Commit Graph

28765 Commits

Author SHA1 Message Date
Sjoerd Meijer 46b5b88387 Clang patch r280064 introduced ways to set the FP exceptions and denormal
types. This is the LLVM counterpart and it adds options that map onto FP
exceptions and denormal build attributes allowing better fp math library
selections.

Differential Revision: https://reviews.llvm.org/D24070

llvm-svn: 280246
2016-08-31 14:17:38 +00:00
Krzysztof Parzyszek 64488118bf Fixed spill stack objects are mutable
Differential Revision: https://reviews.llvm.org/D24039

llvm-svn: 280244
2016-08-31 13:52:17 +00:00
Chad Rosier 1b314fceb2 Fix comments about IndirectBrInst in Instructions.h
Patch by yo (Chiang, Yi-Yo) <yo@skymizer.com>.
Differential Revision: https://reviews.llvm.org/D23982

llvm-svn: 280241
2016-08-31 13:39:34 +00:00
Diana Picus 16c818820b Typo fixes. NFC
llvm-svn: 280229
2016-08-31 12:43:44 +00:00
Igor Kudrin f3c8a9cfbb [Coverage] Make sorting criteria for CounterMappingRegions local.
Move the comparison function into the only place there it is used,
i.e. the call to std::stable_sort in CoverageMappingWriter::write().

Add sorting by region kinds as it is required to ensure stable order
in our tests and to simplify D23987.

Differential Revision: https://reviews.llvm.org/D24034

llvm-svn: 280198
2016-08-31 07:01:17 +00:00
Lang Hames a9c929e18f [ORC][RPC] Fix some bugs in the callB primitive.
Still no unit test due to synchronization bugs on s390. These issues were
discovered in an out-of-tree utility.

llvm-svn: 280163
2016-08-30 21:29:48 +00:00
Tim Northover 991b12bf09 GlobalISel: combine extracts & sequences created for legalization
Legalization ends up creating many G_SEQUENCE/G_EXTRACT pairs which leads to
inefficient codegen (even for -O0), so add a quick pass over the function to
remove them again.

llvm-svn: 280155
2016-08-30 20:51:25 +00:00
David Majnemer ac8cfab51f [COFFObjectFile] Ignore broken symbol table
When binaries are compressed by UPX, information about symbol table
offset and symbol count remain unchanged (but became invalid due to
compression).
This causes failure in the constructor and the rest of the binary cannot
be processed.

Instead, reset symbol related information (symbol/string table pointers,
sizes) - this should disable the related iterators and functions while
the rest of the binary can still be processed.

Patch by Bandzi Michal!

llvm-svn: 280147
2016-08-30 20:20:24 +00:00
Daniel Berlin c943d72d94 IntrArgMemOnly is only defined (and current AA machinery only sanely supports) pointer arguments, and these intrinsics have vector of pointer arguments. Remove ArgMemOnly until we either have the machinery, define a new attribute, or something similar
llvm-svn: 280143
2016-08-30 19:58:48 +00:00
Lang Hames d63c865906 Re-instate recent RPC updates (r280016, r280017, r280027, r280051) with a
workaround for the limitations of MSVC 2013's std::future class.

llvm-svn: 280141
2016-08-30 19:56:15 +00:00
Duncan P. N. Exon Smith 73b8dbdd94 CodeGen: Fixup for r280128, since GCC isn't as permissive as Clang
Fixes the bots, e.g.:
http://lab.llvm.org:8011/builders/lldb-x86_64-ubuntu-14.04-buildserver/builds/10055

llvm-svn: 280135
2016-08-30 19:11:11 +00:00
Saleem Abdulrasool 2613d98f2a Support: add some more ELF constants
Add constants for additional GNU note types and the GNU Notes OS type id.  This
is needed to support printing the notes in ELF binaries.

llvm-svn: 280130
2016-08-30 18:51:59 +00:00
Duncan P. N. Exon Smith f947c3afe1 ADT: Split ilist_node_traits into alloc and callback, NFC
Many lists want to override only allocation semantics, or callbacks for
iplist.  Split these up to prevent code duplication.
- Specialize ilist_alloc_traits to change the implementations of
  deleteNode() and createNode().
- One common desire is to do nothing deleteNode() and disable
  createNode().  Specialize ilist_alloc_traits to inherit from
  ilist_noalloc_traits for that behaviour.
- Specialize ilist_callback_traits to use the addNodeToList(),
  removeNodeFromList(), and transferNodesFromList() callbacks.

As a drive-by, add some coverage to the callback-related unit tests.

llvm-svn: 280128
2016-08-30 18:40:47 +00:00
Zachary Turner fc6e880d6d Rename ArrayRef::keep_front / keep_back to take_front / take_back.
The name decided on was take_, but I only updated it for StringRef
and forgot to do it for ArrayRef.

llvm-svn: 280126
2016-08-30 18:19:18 +00:00
Kyle Butt 61aca6ef79 TailDuplication: Extract Indirect-Branch block limit as option. NFC
The existing code hard-coded a limit of 20 instructions for duplication
when a block ended with an indirect branch. Extract this as an option.
No functional change intended.

llvm-svn: 280125
2016-08-30 18:18:54 +00:00
Duncan P. N. Exon Smith b7668d5164 ADT: Guarantee transferNodesFromList is only called on transfers
Guarantee that ilist_traits<T>::transferNodesFromList is only called
when nodes are actually changing lists.

I also moved all the callbacks to occur *first*, before the operation.
This is the only choice for iplist<T>::merge, so we might as well be
consistent.  I expect this to have no effect in practice, although it
simplifies the logic in both iplist<T>::transfer and iplist<T>::insert.

llvm-svn: 280122
2016-08-30 18:00:45 +00:00
Zachary Turner 624cdc3803 Appease buildbots after r280114.
llvm-svn: 280117
2016-08-30 17:38:28 +00:00
Zachary Turner 84fc059e38 Add StringRef::take_front and StringRef::take_back
Reviewed By: majnemer, rnk
Differential Revision: https://reviews.llvm.org/D23965

llvm-svn: 280114
2016-08-30 17:29:59 +00:00
Zachary Turner 30905f8a40 Add StringRef::contains()
llvm-svn: 280113
2016-08-30 17:29:46 +00:00
Duncan P. N. Exon Smith d476312f49 ADT: Clean up docs and formatting for ilist_traits, NFC
This is a prep commit before splitting up ilist_node_traits and
updating/simplifying call sites.
- Move to top of file (I considered moving to a different file,
  llvm/ADT/ilist_traits.h, but it's really not much code).
- Clang-format.
- Convert comments to doxygen, clean them up, and add TODOs for what I'm
  doing next.

