[Flang][LLVM][OpenMP] Relax target data restrictions to be more inline with the specification

[agozillon]

Currently we emit errors whenever a map is not provided on a target data directive, however, I believe that's incorrect behavior, the specification states:

"At least one map, use_device_addr or use_device_ptr clause must appear on the directive"

So provided one is present, the directive is legal in this case. Slightly different to its siblings (enter/exit/update) which don't have use_device_addr/use_device_ptr.

[llvmbot]

@llvm/pr-subscribers-flang-semantics

@llvm/pr-subscribers-flang-openmp

Author: None (agozillon)

Changes

Currently we emit errors whenever a map is not provided on a target data directive, however, I believe that's incorrect behavior, the specification states:

"At least one map, use_device_addr or use_device_ptr clause must appear on the directive"

So provided one is present, the directive is legal in this case. Slightly different to its siblings (enter/exit/update) which don't have use_device_addr/use_device_ptr.

---

Full diff: https://github.com/llvm/llvm-project/pull/82537.diff

2 Files Affected:

• (modified) flang/test/Semantics/OpenMP/device-constructs.f90 (+11-1)
• (modified) llvm/include/llvm/Frontend/OpenMP/OMP.td (+3-5)

diff --git a/flang/test/Semantics/OpenMP/device-constructs.f90 b/flang/test/Semantics/OpenMP/device-constructs.f90
index 51f00700b6daf7..1ac00ef922c6bd 100644
--- a/flang/test/Semantics/OpenMP/device-constructs.f90
+++ b/flang/test/Semantics/OpenMP/device-constructs.f90
@@ -2,9 +2,11 @@
 ! Check OpenMP clause validity for the following directives:
 !     2.10 Device constructs
 program main
+   use iso_c_binding
 
   real(8) :: arrayA(256), arrayB(256)
   integer :: N
+  type(c_ptr) :: cptr
 
   arrayA = 1.414
   arrayB = 3.14
@@ -135,7 +137,15 @@ program main
   enddo
   !$omp end target data
 
-  !ERROR: At least one of MAP clause must appear on the TARGET DATA directive
+  !$omp target data device(0) use_device_addr(cptr)
+   cptr = c_null_ptr
+  !$omp end target data
+
+  !$omp target data device(0) use_device_addr(cptr)
+   cptr = c_null_ptr
+  !$omp end target data
+
+  !ERROR: At least one of MAP, USE_DEVICE_ADDR, USE_DEVICE_PTR clause must appear on the TARGET DATA directive
   !$omp target data device(0)
   do i = 1, N
      a = 3.14
diff --git a/llvm/include/llvm/Frontend/OpenMP/OMP.td b/llvm/include/llvm/Frontend/OpenMP/OMP.td
index 1481328bf483b8..f44e8f18c99f6a 100644
--- a/llvm/include/llvm/Frontend/OpenMP/OMP.td
+++ b/llvm/include/llvm/Frontend/OpenMP/OMP.td
@@ -710,16 +710,14 @@ def OMP_Requires : Directive<"requires"> {
 }
 def OMP_Nothing : Directive<"nothing"> {}
 def OMP_TargetData : Directive<"target data"> {
-  let allowedClauses = [
-    VersionedClause<OMPC_UseDevicePtr>,
-    VersionedClause<OMPC_UseDeviceAddr, 50>
-  ];
   let allowedOnceClauses = [
     VersionedClause<OMPC_Device>,
     VersionedClause<OMPC_If>
   ];
   let requiredClauses = [
-    VersionedClause<OMPC_Map>
+    VersionedClause<OMPC_Map>,
+    VersionedClause<OMPC_UseDevicePtr>,
+    VersionedClause<OMPC_UseDeviceAddr, 50> 
   ];
 }
 def OMP_TargetEnterData : Directive<"target enter data"> {

[agozillon]

@DominikAdamski found this and another target data related case while looking at the GenASiS benchmark, which I will try to address in a seperate PR in the near future

[raghavendhra]

LGTM!

[skatrak]

Good catch, LGTM as well!

[DominikAdamski]

LGTM

[agozillon]

Small follow up NFC commit to remove the extra space I added by accident (need to find some kind of space highlighting extension for vscode...)