Move some logic to populateLTOPassManager.

This will avoid code duplication in the next commit which calls it directly
from the gold plugin.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216211 91177308-0d34-0410-b5e6-96231b3b80d8
Satiate the sanitizer build bot

This fixes a missing initializer from r216182


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216212 91177308-0d34-0410-b5e6-96231b3b80d8
Rewrite the gold plugin to fix pr19901.

There is a fundamental difference between how the gold API and lib/LTO view
the LTO process.

The gold API talks about a particular symbol in a particular file. The lib/LTO
API talks about a symbol in the merged module.

The merged module is then defined in terms of the IR semantics. In particular,
a linkonce_odr GV is only copied if it is used, since it is valid to drop
unused linkonce_odr GVs.

In the testcase in pr19901 both properties collide. What happens is that gold
asks us to keep a particular linkonce_odr symbol, but the IR linker doesn't
copy it to the merged module and we never have a chance to ask lib/LTO to keep
it.

This patch fixes it by having a more direct implementation of the gold API. If
it asks us to keep a symbol, we change the linkage so it is not linkonce. If it
says we can drop a symbol, we do so. All of this before we even send the module
to lib/Linker.

Since now we don't have to produce LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN,
during symbol resolution we can use a temporary LLVMContext and do lazy
module loading. This allows us to keep the minimum possible amount of
allocated memory around. This should also allow as much parallelism as
we want, since there is no shared context.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216215 91177308-0d34-0410-b5e6-96231b3b80d8
R600/SI: Handle VCC in SIRegisterInfo::getPhysRegSubReg()

This fixes a crash in an ocl conformance test.  The test requries
register spilling and is too big to include.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216216 91177308-0d34-0410-b5e6-96231b3b80d8
R600/SI: Use eliminateFrameIndex() to expand SGPR spill pseudos

This will simplify the SGPR spilling and also allow us to use
MachineFrameInfo for calculating offsets, which should be more
reliable than our custom code.

This fixes a crash in some cases where a register would be spilled
in a branch such that the VGPR defined for spilling did not dominate
all the uses when restoring.

This fixes a crash in an ocl conformance test.  The test requries
register spilling and is too big to include.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216217 91177308-0d34-0410-b5e6-96231b3b80d8
R600/SI: Remove unused SGPR spilling code

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216218 91177308-0d34-0410-b5e6-96231b3b80d8
R600/SI: Make sure SCRATCH_WAVE_OFFSET is added as Live-In to the function

This fixes a crash in an ocl conformance test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216219 91177308-0d34-0410-b5e6-96231b3b80d8
R600/SI: Teach moveToVALU how to handle more S_LOAD_* instructions

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216220 91177308-0d34-0410-b5e6-96231b3b80d8
Explicitly pass ownership of the MemoryBuffer to AddNewSourceBuffer using std::unique_ptr

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216223 91177308-0d34-0410-b5e6-96231b3b80d8