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199 Commits

Author SHA1 Message Date
Sanjoy Das
4cae6b16cb [IR] Make {Call,Invoke}::cloneImpl aware of operand bundles
This was an omission in the patch that landed initial support for
operand bundles.  So far we haven't hit this, but we will once the
inliner is able to inline calls to functions that contain calls with
operand bundles.

llvm-svn: 252645
2015-11-10 20:13:21 +00:00
Sanjoy Das
8cb5aa0766 [IR] Add bounds checking to dataOperandHasImpliedAttr
This is similar to the bounds check added to paramHasAttr in r252073.

llvm-svn: 252130
2015-11-05 01:53:26 +00:00
Sanjoy Das
8361535ee5 [IR] Add a data_operand abstraction
Summary:
Data operands of a call or invoke consist of the call arguments, and
the bundle operands associated with the `call` (or `invoke`)
instruction.  The motivation for this change is that we'd like to be
able to query "argument attributes" like `readonly` and `nocapture`
for bundle operands naturally.

This change also provides a conservative "implementation" for these
attributes for any bundle operand, and an extension point for future
work.

Reviewers: chandlerc, majnemer, reames

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D14305

llvm-svn: 252077
2015-11-04 21:05:24 +00:00
Sanjoy Das
442b82fb2f [IR] Add bounds checking to paramHasAttr
Summary:
This is intended to make a later change simpler.

Note: adding this bounds checking required fixing `X86FastISel`.  As
far I can tell I've preserved original behavior but a careful review
will be appreciated.

Reviewers: reames

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D14304

llvm-svn: 252073
2015-11-04 20:33:45 +00:00
Sanjoy Das
592ded635e [SCEV] Opportunistically interpret unsigned constraints as signed
Summary:
An unsigned comparision is equivalent to is corresponding signed version
if both the operands being compared are positive.  Teach SCEV to use
this fact when profitable.

Reviewers: atrick, hfinkel, reames, nlewycky

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D13687

llvm-svn: 251051
2015-10-22 19:57:34 +00:00
Sanjoy Das
de9991d3c2 [OperandBundles] Make function attributes conservatively correct
Summary:
This makes attribute accessors on `CallInst` and `InvokeInst` do the
(conservatively) right thing.  This essentially involves, in some
cases, *not* falling back querying the attributes on the called
`llvm::Function` when operand bundles are present.

Attributes locally present on the `CallInst` or `InvokeInst` will still
override operand bundle semantics.  The LangRef has been amended to
reflect this.  Note: this change does not do anything prevent
`-function-attrs` from inferring `CallSite` local attributes after
inspecting the called function -- that will be done as a separate
change.

I've used `-adce` and `-early-cse` to test these changes.  There is
nothing special about these passes (and they did not require any
changes) except that they seemed be the easiest way to write the tests.

This change does not add deal with `argmemonly`.  That's a later change
because alias analysis requires a related fix before `argmemonly` can be
tested.

Reviewers: reames, chandlerc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D13961

llvm-svn: 250973
2015-10-22 03:12:22 +00:00
Sanjoy Das
f43d5ab867 [IR] Add operand bundles to CallInst and InvokeInst.
Summary:
This change teaches `CallInst`s and `InvokeInst`s to maintain a set of
operand bundles as part of its operands.  `CallInst`s and `InvokeInst`s
with operand bundles co-allocate some space before their `Use` array to
hold meta information about which of its operands are part of an operand
bundle.

The strings corresponding to the bundle tags are interned into
`LLVMContextImpl::BundleTagCache`

This change does not include any parsing / bitcode support.  That's the
next change.

Depends on D12455.

