RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2025-02-03 10:54:42 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Add checkMulAdd helper function to CheckedArithmetic

Browse Source 
Multiplication followed by addition
(https://en.wikipedia.org/wiki/Multiply–accumulate_operation) is a
sufficiently common use-case to warrant a separate helper.

Differential Revision: https://reviews.llvm.org/D48138

llvm-svn: 334635
This commit is contained in:
George Karpenkov 2018-06-13 18:32:02 +00:00
parent 8af3008c20
commit 0a576bc0e3
2 changed files with 45 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
include/llvm/Support/CheckedArithmetic.h
View File

@ -57,6 +57,16 @@ checkedMul(T LHS, T RHS) {
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 @@ checkedMulUnsigned(T LHS, T RHS) {
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

25
unittests/Support/CheckedArithmeticTest.cpp
View File

@ -32,6 +32,15 @@ TEST(CheckedArithmetic, CheckedMul) {
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 @@ TEST(CheckedArithmetic, CheckedMulSmall) {
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 @@ TEST(CheckedArithmetic, CheckedMulUnsigned) {
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