Commit Graph

378 Commits

Author SHA1 Message Date
Alexey Bataev 16e798873e [OPENMP] Add support for cancel constructs in `target teams distribute
parallel for`.

Add support for cancel/cancellation point directives inside `target
teams distribute parallel for` directives.

llvm-svn: 318881
2017-11-22 21:12:03 +00:00
Alexey Bataev dcb4b8fbc1 [OPENMP] Add support for cancel constructs in [teams] distribute
parallel for directives.

Added codegen/sema support for cancel constructs in [teams] distribute
parallel for directives.

llvm-svn: 318872
2017-11-22 20:19:50 +00:00
Alexey Bataev 931e19bf51 [OPENMP] Capture argument of `device` clause for target-based
directives.

The argument of the `device` clause in target-based executable
directives must be captured to support codegen for the `target`
directives with the `depend` clauses.

llvm-svn: 314686
2017-10-02 16:32:39 +00:00
Alexey Bataev 88202be1f0 [OPENMP] Codegen for 'in_reduction' clause.
Added codegen for task-based directive with in_reduction clause.
```
<body>
```
The next code is emitted:
```
void *td;
...
td = call i8* @__kmpc_task_reduction_init();
...
<type> *priv = (<type> *)call i8* @__kmpc_task_reduction_get_th_data(i32
GTID, i8* td, i8* <orig>)
```

llvm-svn: 309270
2017-07-27 13:20:36 +00:00
Gor Nishanov f5ecb5e1b4 [coroutines] Add serialization/deserialization of coroutines
Reviewers: rsmith

Reviewed By: rsmith

Subscribers: EricWF, cfe-commits

Differential Revision: https://reviews.llvm.org/D35383

llvm-svn: 308996
2017-07-25 18:01:49 +00:00
Alexey Bataev 3b1b8951b9 [OPENMP] Codegen for 'task_reduction' clause.
Added codegen for taskgroup directive with task_reduction clause.
```
<body>
```
The next code is emitted:
```
%struct.kmp_task_red_input_t red_init[n];
void *td;
call void @__kmpc_taskgroup(%ident_t id, i32 gtid)
...
red_init[i].shar = &<item>;
red_init[i].size = sizeof(<item>);
red_init[i].init = (void*)initializer_function;
red_init[i].fini = (void*)destructor_function;
red_init[i].comb = (void*)combiner_function;
red_init[i].flags = flags;
...
td = call i8* @__kmpc_task_reduction_init(i32 gtid, i32 n, i8*
(void*)red_init);
call void @__kmpc_end_taskgroup(%ident_t id, i32 gtid)

void initializer_function(i8* priv) {
  *(<type>*)priv = <red_init>;
  ret void;
}

void destructor_function(i8* priv) {
  (<type>*)priv->~();
  ret void;
}

void combiner_function(i8* inout, i8* in) {
  *(<type>*)inout = *(<type>*)inout <red_id> *(<type>*)in;
  ret void;
}
```

llvm-svn: 308979
2017-07-25 15:53:26 +00:00
Alexey Bataev fa312f33f8 [OPENMP] Initial support for 'in_reduction' clause.
Parsing/sema analysis for 'in_reduction' clause for task-based
directives.

llvm-svn: 308768
2017-07-21 18:48:21 +00:00
Alexey Bataev 169d96a203 [OPENMP] Initial support for 'task_reduction' clause.
Parsing/sema analysis of the 'task_reduction' clause.

llvm-svn: 308352
2017-07-18 20:17:46 +00:00
Richard Smith dbafb6c338 Teach ASTReader how to read only the Preprocessor state from an AST file, not the ASTContext state.
We use this when running a preprocessor-only action on an AST file in order to
avoid paying the runtime cost of loading the extra information.

llvm-svn: 306760
2017-06-29 23:23:46 +00:00
Carlo Bertolli ffafe10fac [OpenMP] Prepare sema to support combined constructs with omp distribute and omp for
https://reviews.llvm.org/D32237

This patch prepares sema with additional fields to support all those composite and combined constructs of OpenMP that include pragma 'distribute' and 'for', such as 'distribute parallel for'. It also extends the regression tests for 'distribute parallel for' and adds a new one.

llvm-svn: 300802
2017-04-20 00:39:39 +00:00
Adam Nemet 484aa45153 Encapsulate FPOptions and use it consistently
Sema holds the current FPOptions which is adjusted by 'pragma STDC
FP_CONTRACT'.  This then gets propagated into expression nodes as they are
built.

