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TrailingObjects::FixedSizeStorage constexpr fixes + tests

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Summary:
This change fixes issues with `LLVM_CONSTEXPR` functions and
`TrailingObjects::FixedSizeStorage`. In particular, some of the
functions marked `LLVM_CONSTEXPR` used by `FixedSizeStorage` were not
implemented such that they evaluate successfully as part of a constant
expression despite constant arguments.

This change also implements a more traditional template-meta path to
accommodate MSVC, and adds unit tests for `FixedSizeStorage`.

Drive-by fix: the access control for members of `TrailingObjectsImpl` is
tightened.

Reviewers: faisalv, rsmith, aaron.ballman

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D22668


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@277270 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hubert Tong 2016-07-30 14:01:00 +00:00
parent f84abb4f62
commit b80ca8647e
4 changed files with 127 additions and 13 deletions
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2
include/llvm/Support/AlignOf.h
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@ -103,7 +103,7 @@ template <typename T> constexpr unsigned AlignOf<T>::Alignment;
/// class besides some cosmetic cleanliness. Example usage:
/// alignOf<int>() returns the alignment of an int.
template <typename T>
inline unsigned alignOf() { return AlignOf<T>::Alignment; }
LLVM_CONSTEXPR inline unsigned alignOf() { return AlignOf<T>::Alignment; }
/// \struct AlignedCharArray
/// \brief Helper for building an aligned character array type.

21
include/llvm/Support/MathExtras.h
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@ -674,6 +674,27 @@ inline uint64_t alignTo(uint64_t Value, uint64_t Align, uint64_t Skew = 0) {
return (Value + Align - 1 - Skew) / Align * Align + Skew;
}
/// Returns the next integer (mod 2**64) that is greater than or equal to
/// \p Value and is a multiple of \c Align. \c Align must be non-zero.
template <uint64_t Align>
LLVM_CONSTEXPR inline uint64_t alignTo(uint64_t Value) {
static_assert(Align != 0u, "Align must be non-zero");
return (Value + Align - 1) / Align * Align;
}
/// \c alignTo for contexts where a constant expression is required.
/// \sa alignTo
///
/// \todo FIXME: remove when \c LLVM_CONSTEXPR becomes really \c constexpr
template <uint64_t Align>
struct AlignTo {
static_assert(Align != 0u, "Align must be non-zero");
template <uint64_t Value>
struct from_value {
static const uint64_t value = (Value + Align - 1) / Align * Align;
};
};
/// Returns the largest uint64_t less than or equal to \p Value and is
/// \p Skew mod \p Align. \p Align must be non-zero
inline uint64_t alignDown(uint64_t Value, uint64_t Align, uint64_t Skew = 0) {

