[PATCH] D139036: [Support][MathExtras] Add variadic SaturatingAdd

[Alexander Shaposhnikov via Phabricator via llvm-commits]

alexander-shaposhnikov updated this revision to Diff 479036.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D139036/new/

https://reviews.llvm.org/D139036

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


Index: llvm/unittests/Support/MathExtrasTest.cpp
===================================================================
--- llvm/unittests/Support/MathExtrasTest.cpp
+++ llvm/unittests/Support/MathExtrasTest.cpp
@@ -309,9 +309,7 @@
   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 +332,38 @@
   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(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) {
Index: llvm/include/llvm/Support/MathExtras.h
===================================================================
--- llvm/include/llvm/Support/MathExtras.h
+++ llvm/include/llvm/Support/MathExtras.h
@@ -753,6 +753,18 @@
     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.


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