Commit Graph

1101 Commits

Author SHA1 Message Date
Michael Ilseman be92bcb341 Use present fast-math flags when applicable in CreateBinOp
We were previously not adding fast-math flags through CreateBinOp()
when it happened to be making a floating point binary operator. This
patch updates it to do so similarly to directly calling CreateF*().

llvm-svn: 196438
2013-12-05 00:32:09 +00:00
Diego Novillo ee592429f1 Fix dominator descendants for unreachable blocks.
When a block is unreachable, asking its dom tree descendants should
return the empty set. However, the computation of the descendants
was causing a segmentation fault because the dom tree node we get
from the basic block is initially NULL.

Fixed by adding a test for a valid dom tree node before we iterate.

The patch also adds some unit tests to the existing dom tree tests.

llvm-svn: 196099
2013-12-02 14:08:27 +00:00
NAKAMURA Takumi c08227de0e [CMake] Also OptionTests can be free from add_dependencies() with add_public_tablegen_target().
llvm-svn: 195928
2013-11-28 17:04:13 +00:00
Chandler Carruth 6378cf539f [PM] Split the CallGraph out from the ModulePass which creates the
CallGraph.

This makes the CallGraph a totally generic analysis object that is the
container for the graph data structure and the primary interface for
querying and manipulating it. The pass logic is separated into its own
class. For compatibility reasons, the pass provides wrapper methods for
most of the methods on CallGraph -- they all just forward.

This will allow the new pass manager infrastructure to provide its own
analysis pass that constructs the same CallGraph object and makes it
available. The idea is that in the new pass manager, the analysis pass's
'run' method returns a concrete analysis 'result'. Here, that result is
a 'CallGraph'. The 'run' method will typically do only minimal work,
deferring much of the work into the implementation of the result object
in order to be lazy about computing things, but when (like DomTree)
there is *some* up-front computation, the analysis does it prior to
handing the result back to the querying pass.

I know some of this is fairly ugly. I'm happy to change it around if
folks can suggest a cleaner interim state, but there is going to be some
amount of unavoidable ugliness during the transition period. The good
thing is that this is very limited and will naturally go away when the
old pass infrastructure goes away. It won't hang around to bother us
later.

Next up is the initial new-PM-style call graph analysis. =]

llvm-svn: 195722
2013-11-26 04:19:30 +00:00
Chandler Carruth c1ff9ed6e0 [PM] Complete the cross-layer interfaces with a Module-to-Function
proxy. This lets a function pass query a module analysis manager.
However, the interface is const to indicate that only cached results can
be safely queried.

With this, I think the new pass manager is largely functionally complete
for modules and analyses. Still lots to test, and need to generalize to
SCCs and Loops, and need to build an adaptor layer to support the use of
existing Pass objects in the new managers.

llvm-svn: 195538
2013-11-23 01:25:07 +00:00
Chandler Carruth 2ad185836f [PM] Rename TestAnalysisPass to TestFunctionAnalysis to clear the way
for a TestModuleAnalysis.

llvm-svn: 195537
2013-11-23 01:25:02 +00:00
Chandler Carruth de9afd845b [PM] Add support to the analysis managers to query explicitly for cached
results.

This is the last piece of infrastructure needed to effectively support
querying *up* the analysis layers. The next step will be to introduce
a proxy which provides access to those layers with appropriate use of
const to direct queries to the safe interface.

llvm-svn: 195525
2013-11-23 00:38:42 +00:00
Chandler Carruth bceeb22905 [PM] Switch the downward invalidation to be incremental where only the
one function's analyses are invalidated at a time. Also switch the
preservation of the proxy to *fully* preserve the lower (function)
analyses.

Combined, this gets both upward and downward analysis invalidation to
a point I'm happy with:

- A function pass invalidates its function analyses, and its parent's
  module analyses.
- A module pass invalidates all of its functions' analyses including the
  set of which functions are in the module.
- A function pass can preserve a module analysis pass.
- If all function passes preserve a module analysis pass, that
  preservation persists. If any doesn't the module analysis is
  invalidated.
- A module pass can opt into managing *all* function analysis
  invalidation itself or *none*.
- The conservative default is none, and the proxy takes the maximally
  conservative approach that works even if the set of functions has
  changed.
- If a module pass opts into managing function analysis invalidation it
  has to propagate the invalidation itself, the proxy just does nothing.

