DoConcurrentLoop¶
DoConcurrentLoop specifies that there are no data dependencies between the iterations of a DO loop.
Declaration¶
Syntax¶
DoConcurrentLoop(do_loop_head head, expr* shared, expr* local, stmt* body)
Arguments¶
head contains do loop concurrent header.
shared contains a list of variables that are shared amongst all threads
local contains a list of variables that are local to each thread
body contains loop body.
Return values¶
None.
Description¶
DoConcurrentLoop specifies that there are no data dependencies between the
iterations of a DO loop. Within the body of a DoConcurrent loop the program
must adhere to a the list of restrictions specified on its use of Fortran
language features. Actions that can't be executed in parallel or that don't
allow all iterations to execute are prohibited, like:
Control flow statements which prevents the loop nest from executing all its iterations.
Image control statements, like
STOP,SYNC,ALLOCATE/DEALLOCATE.
OMPPragma is converted to DoConcurrentLoop in the AST->ASR phase.
Types¶
Accessible global identifier and a sequence of zero or more statements or
construct that make the DO range.
Examples¶
program doconcurrentloop
implicit none
real, dimension(10) :: a
real :: sum
integer :: N, i
N = size(a)
sum = 0
do concurrent (i = 1:N)
a(i) = a(i-1) + 5
end do
call arraySum(a, sum)
contains
subroutine arraySum(a, sum)
real, intent(in) :: a(:)
real, intent(out) :: sum
do concurrent (i = 1:N) reduce(+: s)
sum = sum + a(i)
end do
end subroutine
end program
ASR:
(TranslationUnit
(SymbolTable
1
{
doconcurrentloop:
(Program
(SymbolTable
2
{
a:
(Variable
2
a
[]
Local
()
()
Default
(Array
(Real 4)
[((IntegerConstant 1 (Integer 4))
(IntegerConstant 10 (Integer 4)))]
FixedSizeArray
)
()
Source
Public
Required
.false.
),
arraysum:
(Function
(SymbolTable
3
{
a:
(Variable
3
a
[]
In
()
()
Default
(Array
(Real 4)
[(()
())]
DescriptorArray
)
()
Source
Public
Required
.false.
),
sum:
(Variable
3
sum
[]
Out
()
()
Default
(Real 4)
()
Source
Public
Required
.false.
)
})
arraysum
(FunctionType
[(Array
(Real 4)
[(()
())]
DescriptorArray
)
(Real 4)]
()
Source
Implementation
()
.false.
.false.
.false.
.false.
.false.
[]
.false.
)
[]
[(Var 3 a)
(Var 3 sum)]
[(DoConcurrentLoop
((Var 2 i)
(IntegerConstant 1 (Integer 4))
(Var 2 n)
())
[]
[]
[(Assignment
(Var 3 sum)
(RealBinOp
(Var 3 sum)
Add
(ArrayItem
(Var 3 a)
[(()
(Var 2 i)
())]
(Real 4)
ColMajor
()
)
(Real 4)
()
)
()
)]
)]
()
Public
.false.
.false.
()
),
i:
(Variable
2
i
[]
Local
()
()
Default
(Integer 4)
()
Source
Public
Required
.false.
),
n:
(Variable
2
n
[]
Local
()
()
Default
(Integer 4)
()
Source
Public
Required
.false.
),
sum:
(Variable
2
sum
[]
Local
()
()
Default
(Real 4)
()
Source
Public
Required
.false.
)
})
doconcurrentloop
[]
[(Assignment
(Var 2 n)
(ArraySize
(Var 2 a)
()
(Integer 4)
(IntegerConstant 10 (Integer 4))
)
()
)
(Assignment
(Var 2 sum)
(Cast
(IntegerConstant 0 (Integer 4))
IntegerToReal
(Real 4)
(RealConstant
0.000000
(Real 4)
)
)
()
)
(DoConcurrentLoop
((Var 2 i)
(IntegerConstant 1 (Integer 4))
(Var 2 n)
())
[]
[]
[(Assignment
(ArrayItem
(Var 2 a)
[(()
(Var 2 i)
())]
(Real 4)
ColMajor
()
)
(RealBinOp
(ArrayItem
(Var 2 a)
[(()
(IntegerBinOp
(Var 2 i)
Sub
(IntegerConstant 1 (Integer 4))
(Integer 4)
()
)
())]
(Real 4)
ColMajor
()
)
Add
(Cast
(IntegerConstant 5 (Integer 4))
IntegerToReal
(Real 4)
(RealConstant
5.000000
(Real 4)
)
)
(Real 4)
()
)
()
)]
)
(SubroutineCall
2 arraysum
()
[((ArrayPhysicalCast
(Var 2 a)
FixedSizeArray
DescriptorArray
(Array
(Real 4)
[((IntegerConstant 1 (Integer 4))
(IntegerConstant 10 (Integer 4)))]
DescriptorArray
)
()
))
((Var 2 sum))]
()
)]
)
})
[]
)