[llvm] b56b467 - [ADT] Add Bitfield utilities
Guillaume Chatelet via llvm-commits
llvm-commits at lists.llvm.org
Mon Jun 29 05:48:58 PDT 2020
Author: Guillaume Chatelet
Date: 2020-06-29T12:48:44Z
New Revision: b56b467a9a84510bd1c5a573c863cb86c98afbcd
URL: https://github.com/llvm/llvm-project/commit/b56b467a9a84510bd1c5a573c863cb86c98afbcd
DIFF: https://github.com/llvm/llvm-project/commit/b56b467a9a84510bd1c5a573c863cb86c98afbcd.diff
LOG: [ADT] Add Bitfield utilities
Context:
--------
There are places in LLVM where we need to pack typed fields into opaque values.
For instance, the `XXXInst` classes in `llvm/include/llvm/IR/Instructions.h` that extract informations from `Value::SubclassData` via `getSubclassDataFromInstruction()`.
The bit twiddling is done manually: this impairs readability and prevent consistent handling of out of range values (e.g. https://github.com/llvm/llvm-project/blob/435b458ad0a4630e6126246a6865748104ccad06/llvm/include/llvm/IR/Instructions.h#L564)
More importantly, the bit pattern is scattered throughout the implementation making it hard to pack additionnal fields or check for overlapping bits.
Design decisions:
-----------------
The Bitfield structs are to be declared together so it is clear which bits are used or not.
The code is designed with simplicity in mind, hence a few limitations:
- Storage is limited to a single integer,
- Enum values have to be `unsigned`,
- Storage type has to be `unsigned`,
- There are no automatic detection of overlapping fields (packed bitfield declaration should help though),
- The interface is C like so `storage` needs to be passed in everytime (code is simpler and lifetime considerations more obvious)
RFC: http://lists.llvm.org/pipermail/llvm-dev/2020-June/142196.html
Differential Revision: https://reviews.llvm.org/D81580
Added:
llvm/include/llvm/ADT/Bitfields.h
llvm/unittests/ADT/BitFieldsTest.cpp
Modified:
llvm/unittests/ADT/CMakeLists.txt
Removed:
################################################################################
diff --git a/llvm/include/llvm/ADT/Bitfields.h b/llvm/include/llvm/ADT/Bitfields.h
new file mode 100644
index 000000000000..e15ecea4a190
--- /dev/null
+++ b/llvm/include/llvm/ADT/Bitfields.h
@@ -0,0 +1,282 @@
+//===-- llvm/ADT/Bitfield.h - Get and Set bits in an integer ---*- C++ -*--===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file implements methods to test, set and extract typed bits from packed
+/// unsigned integers.
+///
+/// Why not C++ bitfields?
+/// ----------------------
+/// C++ bitfields do not offer control over the bit layout nor consistent
+/// behavior when it comes to out of range values.
+/// For instance, the layout is implementation defined and adjacent bits may be
+/// packed together but are not required to. This is problematic when storage is
+/// sparse and data must be stored in a particular integer type.
+///
+/// The methods provided in this file ensures precise control over the
+/// layout/storage as well as protection against out of range values.
+///
+/// Usage example
+/// -------------
+/// \code{.cpp}
+/// uint8_t Storage = 0;
+///
+/// // Store and retrieve a single bit as bool.
+/// using Bool = Bitfield::Element<bool, 0, 1>;
+/// Bitfield::set<Bool>(Storage, true);
+/// EXPECT_EQ(Storage, 0b00000001);
+/// // ^
+/// EXPECT_EQ(Bitfield::get<Bool>(Storage), true);
+///
+/// // Store and retrieve a 2 bit typed enum.
+/// // Note: enum underlying type must be unsigned.
+/// enum class SuitEnum : uint8_t { CLUBS, DIAMONDS, HEARTS, SPADES };
+/// // Note: enum maximum value needs to be passed in as last parameter.
