Commit Graph

60 Commits

Author SHA1 Message Date
Roman Lebedev 02569408ef [NFC] BasicBlock: generalize replaceSuccessorsPhiUsesWith(), take Old bb
Thus it does not assume that the old basic block is the basic block
for which we are looking at successors.

Not reviewed, but seems rather trivial, in line with the rest of
previous few patches.

llvm-svn: 359997
2019-05-05 18:59:45 +00:00
Roman Lebedev 1a1b922177 [NFC] BasicBlock: refactor changePhiUses() out of replacePhiUsesWith(), use it
Summary:
It is a common thing to loop over every `PHINode` in some `BasicBlock`
and change old `BasicBlock` incoming block to a new `BasicBlock` incoming block.
`replaceSuccessorsPhiUsesWith()` already had code to do that,
it just wasn't a function.
So outline it into a new function, and use it.

Reviewers: chandlerc, craig.topper, spatel, danielcdh

Reviewed By: craig.topper

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61013

llvm-svn: 359996
2019-05-05 18:59:39 +00:00
Roman Lebedev e3b1d82b53 [NFC] PHINode: introduce replaceIncomingBlockWith() function, use it
Summary:
There is `PHINode::getBasicBlockIndex()`, `PHINode::setIncomingBlock()`
and `PHINode::getNumOperands()`, but no function to replace every
specified `BasicBlock*` predecessor with some other specified `BasicBlock*`.
Clearly, there are a lot of places that could use that functionality.

Reviewers: chandlerc, craig.topper, spatel, danielcdh

Reviewed By: craig.topper

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61011

llvm-svn: 359995
2019-05-05 18:59:30 +00:00
Nick Desaulniers 6a84cd3b8e Revert "[INLINER] allow inlining of address taken blocks"
This reverts commit 19e95fe611.

llvm-svn: 354082
2019-02-14 23:42:21 +00:00
Nick Desaulniers 19e95fe611 [INLINER] allow inlining of address taken blocks
as long as their uses does not contain calls to functions that capture
the argument (potentially allowing the blockaddress to "escape" the
lifetime of the caller).

TODO:
- add more tests
- fix crash in llvm::updateCGAndAnalysisManagerForFunctionPass when
  invoking Transforms/Inline/blockaddress.ll

llvm-svn: 354079
2019-02-14 23:35:53 +00:00
Max Kazantsev 20b9189975 [NFC] Rename DontDeleteUselessPHIs --> KeepOneInputPHIs
llvm-svn: 353801
2019-02-12 07:09:29 +00:00
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Vedant Kumar b264d69de7 [IR] Add Instruction::isLifetimeStartOrEnd, NFC
Instruction::isLifetimeStartOrEnd() checks whether an Instruction is an
llvm.lifetime.start or an llvm.lifetime.end intrinsic.

This was suggested as a cleanup in D55967.

Differential Revision: https://reviews.llvm.org/D56019

llvm-svn: 349964
2018-12-21 21:49:40 +00:00
Vedant Kumar 4de31bba51 [IR] Add hasNPredecessors, hasNPredecessorsOrMore to BasicBlock
Add methods to BasicBlock which make it easier to efficiently check
whether a block has N (or more) predecessors.

This can be more efficient than using pred_size(), which is a linear
time operation.

We might consider adding similar methods for successors. I haven't done
so in this patch because succ_size() is already O(1).

With this patch applied, I measured a 0.065% compile-time reduction in
user time for running `opt -O3` on the sqlite3 amalgamation (30 trials).
The change in mergeStoreIntoSuccessor alone saves 45 million linked list
iterations in a stage2 Release build of llc.

See llvm.org/PR39702 for a harder but more general way of achieving
similar results.

Differential Revision: https://reviews.llvm.org/D54686

llvm-svn: 347256
2018-11-19 19:54:27 +00:00
Chandler Carruth e303c87e19 [TI removal] Make `getTerminator()` return a generic `Instruction`.
This removes the primary remaining API producing `TerminatorInst` which
will reduce the rate at which code is introduced trying to use it and
generally make it much easier to remove the remaining APIs across the
codebase.

Also clean up some of the stragglers that the previous mechanical update
of variables missed.

