3 files changed, 27 insertions, 1 deletions
diff --git a/llvm/include/llvm/ADT/APFloat.h b/llvm/include/llvm/ADT/APFloat.h
index 5984749ea9a..3fe04060fd5 100644
--- a/llvm/include/llvm/ADT/APFloat.h
+++ b/llvm/include/llvm/ADT/APFloat.h
@@ -448,6 +448,9 @@ public:
   /// Returns true if and only if the number has the largest possible finite
   /// magnitude in the current semantics.
   bool isLargest() const;
+  
+  /// Returns true if and only if the number is an exact integer.
+  bool isInteger() const;
 
   /// @}
 
diff --git a/llvm/lib/Support/APFloat.cpp b/llvm/lib/Support/APFloat.cpp
index 91b3db59d0e..19b8221b60c 100644
--- a/llvm/lib/Support/APFloat.cpp
+++ b/llvm/lib/Support/APFloat.cpp
@@ -768,6 +768,15 @@ APFloat::isLargest() const {
 }
 
 bool
+APFloat::isInteger() const {
+  // This could be made more efficient; I'm going for obviously correct.
+  if (!isFinite()) return false;
+  APFloat truncated = *this;
+  truncated.roundToIntegral(rmTowardZero);
+  return compare(truncated) == cmpEqual;
+}
+
+bool
 APFloat::bitwiseIsEqual(const APFloat &rhs) const {
   if (this == &rhs)
     return true;
diff --git a/llvm/unittests/ADT/APFloatTest.cpp b/llvm/unittests/ADT/APFloatTest.cpp
index a4445f6e465..55c3f48f00d 100644
--- a/llvm/unittests/ADT/APFloatTest.cpp
+++ b/llvm/unittests/ADT/APFloatTest.cpp
@@ -1313,7 +1313,21 @@ TEST(APFloatTest, roundToIntegral) {
   P = APFloat::getInf(APFloat::IEEEdouble, true);
   P.roundToIntegral(APFloat::rmTowardZero);
   EXPECT_TRUE(std::isinf(P.convertToDouble()) && P.convertToDouble() < 0.0);
-
+}
+  
+TEST(APFloatTest, isInteger) {
+  APFloat T(-0.0);
+  EXPECT_TRUE(T.isInteger());
+  T = APFloat(3.14159);
+  EXPECT_FALSE(T.isInteger());
+  T = APFloat::getNaN(APFloat::IEEEdouble);
+  EXPECT_FALSE(T.isInteger());
+  T = APFloat::getInf(APFloat::IEEEdouble);
+  EXPECT_FALSE(T.isInteger());
+  T = APFloat::getInf(APFloat::IEEEdouble, true);
+  EXPECT_FALSE(T.isInteger());
+  T = APFloat::getLargest(APFloat::IEEEdouble);
+  EXPECT_TRUE(T.isInteger());
 }
 
 TEST(APFloatTest, getLargest) {