Reviewers: reames, chandlerc, majnemer, dexonsmith, kmod, JosephTremoulet, rnk, bogner

Subscribers: MatzeB, sanjoy, llvm-commits

Differential Revision: http://reviews.llvm.org/D12456

llvm-svn: 248527
2015-09-24 19:14:18 +00:00
Joseph Tremoulet
bce9d857cc [WinEH] Add cleanupendpad instruction
Summary:
Add a `cleanupendpad` instruction, used to mark exceptional exits out of
cleanups (for languages/targets that can abort a cleanup with another
exception).  The `cleanupendpad` instruction is similar to the `catchendpad`
instruction in that it is an EH pad which is the target of unwind edges in
the handler and which itself has an unwind edge to the next EH action.
The `cleanupendpad` instruction, similar to `cleanupret` has a `cleanuppad`
argument indicating which cleanup it exits.  The unwind successors of a
`cleanuppad`'s `cleanupendpad`s must agree with each other and with its
`cleanupret`s.

Update WinEHPrepare (and docs/tests) to accomodate `cleanupendpad`.

Reviewers: rnk, andrew.w.kaylor, majnemer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D12433

llvm-svn: 246751
2015-09-03 09:09:43 +00:00
David Majnemer
8cec64183b [IR] Cleanup EH instructions a little bit
Just a cosmetic change, no functionality change is intended.

llvm-svn: 245818
2015-08-23 19:22:31 +00:00
Joseph Tremoulet
56089ea65e [WinEH] Require token linkage in EH pad/ret signatures
Summary:
WinEHPrepare is going to require that cleanuppad and catchpad produce values
of token type which are consumed by any cleanupret or catchret exiting the
pad.  This change updates the signatures of those operators to require/enforce
that the type produced by the pads is token type and that the rets have an
appropriate argument.

The catchpad argument of a `CatchReturnInst` must be a `CatchPadInst` (and
similarly for `CleanupReturnInst`/`CleanupPadInst`).  To accommodate that
restriction, this change adds a notion of an operator constraint to both
LLParser and BitcodeReader, allowing appropriate sentinels to be constructed
for forward references and appropriate error messages to be emitted for
illegal inputs.

Also add a verifier rule (noted in LangRef) that a catchpad with a catchpad
predecessor must have no other predecessors; this ensures that WinEHPrepare
will see the expected linear relationship between sibling catches on the
same try.

Lastly, remove some superfluous/vestigial casts from instruction operand
setters operating on BasicBlocks.

Reviewers: rnk, majnemer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D12108

llvm-svn: 245797
2015-08-23 00:26:33 +00:00
David Majnemer
85a57db552 [IR] Give catchret an optional 'return value' operand
Some personality routines require funclet exit points to be clearly
marked, this is done by producing a token at the funclet pad and
consuming it at the corresponding ret instruction.  CleanupReturnInst
already had a spot for this operand but CatchReturnInst did not.
Other personality routines don't need to use this which is why it has
been made optional.

llvm-svn: 245149
2015-08-15 02:46:08 +00:00
David Majnemer
10f2d9234b [IR] Add token types
This introduces the basic functionality to support "token types".
The motivation stems from the need to perform operations on a Value
whose provenance cannot be obscured.

There are several applications for such a type but my immediate
motivation stems from WinEH.  Our personality routine enforces a
single-entry - single-exit regime for cleanups.  After several rounds of
optimizations, we may be left with a terminator whose "cleanup-entry
block" is not entirely clear because control flow has merged two
cleanups together.  We have experimented with using labels as operands
inside of instructions which are not terminators to indicate where we
came from but found that LLVM does not expect such exotic uses of
BasicBlocks.

Instead, we can use this new type to clearly associate the "entry point"
and "exit point" of our cleanup.  This is done by having the cleanuppad
yield a Token and consuming it at the cleanupret.
The token type makes it impossible to obscure or otherwise hide the
Value, making it trivial to track the relationship between the two
points.

What is the burden to the optimizer?  Well, it turns out we have already
paid down this cost by accepting that there are certain calls that we
are not permitted to duplicate, optimizations have to watch out for
such instructions anyway.  There are additional places in the optimizer
that we will probably have to update but early examination has given me
the impression that this will not be heroic.