Users of LLVM and out-of-tree code generally will need to update any
explicit variable types to handle this. Replacing `TerminatorInst` with
`Instruction` (or `auto`) almost always works. Most of these edits were
made in prior commits using the perl one-liner:
```
perl -i -ple 's/TerminatorInst(\b.* = .*getTerminator\(\))/Instruction\1/g'
```

This also my break some rare use cases where people overload for both
`Instruction` and `TerminatorInst`, but these should be easily fixed by
removing the `TerminatorInst` overload.

llvm-svn: 344504
2018-10-15 10:42:50 +00:00
Chandler Carruth edb12a838a [TI removal] Make variables declared as `TerminatorInst` and initialized
by `getTerminator()` calls instead be declared as `Instruction`.

This is the biggest remaining chunk of the usage of `getTerminator()`
that insists on the narrow type and so is an easy batch of updates.
Several files saw more extensive updates where this would cascade to
requiring API updates within the file to use `Instruction` instead of
`TerminatorInst`. All of these were trivial in nature (pervasively using
`Instruction` instead just worked).

llvm-svn: 344502
2018-10-15 10:04:59 +00:00
Chandler Carruth 698fbe7b59 [IR] Sink `isExceptional` predicate to `Instruction`, rename it to
`isExceptionalTermiantor` and implement it for opcodes as well following
the common pattern in `Instruction`.

Part of removing `TerminatorInst` from the `Instruction` type hierarchy
to make it easier to share logic and interfaces between instructions
that are both terminators and not terminators.

llvm-svn: 340699
2018-08-26 08:56:42 +00:00
Chandler Carruth 96fc1de77d [IR] Begin removal of TerminatorInst by removing successor manipulation.
The core get and set routines move to the `Instruction` class. These
routines are only valid to call on instructions which are terminators.

The iterator and *generic* range based access move to `CFG.h` where all
the other generic successor and predecessor access lives. While moving
the iterator here, simplify it using the iterator utilities LLVM
provides and updates coding style as much as reasonable. The APIs remain
pointer-heavy when they could better use references, and retain the odd
behavior of `operator*` and `operator->` that is common in LLVM
iterators. Adjusting this API, if desired, should be a follow-up step.

Non-generic range iteration is added for the two instructions where
there is an especially easy mechanism and where there was code
attempting to use the range accessor from a specific subclass:
`indirectbr` and `br`. In both cases, the successors are contiguous
operands and can be easily iterated via the operand list.

This is the first major patch in removing the `TerminatorInst` type from
the IR's instruction type hierarchy. This change was discussed in an RFC
here and was pretty clearly positive:
http://lists.llvm.org/pipermail/llvm-dev/2018-May/123407.html

There will be a series of much more mechanical changes following this
one to complete this move.

Differential Revision: https://reviews.llvm.org/D47467

llvm-svn: 340698
2018-08-26 08:41:15 +00:00
Vedant Kumar 1cb63dc2d5 Rename skipDebugInfo -> skipDebugIntrinsics, NFC
This addresses post-commit feedback about the name 'skipDebugInfo' being
misleading. This name could be interpreted as meaning 'a function that
skips instructions with debug locations'.

The new name, 'skipDebugIntrinsics', makes it clear that this function
only skips debug info intrinsics.

Thanks to Adrian Prantl for pointing this out!

llvm-svn: 335667
2018-06-26 21:16:59 +00:00
Vedant Kumar f01827f2d1 [IR] Introduce helpers to skip debug instructions (NFC)
This patch introduces two helpers to make it easier to ignore debug
intrinsics:

- Instruction::getNextNonDebugInstruction()

This is just like Instruction::getNextNode(), except that it skips debug
info.

- skipDebugInfo(BasicBlock::iterator)

A free function which advances a BasicBlock iterator past any debug
info. This is a no-op when the iterator already points to a non-debug
instruction.

