[flang-commits] [flang] [llvm] [Flang][OpenMP] Add semantic checks for Worshare construct (PR #111358)

[Thirumalai Shaktivel via flang-commits]

https://github.com/Thirumalai-Shaktivel updated https://github.com/llvm/llvm-project/pull/111358

>From 4539432528ff80c6312a0c75ae985c0f2d10bf81 Mon Sep 17 00:00:00 2001
From: Thirumalai-Shaktivel <thirumalaishaktivel at gmail.com>
Date: Mon, 7 Oct 2024 10:34:59 +0000
Subject: [PATCH 1/3] [LLVM-Flang][OpenMP] Add a semantic check for Worshare
 construct

---
 flang/lib/Semantics/check-omp-structure.cpp | 22 ++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/flang/lib/Semantics/check-omp-structure.cpp b/flang/lib/Semantics/check-omp-structure.cpp
index 5ef504aa72326e..de87e8db0e8233 100644
--- a/flang/lib/Semantics/check-omp-structure.cpp
+++ b/flang/lib/Semantics/check-omp-structure.cpp
@@ -68,11 +68,23 @@ class OmpWorkshareBlockChecker {
     if (const auto *e{GetExpr(context_, expr)}) {
       for (const Symbol &symbol : evaluate::CollectSymbols(*e)) {
         const Symbol &root{GetAssociationRoot(symbol)};
-        if (IsFunction(root) && !IsElementalProcedure(root)) {
-          context_.Say(expr.source,
-              "User defined non-ELEMENTAL function "
-              "'%s' is not allowed in a WORKSHARE construct"_err_en_US,
-              root.name());
+        if (IsFunction(root)) {
+          std::string attrs{""};
+          if (!IsElementalProcedure(root)) {
+            attrs = " non-ELEMENTAL";
+          }
+          if (symbol.attrs().test(Attr::IMPURE)) {
+            if (attrs != "") {
+              attrs = "," + attrs;
+            }
+            attrs = " IMPURE" + attrs;
+          }
+          if (attrs != "") {
+            context_.Say(expr.source,
+                "User defined%s function '%s' is not allowed in a "
+                "WORKSHARE construct"_err_en_US,
+                attrs, root.name());
+          }
         }
       }
     }

>From 2f4c87f85ad548a7e4f5e5abf23c53c77f911640 Mon Sep 17 00:00:00 2001
From: Thirumalai-Shaktivel <thirumalaishaktivel at gmail.com>
Date: Mon, 7 Oct 2024 10:35:40 +0000
Subject: [PATCH 2/3] [Flang][OpenMP] Allow Nowait clause only once in the
 workshare construct

---
 llvm/include/llvm/Frontend/OpenMP/OMP.td | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/include/llvm/Frontend/OpenMP/OMP.td b/llvm/include/llvm/Frontend/OpenMP/OMP.td
index fcf087d1f9c6e4..dbcbe75458677b 100644
--- a/llvm/include/llvm/Frontend/OpenMP/OMP.td
+++ b/llvm/include/llvm/Frontend/OpenMP/OMP.td
@@ -1162,7 +1162,7 @@ def OMP_Workshare : Directive<"workshare"> {
   let category = CA_Executable;
 }
 def OMP_EndWorkshare : Directive<"end workshare"> {
-  let allowedClauses = [
+  let allowedOnceClauses = [
     VersionedClause<OMPC_NoWait>,
   ];
   let leafConstructs = OMP_Workshare.leafConstructs;

>From 7e687e38a79dba8690c9154647f2fbed87554893 Mon Sep 17 00:00:00 2001
From: Thirumalai-Shaktivel <thirumalaishaktivel at gmail.com>
Date: Mon, 7 Oct 2024 10:36:05 +0000
Subject: [PATCH 3/3] [Test] Add tests

---
 flang/test/Semantics/OpenMP/workshare02.f90 | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/flang/test/Semantics/OpenMP/workshare02.f90 b/flang/test/Semantics/OpenMP/workshare02.f90
index 11f33d63a3eb80..9c793747ae655e 100644
--- a/flang/test/Semantics/OpenMP/workshare02.f90
+++ b/flang/test/Semantics/OpenMP/workshare02.f90
@@ -9,6 +9,14 @@ module my_mod
   integer function my_func()
     my_func = 10
   end function my_func
+
+  impure integer function impure_my_func()
+    impure_my_func_ = 20
+  end function impure_my_func
+
+  impure elemental integer function impure_ele_my_func()
+    impure_ele_my_func = 20
+  end function impure_ele_my_func
 end module my_mod
 
 subroutine workshare(aa, bb, cc, dd, ee, ff, n)
@@ -61,6 +69,16 @@ subroutine workshare(aa, bb, cc, dd, ee, ff, n)
   j = j - my_func()
   !$omp end atomic
 
+  !ERROR: User defined IMPURE, non-ELEMENTAL function 'impure_my_func' is not allowed in a WORKSHARE construct
+  cc = impure_my_func()
+  !ERROR: User defined IMPURE function 'impure_ele_my_func' is not allowed in a WORKSHARE construct
+  aa(1) = impure_ele_my_func()
+
   !$omp end workshare
 
+  !$omp workshare
+    j = j + 1
+  !ERROR: At most one NOWAIT clause can appear on the END WORKSHARE directive
+  !$omp end workshare nowait nowait
+
 end subroutine workshare