Differential Revision: http://reviews.llvm.org/D11861

llvm-svn: 245029
2015-08-14 05:09:07 +00:00
David Majnemer
895671d0b0 [IR] Cleanup indentation of EH instructions
No functional change is intended, just tidying up whitespace.

llvm-svn: 244966
2015-08-13 22:11:40 +00:00
David Majnemer
115b42e41a [IR] Remove TerminateInst's "NameStr" argument
TerminateInst can't have a name because it doesn't produce a result.  No
functionality change is intended, this is just a cleanup.

llvm-svn: 244276
2015-08-06 21:08:36 +00:00
David Majnemer
cce4d2aeb3 Drive-by fixes for LandingPad -> EHPad
This change was done as an audit and is by inspection.  The new EH
system is still very much a work in progress.  NFC for the landingpad
case.

llvm-svn: 243965
2015-08-04 08:21:40 +00:00
David Majnemer
34ee3789f3 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
80ac5e60bf 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
6310e08ce2 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
Akira Hatanaka
6d78b5b1b5 Add functions for adding and testing string attributes to CallInst. NFC.
This change is needed later when I make changes to attach string function
attributes to llvm.trap and llvm.debugtrap.

llvm-svn: 241304
2015-07-02 22:08:48 +00:00
Pete Cooper
cbf9b4e67d Devirtualize Instruction::clone_impl
llvm-svn: 240588
2015-06-24 20:22:23 +00:00
David Majnemer
c8b1f095a3 Move the personality function from LandingPadInst to Function
The personality routine currently lives in the LandingPadInst.

This isn't desirable because:
- All LandingPadInsts in the same function must have the same
  personality routine.  This means that each LandingPadInst beyond the
  first has an operand which produces no additional information.

- There is ongoing work to introduce EH IR constructs other than
  LandingPadInst.  Moving the personality routine off of any one
  particular Instruction and onto the parent function seems a lot better
  than have N different places a personality function can sneak onto an
  exceptional function.

Differential Revision: http://reviews.llvm.org/D10429

llvm-svn: 239940
2015-06-17 20:52:32 +00:00
Pete Cooper
eeab7b6f62 Rename NumOperands to make it clear its managed by the User. NFC.
This is to try make it very clear that subclasses shouldn't be changing
the value directly.  Now that OperandList for normal instructions is computed
using the NumOperands, its critical that the NumOperands is accurate or we
could compute the wrong offset to the first operand.

I looked over all places which update NumOperands and they are all safe.
Hung off use User's don't use NumOperands to compute the OperandList so they
are safe to continue to manipulate it.  The only other User which changed it
was GlobalVariable which has an optional init list but always allocated space
for a single Use.  It was correctly setting NumOperands to 1 before setting an
initializer, and setting it to 0 after clearing the init list, so the order was safe.

Added some comments to that code to make sure that this isn't changed in future
without being aware of this constraint.

Reviewed by Duncan Exon Smith.

llvm-svn: 239621
2015-06-12 17:48:10 +00:00
Pete Cooper
7cf957b205 Replace all accesses to User::OperandList with getter and setter methods. NFC.
We don't want anyone to access OperandList directly as its going to be removed
and computed instead.  This uses getter's and setter's instead in which we
can later change the underlying implementation of OperandList.

Reviewed by Duncan Exon Smith.

llvm-svn: 239620
2015-06-12 17:48:05 +00:00
Pete Cooper
24aea91aca Stop returning a Use* from allocHungOffUses.
This always just set the User::OperandList which is now set
in that method instead of being returned.

Reviewed by Duncan Exon Smith.

llvm-svn: 239493
2015-06-10 22:38:46 +00:00
Pete Cooper
f609d284a0 Add User::growHungoffUses and use it to grow the hung off uses. NFC.
PhiNode, SwitchInst, LandingPad and IndirectBr all had virtually identical
logic for growing the hung off uses.
Move it to User so that they can all call a single shared implementation.