The only thing really missing is a way to query for a cached analysis or
nothing at all. With this, function passes can more safely request
a cached module analysis pass without fear of it accidentally running
part way through.

llvm-svn: 195519
2013-11-22 23:38:07 +00:00
Chandler Carruth f2edc07571 [PM] Teach the analysis managers to pass themselves as arguments to the
run methods of the analysis passes.

Also generalizes and re-uses the SFINAE for transformation passes so
that users can write an analysis pass and only accept an analysis
manager if that is useful to their pass.

This completes the plumbing to make an analysis manager available
through every pass's run method if desired so that passes no longer need
to be constructed around them.

llvm-svn: 195451
2013-11-22 12:11:02 +00:00
Chandler Carruth bf950c0f6f [PM] Remove the IRUnitT typedef requirement for analysis passes.
Since the analysis managers were split into explicit function and module
analysis managers, it is now completely trivial to specify this when
building up the concept and model types explicitly, and it is impossible
to end up with a type error at run time. We instantiate a template when
registering a pass that will enforce the requirement at a type-system
level, and we produce a dynamic error on all the other query paths to
the analysis manager if the pass in question isn't registered.

llvm-svn: 195447
2013-11-22 11:46:33 +00:00
Chandler Carruth 5bf5e31c5a [PM] Fix the analysis templates' usage of IRUnitT.
This is supposed to be the whole type of the IR unit, and so we
shouldn't pass a pointer to it but rather the value itself. In turn, we
need to provide a 'Module *' as that type argument (for example). This
will become more relevant with SCCs or other units which may not be
passed as a pointer type, but also brings consistency with the
transformation pass templates.

llvm-svn: 195445
2013-11-22 11:34:43 +00:00
Michael Gottesman 983f94a2b6 [block-freq] Update data in test case to be unsigned long long to fix mingw build.
llvm-svn: 195411
2013-11-22 05:00:51 +00:00
Chandler Carruth b3e721995f [PM] Switch analysis managers to be threaded through the run methods
rather than the constructors of passes.

This simplifies the APIs of passes significantly and removes an error
prone pattern where the *same* manager had to be given to every
different layer. With the new API the analysis managers themselves will
have to be cross connected with proxy analyses that allow a pass at one
layer to query for the analysis manager of another layer. The proxy will
both expose a handle to the other layer's manager and it will provide
the invalidation hooks to ensure things remain consistent across layers.
Finally, the outer-most analysis manager has to be passed to the run
method of the outer-most pass manager. The rest of the propagation is
automatic.

I've used SFINAE again to allow passes to completely disregard the
analysis manager if they don't need or want to care. This helps keep
simple things simple for users of the new pass manager.

Also, the system specifically supports passing a null pointer into the
outer-most run method if your pass pipeline neither needs nor wants to
deal with analyses. I find this of dubious utility as while some
*passes* don't care about analysis, I'm not sure there are any
real-world users of the pass manager itself that need to avoid even
creating an analysis manager. But it is easy to support, so there we go.

Finally I renamed the module proxy for the function analysis manager to
the more verbose but less confusing name of
FunctionAnalysisManagerModuleProxy. I hate this name, but I have no idea
what else to name these things. I'm expecting in the fullness of time to
potentially have the complete cross product of types at the proxy layer:

{Module,SCC,Function,Loop,Region}AnalysisManager{Module,SCC,Function,Loop,Region}Proxy

(except for XAnalysisManagerXProxy which doesn't make any sense)

This should make it somewhat easier to do the next phases which is to
build the upward proxy and get its invalidation correct, as well as to
make the invalidation within the Module -> Function mapping pass be more
fine grained so as to invalidate fewer fuction analyses.

After all of the proxy analyses are done and the invalidation working,
I'll finally be able to start working on the next two fun fronts: how to
adapt an existing pass to work in both the legacy pass world and the new
one, and building the SCC, Loop, and Region counterparts. Fun times!

llvm-svn: 195400
2013-11-22 00:43:29 +00:00
Chandler Carruth 2846e9ef15 [PM] Widen the interface for invalidate on an analysis result now that
it is completely optional, and sink the logic for handling the preserved
analysis set into it.

