[flang] [llvm] [Flang] Adding lowering for the allocation and deallocation of coarrays (PR #182110)

[via llvm-commits]

================
@@ -257,6 +258,135 @@ void Fortran::lower::genFormTeamStatement(
                           errMsgAddr);
 }
 
+//===----------------------------------------------------------------------===//
+// COARRAY utils
+//===----------------------------------------------------------------------===//
+
+mlir::DenseI64ArrayAttr
+Fortran::lower::genLowerCoBounds(Fortran::lower::AbstractConverter &converter,
+                                 mlir::Location loc,
+                                 const Fortran::semantics::Symbol &sym) {
+  fir::FirOpBuilder &builder = converter.getFirOpBuilder();
+  mlir::DenseI64ArrayAttr lcobounds;
+
+  if (Fortran::semantics::IsAllocatableOrObjectPointer(&sym))
+    return {};
+  if (const auto *object =
+          sym.GetUltimate()
+              .detailsIf<Fortran::semantics::ObjectEntityDetails>()) {
+    llvm::SmallVector<std::int64_t> lcbs;
+    for (const Fortran::semantics::ShapeSpec &cobounds : object->coshape()) {
+      if (auto lb = cobounds.lbound().GetExplicit()) {
+        if (auto constant = Fortran::evaluate::ToInt64(*lb))
+          lcbs.push_back(*constant);
+        else
+          lcbs.push_back(1); // default lcobounds
+      }
+    }
+    lcobounds = mlir::DenseI64ArrayAttr::get(builder.getContext(), lcbs);
+  }
+  return lcobounds;
+}
+
+mlir::DenseI64ArrayAttr
+Fortran::lower::genUpperCoBounds(Fortran::lower::AbstractConverter &converter,
+                                 mlir::Location loc,
+                                 const Fortran::semantics::Symbol &sym) {
+  fir::FirOpBuilder &builder = converter.getFirOpBuilder();
+  mlir::DenseI64ArrayAttr ucobounds;
+
+  if (Fortran::semantics::IsAllocatableOrObjectPointer(&sym))
+    return {};
+  if (const auto *object =
+          sym.GetUltimate()
+              .detailsIf<Fortran::semantics::ObjectEntityDetails>()) {
+    llvm::SmallVector<std::int64_t> ucbs;
+    for (const Fortran::semantics::ShapeSpec &cobounds : object->coshape()) {
+      if (cobounds.ubound().isStar()) {
+        ucbs.push_back(-1);
+      } else if (auto ub = cobounds.ubound().GetExplicit()) {
+        if (auto constant = Fortran::evaluate::ToInt64(*ub))
+          ucbs.push_back(*constant);
+        else {
+          if (auto lb = cobounds.lbound().GetExplicit()) {
+            if (auto constant2 = Fortran::evaluate::ToInt64(*lb))
+              ucbs.push_back(*constant2);
+            else
+              ucbs.push_back(1); // use lcobound as default value
+          }
+        }
+      }
+    }
+    ucobounds = mlir::DenseI64ArrayAttr::get(builder.getContext(), ucbs);
+  }
+  return ucobounds;
+}
+
+static std::tuple<mlir::DenseI64ArrayAttr, mlir::DenseI64ArrayAttr>
+genCoBoundsAttrs(Fortran::lower::AbstractConverter &converter,
+                 mlir::Location loc,
+                 const Fortran::parser::AllocateCoarraySpec &allocSpec) {
+  fir::FirOpBuilder &builder = converter.getFirOpBuilder();
+  llvm::SmallVector<std::int64_t> lcbs, ucbs;
+
+  const std::list<Fortran::parser::AllocateCoshapeSpec> &coshapeSpecs =
+      std::get<0>(allocSpec.t);
+  for (const Fortran::parser::AllocateCoshapeSpec &coshapeSpec : coshapeSpecs) {
+    std::int64_t lb;
+    if (const std::optional<Fortran::parser::BoundExpr> &lbExpr =
+            std::get<0>(coshapeSpec.t))
+      lb = *Fortran::evaluate::ToInt64(Fortran::semantics::GetExpr(*lbExpr));
+    else
+      lb = 1;
+    lcbs.push_back(lb);
+    ucbs.push_back(*Fortran::evaluate::ToInt64(
+        Fortran::semantics::GetExpr(std::get<1>(coshapeSpec.t))));
----------------
jeanPerier wrote:

I do not think cobounds in allocate statement have to be constant expressions:

```
subroutine test()
 real, allocatable :: co[:, :]
 integer :: n
 n = 100
 allocate(co[n,*])
end
```

`evaluate::ToInt64` is only extracting constants. You will need to evaluate them.

https://github.com/llvm/llvm-project/pull/182110