Object: Add support for bigobj

This adds support for reading the "bigobj" variant of COFF produced by
cl's /bigobj and mingw's -mbig-obj.

The most significant difference that bigobj brings is more than 2**16
sections to COFF.

bigobj brings a few interesting differences with it:
- It doesn't have a Characteristics field in the file header.
- It doesn't have a SizeOfOptionalHeader field in the file header (it's
  only used in executable files).
- Auxiliary symbol records have the same width as a symbol table entry.
  Since symbol table entries are bigger, so are auxiliary symbol
  records.

Write support will come soon.

Differential Revision: http://reviews.llvm.org/D5259

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217496 91177308-0d34-0410-b5e6-96231b3b80d8
ARM: don't size-reduce STMs using the LR register.

The only Thumb-1 multi-store capable of using LR is the PUSH instruction, which
translates to STMDB, so we shouldn't convert STMIAs.

Patch by Sergey Dmitrouk.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217498 91177308-0d34-0410-b5e6-96231b3b80d8
Attempt to pacify buildbots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217499 91177308-0d34-0410-b5e6-96231b3b80d8
Add missing HWEncoding to base register class.

This change gives tblgen the information needed to fill in the
HexagonRegEncodingTable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217500 91177308-0d34-0410-b5e6-96231b3b80d8
[AArch 64] Use a constant pool load for weak symbol references when
using static relocation model and small code model.

Summary: currently we generate GOT based relocations for weak symbol
references regardless of the underlying relocation model. This should
be change so that in static relocation model we use a constant pool
load instead.

Patch from: Keith Walker

Reviewers: Renato Golin, Tim Northover

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217503 91177308-0d34-0410-b5e6-96231b3b80d8
[AArch64] Add experimental PBQP support

This adds target specific support for using the PBQP register allocator on the
AArch64, for the A57 cpu.

By default, the PBQP allocator is not used, unless explicitely required
on the command line with "-aarch64-pbqp".

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217504 91177308-0d34-0410-b5e6-96231b3b80d8
[AArch64] Pacify lld buildbot complaining about an unused static function in release build.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217505 91177308-0d34-0410-b5e6-96231b3b80d8
Merge branch 'master', remote-tracking branch 'trunk/master'
Replace a few virtual with override.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217513 91177308-0d34-0410-b5e6-96231b3b80d8
Fix comments of createReplaceableForwardDecl() and createForwardDecl().

Noticed while trying to understand how the merge of forward decalred types
and defintions work.

Reviewers: echristo, dblaikie, aprantl

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5291

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217514 91177308-0d34-0410-b5e6-96231b3b80d8
Merge branch 'master', remote-tracking branch 'trunk/master'
typo


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217516 91177308-0d34-0410-b5e6-96231b3b80d8
Merge branch 'master', remote-tracking branch 'trunk/master'