This allows us to implement the delegation logic desired in the proxy
module analysis for the function analysis manager where if the proxy
itself is preserved we assume the set of functions hasn't changed and we
do a fine grained invalidation by walking the functions in the module
and running the invalidate for them all at the manager level and letting
it try to invalidate any passes.

This in turn makes it blindingly obvious why we should hoist the
invalidate trait and have two collections of results. That allows
handling invalidation for almost all analyses without indirect calls and
it allows short circuiting when the preserved set is all.

llvm-svn: 195338
2013-11-21 10:53:05 +00:00
Chandler Carruth f6e9986a41 [PM] Add support for using SFINAE to reflect on an analysis's result
type and detect whether or not it provides an 'invalidate' member the
analysis manager should use.

This lets the overwhelming common case of *not* caring about custom
behavior when an analysis is invalidated be the the obvious default
behavior with no code written by the author of an analysis. Only when
they write code specifically to handle invalidation does it get used.

Both cases are actually covered by tests here. The test analysis uses
the default behavior, and the proxy module analysis actually has custom
behavior on invalidation that is firing correctly. (In fact, this is the
analysis which was the primary motivation for having custom invalidation
behavior in the first place.)

llvm-svn: 195332
2013-11-21 09:10:21 +00:00
Chandler Carruth 851a2aa0e0 [PM] Add a module analysis pass proxy for the function analysis manager.
This proxy will fill the role of proxying invalidation events down IR
unit layers so that when a module changes we correctly invalidate
function analyses. Currently this is a very coarse solution -- any
change blows away the entire thing -- but the next step is to make
invalidation handling more nuanced so that we can propagate specific
amounts of invalidation from one layer to the next.

The test is extended to place a module pass between two function pass
managers each of which have preserved function analyses which get
correctly invalidated by the module pass that might have changed what
functions are even in the module.

llvm-svn: 195304
2013-11-21 02:11:31 +00:00
Nick Kledzik 7cd45f29b2 YAML I/O add support for validate()
MappingTrait template specializations can now have a validate() method which 
performs semantic checking. For details, see <http://llvm.org/docs/YamlIO.html>.

llvm-svn: 195286
2013-11-21 00:28:07 +00:00
Nick Kledzik 4761c60eef revert r194655
llvm-svn: 195285
2013-11-21 00:20:10 +00:00
Chandler Carruth c74010df48 Make the moved-from SmallPtrSet be a valid, empty, small-state object.
Enhance the tests to actually require moves in C++11 mode, in addition
to testing the moved-from state. Further enhance the tests to cover
copy-assignment into a moved-from object and moving a large-state
object. (Note that we can't really test small-state vs. large-state as
that isn't an observable property of the API really.) This should finish
addressing review on r195239.

llvm-svn: 195261
2013-11-20 18:29:56 +00:00
Chandler Carruth 6d888bc0da Add a test for assignment operator behavior which was changed in
r195239, as well as a comment about the fact that assigning over
a moved-from object was in fact tested. Addresses some of the review
feedback on r195239.

llvm-svn: 195260
2013-11-20 18:21:25 +00:00
Chandler Carruth c0bfa8c231 [PM] Add the preservation system to the new pass manager.
This adds a new set-like type which represents a set of preserved
analysis passes. The set is managed via the opaque PassT::ID() void*s.
The expected convenience templates for interacting with specific passes
are provided. It also supports a symbolic "all" state which is
represented by an invalid pointer in the set. This state is nicely
saturating as it comes up often. Finally, it supports intersection which
is used when finding the set of preserved passes after N different
transforms.

The pass API is then changed to return the preserved set rather than
a bool. This is much more self-documenting than the previous system.
Returning "none" is a conservatively correct solution just like
returning "true" from todays passes and not marking any passes as
preserved. Passes can also be dynamically preserved or not throughout
the run of the pass, and whatever gets returned is the binding state.
Finally, preserving "all" the passes is allowed for no-op transforms
that simply can't harm such things.

Finally, the analysis managers are changed to instead of blindly
invalidating all of the analyses, invalidate those which were not
preserved. This should rig up all of the basic preservation
functionality. This also correctly combines the preservation moving up
from one IR-layer to the another and the preservation aggregation across
N pass runs. Still to go is incrementally correct invalidation and
preservation across IR layers incrementally during N pass runs. That
will wait until we have a device for even exposing analyses across IR
layers.