This encapsulates FPOptions so that this propagation happens opaquely rather
than directly with the fp_contractable on/off bit.  This allows controlled
transitioning of fp_contractable to a ternary value (off, on, fast).  It will
also allow adding more fast-math flags later.

This is toward moving fp-contraction=fast from an LLVM TargetOption to a
FastMathFlag in order to fix PR25721.

Differential Revision: https://reviews.llvm.org/D31166

llvm-svn: 298877
2017-03-27 19:17:25 +00:00
Eric Fiselier 20f25cb6df [coroutines] Add DependentCoawaitExpr and fix re-building CoroutineBodyStmt.
Summary:
The changes contained in this patch are:

1. Defines a new AST node `CoawaitDependentExpr` for representing co_await expressions while the promise type is still dependent.
2. Correctly detect and transform the 'co_await' operand to  `p.await_transform(<expr>)`  when possible.
3. Change the initial/final suspend points to build during the initial parse, so they have the correct operator co_await lookup results.
4.  Fix transformation of the CoroutineBodyStmt so that it doesn't re-build the final/initial suspends.


@rsmith: This change is a little big, but it's not trivial for me to split it up. Please let me know if you would prefer this submitted as multiple patches.



Reviewers: rsmith, GorNishanov

Reviewed By: rsmith

Subscribers: ABataev, rsmith, mehdi_amini, cfe-commits

Differential Revision: https://reviews.llvm.org/D26057

llvm-svn: 297093
2017-03-06 23:38:15 +00:00
Carlo Bertolli 8429d81202 [OpenMP] Prepare Sema for initial implementation for pragma 'distribute parallel for'
https://reviews.llvm.org/D29922

This patch adds two fields for use in the implementation of 'distribute parallel for':

The increment expression for the distribute loop. As the chunk assigned to a team is executed by multiple threads within the 'parallel for' region, the increment expression has to correspond to the value returned by the related runtime call (for_static_init).
The upper bound of the innermost loop ('for' in 'distribute parallel for') is not the globalUB expression normally used for pragma 'for' when found in isolation. It is instead the upper bound of the chunk assigned to the team ('distribute' loop). In this way, we prevent teams from executing chunks assigned to other teams.
The use of these two fields can be see in a related explanatory patch:
https://reviews.llvm.org/D29508

llvm-svn: 295497
2017-02-17 21:29:13 +00:00
George Burgess IV 758cf9da37 Delete useless / in comment. NFC.
llvm-svn: 295032
2017-02-14 05:52:57 +00:00
Arpith Chacko Jacob 7ecc0b7f3d [OpenMP] Support for thread_limit-clause on the 'target teams' directive.
The thread_limit-clause on the combined directive applies to the
'teams' region of this construct. We modify the ThreadLimitClause
class to capture the clause expression within the 'target' region.

Reviewers: ABataev
Differential Revision: https://reviews.llvm.org/D29087

llvm-svn: 293049
2017-01-25 11:44:35 +00:00
Arpith Chacko Jacob bc126344e1 [OpenMP] Support for num_teams-clause on the 'target teams' directive.
The num_teams-clause on the combined directive applies to the
'teams' region of this construct. We modify the NumTeamsClause
class to capture the clause expression within the 'target' region.

Reviewers: ABataev
Differential Revision: https://reviews.llvm.org/D29085

llvm-svn: 293048
2017-01-25 11:28:18 +00:00
Arpith Chacko Jacob 33c849a007 [OpenMP] Support for the num_threads-clause on 'target parallel'.
The num_threads-clause on the combined directive applies to the
'parallel' region of this construct. We modify the NumThreadsClause
class to capture the clause expression within the 'target' region.

The offload runtime call for 'target parallel' is changed to
__tgt_target_teams() with 1 team and the number of threads set by
this clause or a default if none.

