[LLVMdev] RFC: ThinLTO Impementation Plan

Xinliang David Li
Mon, 18 May 2015 22:17:32 -0000

Sean, thanks for the good feedback.

On Mon, May 18, 2015 at 2:47 PM, Sean Silva <chisophugis at gmail.com>
wrote:

>
>
> On Thu, May 14, 2015 at 9:26 AM, Xinliang David Li <xinliangli at
gmail.com>
> wrote:
>
>> The design objective is to make thinLTO mostly transparent to binutil
>> tools to enable easy integration with any build system in the wild.
>>  'Pass-through' mode with 'ld -r' instead of the
partial LTO mode is
>> another reason.
>>
>
> What is your definition of "the wild" when it comes to build
systems? It
> sounds like your current definition is "autotools/make builds on
typical
> GNU/Linux distros".
>

No, we certainly don't want to define build systems like that :)


>
> Merely having the linker do a "parallel make invocation" as your
proposal
> state already presents a huge barrier to integration with almost any build
> system,
>

That (make based system) is just one common case we want to support first.



> far, far beyond any issues of wrapping bitcode.
>

I think these (bitcode wrapper and build files) are two orthogonal issues
to solve.



> As your proposal admits, you are having to make this part custom for your
> own internal build system. The same is going to be true of every build
> system.
>

yes.


>
> If you are serious about "enable easy integration with any build
system in
> the wild", I would recommend at the very least considering the use
cases of
> a couple different common[1] -G settings of LLVM's own CMake build
> (-GNinja, -G'Visual Studio', -G'Xcode'). From my experience
with "the wild"
> of build systems,
>

yes. We hope to support as many popular build systems as possible.
Initially we will add support for make based and our internal large
distributed systems.  We will later add support for Ninja etc -- (e.g., so
that we can turn on thinLTO for Clang self-build easily).   Support for
different parallel BE invocation build file generators are mostly
incremental work which the community can help contribute.



> I would suggest simply dropping any pretense of having this work with any
> build system with any degree of ease.
>
>
Sorry I give you the impression that build system integration is 'easy'
--
it is not as you have commented. That is why we don't want to make it even
harder by imposing more constraints on the underlying build tools.