llvm-svn: 280109
2016-08-30 17:01:05 +00:00
Duncan P. N. Exon Smith ac79897019 ADT: Split out simple_ilist, a simple intrusive list
Split out a new, low-level intrusive list type with clear semantics.
Unlike iplist (and ilist), all operations on simple_ilist are intrusive,
and simple_ilist never takes ownership of its nodes.  This enables an
intuitive API that has the right defaults for intrusive lists.
- insert() takes references (not pointers!) to nodes (in iplist/ilist,
  passing a reference will cause the node to be copied).
- erase() takes only iterators (like std::list), and does not destroy
  the nodes.
- remove() takes only references and has the same behaviour as erase().
- clear() does not destroy the nodes.
- The destructor does not destroy the nodes.
- New API {erase,remove,clear}AndDispose() take an extra Disposer
  functor for callsites that want to call some disposal routine (e.g.,
  std::default_delete).

This list is not currently configurable, and has no callbacks.

The initial motivation was to fix iplist<>::sort to work correctly (even
with callbacks in ilist_traits<>).  iplist<> uses simple_ilist<>::sort
directly.  The new test in unittests/IR/ModuleTest.cpp crashes without
this commit.

Fixing sort() via a low-level layer provided a good opportunity to:
- Unit test the low-level functionality thoroughly.
- Modernize the API, largely inspired by other intrusive list
  implementations.

Here's a sketch of a longer-term plan:
- Create BumpPtrList<>, a non-intrusive list implemented using
  simple_ilist<>, and use it for the Token list in
  lib/Support/YAMLParser.cpp.  This will factor out the only real use of
  createNode().
- Evolve the iplist<> and ilist<> APIs in the direction of
  simple_ilist<>, making allocation/deallocation explicit at call sites
  (similar to simple_ilist<>::eraseAndDispose()).
- Factor out remaining calls to createNode() and deleteNode() and remove
  the customization from ilist_traits<>.
- Transition uses of iplist<>/ilist<> that don't need callbacks over to
  simple_ilist<>.

llvm-svn: 280107
2016-08-30 16:23:55 +00:00
NAKAMURA Takumi b673b16857 Fixup r279618, instantiate *AnalysisManagerProxy<*AnalysisManager,LazyCallGraph::SCC>, instead of *AnalysisManagerProxy<*AnalysisManager,LazyCallGraph::SCC,LazyCallGraph&>, for PassID.
Or they were not instantiated as expected;

  llvm::InnerAnalysisManagerProxy<llvm::AnalysisManager<llvm::Function>, llvm::LazyCallGraph::SCC>::PassID
  llvm::InnerAnalysisManagerProxy<llvm::AnalysisManager<llvm::Function>, llvm::LazyCallGraph::SCC>::PassID

llvm-svn: 280105
2016-08-30 15:47:13 +00:00
Reid Kleckner 9581f2dda8 Revert "[ORC][RPC] Make the future type of an Orc RPC call Error/Expected rather than"
This reverts commit r280016, and the followups of r280017, r280027,
r280051, r280058, and r280059.

MSVC's implementation of std::promise does not get along with
llvm::Error. It uses its promised value too much like a normal value
type.

llvm-svn: 280100
2016-08-30 15:12:58 +00:00
Nirav Dave d8858cafa9 [MC] Move parser helper functions from Asmparser to MCAsmParser
NFC Intended.

llvm-svn: 280092
2016-08-30 14:15:43 +00:00
Lang Hames 505806ad4d [Support][Error] Suppress warning about unused result.
llvm-svn: 280059
2016-08-30 06:00:21 +00:00
Lang Hames 57bafedfaf [Support] Add a conditionally defined default constructor (available on MSVC
only) for Expected<T> so that it can interoperate with MSVC's std::future
implementation.

MSVC 2013's std::future implementation requires the wrapped type to be default
constructible.

Hopefully this will fix the bot breakage in
http://lab.llvm.org:8011/builders/clang-x86-win2008-selfhost/builds/9937 .

llvm-svn: 280058
2016-08-30 05:32:41 +00:00
James Y Knight d7d9e1069b Replace incorrect "#ifdef DEBUG" with "#ifndef NDEBUG".
The former is simply wrong -- the code will either never be used or will
always be used, rather than being dependent upon whether it's built with
debug assertions enabled.

The macro DEBUG isn't ever set by the llvm build system. But, the macro
DEBUG(X) is defined (unconditionally) if you happen to include
llvm/Support/Debug.h.

The code in Value.h which was erroneously protected by the #ifdef DEBUG
didn't even compile -- you can't cast<> from an LLVMOpaqueValue
directly. Fortunately, it was never invoked, as Core.cpp included
Value.h before Debug.h.

The conditionalized code in AArch64CollectLOH.cpp was previously always
used, as it includes Debug.h.

llvm-svn: 280056
2016-08-30 03:16:16 +00:00
Lang Hames 8427a09d58 [ORC][RPC] Reword 'async' to 'non-blocking' to better reflect call primitive
behaviors, and add a callB (blacking call) primitive.

callB is a blocking call primitive for threaded code where the RPC responses are
being processed on a separate thread. (For single threaded code callST should
continue to be used instead).

No unit test yet: Last time I commited a threaded unit test it deadlocked on
one of the s390x builders. I'll try to re-enable that test first, and add a new
test if I can sort out the deadlock issue.

llvm-svn: 280051
2016-08-30 01:57:06 +00:00
Duncan P. N. Exon Smith 79185d80dc ADT: Explode include/llvm/ADT/{ilist,ilist_node}.h, NFC
I'm working on a lower-level intrusive list that can be used
stand-alone, and splitting the files up a bit will make the code easier
to organize.  Explode the ilist headers in advance to improve blame
lists in the future.
- Move ilist_node_base from ilist_node.h to ilist_node_base.h.
- Move ilist_base from ilist.h to ilist_base.h.
- Move ilist_iterator from ilist.h to ilist_iterator.h.
- Move ilist_node_access from ilist.h to ilist_node.h to support
  ilist_iterator.
- Update unit tests to #include smaller headers.
- Clang-format the moved things.