Reviewers: ABataev
Differential Revision: https://reviews.llvm.org/D29082

llvm-svn: 292997
2017-01-25 00:57:16 +00:00
Arpith Chacko Jacob fe4890a68b [OpenMP] Support for the if-clause on the combined directive 'target parallel'.
The if-clause on the combined directive potentially applies to both the
'target' and the 'parallel' regions.  Codegen'ing the if-clause on the
combined directive requires additional support because the expression in
the clause must be captured by the 'target' capture statement but not
the 'parallel' capture statement.  Note that this situation arises for
other clauses such as num_threads.

The OMPIfClause class inherits OMPClauseWithPreInit to support capturing
of expressions in the clause.  A member CaptureRegion is added to
OMPClauseWithPreInit to indicate which captured statement (in this case
'target' but not 'parallel') captures these expressions.

To ensure correct codegen of captured expressions in the presence of
combined 'target' directives, OMPParallelScope was added to 'parallel'
codegen.

Reviewers: ABataev
Differential Revision: https://reviews.llvm.org/D28781

llvm-svn: 292437
2017-01-18 20:40:48 +00:00
Kelvin Li da68118729 [OpenMP] Sema and parsing for 'target teams distribute simd’ pragma
This patch is to implement sema and parsing for 'target teams distribute simd’ pragma.
    
Differential Revision: https://reviews.llvm.org/D28252

llvm-svn: 291579
2017-01-10 18:08:18 +00:00
Kelvin Li 1851df563d [OpenMP] Sema and parsing for 'target teams distribute parallel for simd’ pragma
This patch is to implement sema and parsing for 'target teams distribute parallel for simd’ pragma.

Differential Revision: https://reviews.llvm.org/D28202

llvm-svn: 290862
2017-01-03 05:23:48 +00:00
Kelvin Li 80e8f56284 [OpenMP] Sema and parsing for 'target teams distribute parallel for’ pragma
This patch is to implement sema and parsing for 'target teams distribute parallel for’ pragma.

Differential Revision: https://reviews.llvm.org/D28160

llvm-svn: 290725
2016-12-29 22:16:30 +00:00
Kelvin Li 83c451e998 [OpenMP] Sema and parsing for 'target teams distribute' pragma
This patch is to implement sema and parsing for 'target teams distribute' pragma.

Differential Revision: https://reviews.llvm.org/D28015

llvm-svn: 290508
2016-12-25 04:52:54 +00:00
David L. Jones b6a8f02251 Rename several methods on ASTRecordReader to follow LLVM style (lowerCamelCase).
Summary:
This follows up to r290217, and makes functions on ASTRecordReader consistent
and valid style.

Reviewers: rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D28008

llvm-svn: 290236
2016-12-21 04:34:52 +00:00
David L. Jones be1557ac32 Store the "current position" index within the ASTRecordReader.
Summary:
For ASTDeclReader and ASTStmtReader, every parameter "unsigned &Idx" ultimately
comes from a variable that is defined on the stack, next to the RecordData. This
change moves that index into the ASTRecordReader.

TypeLocReader cannot be transitioned, due to TableGen-generated code which calls
ASTReader::GetTypeSourceInfo.

Reviewers: rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D27836

llvm-svn: 290217
2016-12-21 00:17:49 +00:00
Kelvin Li bf594a5600 [OpenMP] Sema and parsing for 'target teams' pragma
This patch is to implement sema and parsing for 'target teams' pragma.

Differential Revision: https://reviews.llvm.org/D27818

llvm-svn: 290038
2016-12-17 05:48:59 +00:00
David L. Jones c4808b9e0a Add a class ASTRecordReader which wraps an ASTReader, a RecordData, and ModuleFile.
Summary:
When reading an ASTRecord, each RecordData is logically contained within a
single ModuleFile, and global(er) state is contained by a single ASTReader. This
means that any operations that read from a RecordData and reference an ASTReader
or a ModuleFile, will always reference the same ASTReader or ModuleFile.
ASTRecordReader groups these together so that parameters don't need to be
duplicated ad infinitum. Most uses of the Idx variable seem to be redunant
aliases as well, but I'll leave that for now.

Reviewers: rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D27784

llvm-svn: 289870
2016-12-15 20:53:26 +00:00
Richard Smith 30e304e2a6 Remove custom handling of array copies in lambda by-value array capture and
copy constructors of classes with array members, instead using
ArrayInitLoopExpr to represent the initialization loop.