+/// using Suit = Bitfield::Element<SuitEnum, 1, 2, SuitEnum::SPADES>;
+/// Bitfield::set<Suit>(Storage, SuitEnum::HEARTS);
+/// EXPECT_EQ(Storage, 0b00000101);
+/// // ^^
+/// EXPECT_EQ(Bitfield::get<Suit>(Storage), SuitEnum::HEARTS);
+///
+/// // Store and retrieve a 5 bit value as unsigned.
+/// using Value = Bitfield::Element<unsigned, 3, 5>;
+/// Bitfield::set<Value>(Storage, 10);
+/// EXPECT_EQ(Storage, 0b01010101);
+/// // ^^^^^
+/// EXPECT_EQ(Bitfield::get<Value>(Storage), 10U);
+///
+/// // Interpret the same 5 bit value as signed.
+/// using SignedValue = Bitfield::Element<int, 3, 5>;
+/// Bitfield::set<SignedValue>(Storage, -2);
+/// EXPECT_EQ(Storage, 0b11110101);
+/// // ^^^^^
+/// EXPECT_EQ(Bitfield::get<SignedValue>(Storage), -2);
+///
+/// // Ability to efficiently test if a field is non zero.
+/// EXPECT_TRUE(Bitfield::test<Value>(Storage));
+///
+/// // Alter Storage changes value.
+/// Storage = 0;
+/// EXPECT_EQ(Bitfield::get<Bool>(Storage), false);
+/// EXPECT_EQ(Bitfield::get<Suit>(Storage), SuitEnum::CLUBS);
+/// EXPECT_EQ(Bitfield::get<Value>(Storage), 0U);
+/// EXPECT_EQ(Bitfield::get<SignedValue>(Storage), 0);
+///
+/// Storage = 255;
+/// EXPECT_EQ(Bitfield::get<Bool>(Storage), true);
+/// EXPECT_EQ(Bitfield::get<Suit>(Storage), SuitEnum::SPADES);
+/// EXPECT_EQ(Bitfield::get<Value>(Storage), 31U);
+/// EXPECT_EQ(Bitfield::get<SignedValue>(Storage), -1);
+/// \endcode
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_BITFIELDS_H
+#define LLVM_ADT_BITFIELDS_H
+
+#include <cassert>
+#include <climits> // CHAR_BIT
+#include <cstddef> // size_t
+#include <cstdint> // uintXX_t
+#include <limits> // numeric_limits
+#include <type_traits>
+
+namespace llvm {
+
+namespace bitfields_details {
+
+/// A struct defining useful bit patterns for n-bits integer types.
+template <typename T, unsigned Bits> struct BitPatterns {
+ /// Bit patterns are forged using the equivalent `Unsigned` type because of
+ /// undefined operations over signed types (e.g. Bitwise shift operators).
+ /// Moreover same size casting from unsigned to signed is well defined but not
+ /// the other way around.
+ using Unsigned = typename std::make_unsigned<T>::type;
+ static_assert(sizeof(Unsigned) == sizeof(T), "Types must have same size");
+
+ static constexpr unsigned TypeBits = sizeof(Unsigned) * CHAR_BIT;
+ static_assert(TypeBits >= Bits, "n-bit must fit in T");
+
+ /// e.g. with TypeBits == 8 and Bits == 6.
+ static constexpr Unsigned AllZeros = Unsigned(0); // 00000000
+ static constexpr Unsigned AllOnes = ~Unsigned(0); // 11111111
+ static constexpr Unsigned Umin = AllZeros; // 00000000
+ static constexpr Unsigned Umax = AllOnes >> (TypeBits - Bits); // 00111111
+ static constexpr Unsigned SignBitMask = Unsigned(1) << (Bits - 1); // 00100000
+ static constexpr Unsigned Smax = Umax >> 1U; // 00011111
+ static constexpr Unsigned Smin = ~Smax; // 11100000
+ static constexpr Unsigned SignExtend = Smin << 1U; // 11000000
+};
+
+/// `Compressor` is used to manipulate the bits of a (possibly signed) integer
+/// type so it can be packed and unpacked into a `bits` sized integer,
+/// `Compressor` is specialized on signed-ness so no runtime cost is incurred.