I noticed in transit that there is a simplify_type specialization for
ilist_iterator.  Since there is no longer an implicit conversion from
ilist<T>::iterator to T*, this doesn't make sense (effectively it's a
form of implicit conversion).  For now I've added a FIXME.

llvm-svn: 280047
2016-08-30 01:37:58 +00:00
Kostya Serebryany 5ac427b8e4 [sanitizer-coverage] add two more modes of instrumentation: trace-div and trace-gep, mostly usaful for value-profile-based fuzzing; llvm part
llvm-svn: 280043
2016-08-30 01:12:10 +00:00
Duncan P. N. Exon Smith 5c001c367f ADT: Give ilist<T>::reverse_iterator a handle to the current node
Reverse iterators to doubly-linked lists can be simpler (and cheaper)
than std::reverse_iterator.  Make it so.

In particular, change ilist<T>::reverse_iterator so that it is *never*
invalidated unless the node it references is deleted.  This matches the
guarantees of ilist<T>::iterator.

(Note: MachineBasicBlock::iterator is *not* an ilist iterator, but a
MachineInstrBundleIterator<MachineInstr>.  This commit does not change
MachineBasicBlock::reverse_iterator, but it does update
MachineBasicBlock::reverse_instr_iterator.  See note at end of commit
message for details on bundle iterators.)

Given the list (with the Sentinel showing twice for simplicity):

     [Sentinel] <-> A <-> B <-> [Sentinel]

the following is now true:
 1. begin() represents A.
 2. begin() holds the pointer for A.
 3. end() represents [Sentinel].
 4. end() holds the poitner for [Sentinel].
 5. rbegin() represents B.
 6. rbegin() holds the pointer for B.
 7. rend() represents [Sentinel].
 8. rend() holds the pointer for [Sentinel].

The changes are #6 and #8.  Here are some properties from the old
scheme (which used std::reverse_iterator):
- rbegin() held the pointer for [Sentinel] and rend() held the pointer
  for A;
- operator*() cost two dereferences instead of one;
- converting from a valid iterator to its valid reverse_iterator
  involved a confusing increment; and
- "RI++->erase()" left RI invalid.  The unintuitive replacement was
  "RI->erase(), RE = end()".

With vector-like data structures these properties are hard to avoid
(since past-the-beginning is not a valid pointer), and don't impose a
real cost (since there's still only one dereference, and all iterators
are invalidated on erase).  But with lists, this was a poor design.

Specifically, the following code (which obviously works with normal
iterators) now works with ilist::reverse_iterator as well:

    for (auto RI = L.rbegin(), RE = L.rend(); RI != RE;)
      fooThatMightRemoveArgFromList(*RI++);

Converting between iterator and reverse_iterator for the same node uses
the getReverse() function.

    reverse_iterator iterator::getReverse();
    iterator reverse_iterator::getReverse();

Why doesn't iterator <=> reverse_iterator conversion use constructors?

In order to catch and update old code, reverse_iterator does not even
have an explicit conversion from iterator.  It wouldn't be safe because
there would be no reasonable way to catch all the bugs from the changed
semantic (see the changes at call sites that are part of this patch).

Old code used this API:

    std::reverse_iterator::reverse_iterator(iterator);
    iterator std::reverse_iterator::base();

Here's how to update from old code to new (that incorporates the
semantic change), assuming I is an ilist<>::iterator and RI is an
ilist<>::reverse_iterator:

            [Old]         ==>          [New]
    reverse_iterator(I)       (--I).getReverse()
    reverse_iterator(I)         ++I.getReverse()
  --reverse_iterator(I)           I.getReverse()
    reverse_iterator(++I)         I.getReverse()
          RI.base()          (--RI).getReverse()
          RI.base()            ++RI.getReverse()
        --RI.base()              RI.getReverse()
      (++RI).base()              RI.getReverse()
  delete &*RI, RE = end()         delete &*RI++
  RI->erase(), RE = end()         RI++->erase()

=======================================
Note: bundle iterators are out of scope
=======================================

MachineBasicBlock::iterator, also known as
MachineInstrBundleIterator<MachineInstr>, is a wrapper to represent
MachineInstr bundles.  The idea is that each operator++ takes you to the
beginning of the next bundle.  Implementing a sane reverse iterator for
this is harder than ilist.  Here are the options:
- Use std::reverse_iterator<MBB::i>.  Store a handle to the beginning of
  the next bundle.  A call to operator*() runs a loop (usually
  operator--() will be called 1 time, for unbundled instructions).
  Increment/decrement just works.  This is the status quo.
- Store a handle to the final node in the bundle.  A call to operator*()
  still runs a loop, but it iterates one time fewer (usually
  operator--() will be called 0 times, for unbundled instructions).
  Increment/decrement just works.
- Make the ilist_sentinel<MachineInstr> *always* store that it's the
  sentinel (instead of just in asserts mode).  Then the bundle iterator
  can sniff the sentinel bit in operator++().

I initially tried implementing the end() option as part of this commit,
but updating iterator/reverse_iterator conversion call sites was
error-prone.  I have a WIP series of patches that implements the final
option.

llvm-svn: 280032
2016-08-30 00:13:12 +00:00
Lang Hames bd4a9cbbb6 [ORC][RPC] Fix typo in RPC comments: call primitives on void functions return
future<Error>, not future<bool>.

llvm-svn: 280017
2016-08-29 21:57:52 +00:00
Lang Hames 3d0657d2ee [ORC][RPC] Make the future type of an Orc RPC call Error/Expected rather than
Optional.

For void functions the return type of a nonblocking call changes from
Expected<future<Optional<bool>>> to Expected<future<Error>>, and for functions
returning T the return type changes from Expected<future<Optional<T>>> to
Expected<future<Expected<T>>>.

Inner results need to be checked (since the RPC connection may have dropped
out before a result came back) and Error/Expected provide stronger checking
requirements. It also allows us drop the crufty 'optionalToError' function and
just collapse Errors in the single-threaded call primitives.

llvm-svn: 280016
2016-08-29 21:56:30 +00:00
Tim Northover f8bab1ce0c GlobalISel: use multi-dimensional arrays for legalize actions.
Instead of putting all possible requests into a single table, we can perform
the extremely dense lookup based on opcode and type-index in constant time
using multi-dimensional array-like things.