This exposed a bug in the static analyzer where it was unable to differentiate
between zero-initialized and unknown array values, which has also been fixed
here.

llvm-svn: 289618
2016-12-14 00:03:17 +00:00
Richard Smith 410306bf6e Add two new AST nodes to represent initialization of an array in terms of
initialization of each array element:

 * ArrayInitLoopExpr is a prvalue of array type with two subexpressions:
   a common expression (an OpaqueValueExpr) that represents the up-front
   computation of the source of the initialization, and a subexpression
   representing a per-element initializer
 * ArrayInitIndexExpr is a prvalue of type size_t representing the current
   position in the loop

This will be used to replace the creation of explicit index variables in lambda
capture of arrays and copy/move construction of classes with array elements,
and also C++17 structured bindings of arrays by value (which inexplicably allow
copying an array by value, unlike all of C++'s other array declarations).

No uses of these nodes are introduced by this change, however.

llvm-svn: 289413
2016-12-12 02:53:20 +00:00
Kelvin Li 7ade93f5e2 [OpenMP] Sema and parsing for 'teams distribute parallel for' pragma
This patch is to implement sema and parsing for 'teams distribute parallel for' pragma.
    
Differential Revision: https://reviews.llvm.org/D27345

llvm-svn: 289179
2016-12-09 03:24:30 +00:00
Kelvin Li 579e41ced2 [OpenMP] Sema and parsing for 'teams distribute parallel for simd' pragma
This patch is to implement sema and parsing for 'teams distribute parallel for simd' pragma.

Differential Revision: https://reviews.llvm.org/D27084

llvm-svn: 288294
2016-11-30 23:51:03 +00:00
Kelvin Li 4e325f77a9 Re-apply patch r279045.
llvm-svn: 285066
2016-10-25 12:50:55 +00:00
Richard Smith b2f0f05742 Re-commit r283722, reverted in r283750, with a fix for a CUDA-specific use of
past-the-end iterator.

Original commit message:

P0035R4: Semantic analysis and code generation for C++17 overaligned
allocation.

llvm-svn: 283789
2016-10-10 18:54:32 +00:00
Daniel Jasper e9abe64816 Revert "P0035R4: Semantic analysis and code generation for C++17 overaligned allocation."
This reverts commit r283722. Breaks:
  Clang.SemaCUDA.device-var-init.cu
  Clang.CodeGenCUDA.device-var-init.cu

http://lab.llvm.org:8080/green/job/clang-stage1-cmake-RA-expensive/884/

llvm-svn: 283750
2016-10-10 14:13:55 +00:00
Richard Smith 189e52fcdf P0035R4: Semantic analysis and code generation for C++17 overaligned
allocation.

llvm-svn: 283722
2016-10-10 06:42:31 +00:00
Aleksei Sidorin a693b37e14 [ASTImporter] Implement some expression-related AST node import (part 2)
* Some code cleanup
* Add tests not present in http://reviews.llvm.org/D14286
* Integrate a test suite from Serge Pavlov (http://reviews.llvm.org/D14224)
* ArrayTypeTraitExpr: serialize sub-expression to avoid keeping it undefined
* Implement import of some nodes:
  - ArrayTypeTraitExpr
  - ExpressionTraitExpr
  - OpaqueValueExpr
  - ArraySubscriptExpr
  - ExplicitCastExpr
  - ImplicitValueInitExpr
  - OffsetOfExpr
  - CXXThisExpr
  - CXXThrowExpr
  - CXXNoexceptExpr
  - CXXDefaultArgExpr
  - CXXScalarValueInitExpr
  - CXXBindTemporaryExpr
  - CXXTemporaryObjectExpr
  - MaterializeTemporaryExpr
  - ExprWithCleanups

  - StaticAssertDecl
  - FriendDecl

  - DecayedType

Differential Revision: https://reviews.llvm.org/D14326

llvm-svn: 282572
2016-09-28 10:16:56 +00:00
Diana Picus 8b44bbc077 Revert "[OpenMP] Sema and parsing for 'teams distribute simd’ pragma"
This reverts commit r279003 as it breaks some of our buildbots (e.g.
clang-cmake-aarch64-quick, clang-x86_64-linux-selfhost-modules).