Their destructors were all empty after this change and were deleted.  They all
have virtual clone_impl methods which can be used as vtable anchors.

Reviewed by Duncan Exon Smith.

llvm-svn: 239492
2015-06-10 22:38:41 +00:00
Pete Cooper
f944a82ef6 Delete User::dropHungOffUses and move it in to ~User which is the only caller. NFC.
Now that the subclasses which care about hung off uses let ~User clean it up,
there's no need for a separate method.  Just inline it to ~User and delete it.

Reviewed by Duncan Exon Smith.

llvm-svn: 239491
2015-06-10 22:38:38 +00:00
Pete Cooper
51074a3578 Move the special Phi logic for hung off uses in to User::allocHungOffUses. NFC.
PhiNode's need to allocate space for an array of Use[N] and then BasicBlock*[N].

They had their own allocHungOffUses to handle all of this.  This moves the logic
in to User::allocHungOffUses and PhiNode passes in a bool to say to allocate
the BB* space too.

Reviewed by Duncan Exon Smith.

llvm-svn: 239489
2015-06-10 22:38:30 +00:00
David Blaikie
1aa7d2b449 [opaque pointer type] Explicitly store the pointee type of the result of a GEP
Alternatively, this type could be derived on-demand whenever
getResultElementType is called - if someone thinks that's the better
choice (simple time/space tradeoff), I'm happy to give it a go.

llvm-svn: 238716
2015-06-01 03:09:34 +00:00
Ahmed Bougacha
a689d2cb58 [IR] fptrunc-of-fptrunc isn't an EliminableCastPair.
Double and single rounding can produce different results.
This is the IR counterpart to r228911.

llvm-svn: 238531
2015-05-29 00:04:30 +00:00
Pete Cooper
2c9a26c1e1 Use Op<0> accessor instead of OperandList for Instructions. NFC
This is consistent with other uses of the operand list.  I'm planning a future commit where this will actually matter.

llvm-svn: 237967
2015-05-21 22:48:54 +00:00
David Blaikie
7aa3cb67dd [opaque pointer type] Pass explicit type to Load instruction creation in AutoUpgrade
llvm-svn: 237838
2015-05-20 21:46:30 +00:00
David Blaikie
30e6e29e4a [opaque pointer type] LoadInst: assert that the explicit type matches the implicit one
llvm-svn: 237830
2015-05-20 20:22:31 +00:00
David Blaikie
26b7a1ff69 [opaque pointer type] Pass the explicit function type down to the instruction constructor when parsing invoke instructions
llvm-svn: 237273
2015-05-13 18:35:26 +00:00
David Blaikie
b888632efe [opaque pointer type] Track explicit GEP pointee type through in-memory IR
llvm-svn: 236510
2015-05-05 18:03:48 +00:00
David Blaikie
ba3e12d3c8 [opaque pointer type] Store the value type of an alloca
llvm-svn: 236175
2015-04-29 23:00:35 +00:00
David Blaikie
62279d8d0a Recommit r235458: [opaque pointer type] Avoid using PointerType::getElementType for a few cases of CallInst
(reverted in r235533)

Original commit message:

"Calls to llvm::Value::mutateType are becoming extra-sensitive now that
instructions have extra type information that will not be derived from
operands or result type (alloca, gep, load, call/invoke, etc... ). The
special-handling for mutateType will get more complicated as this work
continues - it might be worth making mutateType virtual & pushing the
complexity down into the classes that need special handling. But with
only two significant uses of mutateType (vectorization and linking) this
seems OK for now.

Totally open to ideas/suggestions/improvements, of course.

