Can the loop variable j be specified in the local specifier of do concurrent in the code below? program do_concurrent_13 implicit none integer, parameter :: Nx = 600, Ny = 450, n_max = 255, dp=kind(0.d0) real(dp), parameter :: xcenter = -0.5_dp, ycenter = 0.0_dp, & width = 4, height = 3, dx_di …

Page 197 of J3/24-007: C1127 A variable-name in a locality-spec shall not be the same as an index-name in the concurrent-header of the same DO CONCURRENT statement. where locality-spec includes local(...), local_init(...), reduce(...), shared(...).

Awesome, thanks @ivanpribec ! I am guessing index-name is what I call the loop variable. I am guessing do concurrent loop variables are automatically “local”?

Yes, index name is the loop iteration variable as the part of index-name = lb : ub : stride. In contrast OpenMP 5.2 (section 5.1.1) allows the loop iteration variable to be in a private clause, but it is not necessary (it is redundant): The loop iteration variable in any associated loop of a loo…

Excellent, thanks @ivanpribec , I think this clarifies it. So the index-name of the kind lb : ub : stride means lb, ub, and stride are implicitly local, and should not be marked explicitly local by the user.

Maybe I phrased that incorrectly, I don’t think the bounds are necessarily local. The whole set of rules can be found in document 007 provided at J3 Fortran - Standing Documents , pages 196 - 203. The lb and ub are “concurrent limits”. They should also not be part of a LOCAL locality spec. It’s left…

I think if default (none) clause is not used then it can be used as default private. Here in your code default private do concurrent (j = 1:Ny) shared(image) local(i, j, x, y, x_0, y_0, x_sqr, y_sqr, n) it is private by default. But in the second case it should be explicitly declared in the loca…

[image] ivanpribec: C1127 A variable-name in a locality-spec shall not be the same as an index-name in the concurrent-header of the same DO CONCURRENT statement. This is a numbered constraint meaning that a standard-conforming Fortran processor (i.e. compiler) should be able to diagnose it (J…

I do not see error or warning by intel in these cases. Do compilers must always conform to the standards?

[image] Shahid: Do compilers must always conform to the standards? It’s important if you want to write portable programs. As you may know, the Intel Fortran compilers can’t be used on all hardware: Intel Fortran on Snapdragon chips Imagine being a handyman and buying an expensive set of wren…

I did some modification just to try program do_concurrent_13 implicit none integer, parameter :: Nx = 600, Ny = 450, n_max = 255, dp=kind(0.d0) real(dp), parameter :: xcenter = -0.5_dp, ycenter = 0.0_dp, & width = 4, height = 3, dx_di = width/Nx, dy_dj = -height/Ny, & x_offset = xcenter - (…

Do concurrent: can loop variable be specified in `local`?

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ivanpribec October 5, 2024, 1:18pm 19

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Do concurrent: can loop variable be specified in `local`?

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