Part of: llvm.org/PR37728
Related to: https://reviews.llvm.org/D47874

Differential Revision: https://reviews.llvm.org/D48305

llvm-svn: 335083
2018-06-19 23:42:17 +00:00
Florian Hahn 147fc016e3 [BasicBlock] Add instructionsWithoutDebug methods to skip debug insts.
Reviewers: aprantl, vsk, mattd, chandlerc

Reviewed By: aprantl, vsk

Differential Revision: https://reviews.llvm.org/D45657

llvm-svn: 330316
2018-04-19 09:48:07 +00:00
Matt Arsenault 344c09202b IR: Fix BasicBlock::phis for empty blocks
llvm-svn: 321567
2017-12-29 19:25:53 +00:00
Hiroshi Yamauchi dce9def3dd Irreducible loop metadata for more accurate block frequency under PGO.
Summary:
Currently the block frequency analysis is an approximation for irreducible
loops.

The new irreducible loop metadata is used to annotate the irreducible loop
headers with their header weights based on the PGO profile (currently this is
approximated to be evenly weighted) and to help improve the accuracy of the
block frequency analysis for irreducible loops.

This patch is a basic support for this.

Reviewers: davidxl

Reviewed By: davidxl

Subscribers: mehdi_amini, llvm-commits, eraman

Differential Revision: https://reviews.llvm.org/D39028

llvm-svn: 317278
2017-11-02 22:26:51 +00:00
Andrew Kaylor d49711996f Restrict the definition of loop preheader to avoid EH blocks
Differential Revision: https://reviews.llvm.org/D34487

llvm-svn: 306070
2017-06-22 23:27:16 +00:00
Chandler Carruth 8fa1e37342 [IR] Add an iterator and range accessor for the PHI nodes of a basic
block.

This allows writing much more natural and readable range based for loops
directly over the PHI nodes. It also takes advantage of the same tricks
for terminating the sequence as the hand coded versions.

I've replaced one example of this mostly to showcase the difference and
I've added a unit test to make sure the facilities really work the way
they're intended. I want to use this inside of SimpleLoopUnswitch but it
seems generally nice.

Differential Revision: https://reviews.llvm.org/D33533

llvm-svn: 303964
2017-05-26 03:10:00 +00:00
Craig Topper 1c78f4a0ff [IR] Share implementation for pairs of const and non-const methods using const_cast. NFCI
llvm-svn: 298830
2017-03-27 05:46:58 +00:00
Craig Topper 74fb7ac2e0 [IR] Share implementation of pairs of const and non-const methods in BasicBlock using the const version instead of the non-const version
Summary:
During post-commit review of a previous change I made it was pointed out that const casting 'this' is technically a bad practice. This patch re-implements all of the methods in BasicBlock that do this to use the const BasicBlock version and const_cast the return value instead.

I think there are still many other classes that do similar things. I may look at more in the future.

Reviewers: dblaikie

Reviewed By: dblaikie

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D31377

llvm-svn: 298827
2017-03-27 02:38:17 +00:00
Craig Topper 6f8e989b21 [IR] Use const_cast to reuse the const version of two BasicBlock methods that are duplicated for both const and non-const. NFC
Similar is already done for other methods in BasicBlock.

llvm-svn: 292753
2017-01-22 06:53:04 +00:00
Mehdi Amini a53d49e1b5 Don't create a SymbolTable in Function when the LLVMContext discards value names (NFC)
The ValueSymbolTable is used to detect name conflict and rename
instructions automatically. This is not needed when the value
names are automatically discarded by the LLVMContext.
No functional change intended, just saving a little bit of memory.

This is a recommit of r281806 after fixing the accessor to return
a pointer instead of a reference and updating all the call-sites.

llvm-svn: 281813
2016-09-17 06:00:02 +00:00
Benjamin Kramer af28e7d6fa Apply clang-tidy's modernize-loop-convert to most of lib/IR.
Only minor manual fixes. No functionality change intended.

llvm-svn: 273813
2016-06-26 14:10:56 +00:00
Reid Kleckner bca59d2a43 Revert "[SimplifyCFG] Extend TryToSimplifyUncondBranchFromEmptyBlock for empty block including lifetime intrinsics"
This reverts commit r268254.

This change causes assertion failures while building Chromium. Reduced
test case coming soon.

llvm-svn: 268288
2016-05-02 19:43:22 +00:00
Hans Wennborg b7599329fc [SimplifyCFG] Extend TryToSimplifyUncondBranchFromEmptyBlock for empty block including lifetime intrinsics
Make it possible that TryToSimplifyUncondBranchFromEmptyBlock merges empty
basic block including lifetime intrinsics as well as phi nodes and
unconditional branch into its successor or predecessor(s).