With this, and a bunch of exceptions, we can roundtrip an indirect call
site through bitcode and IR. (a direct call site is actually trickier...
I haven't figured out how to deal with the IR deserializer's lazy
construction of Function/GlobalVariable decl's based on the type of the
entity which means looking through the "pointer to T" type referring to
the global)"

The remapping done in ValueMapper for LTO was insufficient as the types
weren't correctly mapped (though I was using the post-mapped operands,
some of those operands might not have been mapped yet so the type
wouldn't be post-mapped yet). Instead use the pre-mapped type and
explicitly map all the types.

llvm-svn: 235651
2015-04-23 21:36:23 +00:00
David Blaikie
ec41387ad6 Revert "[opaque pointer type] Avoid using PointerType::getElementType for a few cases of CallInst"
This reverts commit r235458.

It looks like this might be breaking something LTO-ish. Looking into it
& will recommit with a fix/test case/etc once I've got more to go on.

llvm-svn: 235533
2015-04-22 18:16:49 +00:00
David Blaikie
0477b5459c [opaque pointer type] Avoid using PointerType::getElementType for a few cases of CallInst
Calls to llvm::Value::mutateType are becoming extra-sensitive now that
instructions have extra type information that will not be derived from
operands or result type (alloca, gep, load, call/invoke, etc... ). The
special-handling for mutateType will get more complicated as this work
continues - it might be worth making mutateType virtual & pushing the
complexity down into the classes that need special handling. But with
only two significant uses of mutateType (vectorization and linking) this
seems OK for now.

Totally open to ideas/suggestions/improvements, of course.

With this, and a bunch of exceptions, we can roundtrip an indirect call
site through bitcode and IR. (a direct call site is actually trickier...
I haven't figured out how to deal with the IR deserializer's lazy
construction of Function/GlobalVariable decl's based on the type of the
entity which means looking through the "pointer to T" type referring to
the global)

llvm-svn: 235458
2015-04-21 23:26:57 +00:00
Fiona Glaser
c2e9ee5036 InstCombine: fold (sitofp (zext x)) to (uitofp x)
This is okay because the zext guarantees the high bit is zero,
and so the value is unsigned.

llvm-svn: 235364
2015-04-21 00:05:41 +00:00
David Blaikie
7b0ae200c4 [opaque pointer types] Use the pointee type loaded from bitcode when constructing a LoadInst
Now (with a few carefully placed suppressions relating to general type
serialization, etc) we can round trip a simple load through bitcode and
textual IR without calling getElementType on a PointerType.

llvm-svn: 235221
2015-04-17 19:56:21 +00:00
Sanjoy Das
2d08e46e8b [IR] Introduce a dereferenceable_or_null(N) attribute.
Summary:
If a pointer is marked as dereferenceable_or_null(N), LLVM assumes it
is either `null` or `dereferenceable(N)` or both.  This change only
introduces the attribute and adds a token test case for the `llvm-as`
/ `llvm-dis`.  It does not hook up other parts of the optimizer to
actually exploit the attribute -- those changes will come later.

For pointers in address space 0, `dereferenceable(N)` is now exactly
equivalent to `dereferenceable_or_null(N)` && `nonnull`.  For other
address spaces, `dereferenceable(N)` is potentially weaker than
`dereferenceable_or_null(N)` && `nonnull` (since we could have a null
`dereferenceable(N)` pointer).

The motivating case for this change is Java (and other managed
languages), where pointers are either `null` or dereferenceable up to
some usually known-at-compile-time constant offset.

Reviewers: rafael, hfinkel

Reviewed By: hfinkel

Subscribers: nicholas, llvm-commits

Differential Revision: http://reviews.llvm.org/D8650

llvm-svn: 235132
2015-04-16 20:29:50 +00:00
David Blaikie
1c84936605 [opaque pointer type] Avoid using PointerType::getElementType when parsing IR
A few calls are left in for error checking - but I'm commenting those
out & trying to build some IR tests (aiming for Argument Promotion to
start with). When I get any of these tests passing I may add flag to
disable the checking so I can add tests that pass with the assertion in
place.

llvm-svn: 234206
2015-04-06 20:59:48 +00:00
David Blaikie
39f56d0f3c [opaque pointer type] Change GetElementPtrInst::getIndexedType to take the pointee type
This pushes the use of PointerType::getElementType up into several
callers - I'll essentially just have to keep pushing that up the stack
until I can eliminate every call to it...

llvm-svn: 233604
2015-03-30 21:41:43 +00:00
David Blaikie
87be8e95c5 Refactor: Simplify boolean expressions in llvm IR
Simplify boolean expressions using `true` and `false` with `clang-tidy`

Patch by Richard Thomson with a few other simplifications to fix
else-after-returns in the surrounding code.