thanks,

David



> [1] http://llvm.org/docs/GettingStarted.html - "common generators
are"
>
> -- Sean Silva
>
>
>>
>> David
>>
>> On Thu, May 14, 2015 at 7:30 AM, Teresa Johnson <tejohnson at
google.com>
>> wrote:
>>
>>> On Thu, May 14, 2015 at 7:22 AM, Eric Christopher <echristo at
gmail.com>
>>> wrote:
>>> > So, what Alex is saying is that we have these tools as well
and they
>>> > understand bitcode just fine, as well as every object format -
not
>>> just ELF.
>>> > :)
>>>
>>> Right, there are also LLVM specific versions (llvm-ar, llvm-nm)
that
>>> handle bitcode similarly to the way the standard tool + plugin
does.
>>> But the goal we are trying to achieve is to allow the standard
system
>>> versions of the tools to handle these files without requiring a
>>> plugin. I know the LLVM tool handles other object formats, but
I'm not
>>> sure how that helps here? We're not planning to replace those
tools,
>>> just allow the standard system versions to handle the intermediate
>>> objects produced by ThinLTO.
>>>
>>> Thanks,
>>> Teresa
>>>
>>> >
>>> > -eric
>>> >
>>> >
>>> > On Thu, May 14, 2015, 6:55 AM Teresa Johnson <tejohnson at
google.com>
>>> wrote:
>>> >>
>>> >> On Wed, May 13, 2015 at 11:23 PM, Xinliang David Li
>>> >> <xinliangli at gmail.com> wrote:
>>> >> >
>>> >> >
>>> >> > On Wed, May 13, 2015 at 10:46 PM, Alex Rosenberg <
>>> alexr at leftfield.org>
>>> >> > wrote:
>>> >> >>
>>> >> >> "ELF-wrapped bitcode" seems potentially
controversial to me.
>>> >> >>
>>> >> >> What about ar, nm, and various ld implementations
adds this
>>> >> >> requirement?
>>> >> >> What about the LLVM implementations of these
tools is lacking?
>>> >> >
>>> >> >
>>> >> > Sorry I can not parse your questions properly. Can
you make it
>>> clearer?
>>> >>
>>> >> Alex is asking what the issue is with ar, nm, ld -r and
regular
>>> >> bitcode that makes using elf-wrapped bitcode easier.
>>> >>
>>> >> The issue is that generally you need to provide a plugin
to these
>>> >> tools in order for them to understand and handle bitcode
files. We'd
>>> >> like standard tools to work without requiring a plugin as
much as
>>> >> possible. And in some cases we want them to be handled
different than
>>> >> the way bitcode files are handled with the plugin.
>>> >>
>>> >> nm: Without a plugin, normal bitcode files are
inscrutable. When
>>> >> provided the gold plugin it can emit the symbols.
>>> >>
>>> >> ar: Without a plugin, it will create an archive of bitcode
files, but
>>> >> without an index, so it can't be handled by the linker
even with a
>>> >> plugin on an -flto link. When ar is provided the gold
plugin it does
>>> >> create an index, so the linker + gold plugin handle it
appropriately
>>> >> on an -flto link.
>>> >>
>>> >> ld -r: Without a plugin, fails when provided bitcode
inputs. When
>>> >> provided the gold plugin, it handles them but compiles
them all the
>>> >> way through to ELF executable instructions via a partial
LTO link.
>>> >> This is where we would like to differ in behavior (while
also not
>>> >> requiring a plugin) with ELF-wrapped bitcode: we would
like the ld -r
>>> >> output file to still contain ELF-wrapped bitcode, delaying
the LTO
>>> >> until the full link step.
>>> >>
>>> >> Let me know if that helps address your concerns.
>>> >>
>>> >> Thanks,
>>> >> Teresa
>>> >>
>>> >> >
>>> >> > David
>>> >> >
>>> >> >>
>>> >> >>
>>> >> >> Alex
>>> >> >>
>>> >> >> > On May 13, 2015, at 7:44 PM, Teresa Johnson
<
>>> tejohnson at google.com>
>>> >> >> > wrote:
>>> >> >> >
>>> >> >> > I've included below an RFC for
implementing ThinLTO in LLVM,
>>> looking
>>> >> >> > forward to feedback and questions.
>>> >> >> > Thanks!
>>> >> >> > Teresa
>>> >> >> >
>>> >> >> >
>>> >> >> >
>>> >> >> > RFC to discuss plans for implementing
ThinLTO upstream.
>>> Background
>>> >> >> > can
>>> >> >> > be found in slides from EuroLLVM 2015:
>>> >> >> >
>>> >> >> >
>>> >> >> >
>>>
https://drive.google.com/open?id=0B036uwnWM6RWWER1ZEl5SUNENjQ&authuser=0
>>> )
>>> >> >> > As described in the talk, we have a
prototype implementation, and
>>> >> >> > would like to start staging patches
upstream. This RFC describes
>>> a
>>> >> >> > breakdown of the major pieces. We would like
to commit upstream
>>> >> >> > gradually in several stages, with all
functionality off by
>>> default.
>>> >> >> > The core ThinLTO importing support and
