[Flang][OpenMP][Parser] Resolve Declare Target Directive Symbols

[agozillon]

Summary

Currently symbols are not resolved for declare target
after they've been modified by prior passes. This can
lead to missing or incorrect symbols in subsequent
compiler phases when declare target is used with
more complex types e.g. common block.

This patch should allow these symbols to be
resolved appropriately.

[kiranchandramohan]

LG. Please add a -fdebug-dump-symbols test.

[agozillon]

Will add the test with the upstream commit, so that it's reflected in the changes here if that's alright, saves a secondary acceptance!

[kiranchandramohan]

Please add the test along with this patch. You do not need a second acceptance.

[agozillon]

• Add Test and Small Tweak for RequiresMark to mark symbol declare target

[agozillon]

Recent push added test and minor weak to mark symbols for output via dump symbols, similarly to firstprivate. I'll push this commit upstream when the recent change has cleared the patch buildbots.

flang/lib/Semantics/resolve-directives.cpp

526

Made a minor tweak here to allow marking of common block values as OmpDeclareTarget similar to OmpThreadprivate, the output can be seen in the test I've added. But now you can visually see that the common block is captured by a declare target when dumping symbols, although, it may be interesting to extend this in the future to add the clause it was captured with as well (but it's a little unnecessary for the moment).

flang/lib/Semantics/resolve-directives.cpp

public:
   void Post(const parser::OpenMPDeclareSimdConstruct &) { PopContext(); }
 
   bool Pre(const parser::OpenMPRequiresConstruct &x) {
     PushContext(x.source, llvm::omp::Directive::OMPD_requires);
     return true;
   }
   void Post(const parser::OpenMPRequiresConstruct &) { PopContext(); }
 
+  bool Pre(const parser::OpenMPDeclareTargetConstruct &);
+  void Post(const parser::OpenMPDeclareTargetConstruct &) { PopContext(); }
+
   bool Pre(const parser::OpenMPThreadprivate &);
   void Post(const parser::OpenMPThreadprivate &) { PopContext(); }
 
   bool Pre(const parser::OpenMPDeclarativeAllocate &);
   void Post(const parser::OpenMPDeclarativeAllocate &) { PopContext(); }
 
   bool Pre(const parser::OpenMPExecutableAllocate &);
   void Post(const parser::OpenMPExecutableAllocate &);
private:
   static constexpr Symbol::Flags ompFlagsRequireNewSymbol{
       Symbol::Flag::OmpPrivate, Symbol::Flag::OmpLinear,
       Symbol::Flag::OmpFirstPrivate, Symbol::Flag::OmpLastPrivate,
       Symbol::Flag::OmpReduction, Symbol::Flag::OmpCriticalLock,
       Symbol::Flag::OmpCopyIn, Symbol::Flag::OmpUseDevicePtr,
       Symbol::Flag::OmpUseDeviceAddr};
 
   static constexpr Symbol::Flags ompFlagsRequireMark{
-      Symbol::Flag::OmpThreadprivate};
+      Symbol::Flag::OmpThreadprivate, Symbol::Flag::OmpDeclareTarget};
 
   static constexpr Symbol::Flags dataCopyingAttributeFlags{
       Symbol::Flag::OmpCopyIn, Symbol::Flag::OmpCopyPrivate};
 
   std::vector<const parser::Name *> allocateNames_; // on one directive
   UnorderedSymbolSet privateDataSharingAttributeObjects_; // on one directive
   UnorderedSymbolSet stmtFunctionExprSymbols_;
   std::multimap<const parser::Label,
bool OmpAttributeVisitor::Pre(const parser::OpenMPCriticalConstruct &x) {
   }
   if (const auto &endCriticalName{
           std::get<std::optional<parser::Name>>(endCriticalDir.t)}) {
     ResolveOmpName(*endCriticalName, Symbol::Flag::OmpCriticalLock);
   }
   return true;
 }
 
+bool OmpAttributeVisitor::Pre(const parser::OpenMPDeclareTargetConstruct &x) {
+  PushContext(x.source, llvm::omp::Directive::OMPD_declare_target);
+  const auto &spec{std::get<parser::OmpDeclareTargetSpecifier>(x.t)};
+  if (const auto *objectList{parser::Unwrap<parser::OmpObjectList>(spec.u)}) {
+    ResolveOmpObjectList(*objectList, Symbol::Flag::OmpDeclareTarget);
+  } else if (const auto *clauseList{
+                 parser::Unwrap<parser::OmpClauseList>(spec.u)}) {
+    for (const auto &clause : clauseList->v) {
+      if (const auto *toClause{std::get_if<parser::OmpClause::To>(&clause.u)}) {
+        ResolveOmpObjectList(toClause->v, Symbol::Flag::OmpDeclareTarget);
+      } else if (const auto *linkClause{
+                     std::get_if<parser::OmpClause::Link>(&clause.u)}) {
+        ResolveOmpObjectList(linkClause->v, Symbol::Flag::OmpDeclareTarget);
+      }
+    }
+  }
+  return true;
+}
+
 bool OmpAttributeVisitor::Pre(const parser::OpenMPThreadprivate &x) {
   PushContext(x.source, llvm::omp::Directive::OMPD_threadprivate);
   const auto &list{std::get<parser::OmpObjectList>(x.t)};
   ResolveOmpObjectList(list, Symbol::Flag::OmpThreadprivate);
   return true;
 }
 
 bool OmpAttributeVisitor::Pre(const parser::OpenMPDeclarativeAllocate &x) {

flang/test/Semantics/OpenMP/declare-target-common-block.f90

+! RUN: %flang_fc1 -fopenmp -fdebug-dump-symbols %s | FileCheck %s
+
+PROGRAM main
+    !CHECK: one (OmpDeclareTarget) size=4 offset=0: ObjectEntity type: REAL(4)
+    !CHECK: two (OmpDeclareTarget) size=4 offset=4: ObjectEntity type: REAL(4)
+    !CHECK: numbers size=8 offset=0: CommonBlockDetails alignment=4: one two
+    REAL :: one, two
+    COMMON /numbers/ one, two
+    !$omp declare target(/numbers/)
+END