[all-commits] [llvm/llvm-project] 2e353a: [flang][openacc] Relax constraint on OpenACC decla...

[Andre Kuhlenschmidt via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2e353a635b90a6c31eee5fd4ec0335f37f130628
      https://github.com/llvm/llvm-project/commit/2e353a635b90a6c31eee5fd4ec0335f37f130628
  Author: Andre Kuhlenschmidt <andre.kuhlenschmidt at gmail.com>
  Date:   2025-04-14 (Mon, 14 Apr 2025)

  Changed paths:
    M flang/docs/OpenACC.md
    M flang/lib/Semantics/resolve-directives.cpp
    M flang/test/Semantics/OpenACC/acc-declare-validity.f90

  Log Message:
  -----------
  [flang][openacc] Relax constraint on OpenACC declare statement (#135238)

OpenACC declare statements are restricted from having having clauses
that reference assumed size arrays. It should be the case that we can
implement `deviceptr` and `present` clauses for assumed-size arrays.
This is a first step towards relaxing this restriction.

Note running flang on the following example results in an error in
lowering.
```
$ cat t.f90
subroutine vadd (a, b, c, n)
   real(8) :: a(*), b(*), c(*)
!$acc declare deviceptr(a, b, c)
!$acc parallel loop
   do i = 1,n
      c(i) = a(i) + b(i)
   enddo
end subroutine

$ flang -fopenacc -c t.f90
error: loc("/home/akuhlenschmi/work/p4/ta/tests/openacc/src/t.f90":3:7): expect declare attribute on variable in declare operation
error: Lowering to LLVM IR failed
error: loc("/home/akuhlenschmi/work/p4/ta/tests/openacc/src/t.f90":4:7): unsupported OpenACC operation: acc.private.recipe
error: loc("/home/akuhlenschmi/work/p4/ta/tests/openacc/src/t.f90":4:7): LLVM Translation failed for operation: acc.private.recipe
error: failed to create the LLVM module
```

I would like to to share this code, because others are currently working
on the implementation of `deviceptr`, but it is obviously not running
end-to-end. I think the cleanest approach to this would be to put this
exception to the rule behind some feature flag, but I am not certain
what the precedence for that is.



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