[flang][Evaluate] Add AsGenericExpr that takes std::optional

[kparzysz]

AsGenericExpr already returns optional Expr. Making it accept an optional Expr as input would reduce the number of necessary checks when handling frequent optional values in evaluator.

[llvmbot]

@llvm/pr-subscribers-flang-semantics

Author: Krzysztof Parzyszek (kparzysz)

Changes

AsGenericExpr already returns optional Expr. Making it accept an optional Expr as input would reduce the number of necessary checks when handling frequent optional values in evaluator.

---

Full diff: https://github.com/llvm/llvm-project/pull/81264.diff

1 Files Affected:

• (modified) flang/include/flang/Evaluate/tools.h (+8)

diff --git a/flang/include/flang/Evaluate/tools.h b/flang/include/flang/Evaluate/tools.h
index d257da1a709642..f7f155a5da9e13 100644
--- a/flang/include/flang/Evaluate/tools.h
+++ b/flang/include/flang/Evaluate/tools.h
@@ -148,6 +148,14 @@ inline Expr<SomeType> AsGenericExpr(Expr<SomeType> &&x) { return std::move(x); }
 std::optional<Expr<SomeType>> AsGenericExpr(DataRef &&);
 std::optional<Expr<SomeType>> AsGenericExpr(const Symbol &);
 
+// Propagate std::optional from input to output.
+template <typename A>
+std::optional<Expr<SomeType>> AsGenericExpr(std::optional<A> &&x) {
+  if (!x)
+    return std::nullopt;
+  return AsGenericExpr(std::move(*x));
+}
+
 template <typename A>
 common::IfNoLvalue<Expr<SomeKind<ResultType<A>::category>>, A> AsCategoryExpr(
     A &&x) {

[clementval]

Where is it used?

[kparzysz]

Included in another PR: #81626