[PATCH] D48138: Add checkMulAdd helper function to CheckedArithmetic

[George Karpenkov via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL334635: Add checkMulAdd helper function to CheckedArithmetic (authored by george.karpenkov, committed by ).
Herald added a subscriber: llvm-commits.

Changed prior to commit:
  https://reviews.llvm.org/D48138?vs=151201&id=151213#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D48138

Files:
  llvm/trunk/include/llvm/Support/CheckedArithmetic.h
  llvm/trunk/unittests/Support/CheckedArithmeticTest.cpp


Index: llvm/trunk/include/llvm/Support/CheckedArithmetic.h
===================================================================
--- llvm/trunk/include/llvm/Support/CheckedArithmetic.h
+++ llvm/trunk/include/llvm/Support/CheckedArithmetic.h
@@ -57,6 +57,16 @@
   return checkedOp(LHS, RHS, &llvm::APInt::smul_ov);
 }
 
+/// Multiply A and B, and add C to the resulting product.
+/// Return the value if available, None if overflowing.
+template <typename T>
+typename std::enable_if<std::is_signed<T>::value, llvm::Optional<T>>::type
+checkedMulAdd(T A, T B, T C) {
+  if (auto Product = checkedMul(A, B))
+    return checkedAdd(*Product, C);
+  return llvm::None;
+}
+
 /// Add two unsigned integers \p LHS and \p RHS, return wrapped result
 /// if available.
 template <typename T>
@@ -73,6 +83,16 @@
   return checkedOp(LHS, RHS, &llvm::APInt::umul_ov, /*Signed=*/false);
 }
 
+/// Multiply unsigned A and B, and add C to the resulting product.
+/// Return the value if available, None if overflowing.
+template <typename T>
+typename std::enable_if<std::is_unsigned<T>::value, llvm::Optional<T>>::type
+checkedMulAddUnsigned(T A, T B, T C) {
+  if (auto Product = checkedMulUnsigned(A, B))
+    return checkedAddUnsigned(*Product, C);
+  return llvm::None;
+}
+
 } // End llvm namespace
 
 #endif
Index: llvm/trunk/unittests/Support/CheckedArithmeticTest.cpp
===================================================================
--- llvm/trunk/unittests/Support/CheckedArithmeticTest.cpp
+++ llvm/trunk/unittests/Support/CheckedArithmeticTest.cpp
@@ -32,6 +32,15 @@
   EXPECT_EQ(checkedMul<int64_t>(10, 2), Optional<int64_t>(20));
 }
 
+TEST(CheckedArithmetic, CheckedMulAdd) {
+  const int64_t Max = std::numeric_limits<int64_t>::max();
+  const int64_t Min = std::numeric_limits<int64_t>::min();
+  EXPECT_EQ(checkedMulAdd<int64_t>(Max, 1, 2), None);
+  EXPECT_EQ(checkedMulAdd<int64_t>(1, 1, Max), None);
+  EXPECT_EQ(checkedMulAdd<int64_t>(1, -1, Min), None);
+  EXPECT_EQ(checkedMulAdd<int64_t>(10, 2, 3), Optional<int64_t>(23));
+}
+
 TEST(CheckedArithmetic, CheckedMulSmall) {
   const int16_t Max = std::numeric_limits<int16_t>::max();
   const int16_t Min = std::numeric_limits<int16_t>::min();
@@ -41,6 +50,15 @@
   EXPECT_EQ(checkedMul<int16_t>(10, 2), Optional<int16_t>(20));
 }
 
+TEST(CheckedArithmetic, CheckedMulAddSmall) {
+  const int16_t Max = std::numeric_limits<int16_t>::max();
+  const int16_t Min = std::numeric_limits<int16_t>::min();
+  EXPECT_EQ(checkedMulAdd<int16_t>(Max, 1, 2), None);
+  EXPECT_EQ(checkedMulAdd<int16_t>(1, 1, Max), None);
+  EXPECT_EQ(checkedMulAdd<int16_t>(1, -1, Min), None);
+  EXPECT_EQ(checkedMulAdd<int16_t>(10, 2, 3), Optional<int16_t>(23));
+}
+
 TEST(CheckedArithmetic, CheckedAddUnsigned) {
   const uint64_t Max = std::numeric_limits<uint64_t>::max();
   EXPECT_EQ(checkedAddUnsigned<uint64_t>(Max, Max), None);
@@ -55,5 +73,12 @@
   EXPECT_EQ(checkedMulUnsigned<uint64_t>(10, 2), Optional<uint64_t>(20));
 }
 
+TEST(CheckedArithmetic, CheckedMulAddUnsigned) {
+  const uint64_t Max = std::numeric_limits<uint64_t>::max();
+  EXPECT_EQ(checkedMulAddUnsigned<uint64_t>(Max, 1, 2), None);
+  EXPECT_EQ(checkedMulAddUnsigned<uint64_t>(1, 1, Max), None);
+  EXPECT_EQ(checkedMulAddUnsigned<uint64_t>(10, 2, 3), Optional<uint64_t>(23));
+}
+
 
 } // namespace


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