[flang-commits] [flang] [flang][PFT] Mark ASSIGN'd labels as assigned GO TO targets (PR #218674)

[Eugene Epshteyn via flang-commits]

================
@@ -1065,24 +1069,16 @@ class PFTBuilder {
               if (semanticsContext.IsRecordedBranchTarget(target->position))
                 markBranchTarget(eval, *target);
             };
-            const auto &labelList = std::get<std::list<parser::Label>>(s.t);
-            if (!labelList.empty()) {
-              // Explicit target list: `go to v, (l1, l2, ...)`.
-              for (const auto &label : labelList)
-                markIfBranchTarget(label);
-            } else {
-              // No explicit list (`go to v`): fall back to the set of labels
-              // that have been previously ASSIGN'd to v.
-              // TODO: This may miss assignments that appear later in program
-              // order, but it matches the information available at this point
-              // in the walk.
-              const auto *sym = std::get<parser::Name>(s.t).symbol;
-              if (sym) {
-                auto iter = assignSymbolLabelMap->find(*sym);
-                if (iter != assignSymbolLabelMap->end())
-                  for (auto label : iter->second)
-                    markIfBranchTarget(label);
-              }
+            for (const auto &label : std::get<std::list<parser::Label>>(s.t))
+              markIfBranchTarget(label);
+            // TODO: This may miss assignments that appear later in program
----------------
eugeneepshteyn wrote:

Right, so what about
```
subroutine later_assign_earlier_target(a, n)
  integer :: n, i, k
  real :: a(n)
  go to 100
  do i = 1, n
20  a(i) = a(i) + 1.0
  end do
10 go to k, (30, 40)
30 a(1) = 0.0
40 return
100 assign 20 to k
  go to 10
end subroutine
```
... and
```
subroutine later_assign_earlier_target_no_list(a, n, first)
  integer :: n, i, k, first
  real :: a(n)
  if (first /= 0) go to 100
  do i = 1, n
20  a(i) = a(i) + 1.0
  end do
10 go to k
30 a(1) = 0.0
40 return
100 assign 20 to k
  first = 0
  go to 10
end subroutine
```

Do you plan to handle this in a future PR?



https://github.com/llvm/llvm-project/pull/218674