This roughly halves the time spent doing legalization, which was dominated by
queries against the Actions table.

llvm-svn: 280011
2016-08-29 21:00:00 +00:00
Tim Northover edb3c8ccb8 GlobalISel: legalize frem to a libcall on AArch64.
llvm-svn: 279988
2016-08-29 19:07:16 +00:00
Tim Northover fe5f89ba14 GlobalISel: rework CallLowering so that it can be used for libcalls too.
There should be no functional change here, I'm just making the implementation
of "frem" (to libcall) legalization easier for a followup.

llvm-svn: 279987
2016-08-29 19:07:08 +00:00
Vitaly Buka db331d8be7 [asan] Separate calculation of ShadowBytes from calculating ASanStackFrameLayout
Summary: No functional changes, just refactoring to make D23947 simpler.

Reviewers: eugenis

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D23954

llvm-svn: 279982
2016-08-29 17:41:29 +00:00
Gor Nishanov dce9b02677 [Coroutines] Part 9: Add cleanup subfunction.
Summary:
[Coroutines] Part 9: Add cleanup subfunction.

This patch completes coroutine heap allocation elision. Now, the heap elision example from docs\Coroutines.rst compiles and produces expected result (see test/Transform/Coroutines/ex3.ll)

Intrinsic Changes:
* coro.free gets a token parameter tying it to coro.id to allow reliably discovering all coro.frees associated with a particular coroutine.
* coro.id gets an extra parameter that points back to a coroutine function. This allows to check whether a coro.id describes the enclosing function or it belongs to a different function that was later inlined.

CoroSplit now creates three subfunctions:
# f$resume - resume logic
# f$destroy - cleanup logic, followed by a deallocation code
# f$cleanup - just the cleanup code

CoroElide pass during devirtualization replaces coro.destroy with either f$destroy or f$cleanup depending whether heap elision is performed or not.

Other fixes, improvements:
* Fixed buglet in Shape::buildFrame that was not creating coro.save properly if coroutine has more than one suspend point.

* Switched to using variable width suspend index field (no longer limited to 32 bit index field can be as little as i1 or as large as i<whatever-size_t-is>)

Reviewers: majnemer

Subscribers: llvm-commits, mehdi_amini

Differential Revision: https://reviews.llvm.org/D23844

llvm-svn: 279971
2016-08-29 14:34:12 +00:00
Sanjay Patel b57d0a2fda [TargetLowering] remove fdiv and frem from canOpTrap() (PR29114)
Assuming the default FP env, we should not treat fdiv and frem any differently in terms of 
trapping behavior than any other FP op. Ie, FP ops do not trap with the default FP env.

This matches how we treat these ops in IR with isSafeToSpeculativelyExecute(). There's a 
similar bug in Constant::canTrap().

This bug manifests in PR29114:
https://llvm.org/bugs/show_bug.cgi?id=29114
...as a sequence of scalar divisions instead of a vector division on x86 for a <3 x float> 
type.

Differential Revision: https://reviews.llvm.org/D23974

llvm-svn: 279970
2016-08-29 13:32:41 +00:00
Rafael Espindola 46fa231c52 Move code only used by codegen out of MC. NFC.
MC itself never needs to know about these sections.

llvm-svn: 279965
2016-08-29 12:33:42 +00:00
Lang Hames 6b21751ba9 [Orc] Simplify LogicalDylib and move it back inside CompileOnDemandLayer. Also
switch to using one indirect stub manager per logical dylib rather than one per
input module.

LogicalDylib is a helper class used by the CompileOnDemandLayer to manage
symbol resolution between modules during lazy compilation. In particular, it
ensures that internal symbols resolve correctly even in the case where multiple
input modules contain the same internal symbol name (which must to be promoted
to external hidden linkage so that functions in any given module can be split
out by lazy compilation). LogicalDylib's resolution scheme (before this commit)
required one stub-manager per input module. This made recompilation of functions
(by adding a module containing a new definition) difficult, as the stub manager
for any given symbol was bound to the module that supplied the original
definition. By using one stubs manager for the whole logical dylib symbols can
be more easily replaced, although support for doing this is not included in this
patch (it will be implemented in a follow up).

llvm-svn: 279952
2016-08-29 00:54:29 +00:00
Elena Demikhovsky 3622fbfc68 [Loop Vectorizer] Fixed memory confilict checks.
Fixed a bug in run-time checks for possible memory conflicts inside loop.
The bug is in Low <-> High boundaries calculation. The High boundary should be calculated as "last memory access pointer + element size".

Differential revision: https://reviews.llvm.org/D23176

llvm-svn: 279930
2016-08-28 08:53:53 +00:00
Quentin Colombet acb857b831 [RegBankSelect] Do not abort when the target wants to fall back.
llvm-svn: 279906
2016-08-27 02:38:27 +00:00
Quentin Colombet 948abf0a0f [InstructionSelect] Do not abort when the target wants to fall back.
llvm-svn: 279905
2016-08-27 02:38:24 +00:00
Quentin Colombet 5e60bcdeaf [MachineLegalize] Do not abort when the target wants to fall back.
llvm-svn: 279904
2016-08-27 02:38:21 +00:00
Lang Hames 28fa3c519c [ORC] Fix typo in LogicalDylib, add unit test.
llvm-svn: 279892
2016-08-27 00:19:05 +00:00
Quentin Colombet 374796d678 [GlobalISel] Add a fallback path to SDISel.
When global-isel fails on a MachineFunction MF, MF will be cleaned up
and given to SDISel.
Thanks to this fallback, we can already perform correctness test even if
we support only a small portion of the functions in a test.

llvm-svn: 279891
2016-08-27 00:18:31 +00:00
Quentin Colombet 3bb32cc79c [IRTranslator] Do not abort when the target wants to fall back.
Every pass in the GlobalISel pipeline will need to do something similar.

llvm-svn: 279886
2016-08-26 23:49:05 +00:00
Quentin Colombet e076d3094c [MFProperties] Introduce a FailedISel property.
This is used to communicate that the instruction selection pipeline
failed at some point.
Another way to achieve that would be to have some kind of conditional
scheduling in the PassManager, such that we only schedule a pass based
on the success/failure of another one. The property approach has the
advantage of being lightweight and solve the problem at stake.

llvm-svn: 279885
2016-08-26 23:49:01 +00:00
Teresa Johnson 26a462877b [ThinLTO] Move loading of cache entry to client
Summary:
Have the cache pass back the path to the cache entry when it
is ready to be loaded, instead of a buffer.

For gold-plugin we can simply pass this file back to gold directly,
which avoids expensive writing of a separate tmp file. Ensure
the cache entry is not deleted on cleanup by adjusting the setting
of the IsTemporary flags.

