rustc: Rename llalign_of_real to llalign_of_pref

This alignment is the "preferred" alignment of a type, which is not
necessarily the alignment the compiler will use when packing the
type into structures - that is the "ABI" alignment (in LLVM terms).

On x86, 64-bit ints have 8-byte preferred alignment, but 4-byte
ABI alignment.

Author: brson

src/rustc/middle/trans/base.rs

@@ -1896,7 +1896,7 @@ fn make_mono_id(ccx: @crate_ctxt, item: ast::def_id, substs: [ty::t],
                         !ty::type_needs_drop(ccx.tcx, subst) {
                     let llty = type_of(ccx, subst);
                     let size = shape::llsize_of_real(ccx, llty);
-                    let align = shape::llalign_of_real(ccx, llty);
+                    let align = shape::llalign_of_pref(ccx, llty);
                     // Special value for nil to prevent problems with undef
                     // return pointers.
                     if size == 1u && ty::type_is_nil(subst) {

src/rustc/middle/trans/debuginfo.rs

@@ -282,7 +282,7 @@ fn create_block(cx: block) -> @metadata<block_md> {
 fn size_and_align_of(cx: @crate_ctxt, t: ty::t) -> (int, int) {
     let llty = type_of::type_of(cx, t);
     (shape::llsize_of_real(cx, llty) as int,
-     shape::llalign_of_real(cx, llty) as int)
+     shape::llalign_of_pref(cx, llty) as int)
 }
 
 fn create_basic_type(cx: @crate_ctxt, t: ty::t, ty: ast::prim_ty, span: span)

src/rustc/middle/trans/native.rs

@@ -765,7 +765,7 @@ fn trans_intrinsic(ccx: @crate_ctxt, decl: ValueRef, item: @ast::native_item,
               fcx.llretptr);
       }
       "align_of" {
-        Store(bcx, C_uint(ccx, shape::llalign_of_real(ccx, lltp_ty)),
+        Store(bcx, C_uint(ccx, shape::llalign_of_pref(ccx, lltp_ty)),
               fcx.llretptr);
       }
       "get_tydesc" {

src/rustc/middle/trans/shape.rs

@@ -117,7 +117,7 @@ fn largest_variants(ccx: @crate_ctxt, tag_id: ast::def_id) -> [uint] {
             } else {
                 let llty = type_of::type_of(ccx, elem_t);
                 min_size += llsize_of_real(ccx, llty);
-                min_align += llalign_of_real(ccx, llty);
+                min_align += llalign_of_pref(ccx, llty);
             }
         }
 
@@ -190,7 +190,7 @@ fn compute_static_enum_size(ccx: @crate_ctxt, largest_variants: [uint],
 
         let llty = trans::common::T_struct(lltys);
         let dp = llsize_of_real(ccx, llty) as u16;
-        let variant_align = llalign_of_real(ccx, llty) as u8;
+        let variant_align = llalign_of_pref(ccx, llty) as u8;
 
         if max_size < dp { max_size = dp; }
         if max_align < variant_align { max_align = variant_align; }
@@ -202,7 +202,7 @@ fn compute_static_enum_size(ccx: @crate_ctxt, largest_variants: [uint],
     if vec::len(*variants) > 1u {
         let variant_t = T_enum_variant(ccx);
         max_size += llsize_of_real(ccx, variant_t) as u16;
-        let align = llalign_of_real(ccx, variant_t) as u8;
+        let align = llalign_of_pref(ccx, variant_t) as u8;
         if max_align < align { max_align = align; }
     }
 
@@ -630,8 +630,10 @@ fn llsize_of_real(cx: @crate_ctxt, t: TypeRef) -> uint {
     ret llvm::LLVMStoreSizeOfType(cx.td.lltd, t) as uint;
 }
 
-// Returns the real alignment of the given type for the current target.
-fn llalign_of_real(cx: @crate_ctxt, t: TypeRef) -> uint {
+// Returns the preferred alignment of the given type for the current target.
+// The preffered alignment may be larger than the alignment used when
+// packing the type into structs
+fn llalign_of_pref(cx: @crate_ctxt, t: TypeRef) -> uint {
     ret llvm::LLVMPreferredAlignmentOfType(cx.td.lltd, t) as uint;
 }