[flang][acc] Allow nested gang loops inside acc routines

[khaki3]

The following commit incorrectly prohibited nested gang loops inside acc routines. This PR limits the restriction to loops within kernels constructs only. 8470027

[llvmbot]

@llvm/pr-subscribers-flang-semantics

@llvm/pr-subscribers-openacc

Author: None (khaki3)

Changes

The following commit incorrectly prohibited nested gang loops inside acc routines. This PR limits the restriction to loops within kernels constructs only. 8470027

---

Full diff: https://github.com/llvm/llvm-project/pull/158693.diff

3 Files Affected:

• (modified) flang/lib/Semantics/check-acc-structure.cpp (+4-4)
• (modified) flang/lib/Semantics/check-acc-structure.h (+1-1)
• (modified) flang/test/Semantics/OpenACC/acc-loop.f90 (+31)

diff --git a/flang/lib/Semantics/check-acc-structure.cpp b/flang/lib/Semantics/check-acc-structure.cpp
index 6cb7e5e9e6e25..bcb485d4e0f47 100644
--- a/flang/lib/Semantics/check-acc-structure.cpp
+++ b/flang/lib/Semantics/check-acc-structure.cpp
@@ -136,10 +136,10 @@ void AccStructureChecker::CheckNotInComputeConstruct() {
   }
 }
 
-bool AccStructureChecker::IsInsideParallelConstruct() const {
+bool AccStructureChecker::IsInsideKernelsConstruct() const {
   if (auto directive = getParentComputeConstruct())
-    if (*directive == llvm::acc::ACCD_parallel ||
-        *directive == llvm::acc::ACCD_parallel_loop)
+    if (*directive == llvm::acc::ACCD_kernels ||
+        *directive == llvm::acc::ACCD_kernels_loop)
       return true;
   return false;
 }
@@ -293,7 +293,7 @@ void AccStructureChecker::CheckNotInSameOrSubLevelLoopConstruct() {
           bool invalid{false};
           if (parentClause == llvm::acc::Clause::ACCC_gang &&
               cl == llvm::acc::Clause::ACCC_gang) {
-            if (IsInsideParallelConstruct()) {
+            if (!IsInsideKernelsConstruct()) {
               auto parentDim = getGangDimensionSize(parent);
               auto currentDim = getGangDimensionSize(GetContext());
               std::int64_t parentDimNum = 1, currentDimNum = 1;
diff --git a/flang/lib/Semantics/check-acc-structure.h b/flang/lib/Semantics/check-acc-structure.h
index 711d0326349a4..09399297ca4be 100644
--- a/flang/lib/Semantics/check-acc-structure.h
+++ b/flang/lib/Semantics/check-acc-structure.h
@@ -101,7 +101,7 @@ class AccStructureChecker
   bool IsLoopConstruct(llvm::acc::Directive directive) const;
   std::optional<llvm::acc::Directive> getParentComputeConstruct() const;
   bool IsInsideComputeConstruct() const;
-  bool IsInsideParallelConstruct() const;
+  bool IsInsideKernelsConstruct() const;
   void CheckNotInComputeConstruct();
   std::optional<std::int64_t> getGangDimensionSize(
       DirectiveContext &dirContext);
diff --git a/flang/test/Semantics/OpenACC/acc-loop.f90 b/flang/test/Semantics/OpenACC/acc-loop.f90
index 77c427e0a85ae..d3777f48430e5 100644
--- a/flang/test/Semantics/OpenACC/acc-loop.f90
+++ b/flang/test/Semantics/OpenACC/acc-loop.f90
@@ -447,4 +447,35 @@ program openacc_loop_validity
     END DO
   END DO
 
+contains
+
+  subroutine sub1()
+    !$acc routine gang(dim:2)
+    implicit none
+    integer, parameter :: N = 256
+    integer :: i, j
+
+    !$acc loop gang(dim:2)
+    DO j = 1, N
+       !$acc loop gang(dim:1) vector
+       DO i = 1, N
+       END DO
+    END DO
+  end subroutine sub1
+
+  subroutine sub2()
+    !$acc routine gang(dim:2)
+    implicit none
+    integer, parameter :: N = 256
+    integer :: i, j
+
+    !$acc loop gang(dim:2)
+    DO j = 1, N
+       !ERROR: GANG(dim:2) clause is not allowed in the region of a loop with the GANG(dim:2) clause
+       !$acc loop gang(dim:2) vector
+       DO i = 1, N
+       END DO
+    END DO
+  end subroutine sub2
+
 end program openacc_loop_validity

[jeanPerier]

LGTM , nit/suggestion inline.