Differential Revision: http://reviews.llvm.org/D8527

llvm-svn: 233005
2015-03-23 19:51:23 +00:00
Mehdi Amini
f88efe5f8a DataLayout is mandatory, update the API to reflect it with references.
Summary:
Now that the DataLayout is a mandatory part of the module, let's start
cleaning the codebase. This patch is a first attempt at doing that.

This patch is not exactly NFC as for instance some places were passing
a nullptr instead of the DataLayout, possibly just because there was a
default value on the DataLayout argument to many functions in the API.
Even though it is not purely NFC, there is no change in the
validation.

I turned as many pointer to DataLayout to references, this helped
figuring out all the places where a nullptr could come up.

I had initially a local version of this patch broken into over 30
independant, commits but some later commit were cleaning the API and
touching part of the code modified in the previous commits, so it
seemed cleaner without the intermediate state.

Test Plan:

Reviewers: echristo

Subscribers: llvm-commits

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 231740
2015-03-10 02:37:25 +00:00
Benjamin Kramer
fc8295a8f7 Instructions: Use delegated constructors to reduce duplication
NFC.

llvm-svn: 231411
2015-03-05 22:05:26 +00:00
David Majnemer
64cd3dbda5 IR: SrcTy == DstTy doesn't imply that a cast is valid
Cast validity depends on the cast's kind, not just its types.

llvm-svn: 229366
2015-02-16 09:37:35 +00:00
Ramkumar Ramachandra
af4f23c6ae InstCombine: propagate deref via new addDereferenceableAttr
The "dereferenceable" attribute cannot be added via .addAttribute(),
since it also expects a size in bytes. AttrBuilder#addAttribute or
AttributeSet#addAttribute is wrapped by classes Function, InvokeInst,
and CallInst. Add corresponding wrappers to
AttrBuilder#addDereferenceableAttr.

Having done this, propagate the dereferenceable attribute via
gc.relocate, adding a test to exercise it. Note that -datalayout is
required during execution over and above -instcombine, because
InstCombine only optionally requires DataLayoutPass.

Differential Revision: http://reviews.llvm.org/D7510

llvm-svn: 229265
2015-02-14 19:37:54 +00:00
Duncan P. N. Exon Smith
3d57886267 IR: Split Metadata from Value
Split `Metadata` away from the `Value` class hierarchy, as part of
PR21532.  Assembly and bitcode changes are in the wings, but this is the
bulk of the change for the IR C++ API.

I have a follow-up patch prepared for `clang`.  If this breaks other
sub-projects, I apologize in advance :(.  Help me compile it on Darwin
I'll try to fix it.  FWIW, the errors should be easy to fix, so it may
be simpler to just fix it yourself.

This breaks the build for all metadata-related code that's out-of-tree.
Rest assured the transition is mechanical and the compiler should catch
almost all of the problems.

Here's a quick guide for updating your code:

  - `Metadata` is the root of a class hierarchy with three main classes:
    `MDNode`, `MDString`, and `ValueAsMetadata`.  It is distinct from
    the `Value` class hierarchy.  It is typeless -- i.e., instances do
    *not* have a `Type`.

  - `MDNode`'s operands are all `Metadata *` (instead of `Value *`).

  - `TrackingVH<MDNode>` and `WeakVH` referring to metadata can be
    replaced with `TrackingMDNodeRef` and `TrackingMDRef`, respectively.