+/// The `pack` method also checks that the passed in `UserValue` is valid.
+template <typename T, unsigned Bits, bool = std::is_unsigned<T>::value>
+struct Compressor {
+ static_assert(std::is_unsigned<T>::value, "T is unsigned");
+ using BP = BitPatterns<T, Bits>;
+
+ static T pack(T UserValue, T UserMaxValue) {
+ assert(UserValue <= UserMaxValue && "value is too big");
+ assert(UserValue <= BP::Umax && "value is too big");
+ return UserValue;
+ }
+
+ static T unpack(T StorageValue) { return StorageValue; }
+};
+
+template <typename T, unsigned Bits> struct Compressor<T, Bits, false> {
+ static_assert(std::is_signed<T>::value, "T is signed");
+ using BP = BitPatterns<T, Bits>;
+
+ static T pack(T UserValue, T UserMaxValue) {
+ assert(UserValue <= UserMaxValue && "value is too big");
+ assert(UserValue <= T(BP::Smax) && "value is too big");
+ assert(UserValue >= T(BP::Smin) && "value is too small");
+ if (UserValue < 0)
+ UserValue &= ~BP::SignExtend;
+ return UserValue;
+ }
+
+ static T unpack(T StorageValue) {
+ if (StorageValue >= T(BP::SignBitMask))
+ StorageValue |= BP::SignExtend;
+ return StorageValue;
+ }
+};
+
+/// Impl is where Bifield description and Storage are put together to interact
+/// with values.
+template <typename Bitfield, typename StorageType> struct Impl {
+ static_assert(std::is_unsigned<StorageType>::value,
+ "Storage must be unsigned");
+ using IntegerType = typename Bitfield::IntegerType;
+ using C = Compressor<IntegerType, Bitfield::Bits>;
+ using BP = BitPatterns<StorageType, Bitfield::Bits>;
+
+ static constexpr size_t StorageBits = sizeof(StorageType) * CHAR_BIT;
+ static_assert(Bitfield::FirstBit <= StorageBits, "Data must fit in mask");
+ static_assert(Bitfield::LastBit <= StorageBits, "Data must fit in mask");
+ static constexpr StorageType Mask = BP::Umax << Bitfield::Shift;
+
+ /// Checks `UserValue` is within bounds and packs it between `FirstBit` and
+ /// `LastBit` of `Packed` leaving the rest unchanged.
+ static void update(StorageType &Packed, IntegerType UserValue) {
+ const StorageType StorageValue = C::pack(UserValue, Bitfield::UserMaxValue);
+ Packed &= ~Mask;
+ Packed |= StorageValue << Bitfield::Shift;
+ }
+
+ /// Interprets bits between `FirstBit` and `LastBit` of `Packed` as
+ /// an`IntegerType`.
+ static IntegerType extract(StorageType Packed) {
+ const StorageType StorageValue = (Packed & Mask) >> Bitfield::Shift;
+ return C::unpack(StorageValue);
+ }
+
+ /// Interprets bits between `FirstBit` and `LastBit` of `Packed` as
+ /// an`IntegerType`.
+ static StorageType test(StorageType Packed) { return Packed & Mask; }
+};
+
+/// `Bitfield` deals with the following type:
+/// - unsigned enums
+/// - signed and unsigned integer
+/// - `bool`
+/// Internally though we only manipulate integer with well defined and
+/// consistent semantic, this excludes typed enums and `bool` that are replaced
+/// with their unsigned counterparts. The correct type is restored in the public
+/// API.
+template <typename T, bool = std::is_enum<T>::value>
+struct ResolveUnderlyingType {
+ using type = typename std::underlying_type<T>::type;
+};
+template <typename T> struct ResolveUnderlyingType<T, false> {
+ using type = T;
+};
+template <> struct ResolveUnderlyingType<bool, false> {
+ /// In case sizeof(bool) != 1, replace `void` by an additionnal
+ /// std::conditional.