The error is in OpenMP/teams_distribute_simd_ast_print.cpp:
clang: /home/buildslave/buildslave/clang-cmake-aarch64-quick/llvm/include/llvm/ADT/DenseMap.h:527:
bool llvm::DenseMapBase<DerivedT, KeyT, ValueT, KeyInfoT, BucketT>::LookupBucketFor(const LookupKeyT&, const BucketT*&) const
[with LookupKeyT = clang::Stmt*; DerivedT = llvm::DenseMap<clang::Stmt*, long unsigned int>;
      KeyT = clang::Stmt*; ValueT = long unsigned int;
      KeyInfoT = llvm::DenseMapInfo<clang::Stmt*>;
      BucketT = llvm::detail::DenseMapPair<clang::Stmt*, long unsigned int>]:
Assertion `!KeyInfoT::isEqual(Val, EmptyKey) && !KeyInfoT::isEqual(Val, TombstoneKey) &&
"Empty/Tombstone value shouldn't be inserted into map!"' failed.

llvm-svn: 279045
2016-08-18 09:25:07 +00:00
Kelvin Li 0e3bde8216 [OpenMP] Sema and parsing for 'teams distribute simd’ pragma
This patch is to implement sema and parsing for 'teams distribute simd’ pragma.

This patch is originated by Carlo Bertolli.

Differential Revision: https://reviews.llvm.org/D23528

llvm-svn: 279003
2016-08-17 23:13:03 +00:00
Kelvin Li 0253287633 [OpenMP] Sema and parsing for 'teams distribute' pragma
This patch is to implement sema and parsing for 'teams distribute' pragma.

Differential Revision: https://reviews.llvm.org/D23189

llvm-svn: 277818
2016-08-05 14:37:37 +00:00
Samuel Antao 6890b09634 [OpenMP] Code generation for the is_device_ptr clause
Summary: This patch adds support for the is_device_ptr clause. It expands SEMA to use the mappable expression logic that can only be tested with code generation in place and check conflicts with other data sharing related clauses using the mappable expressions infrastructure.

Reviewers: hfinkel, carlo.bertolli, arpith-jacob, kkwli0, ABataev

Subscribers: caomhin, cfe-commits

Differential Revision: https://reviews.llvm.org/D22788

llvm-svn: 276978
2016-07-28 14:25:09 +00:00
Samuel Antao cc10b85789 [OpenMP] Codegen for use_device_ptr clause.
Summary: This patch adds support for the use_device_ptr clause. It includes changes in SEMA that could not be tested without codegen, namely, the use of the first private logic and mappable expressions support.

Reviewers: hfinkel, carlo.bertolli, arpith-jacob, kkwli0, ABataev

Subscribers: caomhin, cfe-commits

Differential Revision: https://reviews.llvm.org/D22691

llvm-svn: 276977
2016-07-28 14:23:26 +00:00
Kelvin Li 986330c190 [OpenMP] Sema and parsing for 'target simd' pragma
This patch is to implement sema and parsing for 'target simd' pragma.

Differential Revision: https://reviews.llvm.org/D22479

llvm-svn: 276203
2016-07-20 22:57:10 +00:00
Erik Pilkington 29099ded0c [ObjC] Implement @available in the Parser and AST
This patch adds a new AST node: ObjCAvailabilityCheckExpr, and teaches the
Parser and Sema to generate it. This node represents an availability check of
the form:

  @available(macos 10.10, *);

Which will eventually compile to a runtime check of the host's OS version. This
is the first patch of the feature I proposed here:
http://lists.llvm.org/pipermail/cfe-dev/2016-July/049851.html

Differential Revision: https://reviews.llvm.org/D22171

llvm-svn: 275654
2016-07-16 00:35:23 +00:00
Kelvin Li a579b9196c [OpenMP] Sema and parsing for 'target parallel for simd' pragma
This patch is to implement sema and parsing for 'target parallel for simd' pragma.