    If you're referring solely to resolved `MDNode`s -- post graph
    construction -- just use `MDNode*`.

  - `MDNode` (and the rest of `Metadata`) have only limited support for
    `replaceAllUsesWith()`.

    As long as an `MDNode` is pointing at a forward declaration -- the
    result of `MDNode::getTemporary()` -- it maintains a side map of its
    uses and can RAUW itself.  Once the forward declarations are fully
    resolved RAUW support is dropped on the ground.  This means that
    uniquing collisions on changing operands cause nodes to become
    "distinct".  (This already happened fairly commonly, whenever an
    operand went to null.)

    If you're constructing complex (non self-reference) `MDNode` cycles,
    you need to call `MDNode::resolveCycles()` on each node (or on a
    top-level node that somehow references all of the nodes).  Also,
    don't do that.  Metadata cycles (and the RAUW machinery needed to
    construct them) are expensive.

  - An `MDNode` can only refer to a `Constant` through a bridge called
    `ConstantAsMetadata` (one of the subclasses of `ValueAsMetadata`).

    As a side effect, accessing an operand of an `MDNode` that is known
    to be, e.g., `ConstantInt`, takes three steps: first, cast from
    `Metadata` to `ConstantAsMetadata`; second, extract the `Constant`;
    third, cast down to `ConstantInt`.

    The eventual goal is to introduce `MDInt`/`MDFloat`/etc. and have
    metadata schema owners transition away from using `Constant`s when
    the type isn't important (and they don't care about referring to
    `GlobalValue`s).

    In the meantime, I've added transitional API to the `mdconst`
    namespace that matches semantics with the old code, in order to
    avoid adding the error-prone three-step equivalent to every call
    site.  If your old code was:

        MDNode *N = foo();
        bar(isa             <ConstantInt>(N->getOperand(0)));
        baz(cast            <ConstantInt>(N->getOperand(1)));
        bak(cast_or_null    <ConstantInt>(N->getOperand(2)));
        bat(dyn_cast        <ConstantInt>(N->getOperand(3)));
        bay(dyn_cast_or_null<ConstantInt>(N->getOperand(4)));

    you can trivially match its semantics with:

        MDNode *N = foo();
        bar(mdconst::hasa               <ConstantInt>(N->getOperand(0)));
        baz(mdconst::extract            <ConstantInt>(N->getOperand(1)));
        bak(mdconst::extract_or_null    <ConstantInt>(N->getOperand(2)));
        bat(mdconst::dyn_extract        <ConstantInt>(N->getOperand(3)));
        bay(mdconst::dyn_extract_or_null<ConstantInt>(N->getOperand(4)));

    and when you transition your metadata schema to `MDInt`:

        MDNode *N = foo();
        bar(isa             <MDInt>(N->getOperand(0)));
        baz(cast            <MDInt>(N->getOperand(1)));
        bak(cast_or_null    <MDInt>(N->getOperand(2)));
        bat(dyn_cast        <MDInt>(N->getOperand(3)));
        bay(dyn_cast_or_null<MDInt>(N->getOperand(4)));

  - A `CallInst` -- specifically, intrinsic instructions -- can refer to
    metadata through a bridge called `MetadataAsValue`.  This is a
    subclass of `Value` where `getType()->isMetadataTy()`.

    `MetadataAsValue` is the *only* class that can legally refer to a
    `LocalAsMetadata`, which is a bridged form of non-`Constant` values
    like `Argument` and `Instruction`.  It can also refer to any other
    `Metadata` subclass.

(I'll break all your testcases in a follow-up commit, when I propagate
this change to assembly.)

llvm-svn: 223802
2014-12-09 18:38:53 +00:00
Juergen Ributzka
a2310d0648 Revert "Move function to obtain branch weights into the BranchInst class. NFC."
This reverts commit r223784 and copies the 'ExtractBranchMetadata' to CodeGenPrepare.

llvm-svn: 223795
2014-12-09 17:32:12 +00:00