Moved the loading of the buffer into llvm-lto2 to maintain current
behavior.

Reviewers: mehdi_amini

Subscribers: llvm-commits, mehdi_amini

Differential Revision: https://reviews.llvm.org/D23946

llvm-svn: 279883
2016-08-26 23:29:14 +00:00
Quentin Colombet 0de43b225f [TargetPassConfig] Add a target hook to know what GlobalISel should do on error.
By default, this hook tells GlobalISel to abort (report a fatal error)
when it encounters an error. The alternative will be to fall back on
SDISel.
This fall back will be removed when the bring-up of GlobalISel is over.

llvm-svn: 279879
2016-08-26 22:32:59 +00:00
Quentin Colombet 380cd3eb23 [MachineFunction] Introduce a reset method.
This method allows to reset the state of a MachineFunction as if it was
just created. This will be used during the bring-up of GlobalISel to
provide a way to fallback on SelectionDAG. That way, we can start doing
correctness testing even if we are not able to select all functions via
the global instruction selector.

llvm-svn: 279876
2016-08-26 22:32:53 +00:00
Quentin Colombet e609a9a80a [MFProperties] Introduce a reset method with no argument.
This method allows to reset all the properties in one go.

llvm-svn: 279874
2016-08-26 22:09:11 +00:00
Quentin Colombet c437aa9c26 [MFProperties][NFC] Rename clear into reset to match BitVector naming.
The name clear is used to reset all the bit in bitvectors and using it
to reset just properties was confusing.

llvm-svn: 279873
2016-08-26 22:09:08 +00:00
Adam Nemet cef3314156 [Inliner] Report when inlining fails because callee's def is unavailable
Summary:
This is obviously an interesting case because it may motivate code
restructuring or LTO.

Reporting this requires instantiation of ORE in the loop where the call
sites are first gathered.  I've checked compile-time
overhead *with* -Rpass-with-hotness and the worst slow-down was 6% in
mcf and quickly tailing off.  As before without -Rpass-with-hotness
there is no overhead.

Because this could be a pretty noisy diagnostics, it is currently
qualified as 'verbose'.  As of this patch, 'verbose' diagnostics are
only emitted with -Rpass-with-hotness, i.e. when the output is expected
to be filtered.

Reviewers: eraman, chandlerc, davidxl, hfinkel

Subscribers: tejohnson, Prazek, davide, llvm-commits

Differential Revision: https://reviews.llvm.org/D23415

llvm-svn: 279860
2016-08-26 20:21:05 +00:00
Rafael Espindola 7775c3310c Make writeToResolutionFile a static helper.
llvm-svn: 279859
2016-08-26 20:19:35 +00:00
Kyle Butt 723aa1327c TailDuplication: Record blocks that received the duplicated block. NFC.
This will allow tail duplication during layout to handle the cfg changes more
cleanly.

llvm-svn: 279858
2016-08-26 20:12:40 +00:00
Teresa Johnson 645ecb108a Streamline LTO getComdat invocation (NFC)
We already have obtained a pointer to the underlying GlobalObject,
use it directly to find the comdat, rather than using the
GlobalValue::getComdat which will do the same thing again.

llvm-svn: 279856
2016-08-26 20:07:15 +00:00
Reid Kleckner a5b1eef846 [MC] Move .cv_loc management logic out of MCContext
MCContext already has many tasks, and separating CodeView out from it is
probably a good idea. The .cv_loc tracking was modelled on the DWARF
tracking which lived directly in MCContext.

Removes the inclusion of MCCodeView.h from MCContext.h, so now there are
only 10 build actions while I hack on CodeView support instead of 265.

llvm-svn: 279847
2016-08-26 17:58:37 +00:00
Tim Northover cecee56abb GlobalISel: legalize sdiv and srem operations.
llvm-svn: 279842
2016-08-26 17:46:13 +00:00
Bob Haarman 3db176410a limit the number of instructions per block examined by dead store elimination
Summary: Dead store elimination gets very expensive when large numbers of instructions need to be analyzed. This patch limits the number of instructions analyzed per store to the value of the memdep-block-scan-limit parameter (which defaults to 100). This resulted in no observed difference in performance of the generated code, and no change in the statistics for the dead store elimination pass, but improved compilation time on some files by more than an order of magnitude.

Reviewers: dexonsmith, bruno, george.burgess.iv, dberlin, reames, davidxl

Subscribers: davide, chandlerc, dberlin, davidxl, eraman, tejohnson, mbodart, llvm-commits

Differential Revision: https://reviews.llvm.org/D15537

llvm-svn: 279833
2016-08-26 16:34:27 +00:00
Adam Nemet 4f155b6e91 [LoopUnroll] Use OptimizationRemarkEmitter directly not via the analysis pass
We can't mark ORE (a function pass) preserved as required by the loop
passes because that is how we ensure that the required passes like
LazyBFI are all available any time ORE is used.  See the new comments in
the patch.

Instead we use it directly just like the inliner does in D22694.

As expected there is some additional overhead after removing the caching
provided by analysis passes.  The worst case, I measured was
LNT/CINT2006_ref/401.bzip2 which regresses by 12%.  As before, this only
affects -Rpass-with-hotness and not default compilation.

llvm-svn: 279829
2016-08-26 15:58:34 +00:00
Eugene Leviant ea877d40b4 Implement getRandomBytes() function
This function allows getting arbitrary sized block of random bytes.
Primary motivation is support for --build-id=uuid in lld.

Differential revision: https://reviews.llvm.org/D23671

llvm-svn: 279807
2016-08-26 08:14:54 +00:00
Akira Hatanaka 6da505e251 Fix the static_assert added in r279536.
The assertion doesn't always hold true as sizeof(SDNodeBits) isn't equal
to sizeof(uint16_t) for some targets. For example, sizeof(SDNodeBits)
evaluates to 1, not 2, for ARM's APCS targets.

llvm-svn: 279797
2016-08-26 00:22:12 +00:00
Tim Northover 6c43b850b7 GlobalISel: add missing type to G_UADDE instructions
llvm-svn: 279762
2016-08-25 17:37:44 +00:00
Tim Northover 438c77ca1a GlobalISel: perform multi-step legalization
llvm-svn: 279758
2016-08-25 17:37:32 +00:00
Kyle Butt c7f1eac514 TailDuplication: Don't pass MMI separately from MF. NFC
MMI must match the function passed, and MF has a handle on MMI. Use that instead
of accepting it as separate argument. No Functional Change.

llvm-svn: 279701
2016-08-25 01:37:07 +00:00
Kyle Butt 3ed4273d33 TailDuplication: Save MF and reduce number of parameters. NFC
Save the function in the class, and then don't pass it around. This reduces the
number of parameters and makes calls to member functions simpler.
No Functional Change.

llvm-svn: 279700
2016-08-25 01:37:03 +00:00
Matthias Braun 1eb473680a MachineFunctionProperties/MIRParser: Rename AllVRegsAllocated->NoVRegs, compute it
Rename AllVRegsAllocated to NoVRegs. This avoids the connotation of
running after register and simply describes that no vregs are used in
a machine function. With that we can simply compute the property and do
not need to dump/parse it in .mir files.

