work_group_barrier
All work-items in a work-group executing the kernel on a processor must execute this function before any are allowed to continue execution beyond the work_group_barrier.
void
work_group_barrier
(
| cl_mem_fence_flags flags) |
void
work_group_barrier
(
| cl_mem_fence_flags flags, |
memory_scope scope
) |
Description
The built-in function barrier
has been renamed work_group_barrier.
For backward compatibility, barrier is
also supported.
All work-items in a work-group executing the kernel on a processor must execute
this function before any are allowed to continue execution beyond the
work_group_barrier.
This function must be encountered by all work-items in a work-group executing the kernel.
These rules apply to ND-ranges implemented with uniform and non-uniform
work-groups.
If work_group_barrier is inside a conditional statement, then all work-items
must enter the conditional if any work-item enters the conditional statement and
executes the work_group_barrier.
If work_group_barrier is inside a loop, all work-items must execute the
work_group_barrier for each iteration of the loop before any are allowed
to continue execution beyond the work_group_barrier.
The work_group_barrier function also supports a
variant that specifies the memory scope. For the
work_group_barrier variant that does not take a
memory scope, the scope is
memory_scope_work_group.
The scope argument specifies whether the memory
accesses of work-items in the work-group to
memory address space(s) identified by flags become
visible to all work-items in the work-group, the
device or all SVM devices.
The work_group_barrier function can also be used
to specify which memory operations i.e. to global
memory, local memory or images become visible to
the appropriate memory scope identified by scope.
The flags argument specifies the memory address
spaces and can be set to 0 or a
combination of the following values ORed together.
When these flags are OR’ed together the
work_group_barrier acts as a combined barrier for
all address spaces specified by the flags ordering
memory accesses both within and across the
specified address spaces.
CLK_LOCAL_MEM_FENCE - The
work_group_barrier function will ensure that all
local memory accesses become visible to all
workitems in the work-group. Note that the value of
scope is ignored as the memory scope is always
memory_scope_work_group.
CLK_GLOBAL_MEM_FENCE – The
work_group_barrier function ensure that all global
memory accesses become visible to the appropriate
scope as given by scope.
CLK_IMAGE_MEM_FENCE – The
work_group_barrier function will ensure that all
image memory accesses become visible to the
appropriate scope as given by scope. The value of
scope must be memory_scope_work_group or
memory_scope_device.
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