tuning will require
>>> frequent
>>> >> >> > change and iteration during testing and
tuning, and for that
>>> part we
>>> >> >> > would like to commit rapidly (off by
default). See the proposed
>>> >> >> > staged
>>> >> >> > implementation described in the
Implementation Plan section.
>>> >> >> >
>>> >> >> >
>>> >> >> > ThinLTO Overview
>>> >> >> > =============>>> >> >>
>
>>> >> >> > See the talk slides linked above for more
details. The following
>>> is a
>>> >> >> > high-level overview of the motivation.
>>> >> >> >
>>> >> >> > Cross Module Optimization (CMO) is an
effective means for
>>> improving
>>> >> >> > runtime performance, by extending the scope
of optimizations
>>> across
>>> >> >> > source module boundaries. Without CMO, the
compiler is limited to
>>> >> >> > optimizing within the scope of single source
modules. Two
>>> solutions
>>> >> >> > for enabling CMO are Link-Time Optimization
(LTO), which is
>>> currently
>>> >> >> > supported in LLVM and GCC, and
Lightweight-Interprocedural
>>> >> >> > Optimization (LIPO). However, each of these
solutions has
>>> limitations
>>> >> >> > that prevent it from being enabled by
default. ThinLTO is a new
>>> >> >> > approach that attempts to address these
limitations, with a goal
>>> of
>>> >> >> > being enabled more broadly. ThinLTO is
designed with many of the
>>> same
>>> >> >> > principals as LIPO, and therefore its
advantages, without any of
>>> its
>>> >> >> > inherent weakness. Unlike in LIPO where the
module group
>>> decision is
>>> >> >> > made at profile training runtime, ThinLTO
makes the decision at
>>> >> >> > compile time, but in a lazy mode that
facilitates large scale
>>> >> >> > parallelism. The serial linker plugin phase
is designed to be
>>> razor
>>> >> >> > thin and blazingly fast. By default this
step only does minimal
>>> >> >> > preparation work to enable the parallel lazy
importing performed
>>> >> >> > later. ThinLTO aims to be scalable like a
regular O2 build,
>>> enabling
>>> >> >> > CMO on machines without large memory
configurations, while also
>>> >> >> > integrating well with distributed build
systems. Results from
>>> early
>>> >> >> > prototyping on SPEC cpu2006 C++ benchmarks
are in line with
>>> >> >> > expectations that ThinLTO can scale like O2
while enabling much
>>> of
>>> >> >> > the
>>> >> >> > CMO performed during a full LTO build.
>>> >> >> >
>>> >> >> >
>>> >> >> > A ThinLTO build is divided into 3 phases,
which are referred to
>>> in
>>> >> >> > the
>>> >> >> > following implementation plan:
>>> >> >> >
>>> >> >> > phase-1: IR and Function Summary Generation
(-c compile)
>>> >> >> > phase-2: Thin Linker Plugin Layer (thin
archive linker step)
>>> >> >> > phase-3: Parallel Backend with Demand-Driven
Importing
>>> >> >> >
>>> >> >> >
>>> >> >> > Implementation Plan
>>> >> >> > ===============>>> >>
>> >
>>> >> >> > This section gives a high-level breakdown of
the ThinLTO support
>>> that
>>> >> >> > will be added, in roughly the order that the
patches would be
>>> staged.
>>> >> >> > The patches are divided into three stages.
The first stage
>>> contains a
>>> >> >> > minimal amount of preparation work that is
not ThinLTO-specific.
>>> The
>>> >> >> > second stage contains most of the
infrastructure for ThinLTO,
>>> which
>>> >> >> > will be off by default. The third stage
includes
>>> >> >> > enhancements/improvements/tunings that can
be performed after the
>>> >> >> > main
>>> >> >> > ThinLTO infrastructure is in.
>>> >> >> >
>>> >> >> > The second and third implementation stages
will initially be very
>>> >> >> > volatile, requiring a lot of iterations and
tuning with large
>>> apps to
>>> >> >> > get stabilized. Therefore it will be
important to do fast
>>> commits for
>>> >> >> > these implementation stages.
>>> >> >> >
>>> >> >> >
>>> >> >> > 1. Stage 1: Preparation
>>> >> >> > -------------------------------
>>> >> >> >
>>> >> >> > The first planned sets of patches are
enablers for ThinLTO work:
>>> >> >> >
>>> >> >> >
>>> >> >> > a. LTO directory structure:
>>> >> >> >
>>> >> >> > Restructure the LTO directory to remove
circular dependence when
>>> >> >> > ThinLTO pass added. Because ThinLTO is being
implemented as a SCC
>>> >> >> > pass
>>> >> >> > within Transforms/IPO, and leverages the
LTOModule class for
>>> linking
>>> >> >> > in functions from modules, IPO then requires