+ using type = std::conditional<sizeof(bool) == 1, uint8_t, void>::type;
+};
+
+} // namespace bitfields_details
+
+/// Holds functions to get, set or test bitfields.
+struct Bitfield {
+ /// Describes an element of a Bitfield. This type is then used with the
+ /// Bitfield static member functions.
+ /// \param T, the type of the field once in unpacked form,
+ /// \param Offset, the position of the first bit,
+ /// \param Size, the size of the field,
+ /// \param MaxValue, For enums the maximum enum allowed.
+ template <typename T, unsigned Offset, unsigned Size,
+ T MaxValue = std::is_enum<T>::value
+ ? T(0) // coupled with static_assert below
+ : std::numeric_limits<T>::max()>
+ struct Element {
+ using Type = T;
+ using IntegerType =
+ typename bitfields_details::ResolveUnderlyingType<T>::type;
+ static constexpr unsigned Shift = Offset;
+ static constexpr unsigned Bits = Size;
+ static constexpr unsigned FirstBit = Offset;
+ static constexpr unsigned LastBit = Shift + Bits;
+
+ private:
+ template <typename, typename> friend struct bitfields_details::Impl;
+
+ static_assert(Bits > 0, "Bits must be non zero");
+ static constexpr size_t TypeBits = sizeof(IntegerType) * CHAR_BIT;
+ static_assert(Bits <= TypeBits, "Bits may not be greater than T size");
+ static_assert(!std::is_enum<T>::value || MaxValue != T(0),
+ "Enum Bitfields must provide a MaxValue");
+ static_assert(!std::is_enum<T>::value ||
+ std::is_unsigned<IntegerType>::value,
+ "Enum must be unsigned");
+ static_assert(std::is_integral<IntegerType>::value &&
+ std::numeric_limits<IntegerType>::is_integer,
+ "IntegerType must be an integer type");
+
+ static constexpr IntegerType UserMaxValue =
+ static_cast<IntegerType>(MaxValue);
+ };
+
+ /// Unpacks the field from the `Packed` value.
+ template <typename Bitfield, typename StorageType>
+ static typename Bitfield::Type get(StorageType Packed) {
+ using I = bitfields_details::Impl<Bitfield, StorageType>;
+ return static_cast<typename Bitfield::Type>(I::extract(Packed));
+ }
+
+ /// Return a non-zero value if the field is non-zero.
+ /// It is more efficient than `getField`.
+ template <typename Bitfield, typename StorageType>
+ static StorageType test(StorageType Packed) {
+ using I = bitfields_details::Impl<Bitfield, StorageType>;
+ return I::test(Packed);
+ }
+
+ /// Sets the typed value in the provided `Packed` value.
+ /// The method will asserts if the provided value is too big to fit in.
+ template <typename Bitfield, typename StorageType>
+ static void set(StorageType &Packed, typename Bitfield::Type Value) {
+ using I = bitfields_details::Impl<Bitfield, StorageType>;
+ I::update(Packed, static_cast<typename Bitfield::IntegerType>(Value));
+ }
+
+ /// Returns whether the two bitfields share common bits.
+ template <typename A, typename B> static constexpr bool isOverlapping() {
+ return A::LastBit > B::FirstBit && B::LastBit > A::FirstBit;
+ }
+};
+
+} // namespace llvm
+
+#endif // LLVM_ADT_BITFIELDS_H
diff --git a/llvm/unittests/ADT/BitFieldsTest.cpp b/llvm/unittests/ADT/BitFieldsTest.cpp
new file mode 100644
index 000000000000..759c18394995
--- /dev/null
+++ b/llvm/unittests/ADT/BitFieldsTest.cpp
@@ -0,0 +1,244 @@
+//===- llvm/unittests/ADT/BitFieldsTest.cpp - BitFields unit tests --------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/Bitfields.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+TEST(BitfieldsTest, Example) {
+ uint8_t Storage = 0;
+
+ // Store and retrieve a single bit as bool.
