If the loop counter is not declared in the context of the loop and it is
private, such loop counters should not be captured in the outlined
regions.
llvm-svn: 345505
Summary:
For the following code:
```
int i;
#pragma omp taskloop
for (i = 0; i < 100; ++i)
{}
#pragma omp taskloop nogroup
for (i = 0; i < 100; ++i)
{}
```
Clang emits the following LLVM IR:
```
...
call void @__kmpc_taskgroup(%struct.ident_t* @0, i32 %0)
%2 = call i8* @__kmpc_omp_task_alloc(%struct.ident_t* @0, i32 %0, i32 1, i64 80, i64 8, i32 (i32, i8*)* bitcast (i32 (i32, %struct.kmp_task_t_with_privates*)* @.omp_task_entry. to i32 (i32, i8*)*))
...
call void @__kmpc_taskloop(%struct.ident_t* @0, i32 %0, i8* %2, i32 1, i64* %8, i64* %9, i64 %13, i32 0, i32 0, i64 0, i8* null)
call void @__kmpc_end_taskgroup(%struct.ident_t* @0, i32 %0)
...
%15 = call i8* @__kmpc_omp_task_alloc(%struct.ident_t* @0, i32 %0, i32 1, i64 80, i64 8, i32 (i32, i8*)* bitcast (i32 (i32, %struct.kmp_task_t_with_privates.1*)* @.omp_task_entry..2 to i32 (i32, i8*)*))
...
call void @__kmpc_taskloop(%struct.ident_t* @0, i32 %0, i8* %15, i32 1, i64* %21, i64* %22, i64 %26, i32 0, i32 0, i64 0, i8* null)
```
The first set of instructions corresponds to the first taskloop construct. It is important to note that the implicit taskgroup region associated with the taskloop construct has been materialized in our IR: the `__kmpc_taskloop` occurs inside a taskgroup region. Note also that this taskgroup region does not exist in our second taskloop because we are using the `nogroup` clause.
The issue here is the 4th argument of the kmpc_taskloop call, starting from the end, is always a zero. Checking the LLVM OpenMP RT implementation, we see that this argument corresponds to the nogroup parameter:
```
void __kmpc_taskloop(ident_t *loc, int gtid, kmp_task_t *task, int if_val,
kmp_uint64 *lb, kmp_uint64 *ub, kmp_int64 st, int nogroup,
int sched, kmp_uint64 grainsize, void *task_dup);
```
So basically we always tell to the RT to do another taskgroup region. For the first taskloop, this means that we create two taskgroup regions. For the second example, it means that despite the fact we had a nogroup clause we are going to have a taskgroup region, so we unnecessary wait until all descendant tasks have been executed.
Reviewers: ABataev
Reviewed By: ABataev
Subscribers: rogfer01, cfe-commits
Differential Revision: https://reviews.llvm.org/D53636
llvm-svn: 345180
only.
Added support for -fopenmp-simd option that allows compilation of
simd-based constructs without emission of OpenMP runtime calls.
llvm-svn: 321560
If both taskloop and task directives are used at the same time in one
program, we may ran into the situation when the particular type for task
directive is reused for taskloop directives. Patch fixes this problem.
llvm-svn: 315464
If taskloop directive has no associated nogroup clause, it must emitted
inside implicit taskgroup block. Runtime supports it, but we need to
generate implicit taskgroup block explicitly to support future
reductions codegen.
llvm-svn: 307822
directives.
'kmp_task_t' record type added a new field for 'priority' clause and
changed the representation of pointer to destructors for privates used
within loop-based directives.
Old representation:
typedef struct kmp_task { /* GEH: Shouldn't this be
aligned somehow? */
void *shareds; /**< pointer to block of
pointers to shared vars */
kmp_routine_entry_t routine; /**< pointer to routine
to call for executing task */
kmp_int32 part_id; /**< part id for the
task */
kmp_routine_entry_t destructors; /* pointer to function to
invoke deconstructors of firstprivate C++ objects */
/* private vars */
} kmp_task_t;
New representation:
typedef struct kmp_task { /* GEH: Shouldn't this be
aligned somehow? */
void *shareds; /**< pointer to block of
pointers to shared vars */
kmp_routine_entry_t routine; /**< pointer to routine
to call for executing task */
kmp_int32 part_id; /**< part id for the
task */
kmp_cmplrdata_t data1; /* Two known
optional additions: destructors and priority */
kmp_cmplrdata_t data2; /* Process
destructors first, priority second */
/* future data */
/* private vars */
} kmp_task_t;
Also excessive initialization of 'destructors' fields to 'null' was
removed from codegen if it is known that no destructors shal be used.
Currently a special bit is used in 'kmp_tasking_flags_t' bitfields
('destructors_thunk' bitfield).
llvm-svn: 271201
directives.
OpenMP 4.5 supports clause 'priority' in task-based directives. Patch
adds initial codegen support for this clause in codegen.
llvm-svn: 269050
If private variables require destructors call at the deletion of the
task, additional flag in task flags must be set. Patch fixes this
problem.
llvm-svn: 269039
directive.
OpenMP 4.5 defines 'taskloop' directive and 2 additional clauses
'grainsize' and 'num_tasks' for this directive. Patch adds codegen for
these clauses.
These clauses are generated as arguments of the '__kmpc_taskloop'
libcall and are encoded the following way:
void __kmpc_taskloop(ident_t *loc, int gtid, kmp_task_t *task, int if_val, kmp_uint64 *lb, kmp_uint64 *ub, kmp_int64 st, int nogroup, int sched, kmp_uint64 grainsize, void *task_dup);
If 'grainsize' is specified, 'sched' argument must be set to '1' and
'grainsize' argument must be set to the value of the 'grainsize' clause.
If 'num_tasks' is specified, 'sched' argument must be set to '2' and
'grainsize' argument must be set to the value of the 'num_tasks' clause.
It is possible because these 2 clauses are mutually exclusive and can't
be used at the same time on the same directive.
If none of these clauses is specified, 'sched' argument must be set to
'0'.
llvm-svn: 267862
The taskloop construct specifies that the iterations of one or more associated loops will be executed in parallel using OpenMP tasks. The iterations are distributed across tasks created by the construct and scheduled to be executed.
The next code will be generated for the taskloop directive:
#pragma omp taskloop num_tasks(N) lastprivate(j)
for( i=0; i<N*GRAIN*STRIDE-1; i+=STRIDE ) {
int th = omp_get_thread_num();
#pragma omp atomic
counter++;
#pragma omp atomic
th_counter[th]++;
j = i;
}
Generated code:
task = __kmpc_omp_task_alloc(NULL,gtid,1,sizeof(struct
task),sizeof(struct shar),&task_entry);
psh = task->shareds;
psh->pth_counter = &th_counter;
psh->pcounter = &counter;
psh->pj = &j;
task->lb = 0;
task->ub = N*GRAIN*STRIDE-2;
task->st = STRIDE;
__kmpc_taskloop(
NULL, // location
gtid, // gtid
task, // task structure
1, // if clause value
&task->lb, // lower bound
&task->ub, // upper bound
STRIDE, // loop increment
0, // 1 if nogroup specified
2, // schedule type: 0-none, 1-grainsize, 2-num_tasks
N, // schedule value (ignored for type 0)
(void*)&__task_dup_entry // tasks duplication routine
);
llvm-svn: 267395
Alexey Bataev