If successor of empty block has single predecessor, all contents including
lifetime intrinsics are sinked into the successor. Otherwise, they are
hoisted into its predecessor(s) and then merged into the predecessor(s).

Patch by Josh Yoon <josh.yoon@samsung.com>!

Differential Revision: http://reviews.llvm.org/D19257

llvm-svn: 268254
2016-05-02 17:22:54 +00:00
Sanjoy Das b51325dbdb Introduce @llvm.experimental.deoptimize
Summary:
This intrinsic, together with deoptimization operand bundles, allow
frontends to express transfer of control and frame-local state from
one (typically more specialized, hence faster) version of a function
into another (typically more generic, hence slower) version.

In languages with a fully integrated managed runtime this intrinsic can
be used to implement "uncommon trap" like functionality.  In unmanaged
languages like C and C++, this intrinsic can be used to represent the
slow paths of specialized functions.

Note: this change does not address how `@llvm.experimental_deoptimize`
is lowered.  That will be done in a later change.

Reviewers: chandlerc, rnk, atrick, reames

Subscribers: llvm-commits, kmod, mjacob, maksfb, mcrosier, JosephTremoulet

Differential Revision: http://reviews.llvm.org/D17732

llvm-svn: 263281
2016-03-11 19:08:34 +00:00
Duncan P. N. Exon Smith a848c47130 ADT: Stop using getNodePtrUnchecked on end() iterators
Stop using `getNodePtrUnchecked()` when building IR.  Eventually a
dereference will be required to get at the downcast node, since the
iterator will only store an `ilist_node_base` of some sort.

This should have no functionality change for now, but is a path towards
removing some more UB from ilist.

llvm-svn: 261495
2016-02-21 19:52:15 +00:00
Duncan P. N. Exon Smith 52888a6738 IR: Remove implicit iterator conversions from lib/IR, NFC
Stop converting implicitly between iterators and pointers/references in
lib/IR.  For convenience, I've added a `getIterator()` accessor to
`ilist_node` so that callers don't need to know how to spell the
iterator class (i.e., they can use `X.getIterator()` instead of
`Function::iterator(X)`).

I'll eventually disallow these implicit conversions entirely, but
there's a lot of code, so it doesn't make sense to do it all in one
patch.  One library or so at a time.

Why?  To root out cases of `getNextNode()` and `getPrevNode()` being
used in iterator logic.  The design of `ilist` makes that invalid when
the current node could be at the back of the list, but it happens to
"work" right now because of a bug where those functions never return
`nullptr` if you're using a half-node sentinel.  Before I can fix the
function, I have to remove uses of it that rely on it misbehaving.
(Maybe the function should just be deleted anyway?  But I don't want
deleting it -- potentially a huge project -- to block fixing
ilist/iplist.)

llvm-svn: 249782
2015-10-08 23:49:46 +00:00
Duncan P. N. Exon Smith 37bf678a0d IR: Create SymbolTableList wrapper around iplist, NFC
Create `SymbolTableList`, a wrapper around `iplist` for lists that
automatically manage a symbol table.  This commit reduces a ton of code
duplication between the six traits classes that were used previously.

As a drive by, reduce the number of template parameters from 2 to 1 by
using a SymbolTableListParentType metafunction (I originally had this as
a separate commit, but it touched most of the same lines so I squashed
them).

I'm in the process of trying to remove the UB in `createSentinel()` (see
the FIXMEs I added for `ilist_embedded_sentinel_traits` and
`ilist_half_embedded_sentinel_traits`).  My eventual goal is to separate
the list logic into a base class layer that knows nothing about (and
isn't templated on) the downcasted nodes -- removing the need to invoke
UB -- but for now I'm just trying to get a handle on all the current use
cases (and cleaning things up as I see them).

Besides these six SymbolTable lists, there are two others that use the
addNode/removeNode/transferNodes() hooks: the `MachineInstruction` and
`MachineBasicBlock` lists.  Ideally there'll be a way to factor these
hooks out of the low-level API entirely, but I'm not quite there yet.

llvm-svn: 249602
2015-10-07 20:05:10 +00:00
Hans Wennborg 083ca9bb32 Fix Clang-tidy modernize-use-nullptr warnings in source directories and generated files; other minor cleanups.
Patch by Eugene Zelenko!