Differential Revision: http://reviews.llvm.org/D23850

llvm-svn: 279698
2016-08-25 01:27:13 +00:00
Matthias Braun 23a6b92f63 MIRYamlMapping cleanup
Missed two lines got lost when cherry picking old commits to master.

llvm-svn: 279682
2016-08-24 22:41:46 +00:00
Matthias Braun f1b20c5225 MachineRegisterInfo/MIR: Initialize tracksSubRegLiveness early, do not print/parser it
tracksSubRegLiveness only depends on the Subtarget and a cl::opt, there
is not need to change it or save/parse it in a .mir file.
Make the field const and move the initialization LiveIntervalAnalysis to the
MachineRegisterInfo constructor. Also cleanup some code and fix some
instances which better use MachineRegisterInfo::subRegLivenessEnabled() instead
of TargetSubtargetInfo::enableSubRegLiveness().

llvm-svn: 279676
2016-08-24 22:17:45 +00:00
Changpeng Fang 75f0968b39 AMDGCN/SI: Implement readlane/readfirstlane intrinsics
Summary:
  This patch implements readlane/readfirstlane intrinsics.
TODO: need to define a new register class to consider the case
that the source could be a vector register or M0.

Reviewed by:
  arsenm and tstellarAMD

Differential Revision:
  http://reviews.llvm.org/D22489

llvm-svn: 279660
2016-08-24 20:35:23 +00:00
David Blaikie a01f295322 DebugInfo: Add flag to CU to disable emission of inline debug info into the skeleton CU
In cases where .dwo/.dwp files are guaranteed to be available, skipping
the extra online (in the .o file) inline info can save a substantial
amount of space - see the original r221306 for more details there.

llvm-svn: 279650
2016-08-24 18:29:49 +00:00
Krzysztof Parzyszek a7ed090bba Create subranges for new intervals resulting from live interval splitting
The register allocator can split a live interval of a register into a set
of smaller intervals. After the allocation of registers is complete, the
rewriter will modify the IR to replace virtual registers with the corres-
ponding physical registers. At this stage, if a register corresponding
to a subregister of a virtual register is used, the rewriter will check
if that subregister is undefined, and if so, it will add the <undef> flag
to the machine operand. The function verifying liveness of the subregis-
ter would assume that it is undefined, unless any of the subranges of the
live interval proves otherwise.
The problem is that the live intervals created during splitting do not
have any subranges, even if the original parent interval did. This could
result in the <undef> flag placed on a register that is actually defined.

Differential Revision: http://reviews.llvm.org/D21189

llvm-svn: 279625
2016-08-24 13:37:55 +00:00
Chandler Carruth 8882346842 [PM] Introduce basic update capabilities to the new PM's CGSCC pass
manager, including both plumbing and logic to handle function pass
updates.

There are three fundamentally tied changes here:
1) Plumbing *some* mechanism for updating the CGSCC pass manager as the
   CG changes while passes are running.
2) Changing the CGSCC pass manager infrastructure to have support for
   the underlying graph to mutate mid-pass run.
3) Actually updating the CG after function passes run.

I can separate them if necessary, but I think its really useful to have
them together as the needs of #3 drove #2, and that in turn drove #1.

The plumbing technique is to extend the "run" method signature with
extra arguments. We provide the call graph that intrinsically is
available as it is the basis of the pass manager's IR units, and an
output parameter that records the results of updating the call graph
during an SCC passes's run. Note that "...UpdateResult" isn't a *great*
name here... suggestions very welcome.

I tried a pretty frustrating number of different data structures and such
for the innards of the update result. Every other one failed for one
reason or another. Sometimes I just couldn't keep the layers of
complexity right in my head. The thing that really worked was to just
directly provide access to the underlying structures used to walk the
call graph so that their updates could be informed by the *particular*
nature of the change to the graph.

The technique for how to make the pass management infrastructure cope
with mutating graphs was also something that took a really, really large
number of iterations to get to a place where I was happy. Here are some
of the considerations that drove the design:

- We operate at three levels within the infrastructure: RefSCC, SCC, and
  Node. In each case, we are working bottom up and so we want to
  continue to iterate on the "lowest" node as the graph changes. Look at
  how we iterate over nodes in an SCC running function passes as those
  function passes mutate the CG. We continue to iterate on the "lowest"
  SCC, which is the one that continues to contain the function just
  processed.

- The call graph structure re-uses SCCs (and RefSCCs) during mutation
  events for the *highest* entry in the resulting new subgraph, not the
  lowest. This means that it is necessary to continually update the
  current SCC or RefSCC as it shifts. This is really surprising and
  subtle, and took a long time for me to work out. I actually tried
  changing the call graph to provide the opposite behavior, and it
  breaks *EVERYTHING*. The graph update algorithms are really deeply
  tied to this particualr pattern.

- When SCCs or RefSCCs are split apart and refined and we continually
  re-pin our processing to the bottom one in the subgraph, we need to
  enqueue the newly formed SCCs and RefSCCs for subsequent processing.
  Queuing them presents a few challenges:
  1) SCCs and RefSCCs use wildly different iteration strategies at
     a high level. We end up needing to converge them on worklist
     approaches that can be extended in order to be able to handle the
     mutations.
  2) The order of the enqueuing need to remain bottom-up post-order so
     that we don't get surprising order of visitation for things like
     the inliner.
  3) We need the worklists to have set semantics so we don't duplicate
     things endlessly. We don't need a *persistent* set though because
     we always keep processing the bottom node!!!! This is super, super
     surprising to me and took a long time to convince myself this is
     correct, but I'm pretty sure it is... Once we sink down to the
     bottom node, we can't re-split out the same node in any way, and
     the postorder of the current queue is fixed and unchanging.
  4) We need to make sure that the "current" SCC or RefSCC actually gets
     enqueued here such that we re-visit it because we continue
     processing a *new*, *bottom* SCC/RefSCC.