+ using Bool = Bitfield::Element<bool, 0, 1>;
+ Bitfield::set<Bool>(Storage, true);
+ EXPECT_EQ(Storage, 0b00000001);
+ // ^
+ EXPECT_EQ(Bitfield::get<Bool>(Storage), true);
+
+ // Store and retrieve a 2 bit typed enum.
+ // Note: enum underlying type must be unsigned.
+ enum class SuitEnum : uint8_t { CLUBS, DIAMONDS, HEARTS, SPADES };
+ // Note: enum maximum value needs to be passed in as last parameter.
+ using Suit = Bitfield::Element<SuitEnum, 1, 2, SuitEnum::SPADES>;
+ Bitfield::set<Suit>(Storage, SuitEnum::HEARTS);
+ EXPECT_EQ(Storage, 0b00000101);
+ // ^^
+ EXPECT_EQ(Bitfield::get<Suit>(Storage), SuitEnum::HEARTS);
+
+ // Store and retrieve a 5 bit value as unsigned.
+ using Value = Bitfield::Element<unsigned, 3, 5>;
+ Bitfield::set<Value>(Storage, 10);
+ EXPECT_EQ(Storage, 0b01010101);
+ // ^^^^^
+ EXPECT_EQ(Bitfield::get<Value>(Storage), 10U);
+
+ // Interpret the same 5 bit value as signed.
+ using SignedValue = Bitfield::Element<int, 3, 5>;
+ Bitfield::set<SignedValue>(Storage, -2);
+ EXPECT_EQ(Storage, 0b11110101);
+ // ^^^^^
+ EXPECT_EQ(Bitfield::get<SignedValue>(Storage), -2);
+
+ // Ability to efficiently test if a field is non zero.
+ EXPECT_TRUE(Bitfield::test<Value>(Storage));
+
+ // Alter Storage changes value.
+ Storage = 0;
+ EXPECT_EQ(Bitfield::get<Bool>(Storage), false);
+ EXPECT_EQ(Bitfield::get<Suit>(Storage), SuitEnum::CLUBS);
+ EXPECT_EQ(Bitfield::get<Value>(Storage), 0U);
+ EXPECT_EQ(Bitfield::get<SignedValue>(Storage), 0);
+
+ Storage = 255;
+ EXPECT_EQ(Bitfield::get<Bool>(Storage), true);
+ EXPECT_EQ(Bitfield::get<Suit>(Storage), SuitEnum::SPADES);
+ EXPECT_EQ(Bitfield::get<Value>(Storage), 31U);
+ EXPECT_EQ(Bitfield::get<SignedValue>(Storage), -1);
+}
+
+TEST(BitfieldsTest, FirstBit) {
+ uint8_t Storage = 0;
+ using FirstBit = Bitfield::Element<bool, 0, 1>;
+ // Set true
+ Bitfield::set<FirstBit>(Storage, true);
+ EXPECT_EQ(Bitfield::get<FirstBit>(Storage), true);
+ EXPECT_EQ(Storage, 0x1ULL);
+ // Set false
+ Bitfield::set<FirstBit>(Storage, false);
+ EXPECT_EQ(Bitfield::get<FirstBit>(Storage), false);
+ EXPECT_EQ(Storage, 0x0ULL);
+}
+
+TEST(BitfieldsTest, SecondBit) {
+ uint8_t Storage = 0;
+ using SecondBit = Bitfield::Element<bool, 1, 1>;
+ // Set true
+ Bitfield::set<SecondBit>(Storage, true);
+ EXPECT_EQ(Bitfield::get<SecondBit>(Storage), true);
+ EXPECT_EQ(Storage, 0x2ULL);
+ // Set false
+ Bitfield::set<SecondBit>(Storage, false);
+ EXPECT_EQ(Bitfield::get<SecondBit>(Storage), false);
+ EXPECT_EQ(Storage, 0x0ULL);
+}
+
+TEST(BitfieldsTest, LastBit) {
+ uint8_t Storage = 0;
+ using LastBit = Bitfield::Element<bool, 7, 1>;