While the core of this change is obvious, I'm not happy with the current
testing, so will improve it to cover at least some of the invalidation
that I can test easily in a subsequent commit.

llvm-svn: 195241
2013-11-20 11:31:50 +00:00
Chandler Carruth 55758e9691 Give SmallPtrSet move semantics when we have R-value references.
Somehow, this ADT got missed which is moderately terrifying considering
the efficiency of move for it.

The code to implement move semantics for it is pretty horrible
currently but was written to reasonably closely match the rest of the
code. Unittests that cover both copying and moving (at a basic level)
added.

llvm-svn: 195239
2013-11-20 11:14:33 +00:00
Chandler Carruth d895e29e88 [PM] Make the function pass manager more regular.
The FunctionPassManager is now itself a function pass. When run over
a function, it runs all N of its passes over that function. This is the
1:N mapping in the pass dimension only. This allows it to be used in
either a ModulePassManager or potentially some other manager that
works on IR units which are supersets of Functions.

This commit also adds the obvious adaptor to map from a module pass to
a function pass, running the function pass across every function in the
module.

The test has been updated to use this new pattern.

llvm-svn: 195192
2013-11-20 04:39:16 +00:00
Chandler Carruth ed1ffe0197 [PM] Split the analysis manager into a function-specific interface and
a module-specific interface. This is the first of many steps necessary
to generalize the infrastructure such that we can support both
a Module-to-Function and Module-to-SCC-to-Function pass manager
nestings.

After a *lot* of attempts that never worked and didn't even make it to
a committable state, it became clear that I had gotten the layering
design of analyses flat out wrong. Four days later, I think I have most
of the plan for how to correct this, and I'm starting to reshape the
code into it. This is just a baby step I'm afraid, but starts separating
the fundamentally distinct concepts of function analysis passes and
module analysis passes so that in subsequent steps we can effectively
layer them, and have a consistent design for the eventual SCC layer.

As part of this, I've started some interface changes to make passes more
regular. The module pass accepts the module in the run method, and some
of the constructor parameters are gone. I'm still working out exactly
where constructor parameters vs. method parameters will be used, so
I expect this to fluctuate a bit.

This actually makes the invalidation less "correct" at this phase,
because now function passes don't invalidate module analysis passes, but
that was actually somewhat of a misfeature. It will return in a better
factored form which can scale to other units of IR. The documentation
has gotten less verbose and helpful.

llvm-svn: 195189
2013-11-20 04:01:38 +00:00
John Thompson 48e018a314 YAML I/O - Added default trait support for std:string. Making another attempt at this, this time doing a clean build on Linux, and running the LLVM, clang, and extra tests, to try to make sure there's no problems.
llvm-svn: 195134
2013-11-19 17:28:21 +00:00
Michael Ilseman d930c19d20 Add support for software expansion of 64-bit integer division instructions.
Patch by Dmitri Shtilman!

llvm-svn: 195116
2013-11-19 06:54:19 +00:00
Juergen Ributzka 05c5a93283 [weak vtables] Place class definitions into anonymous namespaces to prevent weak vtables.
This patch places class definitions in implementation files into anonymous
namespaces to prevent weak vtables. This eliminates the need of providing an
out-of-line definition to pin the vtable explicitly to the file.

llvm-svn: 195092
2013-11-19 03:08:35 +00:00
Juergen Ributzka d12ccbd343 [weak vtables] Remove a bunch of weak vtables
This patch removes most of the trivial cases of weak vtables by pinning them to
a single object file. The memory leaks in this version have been fixed. Thanks
Alexey for pointing them out.

Differential Revision: http://llvm-reviews.chandlerc.com/D2068

Reviewed by Andy

llvm-svn: 195064
2013-11-19 00:57:56 +00:00
Alexander Kornienko 681e37cbf6 Recover gracefully when deserializing invalid YAML input.
Fixes http://llvm.org/PR16221, http://llvm.org/PR15927
Phabricator: http://llvm-reviews.chandlerc.com/D1236

Patch by Andrew Tulloch!

