[Impala-CR](cdh5-trunk) Upgrade LLVM to 3.8.0

["Tim Armstrong (Code Review)" <ge...@cloudera.org>]

Tim Armstrong has uploaded a new patch set (#6).

Change subject: Upgrade LLVM to 3.8.0
......................................................................

Upgrade LLVM to 3.8.0

This requires various changes for Impala to be fully functional with the
new version of LLVM.

The original JIT was removed from LLVM, we need to switch to the new
MCJIT API and implementation.

MCJIT only supports module-at-a-time compilation, so the module must
be finalised before any compilation happens. We did't depend on the
old behaviour deeply, but various small fixes were required.

MCJIT requires that every IR module has a name.

We relied on the old JIT's workaround for the __dso_handle symbol,
which we have to emulate for MCJIT with a customer memory manager
until we can get rid of global initialisers in cross-compiled code.

LLVM made a number of incompatible API changes and reorganised headers.

Clang took over responsibility for padding structs by marking structs
as packed and inserting bytes so that members are aligned correctly
(previously it relies LLVM aligning struct members based on the
target's alignment rules). This means Impala also needs to manually
pad its structs since clang-emitted structs look to LLVM like they have
do not need to be inlined.

Our inlining pass would require some modification to work and is
redundant with LLVM's inlining pass, so was removed along with the
unused subexpr elimination pass.

LLVM now depends on another system library libtinfo, so we use
llvm-config to get the required system libs directly.

There were various issues with __builtin_add_overflow and
__builtin_mul_overflow that are newly available in LLVM 3.8.
First, LLVM emitted a call to a function in libclang_rt, which
we don't link in and has symbols that conflict with
the gcc runtime library. Second, the performance actually regressed
by using the builtins (I tested this manually by copying across the
definition of the required function).

Change-Id: I17d7afd05ad3b472a0bfe035bfc3daada5597b2d
---
M be/CMakeLists.txt
M be/src/benchmarks/hash-benchmark.cc
M be/src/codegen/CMakeLists.txt
M be/src/codegen/codegen-anyval.cc
M be/src/codegen/instruction-counter-test.cc
M be/src/codegen/llvm-codegen-test.cc
M be/src/codegen/llvm-codegen.cc
M be/src/codegen/llvm-codegen.h
A be/src/codegen/mcjit-mem-mgr.h
D be/src/codegen/subexpr-elimination.cc
D be/src/codegen/subexpr-elimination.h
M be/src/exec/aggregation-node.cc
M be/src/exec/hash-join-node.cc
M be/src/exec/hash-table.cc
M be/src/exec/hdfs-avro-scanner.cc
M be/src/exec/hdfs-scanner.cc
M be/src/exec/old-hash-table.cc
M be/src/exec/partitioned-aggregation-node.cc
M be/src/exec/partitioned-hash-join-node.cc
M be/src/exec/text-converter.cc
M be/src/exprs/expr.cc
M be/src/exprs/scalar-fn-call.cc
M be/src/exprs/slot-ref.cc
M be/src/runtime/decimal-value.inline.h
M be/src/runtime/descriptors.cc
M bin/impala-config.sh
M cmake_modules/FindLlvm.cmake
27 files changed, 432 insertions(+), 627 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala refs/changes/86/2486/6
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I17d7afd05ad3b472a0bfe035bfc3daada5597b2d
Gerrit-PatchSet: 6
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Tim Armstrong <ta...@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dh...@cloudera.com>
Gerrit-Reviewer: Michael Ho <kw...@cloudera.com>
Gerrit-Reviewer: Skye Wanderman-Milne <sk...@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <ta...@cloudera.com>