From 7fd61457eaeb35a8f6a6fdd820b7254c993f2603 Mon Sep 17 00:00:00 2001
From: Jay Foad <jay.foad@amd.com>
Date: Thu, 27 Feb 2020 09:50:29 +0000
Subject: [PATCH] [APFloat] Overload unary operator-

Summary:
We already have overloaded binary arithemetic operators so you can write
A+B etc. This patch lets you write -A instead of neg(A).

Subscribers: hiraditya, dexonsmith, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75236
---
 include/llvm/ADT/APFloat.h    |  7 +++++++
 unittests/ADT/APFloatTest.cpp | 11 +++++++++++
 2 files changed, 18 insertions(+)

diff --git a/include/llvm/ADT/APFloat.h b/include/llvm/ADT/APFloat.h
index ce8fd6536b4..99d1b12feda 100644
--- a/include/llvm/ADT/APFloat.h
+++ b/include/llvm/ADT/APFloat.h
@@ -1036,6 +1036,13 @@ public:
     APFLOAT_DISPATCH_ON_SEMANTICS(next(nextDown));
   }
 
+  /// Negate an APFloat.
+  APFloat operator-() const {
+    APFloat Result(*this);
+    Result.changeSign();
+    return Result;
+  }
+
   /// Add two APFloats, rounding ties to the nearest even.
   /// No error checking.
   APFloat operator+(const APFloat &RHS) const {
diff --git a/unittests/ADT/APFloatTest.cpp b/unittests/ADT/APFloatTest.cpp
index 6822161729b..9f68bf151e2 100644
--- a/unittests/ADT/APFloatTest.cpp
+++ b/unittests/ADT/APFloatTest.cpp
@@ -2990,6 +2990,17 @@ TEST(APFloatTest, neg) {
   EXPECT_TRUE(Inf.bitwiseIsEqual(neg(NegInf)));
   EXPECT_TRUE(NegQNaN.bitwiseIsEqual(neg(QNaN)));
   EXPECT_TRUE(QNaN.bitwiseIsEqual(neg(NegQNaN)));
+
+  EXPECT_TRUE(NegOne.bitwiseIsEqual(-One));
+  EXPECT_TRUE(One.bitwiseIsEqual(-NegOne));
+  EXPECT_TRUE(NegZero.bitwiseIsEqual(-Zero));
+  EXPECT_TRUE(Zero.bitwiseIsEqual(-NegZero));
+  EXPECT_TRUE(NegInf.bitwiseIsEqual(-Inf));
+  EXPECT_TRUE(Inf.bitwiseIsEqual(-NegInf));
+  EXPECT_TRUE(NegInf.bitwiseIsEqual(-Inf));
+  EXPECT_TRUE(Inf.bitwiseIsEqual(-NegInf));
+  EXPECT_TRUE(NegQNaN.bitwiseIsEqual(-QNaN));
+  EXPECT_TRUE(QNaN.bitwiseIsEqual(-NegQNaN));
 }
 
 TEST(APFloatTest, ilogb) {