the LTO library.
>>> This
>>> >> >> > creates a circular dependence between LTO
and IPO. To break
>>> that, we
>>> >> >> > need to split the lib/LTO directory/library
into lib/LTO/CodeGen
>>> and
>>> >> >> > lib/LTO/Module, containing LTOCodeGenerator
and LTOModule,
>>> >> >> > respectively. Only LTOCodeGenerator has a
dependence on IPO,
>>> removing
>>> >> >> > the circular dependence.
>>> >> >> >
>>> >> >> >
>>> >> >> > b. ELF wrapper generation support:
>>> >> >> >
>>> >> >> > Implement ELF wrapped bitcode writer. In
order to more easily
>>> >> >> > interact
>>> >> >> > with tools such as $AR, $NM, and “$LD -r” we
plan to emit the
>>> phase-1
>>> >> >> > bitcode wrapped in ELF via the .llvmbc
section, along with a
>>> symbol
>>> >> >> > table. The goal is both to interact with
these tools without
>>> >> >> > requiring
>>> >> >> > a plugin, and also to avoid doing partial
LTO/ThinLTO across
>>> files
>>> >> >> > linked with “$LD -r” (i.e. the resulting
object file should still
>>> >> >> > contain ELF-wrapped bitcode to enable
ThinLTO at the full link
>>> step).
>>> >> >> > I will send a separate design document for
these changes, but the
>>> >> >> > following is a high-level overview.
>>> >> >> >
>>> >> >> > Support was added to LLVM for reading
ELF-wrapped bitcode
>>> >> >> > (http://reviews.llvm.org/rL218078), but
there does not yet exist
>>> >> >> > support in LLVM/Clang for emitting bitcode
wrapped in ELF. I
>>> plan to
>>> >> >> > add support for optionally generating
bitcode in an ELF file
>>> >> >> > containing a single .llvmbc section holding
the bitcode.
>>> >> >> > Specifically,
>>> >> >> > the patch would add new options
“emit-llvm-bc-elf” (object file)
>>> and
>>> >> >> > corresponding “emit-llvm-elf” (textual
assembly code equivalent).
>>> >> >> > Eventually these would be automatically
triggered under
>>> “-fthinlto
>>> >> >> > -c”
>>> >> >> > and “-fthinlto -S”, respectively.
>>> >> >> >
>>> >> >> > Additionally, a symbol table will be
generated in the ELF file,
>>> >> >> > holding the function symbols within the
bitcode. This facilitates
>>> >> >> > handling archives of the ELF-wrapped bitcode
created with $AR,
>>> since
>>> >> >> > the archive will have a symbol table as
well. The archive symbol
>>> >> >> > table
>>> >> >> > enables gold to extract and pass to the
plugin the constituent
>>> >> >> > ELF-wrapped bitcode files. To support the
concatenated llvmbc
>>> section
>>> >> >> > generated by “$LD -r”, some handling needs
to be added to gold
>>> and to
>>> >> >> > the backend driver to process each original
module’s bitcode.
>>> >> >> >
>>> >> >> > The function index/summary will later be
added as a special ELF
>>> >> >> > section alongside the .llvmbc sections.
>>> >> >> >
>>> >> >> >
>>> >> >> > 2. Stage 2: ThinLTO Infrastructure
>>> >> >> >
----------------------------------------------
>>> >> >> >
>>> >> >> > The next set of patches adds the base
implementation of the
>>> ThinLTO
>>> >> >> > infrastructure, specifically those required
to make ThinLTO
>>> >> >> > functional
>>> >> >> > and generate correct but not necessarily
high-performing
>>> binaries. It
>>> >> >> > also does not include support to make debug
support under -g
>>> >> >> > efficient
>>> >> >> > with ThinLTO.
>>> >> >> >
>>> >> >> >
>>> >> >> > a. Clang/LLVM/gold linker options:
>>> >> >> >
>>> >> >> > An early set of clang/llvm patches is needed
to provide options
>>> to
>>> >> >> > enable ThinLTO (off by default), so that the
rest of the
>>> >> >> > implementation can be disabled by default as
it is added.
>>> >> >> > Specifically, clang options -fthinlto (used
instead of -flto)
>>> will
>>> >> >> > cause clang to invoke the phase-1 emission
of LLVM bitcode and
>>> >> >> > function summary/index on a compile step,
and pass the
>>> appropriate
>>> >> >> > option to the gold plugin on a link step.
The -thinlto option
>>> will be
>>> >> >> > added to the gold plugin and llvm-lto tool
to launch the phase-2
>>> thin
>>> >> >> > archive step. The -thinlto option will also
be added to the ‘opt’
>>> >> >> > tool
>>> >> >> > to invoke it as a phase-3 parallel backend
instance.
>>> >> >> >
>>> >> >> >
>>> >> >> > b. Thin-archive linking support in Gold
plugin and llvm-lto:
>>> >> >> >
>>> >> >> > Under the new plugin option (see above), the
plugin needs to
>>> perform