+ // Set true
+ Bitfield::set<LastBit>(Storage, true);
+ EXPECT_EQ(Bitfield::get<LastBit>(Storage), true);
+ EXPECT_EQ(Storage, 0x80ULL);
+ // Set false
+ Bitfield::set<LastBit>(Storage, false);
+ EXPECT_EQ(Bitfield::get<LastBit>(Storage), false);
+ EXPECT_EQ(Storage, 0x0ULL);
+}
+
+TEST(BitfieldsTest, LastBitUint64) {
+ uint64_t Storage = 0;
+ using LastBit = Bitfield::Element<bool, 63, 1>;
+ // Set true
+ Bitfield::set<LastBit>(Storage, true);
+ EXPECT_EQ(Bitfield::get<LastBit>(Storage), true);
+ EXPECT_EQ(Storage, 0x8000000000000000ULL);
+ // Set false
+ Bitfield::set<LastBit>(Storage, false);
+ EXPECT_EQ(Bitfield::get<LastBit>(Storage), false);
+ EXPECT_EQ(Storage, 0x0ULL);
+}
+
+TEST(BitfieldsTest, Enum) {
+ enum Enum : unsigned { Zero = 0, Two = 2, LAST = Two };
+
+ uint8_t Storage = 0;
+ using OrderingField = Bitfield::Element<Enum, 1, 2, LAST>;
+ EXPECT_EQ(Bitfield::get<OrderingField>(Storage), Zero);
+ Bitfield::set<OrderingField>(Storage, Two);
+ EXPECT_EQ(Bitfield::get<OrderingField>(Storage), Two);
+ EXPECT_EQ(Storage, 0b00000100);
+ // value 2 in ^^
+}
+
+TEST(BitfieldsTest, EnumClass) {
+ enum class Enum : unsigned { Zero = 0, Two = 2, LAST = Two };
+
+ uint8_t Storage = 0;
+ using OrderingField = Bitfield::Element<Enum, 1, 2, Enum::LAST>;
+ EXPECT_EQ(Bitfield::get<OrderingField>(Storage), Enum::Zero);
+ Bitfield::set<OrderingField>(Storage, Enum::Two);
+ EXPECT_EQ(Bitfield::get<OrderingField>(Storage), Enum::Two);
+ EXPECT_EQ(Storage, 0b00000100);
+ // value 2 in ^^
+}
+
+TEST(BitfieldsTest, OneBitSigned) {
+ uint8_t Storage = 0;
+ using SignedField = Bitfield::Element<int, 1, 1>;
+ EXPECT_EQ(Bitfield::get<SignedField>(Storage), 0);
+ EXPECT_EQ(Storage, 0b00000000);
+ // value 0 in ^
+ Bitfield::set<SignedField>(Storage, -1);
+ EXPECT_EQ(Bitfield::get<SignedField>(Storage), -1);
+ EXPECT_EQ(Storage, 0b00000010);
+ // value 1 in ^
+}
+
+TEST(BitfieldsTest, TwoBitSigned) {
+ uint8_t Storage = 0;
+ using SignedField = Bitfield::Element<int, 1, 2>;
+ EXPECT_EQ(Bitfield::get<SignedField>(Storage), 0);
+ EXPECT_EQ(Storage, 0b00000000);
+ // value 0 in ^^
+ Bitfield::set<SignedField>(Storage, 1);
+ EXPECT_EQ(Bitfield::get<SignedField>(Storage), 1);
+ EXPECT_EQ(Storage, 0b00000010);
+ // value 1 in ^^
+ Bitfield::set<SignedField>(Storage, -1);
+ EXPECT_EQ(Bitfield::get<SignedField>(Storage), -1);
+ EXPECT_EQ(Storage, 0b00000110);
+ // value -1 in ^^
+ Bitfield::set<SignedField>(Storage, -2);
+ EXPECT_EQ(Bitfield::get<SignedField>(Storage), -2);
+ EXPECT_EQ(Storage, 0b00000100);
+ // value -2 in ^^
+}
+
+TEST(BitfieldsTest, isOverlapping) {
+ // 01234567