Differential Revision: http://reviews.llvm.org/D13321

llvm-svn: 249482
2015-10-06 23:24:35 +00:00
Pete Cooper ebcd748927 Convert a bunch of loops to foreach. NFC.
After r244074, we now have a successors() method to iterate over
all the successors of a TerminatorInst.  This commit changes a bunch
of eligible loops to use it.

llvm-svn: 244260
2015-08-06 20:22:46 +00:00
David Majnemer 654e130b6e New EH representation for MSVC compatibility
This introduces new instructions neccessary to implement MSVC-compatible
exception handling support.  Most of the middle-end and none of the
back-end haven't been audited or updated to take them into account.

Differential Revision: http://reviews.llvm.org/D11097

llvm-svn: 243766
2015-07-31 17:58:14 +00:00
David Majnemer db82d2f338 Revert the new EH instructions
This reverts commits r241888-r241891, I didn't mean to commit them.

llvm-svn: 241893
2015-07-10 07:15:17 +00:00
David Majnemer ae2ffc8a8c New EH representation for MSVC compatibility
Summary:
This introduces new instructions neccessary to implement MSVC-compatible
exception handling support.  Most of the middle-end and none of the
back-end haven't been audited or updated to take them into account.

Reviewers: rnk, JosephTremoulet, reames, nlewycky, rjmccall

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D11041

llvm-svn: 241888
2015-07-10 07:00:44 +00:00
David Majnemer 6cc21f909c Revert "Revert r241570, it caused PR24053"
This reverts commit r241602.  We had a latent bug in SCCP where we would
make a basic block empty and then proceed to ask questions about it's
terminator.

llvm-svn: 241616
2015-07-07 18:49:41 +00:00
Nico Weber feb13e9e09 Revert r241570, it caused PR24053
llvm-svn: 241602
2015-07-07 16:42:50 +00:00
David Majnemer 381326d771 [IR] Make getFirstNonPHI return null if the BB is empty
getFirstNonPHI's documentation states that it returns null if there is
no non-PHI instruction.  However, it instead returns a pointer to the
end iterator.  The implementation of getFirstNonPHI claims that
dereferencing the iterator will result in an assertion failure but this
doesn't occur.  Instead, machinery like getFirstInsertionPt will attempt
to isa<> this invalid memory which results in unpredictable behavior.
Instead, make getFirst* return null if no such instruction exists.

llvm-svn: 241570
2015-07-07 09:15:29 +00:00
Alexey Samsonov 770f65ca6a Set proper debug location for branch added in BasicBlock::splitBasicBlock().
This improves debug locations in passes that do a lot of basic block
transformations. Important case is LoopUnroll pass, the test for correct
debug locations accompanies this change.

Test Plan: regression test suite

Reviewers: dblaikie, sanjoy

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D10367

llvm-svn: 239551
2015-06-11 18:25:54 +00:00
Philip Reames 38840245e4 [PlaceSafepoints] Cleanup InsertSafepointPoll function
While working on another change, I noticed that the naming in this function was mildly deceptive.  While fixing that, I took the oppurtunity to modernize some of the code.  NFC intended.

llvm-svn: 238252
2015-05-26 21:03:23 +00:00
Jingyue Wu 154eb5aa1d Add a speculative execution pass
Summary:
This is a pass for speculative execution of instructions for simple if-then (triangle) control flow. It's aimed at GPUs, but could perhaps be used in other contexts. Enabling this pass gives us a 1.0% geomean improvement on Google benchmark suites, with one benchmark improving 33%.

Credit goes to Jingyue Wu for writing an earlier version of this pass.

Patched by Bjarke Roune. 

Test Plan:
This patch adds a set of tests in test/Transforms/SpeculativeExecution/spec.ll
The pass is controlled by a flag which defaults to having the pass not run.

