From 7aa1c321f00d29fdc84e9a03080853aa25dd06fc Mon Sep 17 00:00:00 2001
From: Shuxin Yang <shuxin.llvm@gmail.com>
Date: Mon, 7 Jan 2013 18:59:35 +0000
Subject: Implement APFloat::isDenormal()

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171764 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/ADT/APFloat.h    |  1 +
 lib/Support/APFloat.cpp       |  7 ++++++
 unittests/ADT/APFloatTest.cpp | 52 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+)

diff --git a/include/llvm/ADT/APFloat.h b/include/llvm/ADT/APFloat.h
index 31c6e6adbf..93d343a512 100644
--- a/include/llvm/ADT/APFloat.h
+++ b/include/llvm/ADT/APFloat.h
@@ -327,6 +327,7 @@ namespace llvm {
     bool isNegative() const { return sign; }
     bool isPosZero() const { return isZero() && !isNegative(); }
     bool isNegZero() const { return isZero() && isNegative(); }
+    bool isDenormal() const;
 
     APFloat& operator=(const APFloat &);
 
diff --git a/lib/Support/APFloat.cpp b/lib/Support/APFloat.cpp
index 17f38918b3..0e3c619170 100644
--- a/lib/Support/APFloat.cpp
+++ b/lib/Support/APFloat.cpp
@@ -696,6 +696,13 @@ APFloat::operator=(const APFloat &rhs)
   return *this;
 }
 
+bool
+APFloat::isDenormal() const {
+  return isNormal() && (exponent == semantics->minExponent) &&
+         (APInt::tcExtractBit(significandParts(), 
+                              semantics->precision - 1) == 0);
+}
+
 bool
 APFloat::bitwiseIsEqual(const APFloat &rhs) const {
   if (this == &rhs)
diff --git a/unittests/ADT/APFloatTest.cpp b/unittests/ADT/APFloatTest.cpp
index ff350a7872..7345e124cd 100644
--- a/unittests/ADT/APFloatTest.cpp
+++ b/unittests/ADT/APFloatTest.cpp
@@ -33,6 +33,58 @@ static std::string convertToString(double d, unsigned Prec, unsigned Pad) {
 
 namespace {
 
+TEST(APFloatTest, Denormal) {
+  APFloat::roundingMode rdmd = APFloat::rmNearestTiesToEven;
+
+  // Test single precision
+  {
+    const char *MinNormalStr = "1.17549435082228750797e-38";
+    EXPECT_FALSE(APFloat(APFloat::IEEEsingle, MinNormalStr).isDenormal());
+    EXPECT_FALSE(APFloat(APFloat::IEEEsingle, 0.0).isDenormal());
+
+    APFloat Val2(APFloat::IEEEsingle, 2.0e0);
+    APFloat T(APFloat::IEEEsingle, MinNormalStr);
+    T.divide(Val2, rdmd);
+    EXPECT_TRUE(T.isDenormal());
+  }
+
+  // Test double precision
+  {
+    const char *MinNormalStr = "2.22507385850720138309e-308";
+    EXPECT_FALSE(APFloat(APFloat::IEEEdouble, MinNormalStr).isDenormal());
+    EXPECT_FALSE(APFloat(APFloat::IEEEdouble, 0.0).isDenormal());
+
+    APFloat Val2(APFloat::IEEEdouble, 2.0e0);
+    APFloat T(APFloat::IEEEdouble, MinNormalStr);
+    T.divide(Val2, rdmd);
+    EXPECT_TRUE(T.isDenormal());
+  }
+
+  // Test Intel double-ext
+  {
+    const char *MinNormalStr = "3.36210314311209350626e-4932";
+    EXPECT_FALSE(APFloat(APFloat::x87DoubleExtended, MinNormalStr).isDenormal());
+    EXPECT_FALSE(APFloat(APFloat::x87DoubleExtended, 0.0).isDenormal());
+
+    APFloat Val2(APFloat::x87DoubleExtended, 2.0e0);
+    APFloat T(APFloat::x87DoubleExtended, MinNormalStr);
+    T.divide(Val2, rdmd);
+    EXPECT_TRUE(T.isDenormal());
+  }
+
+  // Test quadruple precision
+  {
+    const char *MinNormalStr = "3.36210314311209350626267781732175260e-4932";
+    EXPECT_FALSE(APFloat(APFloat::IEEEquad, MinNormalStr).isDenormal());
+    EXPECT_FALSE(APFloat(APFloat::IEEEquad, 0.0).isDenormal());
+
+    APFloat Val2(APFloat::IEEEquad, 2.0e0);
+    APFloat T(APFloat::IEEEquad, MinNormalStr);
+    T.divide(Val2, rdmd);
+    EXPECT_TRUE(T.isDenormal());
+  }
+}
+
 TEST(APFloatTest, Zero) {
   EXPECT_EQ(0.0f,  APFloat(0.0f).convertToFloat());
   EXPECT_EQ(-0.0f, APFloat(-0.0f).convertToFloat());
-- 
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