llvm-svn: 195016
2013-11-18 15:50:04 +00:00
Alexey Samsonov 49109a279c Revert r194865 and r194874.
This change is incorrect. If you delete virtual destructor of both a base class
and a subclass, then the following code:
  Base *foo = new Child();
  delete foo;
will not cause the destructor for members of Child class. As a result, I observe
plently of memory leaks. Notable examples I investigated are:
ObjectBuffer and ObjectBufferStream, AttributeImpl and StringSAttributeImpl.

llvm-svn: 194997
2013-11-18 09:31:53 +00:00
Michael Gottesman 4d078a3d6f [block-freq] Add BlockFrequency::scale that returns a remainder from the division and make the private scale in BlockFrequency more performant.
This change is the first in a series of changes improving LLVM's Block
Frequency propogation implementation to not lose probability mass in
branchy code when propogating block frequency information from a basic
block to its successors. This patch is a simple infrastructure
improvement that does not actually modify the block frequency
algorithm. The specific changes are:

1. Changes the division algorithm used when scaling block frequencies by
branch probabilities to a short division algorithm. This gives us the
remainder for free as well as provides a nice speed boost. When I
benched the old routine and the new routine on a Sandy Bridge iMac with
disabled turbo mode performing 8192 iterations on an array of length
32768, I saw ~600% increase in speed in mean/median performance.

2. Exposes a scale method that returns a remainder. This is important so
we can ensure that when we scale a block frequency by some branch
probability BP = N/D, the remainder from the division by D can be
retrieved and propagated to other children to ensure no probability mass
is lost (more to come on this).

llvm-svn: 194950
2013-11-17 03:25:24 +00:00
Chandler Carruth a8df47603a [PM] Completely remove support for explicit 'require' methods on the
AnalysisManager. All this method did was assert something and we have
a perfectly good way to trigger that assert from the query path.

llvm-svn: 194947
2013-11-17 03:18:05 +00:00
Juergen Ributzka dbedae89b9 [weak vtables] Remove a bunch of weak vtables
This patch removes most of the trivial cases of weak vtables by pinning them to
a single object file.

Differential Revision: http://llvm-reviews.chandlerc.com/D2068

Reviewed by Andy

llvm-svn: 194865
2013-11-15 22:34:48 +00:00
Rui Ueyama e448f9e418 Path: Recognize COFF import library file magic.
Summary: Make identify_magic to recognize COFF import file.

Reviewers: Bigcheese

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D2165

llvm-svn: 194852
2013-11-15 21:22:02 +00:00
Benjamin Kramer 63d39da992 Give unit test its own LLVMContext so MDNodes aren't leaked even if we never call llvm_shutdown.
Found by valgrind.

llvm-svn: 194797
2013-11-15 09:34:33 +00:00
Matt Arsenault b03bd4d96b Add addrspacecast instruction.
Patch by Michele Scandale!

llvm-svn: 194760
2013-11-15 01:34:59 +00:00
Rui Ueyama 829c4392e1 Recognize 0x0000 as a COFF file magic.
Summary:
Some machine-type-neutral object files containing only undefined symbols
actually do exist in the Windows standard library. Need to recognize them
as COFF files.

Reviewers: Bigcheese

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D2164

llvm-svn: 194734
2013-11-14 22:09:08 +00:00
Nick Kledzik 4a9f00d8cb remove extra semicolon
llvm-svn: 194658
2013-11-14 03:03:05 +00:00
Nick Kledzik dd34f77cbd Add dyn_cast<> support to YAML I/O's IO class
llvm-svn: 194655
2013-11-14 02:38:07 +00:00
Nick Kledzik 1e6033ca33 Add simple support for tags in YAML I/O
llvm-svn: 194644
2013-11-14 00:59:59 +00:00
Rui Ueyama 5e3de7a7eb Path: Add tests for existing file magics.
llvm-svn: 194607
2013-11-13 21:55:41 +00:00
Rui Ueyama 89d1bdb687 Whitespace.
llvm-svn: 194605
2013-11-13 20:31:21 +00:00
Chandler Carruth ccb190972e Fix a null pointer dereference when copying a null polymorphic pointer.
This bug only bit the C++98 build bots because all of the actual uses
really do move. ;] But not *quite* ready to do the whole C++11 switch
yet, so clean it up. Also add a unit test that catches this immediately.

llvm-svn: 194548
2013-11-13 02:48:20 +00:00
Chandler Carruth 74015a7084 Introduce an AnalysisManager which is like a pass manager but with a lot
more smarts in it. This is where most of the interesting logic that used
to live in the implicit-scheduling-hackery of the old pass manager will
live.