Reviewers: eliben, dberlin, meheff, jingyue, hfinkel

Reviewed By: jingyue, hfinkel

Subscribers: majnemer, jholewinski, llvm-commits

Differential Revision: http://reviews.llvm.org/D9360

llvm-svn: 237459
2015-05-15 17:54:48 +00:00
Daniel Berlin 0bf7ff56a6 Return iterator from BasicBlock::eraseFromParent
Summary:
Same as the last patch, but for BasicBlock
(Requires same code movement)

Reviewers: chandlerc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D8801

llvm-svn: 233992
2015-04-03 01:20:33 +00:00
Mehdi Amini 9a9738f6e5 Remove getDataLayout() from Instruction/GlobalValue/BasicBlock/Function
Summary:
This does not conceptually belongs here. Instead provide a shortcut
getModule() that provides access to the DataLayout.

Reviewers: chandlerc, echristo

Reviewed By: echristo

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D8027

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 231147
2015-03-03 22:01:13 +00:00
Sanjay Patel af0ff1093e remove function names from comments; NFC
llvm-svn: 230771
2015-02-27 18:07:41 +00:00
Philip Reames 47cc673e1f Add a pass for inserting safepoints into (nearly) arbitrary IR
This pass is responsible for figuring out where to place call safepoints and safepoint polls. It doesn't actually make the relocations explicit; that's the job of the RewriteStatepointsForGC pass (http://reviews.llvm.org/D6975).

Note that this code is not yet finalized.  Its moving in tree for incremental development, but further cleanup is needed and will happen over the next few days.  It is not yet part of the standard pass order.  

Planned changes in the near future:
 - I plan on restructuring the statepoint rewrite to use the functions add to the IRBuilder a while back. 
 - In the current pass, the function "gc.safepoint_poll" is treated specially but is not an intrinsic. I plan to make identifying the poll function a property of the GCStrategy at some point in the near future.
 - As follow on patches, I will be separating a collection of test cases we have out of tree and submitting them upstream. 
 - It's not explicit in the code, but these two patches are introducing a new state for a statepoint which looks a lot like a patchpoint. There's no a transient form which doesn't yet have the relocations explicitly represented, but does prevent reordering of memory operations. Once this is in, I need to update actually make this explicit by reserving the 'unused' argument of the statepoint as a flag, updating the docs, and making the code explicitly check for such a thing. This wasn't really planned, but once I split the two passes - which was done for other reasons - the intermediate state fell out. Just reminds us once again that we need to merge statepoints and patchpoints at some point in the not that distant future.

Future directions planned:
 - Identifying more cases where a backedge safepoint isn't required to ensure timely execution of a safepoint poll.
 - Tweaking the insertion process to generate easier to optimize IR. (For example, investigating making SplitBackedge) the default.
 - Adding opt-in flags for a GCStrategy to use this pass. Once done, add this pass to the actual pass ordering.

Differential Revision: http://reviews.llvm.org/D6981

llvm-svn: 228090
2015-02-04 00:37:33 +00:00
Rafael Espindola 366e5c1bf1 The leak detector is dead, long live asan and valgrind.
In resent times asan and valgrind have found way more memory management bugs
in llvm than the special purpose leak detector.

llvm-svn: 224703
2014-12-22 13:00:36 +00:00
Reid Kleckner e31acf239a Move helper for getting a terminating musttail call to BasicBlock
No functional change.  To be used in future commits that need to look
for such instructions.

Reviewed By: rafael

Differential Revision: http://reviews.llvm.org/D4504

llvm-svn: 215413
2014-08-12 00:05:15 +00:00
Duncan P. N. Exon Smith 17cbb97882 IR: Add BasicBlock::insertInto()
Although unlinked `BasicBlock`s can be created, there's currently no way
to insert them into `Function`s after the fact.  In particular,
`moveAfter()` and `moveBefore()` require that the basic block is already
linked.

Extract the logic for initially linking a `BasicBlock` out of the
constructor and into a member function that can be used for lazy
insertion.

  - Asserts that the basic block is currently unlinked.
  - Matches the logic of the constructor.
  - Changed the constructor to use it since the logic matches.

This is needed in a follow-up commit for PR5680.

llvm-svn: 214563
2014-08-01 21:22:04 +00:00
Duncan P. N. Exon Smith 6c99015fe2 Revert "[C++11] Add predecessors(BasicBlock *) / successors(BasicBlock *) iterator ranges."
This reverts commit r213474 (and r213475), which causes a miscompile on
a stage2 LTO build.  I'll reply on the list in a moment.

llvm-svn: 213562
2014-07-21 17:06:51 +00:00