+ // A: --------
+ // B: ---
+ // C: ---
+ // D: ---
+ using A = Bitfield::Element<unsigned, 0, 8>;
+ using B = Bitfield::Element<unsigned, 3, 3>;
+ using C = Bitfield::Element<unsigned, 1, 3>;
+ using D = Bitfield::Element<unsigned, 4, 3>;
+ EXPECT_TRUE((Bitfield::isOverlapping<A, B>()));
+ EXPECT_TRUE((Bitfield::isOverlapping<A, C>()));
+ EXPECT_TRUE((Bitfield::isOverlapping<A, B>()));
+ EXPECT_TRUE((Bitfield::isOverlapping<A, D>()));
+
+ EXPECT_TRUE((Bitfield::isOverlapping<B, C>()));
+ EXPECT_TRUE((Bitfield::isOverlapping<B, D>()));
+ EXPECT_FALSE((Bitfield::isOverlapping<C, D>()));
+}
+
+TEST(BitfieldsTest, FullUint64) {
+ uint64_t Storage = 0;
+ using Value = Bitfield::Element<uint64_t, 0, 64>;
+ Bitfield::set<Value>(Storage, -1ULL);
+ EXPECT_EQ(Bitfield::get<Value>(Storage), -1ULL);
+ Bitfield::set<Value>(Storage, 0ULL);
+ EXPECT_EQ(Bitfield::get<Value>(Storage), 0ULL);
+}
+
+TEST(BitfieldsTest, FullInt64) {
+ uint64_t Storage = 0;
+ using Value = Bitfield::Element<int64_t, 0, 64>;
+ Bitfield::set<Value>(Storage, -1);
+ EXPECT_EQ(Bitfield::get<Value>(Storage), -1);
+ Bitfield::set<Value>(Storage, 0);
+ EXPECT_EQ(Bitfield::get<Value>(Storage), 0);
+}
+
+#ifdef EXPECT_DEBUG_DEATH
+
+TEST(BitfieldsTest, ValueTooBigBool) {
+ uint64_t Storage = 0;
+ using A = Bitfield::Element<unsigned, 0, 1>;
+ Bitfield::set<A>(Storage, true);
+ Bitfield::set<A>(Storage, false);
+ EXPECT_DEBUG_DEATH(Bitfield::set<A>(Storage, 2), "value is too big");
+}
+
+TEST(BitfieldsTest, ValueTooBigInt) {
+ uint64_t Storage = 0;
+ using A = Bitfield::Element<unsigned, 0, 2>;
+ Bitfield::set<A>(Storage, 3);
+ EXPECT_DEBUG_DEATH(Bitfield::set<A>(Storage, 4), "value is too big");
+ EXPECT_DEBUG_DEATH(Bitfield::set<A>(Storage, -1), "value is too big");
+}
+
+TEST(BitfieldsTest, ValueTooBigBounded) {
+ uint8_t Storage = 0;
+ using A = Bitfield::Element<int, 1, 2>;
+ Bitfield::set<A>(Storage, 1);
+ Bitfield::set<A>(Storage, 0);
+ Bitfield::set<A>(Storage, -1);
+ Bitfield::set<A>(Storage, -2);
+ EXPECT_DEBUG_DEATH(Bitfield::set<A>(Storage, 2), "value is too big");
+ EXPECT_DEBUG_DEATH(Bitfield::set<A>(Storage, -3), "value is too small");
+}
+
+#endif
+
+} // namespace
diff --git a/llvm/unittests/ADT/CMakeLists.txt b/llvm/unittests/ADT/CMakeLists.txt
index 8879a2a00587..cff3911e339f 100644
--- a/llvm/unittests/ADT/CMakeLists.txt
+++ b/llvm/unittests/ADT/CMakeLists.txt
@@ -8,6 +8,7 @@ add_llvm_unittest(ADTTests
APIntTest.cpp
APSIntTest.cpp
ArrayRefTest.cpp
+ BitFieldsTest.cpp
BitmaskEnumTest.cpp
BitVectorTest.cpp
BreadthFirstIteratorTest.cpp
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