Like the previous commits, note that this is a very early prototype!
I expect substantial changes before this is ready to use.

The core of the design is the following:

- We have an AnalysisManager which can be used across a series of
  passes over a module.
- The code setting up a pass pipeline registers the analyses available
  with the manager.
- Individual transform passes can check than an analysis manager
  provides the analyses they require in order to fail-fast.
- There is *no* implicit registration or scheduling.
- Analysis passes are different from other passes: they produce an
  analysis result that is cached and made available via the analysis
  manager.
- Cached results are invalidated automatically by the pass managers.
- When a transform pass requests an analysis result, either the analysis
  is run to produce the result or a cached result is provided.

There are a few aspects of this design that I *know* will change in
subsequent commits:
- Currently there is no "preservation" system, that needs to be added.
- All of the analysis management should move up to the analysis library.
- The analysis management needs to support at least SCC passes. Maybe
  loop passes. Living in the analysis library will facilitate this.
- Need support for analyses which are *both* module and function passes.
- Need support for pro-actively running module analyses to have cached
  results within a function pass manager.
- Need a clear design for "immutable" passes.
- Need support for requesting cached results when available and not
  re-running the pass even if that would be necessary.
- Need more thorough testing of all of this infrastructure.

There are other aspects that I view as open questions I'm hoping to
resolve as I iterate a bit on the infrastructure, and especially as
I start writing actual passes against this.
- Should we have separate management layers for function, module, and
  SCC analyses? I think "yes", but I'm not yet ready to switch the code.
  Adding SCC support will likely resolve this definitively.
- How should the 'require' functionality work? Should *that* be the only
  way to request results to ensure that passes always require things?
- How should preservation work?
- Probably some other things I'm forgetting. =]

Look forward to more patches in shorter order now that this is in place.

llvm-svn: 194538
2013-11-13 01:12:08 +00:00
Chandler Carruth 90a835d2a0 [PM] Start sketching out the new module and function pass manager.
This is still just a skeleton. I'm trying to pull together the
experimentation I've done into committable chunks, and this is the first
coherent one. Others will follow in hopefully short order that move this
more toward a useful initial implementation. I still expect the design
to continue evolving in small ways as I work through the different
requirements and features needed here though.

Keep in mind, all of this is off by default.

Currently, this mostly exercises the use of a polymorphic smart pointer
and templates to hide the polymorphism for the pass manager from the
pass implementation. The next step will be more significant, adding the
first framework of analysis support.

llvm-svn: 194325
2013-11-09 13:09:08 +00:00
Chandler Carruth 7caea41545 Move the old pass manager infrastructure into a legacy namespace and
give the files a legacy prefix in the right directory. Use forwarding
headers in the old locations to paper over the name change for most
clients during the transitional period.

No functionality changed here! This is just clearing some space to
reduce renaming churn later on with a new system.

Even when the new stuff starts to go in, it is going to be hidden behind
a flag and off-by-default as it is still WIP and under development.

This patch is specifically designed so that very little out-of-tree code
has to change. I'm going to work as hard as I can to keep that the case.
Only direct forward declarations of the PassManager class are impacted
by this change.

llvm-svn: 194324
2013-11-09 12:26:54 +00:00
Chandler Carruth 42fabdead0 Switch to allow implicit construction. In many cases, we're wrapping
a derived type and this makes it *much* easier to write this code.

llvm-svn: 194321
2013-11-09 05:55:03 +00:00
Chandler Carruth b32a79f935 Test the polymorphic behavior of this utility.
llvm-svn: 194320
2013-11-09 04:58:13 +00:00
Chandler Carruth ff272ac0e1 Use something really explicit to test "move semantics" on builds without
r-value references. I still want to test that when we have them,
llvm_move is actually a move.

Have I mentioned that I really want to move to C++11? ;]

llvm-svn: 194318
2013-11-09 04:49:27 +00:00
Chandler Carruth b3b79ce632 Add the critically missing 'clone' method. =]
Clang managed to never instantiate the copy constructor. Added tests to
ensure this path is tested.

We could still use tests for the polymorphic nature. Those coming up
next.

llvm-svn: 194317
2013-11-09 04:32:34 +00:00