From 6c61edcbab1ccfe456a1cade499a3c48d43c616f Mon Sep 17 00:00:00 2001
From: Jay Foad <jay.foad@amd.com>
Date: Thu, 27 Feb 2020 09:57:16 +0000
Subject: [PATCH] [APFloat] Overload comparison operators

Summary:
These implement the usual IEEE-style floating point comparison
semantics, e.g. +0.0 == -0.0 and all operators except != return false
if either argument is NaN.

Subscribers: arsenm, jvesely, nhaehnle, hiraditya, dexonsmith, kerbowa, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75237
---
 llvm/include/llvm/ADT/APFloat.h    | 22 ++++++++++++-
 llvm/unittests/ADT/APFloatTest.cpp | 65 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+), 1 deletion(-)

diff --git a/llvm/include/llvm/ADT/APFloat.h b/llvm/include/llvm/ADT/APFloat.h
index 99d1b12..e5b999e 100644
--- a/llvm/include/llvm/ADT/APFloat.h
+++ b/llvm/include/llvm/ADT/APFloat.h
@@ -1125,7 +1125,27 @@ public:
   double convertToDouble() const { return getIEEE().convertToDouble(); }
   float convertToFloat() const { return getIEEE().convertToFloat(); }
 
-  bool operator==(const APFloat &) const = delete;
+  bool operator==(const APFloat &RHS) const { return compare(RHS) == cmpEqual; }
+
+  bool operator!=(const APFloat &RHS) const { return compare(RHS) != cmpEqual; }
+
+  bool operator<(const APFloat &RHS) const {
+    return compare(RHS) == cmpLessThan;
+  }
+
+  bool operator>(const APFloat &RHS) const {
+    return compare(RHS) == cmpGreaterThan;
+  }
+
+  bool operator<=(const APFloat &RHS) const {
+    cmpResult Res = compare(RHS);
+    return Res == cmpLessThan || Res == cmpEqual;
+  }
+
+  bool operator>=(const APFloat &RHS) const {
+    cmpResult Res = compare(RHS);
+    return Res == cmpGreaterThan || Res == cmpEqual;
+  }
 
   cmpResult compare(const APFloat &RHS) const {
     assert(&getSemantics() == &RHS.getSemantics() &&
diff --git a/llvm/unittests/ADT/APFloatTest.cpp b/llvm/unittests/ADT/APFloatTest.cpp
index 9f68bf1..7814d94 100644
--- a/llvm/unittests/ADT/APFloatTest.cpp
+++ b/llvm/unittests/ADT/APFloatTest.cpp
@@ -2932,6 +2932,71 @@ TEST(APFloatTest, operatorOverloads) {
   EXPECT_TRUE(One.bitwiseIsEqual(Two / Two));
 }
 
+TEST(APFloatTest, Comparisons) {
+  enum {MNan, MInf, MBig, MOne, MZer, PZer, POne, PBig, PInf, PNan, NumVals};
+  APFloat Vals[NumVals] = {
+    APFloat::getNaN(APFloat::IEEEsingle(), true),
+    APFloat::getInf(APFloat::IEEEsingle(), true),
+    APFloat::getLargest(APFloat::IEEEsingle(), true),
+    APFloat(APFloat::IEEEsingle(), "-0x1p+0"),
+    APFloat::getZero(APFloat::IEEEsingle(), true),
+    APFloat::getZero(APFloat::IEEEsingle(), false),
+    APFloat(APFloat::IEEEsingle(), "0x1p+0"),
+    APFloat::getLargest(APFloat::IEEEsingle(), false),
+    APFloat::getInf(APFloat::IEEEsingle(), false),
+    APFloat::getNaN(APFloat::IEEEsingle(), false),
+  };
+  using Relation = void (*)(const APFloat &, const APFloat &);
+  Relation LT = [](const APFloat &LHS, const APFloat &RHS) {
+    EXPECT_FALSE(LHS == RHS);
+    EXPECT_TRUE(LHS != RHS);
+    EXPECT_TRUE(LHS < RHS);
+    EXPECT_FALSE(LHS > RHS);
+    EXPECT_TRUE(LHS <= RHS);
+    EXPECT_FALSE(LHS >= RHS);
+  };
+  Relation EQ = [](const APFloat &LHS, const APFloat &RHS) {
+    EXPECT_TRUE(LHS == RHS);
+    EXPECT_FALSE(LHS != RHS);
+    EXPECT_FALSE(LHS < RHS);
+    EXPECT_FALSE(LHS > RHS);
+    EXPECT_TRUE(LHS <= RHS);
+    EXPECT_TRUE(LHS >= RHS);
+  };
+  Relation GT = [](const APFloat &LHS, const APFloat &RHS) {
+    EXPECT_FALSE(LHS == RHS);
+    EXPECT_TRUE(LHS != RHS);
+    EXPECT_FALSE(LHS < RHS);
+    EXPECT_TRUE(LHS > RHS);
+    EXPECT_FALSE(LHS <= RHS);
+    EXPECT_TRUE(LHS >= RHS);
+  };
+  Relation UN = [](const APFloat &LHS, const APFloat &RHS) {
+    EXPECT_FALSE(LHS == RHS);
+    EXPECT_TRUE(LHS != RHS);
+    EXPECT_FALSE(LHS < RHS);
+    EXPECT_FALSE(LHS > RHS);
+    EXPECT_FALSE(LHS <= RHS);
+    EXPECT_FALSE(LHS >= RHS);
+  };
+  Relation Relations[NumVals][NumVals] = {
+    //          -N  -I  -B  -1  -0  +0  +1  +B  +I  +N
+    /* MNan */ {UN, UN, UN, UN, UN, UN, UN, UN, UN, UN},
+    /* MInf */ {UN, EQ, LT, LT, LT, LT, LT, LT, LT, UN},
+    /* MBig */ {UN, GT, EQ, LT, LT, LT, LT, LT, LT, UN},
+    /* MOne */ {UN, GT, GT, EQ, LT, LT, LT, LT, LT, UN},
+    /* MZer */ {UN, GT, GT, GT, EQ, EQ, LT, LT, LT, UN},
+    /* PZer */ {UN, GT, GT, GT, EQ, EQ, LT, LT, LT, UN},
+    /* POne */ {UN, GT, GT, GT, GT, GT, EQ, LT, LT, UN},
+    /* PBig */ {UN, GT, GT, GT, GT, GT, GT, EQ, LT, UN},
+    /* PInf */ {UN, GT, GT, GT, GT, GT, GT, GT, EQ, UN},
+    /* PNan */ {UN, UN, UN, UN, UN, UN, UN, UN, UN, UN},
+  };
+  for (unsigned I = 0; I < NumVals; ++I)
+    for (unsigned J = 0; J < NumVals; ++J)
+      Relations[I][J](Vals[I], Vals[J]);
+}
+
 TEST(APFloatTest, abs) {
   APFloat PInf = APFloat::getInf(APFloat::IEEEsingle(), false);
   APFloat MInf = APFloat::getInf(APFloat::IEEEsingle(), true);
-- 
2.7.4