[flang-commits] [flang] [flang][OpenMP] Support custom mappers in target update to/from clauses (PR #169673)

[Krish Gupta via flang-commits]

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@@ -1876,6 +1878,64 @@ bool OmpVisitor::Pre(const parser::OmpMapClause &x) {
   return true;
 }
 
+bool OmpVisitor::Pre(const parser::OmpClause::To &x) {
+  // Resolve mapper names in "to" clauses (e.g., for target update)
+  auto &mods{OmpGetModifiers(x.v)};
+  if (auto *mapper{OmpGetUniqueModifier<parser::OmpMapper>(mods)}) {
+    if (auto *symbol{FindSymbol(currScope(), mapper->v)}) {
+      auto &ultimate{symbol->GetUltimate()};
+      auto *misc{ultimate.detailsIf<MiscDetails>()};
+      auto *md{ultimate.detailsIf<MapperDetails>()};
+      if (!md && (!misc || misc->kind() != MiscDetails::Kind::ConstructName))
+        context().Say(mapper->v.source,
+            "Name '%s' should be a mapper name"_err_en_US, mapper->v.source);
+      else
+        mapper->v.symbol = symbol;
+    } else {
+      // Allow the special 'default' mapper identifier without prior
+      // declaration so lowering can recognize and handle it. Emit an
+      // error for any other missing mapper identifier.
+      if (mapper->v.source.ToString() == "default") {
+        mapper->v.symbol = &MakeSymbol(
+            mapper->v, MiscDetails{MiscDetails::Kind::ConstructName});
+      } else {
+        context().Say(
+            mapper->v.source, "'%s' not declared"_err_en_US, mapper->v.source);
+      }
+    }
+  }
+  return true;
+}
+
+bool OmpVisitor::Pre(const parser::OmpClause::From &x) {
+  // Resolve mapper names in "from" clauses (e.g., for target update)
+  auto &mods{OmpGetModifiers(x.v)};
+  if (auto *mapper{OmpGetUniqueModifier<parser::OmpMapper>(mods)}) {
+    if (auto *symbol{FindSymbol(currScope(), mapper->v)}) {
+      auto &ultimate{symbol->GetUltimate()};
+      auto *misc{ultimate.detailsIf<MiscDetails>()};
+      auto *md{ultimate.detailsIf<MapperDetails>()};
+      if (!md && (!misc || misc->kind() != MiscDetails::Kind::ConstructName))
+        context().Say(mapper->v.source,
+            "Name '%s' should be a mapper name"_err_en_US, mapper->v.source);
+      else
+        mapper->v.symbol = symbol;
+    } else {
+      // Allow the special 'default' mapper identifier without prior
+      // declaration so lowering can recognize and handle it. Emit an
+      // error for any other missing mapper identifier.
+      if (mapper->v.source.ToString() == "default") {
+        mapper->v.symbol = &MakeSymbol(
+            mapper->v, MiscDetails{MiscDetails::Kind::ConstructName});
+      } else {
+        context().Say(
+            mapper->v.source, "'%s' not declared"_err_en_US, mapper->v.source);
+      }
+    }
+  }
+  return true;
----------------
KrxGu wrote:

Thanks. yes, I will extract a ResolveMapperModifier helper and update Pre(To)/Pre(From) to call it. I’ll also simplify the semantics test and move the lowering test as suggested; I plan to push the refactor + simplified semantics test in the next commit and then handle the lowering/offload test afterward.

https://github.com/llvm/llvm-project/pull/169673