[flang-commits] [PATCH] D154371: [flang] Warn about overflow after folding HYPOT

[Peter Klausler via Phabricator via flang-commits]

klausler created this revision.
klausler added a reviewer: vdonaldson.
klausler added a project: Flang.
Herald added subscribers: sunshaoce, jdoerfert.
Herald added a project: All.
klausler requested review of this revision.

The code that folds the intrinsic function HYPOT was neglecting to
warn the programmer about overflow when it occurs.


https://reviews.llvm.org/D154371

Files:
  flang/lib/Evaluate/fold-real.cpp
  flang/test/Evaluate/errors01.f90


Index: flang/test/Evaluate/errors01.f90
===================================================================
--- flang/test/Evaluate/errors01.f90
+++ flang/test/Evaluate/errors01.f90
@@ -163,6 +163,8 @@
     real, parameter :: bad3 = dim(huge(1.),-.5*huge(1.))
     !CHECK: warning: DIM intrinsic folding overflow
     integer, parameter :: bad4 = dim(huge(1),-1)
+    !CHECK: warning: HYPOT intrinsic folding overflow
+    real, parameter :: bad5 = hypot(huge(0.), huge(0.))
     !CHECK: warning: overflow on REAL(8) to REAL(4) conversion
     x = 1.D40
   end subroutine
Index: flang/lib/Evaluate/fold-real.cpp
===================================================================
--- flang/lib/Evaluate/fold-real.cpp
+++ flang/lib/Evaluate/fold-real.cpp
@@ -166,8 +166,13 @@
     CHECK(args.size() == 2);
     return FoldElementalIntrinsic<T, T, T>(context, std::move(funcRef),
         ScalarFunc<T, T, T>(
-            [](const Scalar<T> &x, const Scalar<T> &y) -> Scalar<T> {
-              return x.HYPOT(y).value;
+            [&](const Scalar<T> &x, const Scalar<T> &y) -> Scalar<T> {
+              ValueWithRealFlags<Scalar<T>> result{x.HYPOT(y)};
+              if (result.flags.test(RealFlag::Overflow)) {
+                context.messages().Say(
+                    "HYPOT intrinsic folding overflow"_warn_en_US);
+              }
+              return result.value;
             }));
   } else if (name == "max") {
     return FoldMINorMAX(context, std::move(funcRef), Ordering::Greater);


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