- We also need the ability to *skip* SCCs and RefSCCs that get merged
  into a larger component. We even need the ability to skip *nodes* from
  an SCC that are no longer part of that SCC.

This led to the design you see in the patch which uses SetVector-based
worklists. The RefSCC worklist is always empty until an update occurs
and is just used to handle those RefSCCs created by updates as the
others don't even exist yet and are formed on-demand during the
bottom-up walk. The SCC worklist is pre-populated from the RefSCC, and
we push new SCCs onto it and blacklist existing SCCs on it to get the
desired processing.

We then *directly* update these when updating the call graph as I was
never able to find a satisfactory abstraction around the update
strategy.

Finally, we need to compute the updates for function passes. This is
mostly used as an initial customer of all the update mechanisms to drive
their design to at least cover some real set of use cases. There are
a bunch of interesting things that came out of doing this:

- It is really nice to do this a function at a time because that
  function is likely hot in the cache. This means we want even the
  function pass adaptor to support online updates to the call graph!

- To update the call graph after arbitrary function pass mutations is
  quite hard. We have to build a fairly comprehensive set of
  data structures and then process them. Fortunately, some of this code
  is related to the code for building the cal graph in the first place.
  Unfortunately, very little of it makes any sense to share because the
  nature of what we're doing is so very different. I've factored out the
  one part that made sense at least.

- We need to transfer these updates into the various structures for the
  CGSCC pass manager. Once those were more sanely worked out, this
  became relatively easier. But some of those needs necessitated changes
  to the LazyCallGraph interface to make it significantly easier to
  extract the changed SCCs from an update operation.

- We also need to update the CGSCC analysis manager as the shape of the
  graph changes. When an SCC is merged away we need to clear analyses
  associated with it from the analysis manager which we didn't have
  support for in the analysis manager infrsatructure. New SCCs are easy!
  But then we have the case that the original SCC has its shape changed
  but remains in the call graph. There we need to *invalidate* the
  analyses associated with it.

- We also need to invalidate analyses after we *finish* processing an
  SCC. But the analyses we need to invalidate here are *only those for
  the newly updated SCC*!!! Because we only continue processing the
  bottom SCC, if we split SCCs apart the original one gets invalidated
  once when its shape changes and is not processed farther so its
  analyses will be correct. It is the bottom SCC which continues being
  processed and needs to have the "normal" invalidation done based on
  the preserved analyses set.

All of this is mostly background and context for the changes here.

Many thanks to all the reviewers who helped here. Especially Sanjoy who
caught several interesting bugs in the graph algorithms, David, Sean,
and others who all helped with feedback.

Differential Revision: http://reviews.llvm.org/D21464

llvm-svn: 279618
2016-08-24 09:37:14 +00:00
Matthias Braun 733fe3676c CodeGen: Remove MachineFunctionAnalysis => Enable (Machine)ModulePasses
Re-apply this patch, hopefully I will get away without any warnings
in the constructor now.

This patch removes the MachineFunctionAnalysis. Instead we keep a
map from IR Function to MachineFunction in the MachineModuleInfo.

This allows the insertion of ModulePasses into the codegen pipeline
without breaking it because the MachineFunctionAnalysis gets dropped
before a module pass.

Peak memory should stay unchanged without a ModulePass in the codegen
pipeline: Previously the MachineFunction was freed at the end of a codegen
function pipeline because the MachineFunctionAnalysis was dropped; With
this patch the MachineFunction is freed after the AsmPrinter has
finished.

Differential Revision: http://reviews.llvm.org/D23736

llvm-svn: 279602
2016-08-24 01:52:46 +00:00
Matthias Braun 79f85b3b8f MIRParser/MIRPrinter: Compute isSSA instead of printing/parsing it.
Specifying isSSA is an extra line at best and results in invalid MI at
worst. Compute the value instead.

Differential Revision: http://reviews.llvm.org/D22722

llvm-svn: 279600
2016-08-24 01:32:41 +00:00
Matthias Braun c3b2e80b9d MachineModuleInfo: Avoid dummy constructor, use INITIALIZE_TM_PASS
Change this pass constructor to just accept a const TargetMachine * and
use INITIALIZE_TM_PASS, that way we can get rid of the dummy
constructor. The pass will still fail when calling the default
constructor leading to TM == nullptr, this is no different than before
but is more in line what other codegen passes are doing and avoids the
dummy constructor.

llvm-svn: 279598
2016-08-24 00:42:05 +00:00
Philip Reames d06a1b4cdc [stackmaps] Remove an unneeded member variable [NFC]
llvm-svn: 279590
2016-08-23 23:58:08 +00:00
Philip Reames e83c4b30ca [stackmaps] More extraction of common code [NFCI]
General cleanup before starting to work on the part I want to actually change.

llvm-svn: 279586
2016-08-23 23:33:29 +00:00
Michael Zolotukhin bd63d436c1 [LoopUnroll] By default disable unrolling when optimizing for size.
Summary:
In clang commit r268509 we started to invoke loop-unroll pass from the
driver even under -Os. However, we happen to not initialize optsize
thresholds properly, which si fixed with this change.

r268509 led to some big compile time regressions, because we started to
unroll some loops that we didn't unroll before. With this change I hope
to recover most of the regressions. We still are slightly slower than
before, because we do some checks here and there in loop-unrolling
before we bail out, but at least the slowdown is not that huge now.

Reviewers: hfinkel, chandlerc

Subscribers: mzolotukhin, llvm-commits

Differential Revision: https://reviews.llvm.org/D23388

llvm-svn: 279585
2016-08-23 23:13:15 +00:00
Richard Smith eae6138936 Remove unused data member to unbreak -Werror builds.
llvm-svn: 279581
2016-08-23 22:10:46 +00:00
Richard Smith 8c3fbdc6c4 Revert r279564. It introduces undefined behavior (binding a reference to a
dereferenced null pointer) in MachineModuleInfo::MachineModuleInfo that causes
-Werror builds (including several buildbots) to fail.

llvm-svn: 279580
2016-08-23 22:08:27 +00:00
Mehdi Amini adc0e26bef [ThinLTO] Add caching to the new LTO API
Add the ability to plug a cache on the LTO API.
I tried to write such that a linker implementation can
control the cache backend. This is intrusive and I'm
not totally happy with it, but I can't figure out a
better design right now.

