Rewrite BitReaderTest, NFC

Rewrite the single unit test in `BitReaderTest` so that it's easier to
add more tests.

  - Parse from an assembly string rather than using API.
  - Use more helper functions.
  - Use a separate context for the module on the other side.

Aside from relying on the assembly parser, there's no functionality
change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214556 91177308-0d34-0410-b5e6-96231b3b80d8
Try to fix configure+make after r214556

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214558 91177308-0d34-0410-b5e6-96231b3b80d8
BitcodeReader: Fix some BlockAddress forward reference corner cases

`BlockAddress`es are interesting in that they can reference basic blocks
from *outside* the block's function.  Since basic blocks are not global
values, this presents particular challenges for lazy parsing.

One corner case was found in PR11677 and fixed in r147425.  In that
case, a global variable references a block address.  It's necessary to
load the relevant function to resolve the forward reference before doing
anything with the module.

By inspection, I found (and have fixed here) two other cases:

  - An instruction from one function references a block address from
    another function, and only the first function is lazily loaded.

    I fixed this the same way as PR11677: by eagerly loading the
    referenced function.

  - A function whose block address is taken is dematerialized, leaving
    invalid references to it.

    I fixed this by refusing to dematerialize functions whose block
    addresses are taken (if you have to load it, you can't unload it).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214559 91177308-0d34-0410-b5e6-96231b3b80d8
Add a non-const subtarget returning function to the target machine
so that we can use it to get the old-style JIT out of the subtarget.

This code should be removed when the old-style JIT is removed
(imminently).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214560 91177308-0d34-0410-b5e6-96231b3b80d8
[dfsan] Correctly handle loads and stores of zero size.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214561 91177308-0d34-0410-b5e6-96231b3b80d8
IR: Add BasicBlock::insertInto()

Although unlinked `BasicBlock`s can be created, there's currently no way
to insert them into `Function`s after the fact.  In particular,
`moveAfter()` and `moveBefore()` require that the basic block is already
linked.

Extract the logic for initially linking a `BasicBlock` out of the
constructor and into a member function that can be used for lazy
insertion.

  - Asserts that the basic block is currently unlinked.
  - Matches the logic of the constructor.
  - Changed the constructor to use it since the logic matches.

This is needed in a follow-up commit for PR5680.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214563 91177308-0d34-0410-b5e6-96231b3b80d8
docs: Strongly recommend setting rpath when using a local GCC toolchain

Users keep emailing us about the difficulties of getting LD_LIBRARY_PATH
into their environment, which should be completely unecessary. Try to
strengthen the rpath recommentation by putting in an example cmake
invocation.

Speaking of which, we might want to make CMake the recommended build
system in GettingStarted.html.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214565 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Move code for generating REGISTER_LOAD into R600ISelLowering.cpp

SI doesn't use REGISTER_LOAD anymore, but it was still hitting this code
path for 8-bit and 16-bit private loads.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214566 91177308-0d34-0410-b5e6-96231b3b80d8
R600/SI: Remove leftover debugging code

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214569 91177308-0d34-0410-b5e6-96231b3b80d8