Differential Revision: http://reviews.llvm.org/D22096

llvm-svn: 275365
2016-07-14 02:54:56 +00:00
Richard Smith a547eb27fa P0305R0: Semantic analysis and code generation for C++17 init-statement for 'if' and 'switch':
if (stmt; condition) { ... }

Patch by Anton Bikineev! Some minor formatting and comment tweets by me.

llvm-svn: 275350
2016-07-14 00:11:03 +00:00
Carlo Bertolli 70594e9282 [OpenMP] Initial implementation of parse+sema for OpenMP clause 'is_device_ptr' of target
http://reviews.llvm.org/D22070

llvm-svn: 275282
2016-07-13 17:16:49 +00:00
Carlo Bertolli 2404b17192 [OpenMP] Initial implementation of parse+sema for clause use_device_ptr of 'target data'
http://reviews.llvm.org/D21904

This patch is similar to the implementation of 'private' clause: it adds a list of private pointers to be used within the target data region to store the device pointers returned by the runtime.
Please refer to the following document for a full description of what the runtime witll return in this case (page 10 and 11):
https://github.com/clang-omp/OffloadingDesign

I am happy to answer any question related to the runtime interface to help reviewing this patch.

llvm-svn: 275271
2016-07-13 15:37:16 +00:00
Kelvin Li 787f3fcc6b [OpenMP] Sema and parsing for 'distribute simd' pragma
Summary: This patch is an implementation of sema and parsing for the OpenMP composite pragma 'distribute simd'.

Differential Revision: http://reviews.llvm.org/D22007

llvm-svn: 274604
2016-07-06 04:45:38 +00:00
Kelvin Li 4a39add05e [OpenMP] Sema and parse for 'distribute parallel for simd'
Summary: This patch is an implementation of sema and parsing for the OpenMP composite pragma 'distribute parallel for simd'.

Differential Revision: http://reviews.llvm.org/D21977

llvm-svn: 274530
2016-07-05 05:00:15 +00:00
Richard Smith 5179eb7821 P0136R1, DR1573, DR1645, DR1715, DR1736, DR1903, DR1941, DR1959, DR1991:
Replace inheriting constructors implementation with new approach, voted into
C++ last year as a DR against C++11.

Instead of synthesizing a set of derived class constructors for each inherited
base class constructor, we make the constructors of the base class visible to
constructor lookup in the derived class, using the normal rules for
using-declarations.

For constructors, UsingShadowDecl now has a ConstructorUsingShadowDecl derived
class that tracks the requisite additional information. We create shadow
constructors (not found by name lookup) in the derived class to model the
actual initialization, and have a new expression node,
CXXInheritedCtorInitExpr, to model the initialization of a base class from such
a constructor. (This initialization is special because it performs real perfect
forwarding of arguments.)

In cases where argument forwarding is not possible (for inalloca calls,
variadic calls, and calls with callee parameter cleanup), the shadow inheriting
constructor is not emitted and instead we directly emit the initialization code
into the caller of the inherited constructor.

Note that this new model is not perfectly compatible with the old model in some
corner cases. In particular:
 * if B inherits a private constructor from A, and C uses that constructor to
   construct a B, then we previously required that A befriends B and B
   befriends C, but the new rules require A to befriend C directly, and
 * if a derived class has its own constructors (and so its implicit default
   constructor is suppressed), it may still inherit a default constructor from
   a base class

llvm-svn: 274049
2016-06-28 19:03:57 +00:00
Carlo Bertolli 9925f15661 Resubmission of http://reviews.llvm.org/D21564 after fixes.
[OpenMP] Initial implementation of parse and sema for composite pragma 'distribute parallel for'

This patch is an initial implementation for #distribute parallel for.
The main differences that affect other pragmas are:

The implementation of 'distribute parallel for' requires blocking of the associated loop, where blocks are "distributed" to different teams and iterations within each block are scheduled to parallel threads within each team. To implement blocking, sema creates two additional worksharing directive fields that are used to pass the team assigned block lower and upper bounds through the outlined function resulting from 'parallel'. In this way, scheduling for 'for' to threads can use those bounds.
As a consequence of blocking, the stride of 'distribute' is not 1 but it is equal to the blocking size. This is returned by the runtime and sema prepares a DistIncrExpr variable to hold that value.
As a consequence of blocking, the global upper bound (EnsureUpperBound) expression of the 'for' is not the original loop upper bound (e.g. in for(i = 0 ; i < N; i++) this is 'N') but it is the team-assigned block upper bound. Sema creates a new expression holding the calculation of the actual upper bound for 'for' as UB = min(UB, PrevUB), where UB is the loop upper bound, and PrevUB is the team-assigned block upper bound.

llvm-svn: 273884
2016-06-27 14:55:37 +00:00