Differential Revision: https://reviews.llvm.org/D23599

llvm-svn: 279576
2016-08-23 21:30:12 +00:00
Philip Reames 570dd009c3 [stackmaps] Extract out magic constants [NFCI]
This is a first step towards clarifying the exact MI semantics of stackmap's "live values".  

llvm-svn: 279574
2016-08-23 21:21:43 +00:00
Matthias Braun 90799ce8b2 MachineFunction: Introduce NoPHIs property
I want to compute the SSA property of .mir files automatically in
upcoming patches. The problem with this is that some inputs will be
reported as static single assignment with some passes claiming not to
support SSA form.  In reality though those passes do not support PHI
instructions => Track the presence of PHI instructions separate from the
SSA property.

Differential Revision: https://reviews.llvm.org/D22719

llvm-svn: 279573
2016-08-23 21:19:49 +00:00
Tim Northover bdf67c9a00 GlobalISel: make truncate/extend casts uniform
They really should have both types represented, but early variants were created
before MachineInstrs could have multiple types so they're rather ambiguous.

llvm-svn: 279567
2016-08-23 21:01:33 +00:00
Tim Northover 6cd4b23a0f GlobalISel: legalize integer comparisons on AArch64.
Next step is doing both legalizations at the same time! Marvel at GlobalISel's
cunning.

llvm-svn: 279566
2016-08-23 21:01:26 +00:00
Tim Northover b3a0be4d38 GlobalISel: legalize conditional branches on AArch64.
llvm-svn: 279565
2016-08-23 21:01:20 +00:00
Matthias Braun 4c1f1f120c CodeGen: Remove MachineFunctionAnalysis => Enable (Machine)ModulePasses
Re-apply this commit with the deletion of a MachineFunction delegated to
a separate pass to avoid use after free when doing this directly in
AsmPrinter.

This patch removes the MachineFunctionAnalysis. Instead we keep a
map from IR Function to MachineFunction in the MachineModuleInfo.

This allows the insertion of ModulePasses into the codegen pipeline
without breaking it because the MachineFunctionAnalysis gets dropped
before a module pass.

Peak memory should stay unchanged without a ModulePass in the codegen
pipeline: Previously the MachineFunction was freed at the end of a codegen
function pipeline because the MachineFunctionAnalysis was dropped; With
this patch the MachineFunction is freed after the AsmPrinter has
finished.

Differential Revision: http://reviews.llvm.org/D23736

llvm-svn: 279564
2016-08-23 20:58:29 +00:00
Tim Northover a01bece1dc GlobalISel: extend legalizer interface to handle multiple types.
Instructions like G_ICMP have multiple types that may need to be legalized (the
boolean output and nearly arbitrary inputs in this case). So the legalizer must
be capable of deciding what to do for each of them separately.

llvm-svn: 279554
2016-08-23 19:30:42 +00:00
Mehdi Amini e7494530b2 Stop always creating and running an LTO compilation if there is not a single LTO object
Summary:
I assume there was a use case, so maybe this strawman patch will help
clarifying if it is legit.
In any case the current situation is not legit: a ThinLTO compilation
should not trigger an unexpected full LTO compilation.
Right now, adding a --save-temps option triggers this and makes the
number of output differs.

Reviewers: tejohnson

Subscribers: pcc, llvm-commits, mehdi_amini

Differential Revision: https://reviews.llvm.org/D23600

llvm-svn: 279550
2016-08-23 18:39:12 +00:00
Justin Lebar 1972e222ea [SelectionDAG] Use a union of bitfield structs for SDNode::SubclassData.
Summary:
This greatly simplifies our handling of SDNode::SubclassData.

NFC, hopefully.  :)

See discussion in D23035 for discussion about the design API of these
bitfields.

Reviewers: chandlerc

Subscribers: llvm-commits, rnk

Differential Revision: https://reviews.llvm.org/D23036

llvm-svn: 279537
2016-08-23 17:18:11 +00:00
Xinliang David Li 530e9a8f54 Fix windows build failure
llvm-svn: 279525
2016-08-23 16:00:54 +00:00
Xinliang David Li dc49140b44 [Profile] refactor meta data copying/swapping code
Differential Revision: http://reviews.llvm.org/D23619

llvm-svn: 279523
2016-08-23 15:39:03 +00:00
Adrian Prantl 298d546297 Work around PR29097 to get the module bots going again.
This replaces an =default constructor with an explicit definition.

llvm-svn: 279522
2016-08-23 15:38:59 +00:00
Davide Italiano fc4430ea45 [LTOCodeGenerator] Reduce code duplication. NFCI.
llvm-svn: 279514
2016-08-23 12:32:57 +00:00
Matthias Braun 7f66202d38 Revert "(HEAD -> master, origin/master, origin/HEAD) CodeGen: Remove MachineFunctionAnalysis => Enable (Machine)ModulePasses"
Reverting while tracking down a use after free.

This reverts commit r279502.

llvm-svn: 279503
2016-08-23 05:17:11 +00:00
Matthias Braun fd936841eb CodeGen: Remove MachineFunctionAnalysis => Enable (Machine)ModulePasses
This patch removes the MachineFunctionAnalysis. Instead we keep a
map from IR Function to MachineFunction in the MachineModuleInfo.

This allows the insertion of ModulePasses into the codegen pipeline
without breaking it because the MachineFunctionAnalysis gets dropped
before a module pass.

Peak memory should stay unchanged without a ModulePass in the codegen
pipeline: Previously the MachineFunction was freed at the end of a codegen
function pipeline because the MachineFunctionAnalysis was dropped; With
this patch the MachineFunction is freed after the AsmPrinter has
finished.

Differential Revision: http://reviews.llvm.org/D23736

llvm-svn: 279502
2016-08-23 03:20:09 +00:00
Duncan P. N. Exon Smith 9f5c83b914 ADT: Separate some list manipulation API into ilist_base, NFC
Separate algorithms in iplist<T> that don't depend on T into ilist_base,
and unit test them.

While I was adding unit tests for these algorithms anyway, I also added
unit tests for ilist_node_base and ilist_sentinel<T>.

To make the algorithms and unit tests easier to write, I also did the
following minor changes as a drive-by:
- encapsulate Prev/Next in ilist_node_base to so that algorithms are
  easier to read, and
- update ilist_node_access API to take nodes by reference.

There should be no real functionality change here.

llvm-svn: 279484
2016-08-22 22:21:07 +00:00