From 943b50289b6ee51ffe2d4092dd7a545ff2b24058 Mon Sep 17 00:00:00 2001
From: peter klausler <pklausler@nvidia.com>
Date: Fri, 20 Jul 2018 13:52:52 -0700
Subject: [PATCH] [flang] Real->Integer conversion folding

Original-commit: flang-compiler/f18@5ad6505e782c9f5d748ff0c2d06be0f02c283694
Reviewed-on: https://github.com/flang-compiler/f18/pull/144
Tree-same-pre-rewrite: false
---
 flang/lib/evaluate/expression.cc | 23 +++++++++++++++++++++++
 flang/lib/evaluate/expression.h  |  4 +---
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/flang/lib/evaluate/expression.cc b/flang/lib/evaluate/expression.cc
index 9b499cd7b29f..b453435214ab 100644
--- a/flang/lib/evaluate/expression.cc
+++ b/flang/lib/evaluate/expression.cc
@@ -241,6 +241,29 @@ auto IntegerExpr<KIND>::ConvertInteger::FoldScalar(FoldingContext &context,
       c.u);
 }
 
+template<int KIND>
+auto IntegerExpr<KIND>::ConvertReal::FoldScalar(FoldingContext &context,
+    const CategoryScalar<Category::Real> &c) -> std::optional<Scalar> {
+  return std::visit(
+      [&](auto &x) -> std::optional<Scalar> {
+        auto converted{x.template ToInteger<Scalar>()};
+        if (context.messages != nullptr) {
+          if (converted.flags.test(RealFlag::Overflow)) {
+            context.messages->Say(
+                context.at, "real->integer conversion overflowed"_en_US);
+            return {};
+          }
+          if (converted.flags.test(RealFlag::InvalidArgument)) {
+            context.messages->Say(
+                context.at, "real->integer conversion: invalid argument"_en_US);
+            return {};
+          }
+        }
+        return {std::move(converted.value)};
+      },
+      c.u);
+}
+
 template<int KIND>
 auto IntegerExpr<KIND>::Negate::FoldScalar(
     FoldingContext &context, const Scalar &c) -> std::optional<Scalar> {
diff --git a/flang/lib/evaluate/expression.h b/flang/lib/evaluate/expression.h
index 899b45b00c62..263f4220d349 100644
--- a/flang/lib/evaluate/expression.h
+++ b/flang/lib/evaluate/expression.h
@@ -152,9 +152,7 @@ public:
     using Unary<ConvertReal, Result, GenericRealExpr,
         CategoryScalar<Category::Real>>::Unary;
     static std::optional<Scalar> FoldScalar(
-        FoldingContext &, const CategoryScalar<Category::Real> &) {
-      return {};
-    }  // TODO
+        FoldingContext &, const CategoryScalar<Category::Real> &);
   };
 
   template<typename CRTP> using Un = Unary<CRTP, Result, Expr>;