[llvm] d59a196 - [Support][MathExtras] Add variadic SaturatingAdd

[Alexander Shaposhnikov via llvm-commits]

Author: Alexander Shaposhnikov
Date: 2022-12-01T20:24:49Z
New Revision: d59a196b8cb8bb59e38ab2bd93b3454141e33bc9

URL: https://github.com/llvm/llvm-project/commit/d59a196b8cb8bb59e38ab2bd93b3454141e33bc9
DIFF: https://github.com/llvm/llvm-project/commit/d59a196b8cb8bb59e38ab2bd93b3454141e33bc9.diff

LOG: [Support][MathExtras] Add variadic SaturatingAdd

Add variadic SaturatingAdd.

Test plan: ninja check-llvm-unit check-all

Differential revision: https://reviews.llvm.org/D139036

Added: 
    

Modified: 
    llvm/include/llvm/Support/MathExtras.h
    llvm/unittests/Support/MathExtrasTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Support/MathExtras.h b/llvm/include/llvm/Support/MathExtras.h
index 7e26e01f617fa..ddde8a2607536 100644
--- a/llvm/include/llvm/Support/MathExtras.h
+++ b/llvm/include/llvm/Support/MathExtras.h
@@ -753,6 +753,18 @@ SaturatingAdd(T X, T Y, bool *ResultOverflowed = nullptr) {
     return Z;
 }
 
+/// Add multiple unsigned integers of type T.  Clamp the result to the
+/// maximum representable value of T on overflow.
+template <class T, class... Ts>
+std::enable_if_t<std::is_unsigned_v<T>, T> SaturatingAdd(T X, T Y, T Z,
+                                                         Ts... Args) {
+  bool Overflowed = false;
+  T XY = SaturatingAdd(X, Y, &Overflowed);
+  if (Overflowed)
+    return SaturatingAdd(std::numeric_limits<T>::max(), T(1), Args...);
+  return SaturatingAdd(XY, Z, Args...);
+}
+
 /// Multiply two unsigned integers, X and Y, of type T.  Clamp the result to the
 /// maximum representable value of T on overflow.  ResultOverflowed indicates if
 /// the result is larger than the maximum representable value of type T.

diff  --git a/llvm/unittests/Support/MathExtrasTest.cpp b/llvm/unittests/Support/MathExtrasTest.cpp
index 23034d64028c6..855871985891f 100644
--- a/llvm/unittests/Support/MathExtrasTest.cpp
+++ b/llvm/unittests/Support/MathExtrasTest.cpp
@@ -309,9 +309,7 @@ TEST(MathExtras, alignTo) {
   EXPECT_EQ(552u, alignTo(321, 255, 42));
 }
 
-template<typename T>
-void SaturatingAddTestHelper()
-{
+template <typename T> void SaturatingAddTestHelper() {
   const T Max = std::numeric_limits<T>::max();
   bool ResultOverflowed;
 
@@ -334,6 +332,42 @@ void SaturatingAddTestHelper()
   EXPECT_EQ(Max, SaturatingAdd(Max, Max));
   EXPECT_EQ(Max, SaturatingAdd(Max, Max, &ResultOverflowed));
   EXPECT_TRUE(ResultOverflowed);
+
+  EXPECT_EQ(T(6), SaturatingAdd(T(1), T(2), T(3)));
+  EXPECT_EQ(T(6), SaturatingAdd(T(1), T(2), T(3), &ResultOverflowed));
+  EXPECT_FALSE(ResultOverflowed);
+
+  EXPECT_EQ(T(10), SaturatingAdd(T(1), T(2), T(3), T(4)));
+  EXPECT_EQ(T(10), SaturatingAdd(T(1), T(2), T(3), T(4), &ResultOverflowed));
+  EXPECT_FALSE(ResultOverflowed);
+
+  EXPECT_EQ(Max, SaturatingAdd(Max, T(0), T(0)));
+  EXPECT_EQ(Max, SaturatingAdd(Max, T(0), T(0), &ResultOverflowed));
+  EXPECT_FALSE(ResultOverflowed);
+
+  EXPECT_EQ(Max, SaturatingAdd(T(0), T(0), Max));
+  EXPECT_EQ(Max, SaturatingAdd(T(0), T(0), Max, &ResultOverflowed));
+  EXPECT_FALSE(ResultOverflowed);
+
+  EXPECT_EQ(Max, SaturatingAdd(Max, T(0), T(1)));
+  EXPECT_EQ(Max, SaturatingAdd(Max, T(0), T(1), &ResultOverflowed));
+  EXPECT_TRUE(ResultOverflowed);
+
+  EXPECT_EQ(Max, SaturatingAdd(T(0), T(1), Max));
+  EXPECT_EQ(Max, SaturatingAdd(T(0), T(1), Max, &ResultOverflowed));
+  EXPECT_TRUE(ResultOverflowed);
+
+  EXPECT_EQ(Max, SaturatingAdd(T(1), T(Max - 2), T(1)));
+  EXPECT_EQ(Max, SaturatingAdd(T(1), T(Max - 2), T(1), &ResultOverflowed));
+  EXPECT_FALSE(ResultOverflowed);
+
+  EXPECT_EQ(Max, SaturatingAdd(T(1), T(1), T(Max - 2)));
+  EXPECT_EQ(Max, SaturatingAdd(T(1), T(1), T(Max - 2), &ResultOverflowed));
+  EXPECT_FALSE(ResultOverflowed);
+
+  EXPECT_EQ(Max, SaturatingAdd(Max, Max, Max));
+  EXPECT_EQ(Max, SaturatingAdd(Max, Max, Max, &ResultOverflowed));
+  EXPECT_TRUE(ResultOverflowed);
 }
 
 TEST(MathExtras, SaturatingAdd) {