>>> >> >> > the phase-2 (thin archive) link which simply
emits a combined
>>> >> >> > function
>>> >> >> > map from the linked modules, without
actually performing the
>>> normal
>>> >> >> > link. Corresponding support should be added
to the standalone
>>> >> >> > llvm-lto
>>> >> >> > tool to enable testing/debugging without
involving the linker and
>>> >> >> > plugin.
>>> >> >> >
>>> >> >> >
>>> >> >> > c. ThinLTO backend support:
>>> >> >> >
>>> >> >> > Support for invoking a phase-3 backend
invocation (including
>>> >> >> > importing) on a module should be added to
the ‘opt’ tool under
>>> the
>>> >> >> > new
>>> >> >> > option. The main change under the option is
to instantiate a
>>> Linker
>>> >> >> > object used to manage the process of linking
imported functions
>>> into
>>> >> >> > the module, efficient read of the combined
function map, and
>>> enable
>>> >> >> > the ThinLTO import pass.
>>> >> >> >
>>> >> >> >
>>> >> >> > d. Function index/summary support:
>>> >> >> >
>>> >> >> > This includes infrastructure for writing and
reading the function
>>> >> >> > index/summary section. As noted earlier this
will be encoded in a
>>> >> >> > special ELF section within the module,
alongside the .llvmbc
>>> section
>>> >> >> > containing the bitcode. The thin archive
generated by phase-2 of
>>> >> >> > ThinLTO simply contains all of the function
index/summary
>>> sections
>>> >> >> > across the linked modules, organized for
efficient function
>>> lookup.
>>> >> >> >
>>> >> >> > Each function available for importing from
the module contains an
>>> >> >> > entry in the module’s function index/summary
section and in the
>>> >> >> > resulting combined function map. Each
function entry contains
>>> that
>>> >> >> > function’s offset within the bitcode file,
used to efficiently
>>> locate
>>> >> >> > and quickly import just that function. The
entry also contains
>>> >> >> > summary
>>> >> >> > information (e.g. basic information
determined during parsing
>>> such as
>>> >> >> > the number of instructions in the function),
that will be used to
>>> >> >> > help
>>> >> >> > guide later import decisions. Because the
contents of this
>>> section
>>> >> >> > will change frequently during ThinLTO
tuning, it should also be
>>> >> >> > marked
>>> >> >> > with a version id for backwards
compatibility or version
>>> checking.
>>> >> >> >
>>> >> >> >
>>> >> >> > e. ThinLTO importing support:
>>> >> >> >
>>> >> >> > Support for the mechanics of importing
functions from other
>>> modules,
>>> >> >> > which can go in gradually as a set of
patches since it will be
>>> off by
>>> >> >> > default. Separate patches can include:
>>> >> >> >
>>> >> >> > - BitcodeReader changes to use function
index to
>>> import/deserialize
>>> >> >> > single function of interest (small changes,
leverages existing
>>> lazy
>>> >> >> > streamer support).
>>> >> >> >
>>> >> >> > - Minor LTOModule changes to pass the
ThinLTO function to import
>>> and
>>> >> >> > its index into bitcode reader.
>>> >> >> >
>>> >> >> > - Marking of imported functions (for use in
ThinLTO-specific
>>> symbol
>>> >> >> > linking and global DCE, for example). This
can be in-memory
>>> >> >> > initially,
>>> >> >> > but IR support may be required in order to
support streaming
>>> bitcode
>>> >> >> > out and back in again after importing.
>>> >> >> >
>>> >> >> > - ModuleLinker changes to do
ThinLTO-specific symbol linking and
>>> >> >> > static promotion when necessary. The linkage
type of imported
>>> >> >> > functions changes to
AvailableExternallyLinkage, for example.
>>> Statics
>>> >> >> > must be promoted in certain cases, and
renamed in consistent
>>> ways.
>>> >> >> >
>>> >> >> > - GlobalDCE changes to support removing
imported functions that
>>> were
>>> >> >> > not inlined (very small changes to existing
pass logic).
>>> >> >> >
>>> >> >> >
>>> >> >> > f. ThinLTO Import Driver SCC pass:
>>> >> >> >
>>> >> >> > Adds Transforms/IPO/ThinLTO.cpp with
framework for doing ThinLTO
>>> via
>>> >> >> > an SCC pass, enabled only under -fthinlto
options. The pass
>>> includes
>>> >> >> > utilizing the thin archive (global function
index/summary),
>>> import
>>> >> >> > decision heuristics, invocation of
LTOModule/ModuleLinker
>>> routines
>>> >> >> > that perform the import, and any necessary
callgraph updates and
>>> >> >> > verification.
>>> >> >> >
>>> >> >> >
>>> >> >> > g. Backend Driver:
>>> >> >> >
>>> >> >> > For a single node build, the gold plugin can
simply write a
>>> makefile
>>> >> >> > and fork the parallel backend instances
directly via parallel
>>> make.
>>> >> >> >
>>> >> >> >
>>> >> >> > 3. Stage 3: ThinLTO Tuning and Enhancements
>>> >> >> >
----------------------------------------------------------------
>>> >> >> >
>>> >> >> > This refers to the patches that are not
required for ThinLTO to
>>> work,
>>> >> >> > but rather to improve compile time, memory,
run-time performance
>>> and
>>> >> >> > usability.
>>> >> >> >
>>> >> >> >
>>> >> >> > a. Lazy Debug Metadata Linking:
>>> >> >> >
>>> >> >> > The prototype implementation included lazy
importing of
>>> module-level
>>> >> >> > metadata during the ThinLTO pass
finalization (i.e. after all
>>> >> >> > function
>>> >> >> > importing is complete). This actually
applies to all module-level
>>> >> >> > metadata, not just debug, although it is the
largest. This can be
>>> >> >> > added as a separate set of patches. Changes
to BitcodeReader,
>>> >> >> > ValueMapper, ModuleLinker
>>> >> >> >
>>> >> >> >
>>> >> >> > b. Import Tuning:
>>> >> >> >
>>> >> >> > Tuning the import strategy will be an
iterative process that will
>>> >> >> > continue to be refined over time. It
involves several different
>>> types
>>> >> >> > of changes: adding support for recording
additional metrics in
>>> the
>>> >> >> > function summary, such as profile data and
optional
>>> heavier-weight
>>> >> >> > IPA
>>> >> >> > analyses, and tuning the import heuristics
based on the summary
>>> and
>>> >> >> > callsite context.
>>> >> >> >
>>> >> >> >
>>> >> >> > c. Combined Function Map Pruning:
>>> >> >> >
>>> >> >> > The combined function map can be pruned of
functions that are
>>> >> >> > unlikely
>>> >> >> > to benefit from being imported. For example,
during the phase-2
>>> thin
>>> >> >> > archive plug step we can safely omit large
and (with profile
>>> data)
>>> >> >> > cold functions, which are unlikely to
benefit from being inlined.
>>> >> >> > Additionally, all but one copy of comdat
functions can be
>>> suppressed.
>>> >> >> >
>>> >> >> >
>>> >> >> > d. Distributed Build System Integration:
>>> >> >> >
>>> >> >> > For a distributed build system, the gold
plugin should write the
>>> >> >> > parallel backend invocations into a
makefile, including the
>>> mapping
>>> >> >> > from the IR file to the real object file
path, and exit.
>>> Additional
>>> >> >> > work needs to be done in the distributed
build system itself to
>>> >> >> > distribute and dispatch the parallel backend
jobs to the build
>>> >> >> > cluster.
>>> >> >> >
>>> >> >> >
>>> >> >> > e. Dependence Tracking and Incremental
Compiles:
>>> >> >> >
>>> >> >> > In order to support build systems that stage
from local disks or
>>> >> >> > network storage, the plugin will optionally
support computation
>>> of
>>> >> >> > dependent sets of IR files that each module
may import from.
>>> This can
>>> >> >> > be computed from profile data, if it exists,
or from the symbol
>>> table
>>> >> >> > and heuristics if not. These dependence sets
also enable support
>>> for
>>> >> >> > incremental backend compiles.
>>> >> >> >
>>> >> >> >
>>> >> >> >
>>> >> >> > --
>>> >> >> > Teresa Johnson | Software Engineer |
tejohnson at google.com |
>>> >> >> > 408-460-2413
>>> >> >> >
>>> >> >> >
_______________________________________________
>>> >> >> > LLVM Developers mailing list
>>> >> >> > LLVMdev at cs.uiuc.edu
http://llvm.cs.uiuc.edu
>>> >> >> >
http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>> >> >>
>>> >> >> _______________________________________________
>>> >> >> LLVM Developers mailing list
>>> >> >> LLVMdev at cs.uiuc.edu
http://llvm.cs.uiuc.edu
>>> >> >> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>> >> >
>>> >> >
>>> >>
>>> >>
>>> >>
>>> >> --
>>> >> Teresa Johnson | Software Engineer | tejohnson at
google.com |
>>> 408-460-2413
>>> >>
>>> >> _______________________________________________
>>> >> LLVM Developers mailing list
>>> >> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>> >> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>
>>>
>>>
>>> --
>>> Teresa Johnson | Software Engineer | tejohnson at google.com |
408-460-2413
>>>
>>
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>>
>
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