout {
 
 #[test]
 fn test_layout_for_size() {
+    use std::mem;
+
     let ptr_size = mem::size_of::<*mut ()>();
-    assert_eq!(Layout::for_size(ptr_size), Layout::new(ptr_size, ptr_size));
     assert_eq!(
-        Layout::for_size(3 * ptr_size),
+        Layout::for_size_internal(ptr_size, ptr_size),
+        Layout::new(ptr_size, ptr_size)
+    );
+    assert_eq!(
+        Layout::for_size_internal(ptr_size, 3 * ptr_size),
         Layout::new(3 * ptr_size, ptr_size)
     );
 }
@@ -39,13 +45,9 @@ impl Layout {
         }
     }
 
-    /// Creates a non-packed layout for a given size, trying to use the maximum
-    /// alignment possible.
-    pub fn for_size(size: usize) -> Self {
+    fn for_size_internal(ptr_size: usize, size: usize) -> Self {
         let mut next_align = 2;
-        while size % next_align == 0 &&
-            next_align <= mem::size_of::<*mut ()>()
-        {
+        while size % next_align == 0 && next_align <= ptr_size {
             next_align *= 2;
         }
         Layout {
@@ -55,6 +57,12 @@ impl Layout {
         }
     }
 
+    /// Creates a non-packed layout for a given size, trying to use the maximum
+    /// alignment possible.
+    pub fn for_size(ctx: &BindgenContext, size: usize) -> Self {
+        Self::for_size_internal(ctx.target_pointer_size(), size)
+    }
+
     /// Is this a zero-sized layout?
     pub fn is_zero(&self) -> bool {
         self.size == 0 && self.align == 0

src/ir/ty.rs

@@ -16,7 +16,6 @@ use clang::{self, Cursor};
 use parse::{ClangItemParser, ParseError, ParseResult};
 use std::borrow::Cow;
 use std::io;
-use std::mem;
 
 /// The base representation of a type in bindgen.
 ///
@@ -232,8 +231,6 @@ impl Type {
 
     /// What is the layout of this type?
     pub fn layout(&self, ctx: &BindgenContext) -> Option<Layout> {
-        use std::mem;
-
         self.layout.or_else(|| {
             match self.kind {
                 TypeKind::Comp(ref ci) => ci.layout(ctx),
@@ -242,8 +239,8 @@ impl Type {
                 TypeKind::Pointer(..) |
                 TypeKind::BlockPointer => {
                     Some(Layout::new(
-                        mem::size_of::<*mut ()>(),
-                        mem::align_of::<*mut ()>(),
+                        ctx.target_pointer_size(),
+                        ctx.target_pointer_size(),
                     ))
                 }
                 TypeKind::ResolvedTypeRef(inner) => {
@@ -596,17 +593,6 @@ pub enum FloatKind {
     Float128,
 }
 
-impl FloatKind {
-    /// If this type has a known size, return it (in bytes).
-    pub fn known_size(&self) -> usize {
-        match *self {
-            FloatKind::Float => mem::size_of::<f32>(),
-            FloatKind::Double | FloatKind::LongDouble => mem::size_of::<f64>(),
-            FloatKind::Float128 => mem::size_of::<f64>() * 2,
-        }
-    }
-}
-
 /// The different kinds of types that we can parse.
 #[derive(Debug)]
 pub enum TypeKind {