68
include/llvm/Support/TrailingObjects.h
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@ -127,14 +127,14 @@ template <typename Ty1, typename Ty2> struct ExtractSecondType {
template <int Align, typename BaseTy, typename TopTrailingObj, typename PrevTy,
typename... MoreTys>
struct TrailingObjectsImpl {
class TrailingObjectsImpl {
// The main template definition is never used -- the two
// specializations cover all possibilities.
};
template <int Align, typename BaseTy, typename TopTrailingObj, typename PrevTy,
typename NextTy, typename... MoreTys>
struct TrailingObjectsImpl<Align, BaseTy, TopTrailingObj, PrevTy, NextTy,
class TrailingObjectsImpl<Align, BaseTy, TopTrailingObj, PrevTy, NextTy,
MoreTys...>
: public TrailingObjectsImpl<Align, BaseTy, TopTrailingObj, NextTy,
MoreTys...> {
@ -142,14 +142,19 @@ struct TrailingObjectsImpl<Align, BaseTy, TopTrailingObj, PrevTy, NextTy,
typedef TrailingObjectsImpl<Align, BaseTy, TopTrailingObj, NextTy, MoreTys...>
ParentType;
// Ensure the methods we inherit are not hidden.
using ParentType::getTrailingObjectsImpl;
using ParentType::additionalSizeToAllocImpl;
struct RequiresRealignment {
static const bool value =
llvm::AlignOf<PrevTy>::Alignment < llvm::AlignOf<NextTy>::Alignment;
};
static LLVM_CONSTEXPR bool requiresRealignment() {
return llvm::AlignOf<PrevTy>::Alignment < llvm::AlignOf<NextTy>::Alignment;
return RequiresRealignment::value;
}
protected:
// Ensure the inherited getTrailingObjectsImpl is not hidden.
using ParentType::getTrailingObjectsImpl;
// These two functions are helper functions for
// TrailingObjects::getTrailingObjects. They recurse to the left --
// the result for each type in the list of trailing types depends on
@ -195,20 +200,37 @@ struct TrailingObjectsImpl<Align, BaseTy, TopTrailingObj, PrevTy, NextTy,
static LLVM_CONSTEXPR size_t additionalSizeToAllocImpl(
size_t SizeSoFar, size_t Count1,
typename ExtractSecondType<MoreTys, size_t>::type... MoreCounts) {
return additionalSizeToAllocImpl(
return ParentType::additionalSizeToAllocImpl(
(requiresRealignment()
? llvm::alignTo(SizeSoFar, llvm::alignOf<NextTy>())
? llvm::alignTo<llvm::AlignOf<NextTy>::Alignment>(SizeSoFar)
: SizeSoFar) +
sizeof(NextTy) * Count1,
MoreCounts...);
}
// additionalSizeToAllocImpl for contexts where a constant expression is
// required.
// FIXME: remove when LLVM_CONSTEXPR becomes really constexpr
template <size_t SizeSoFar, size_t Count1, size_t... MoreCounts>
struct AdditionalSizeToAllocImpl {
static_assert(sizeof...(MoreTys) == sizeof...(MoreCounts),
"Number of counts do not match number of types");
static const size_t value = ParentType::template AdditionalSizeToAllocImpl<
(RequiresRealignment::value
? llvm::AlignTo<llvm::AlignOf<NextTy>::Alignment>::
template from_value<SizeSoFar>::value
: SizeSoFar) +
sizeof(NextTy) * Count1,
MoreCounts...>::value;
};
};
// The base case of the TrailingObjectsImpl inheritance recursion,
// when there's no more trailing types.
template <int Align, typename BaseTy, typename TopTrailingObj, typename PrevTy>
struct TrailingObjectsImpl<Align, BaseTy, TopTrailingObj, PrevTy>
class TrailingObjectsImpl<Align, BaseTy, TopTrailingObj, PrevTy>
: public TrailingObjectsAligner<Align> {
protected:
// This is a dummy method, only here so the "using" doesn't fail --
// it will never be called, because this function recurses backwards
// up the inheritance chain to subclasses.
@ -218,6 +240,13 @@ struct TrailingObjectsImpl<Align, BaseTy, TopTrailingObj, PrevTy>
return SizeSoFar;
}
// additionalSizeToAllocImpl for contexts where a constant expression is
// required.
// FIXME: remove when LLVM_CONSTEXPR becomes really constexpr
template <size_t SizeSoFar> struct AdditionalSizeToAllocImpl {
static const size_t value = SizeSoFar;
};
template <bool CheckAlignment> static void verifyTrailingObjectsAlignment() {}
};
@ -235,7 +264,7 @@ class TrailingObjects : private trailing_objects_internal::TrailingObjectsImpl<
BaseTy, TrailingTys...> {
template <int A, typename B, typename T, typename P, typename... M>
friend struct trailing_objects_internal::TrailingObjectsImpl;
friend class trailing_objects_internal::TrailingObjectsImpl;
template <typename... Tys> class Foo {};
@ -343,6 +372,21 @@ public:
return sizeof(BaseTy) + ParentType::additionalSizeToAllocImpl(0, Counts...);
}
// totalSizeToAlloc for contexts where a constant expression is required.
// FIXME: remove when LLVM_CONSTEXPR becomes really constexpr
template <typename... Tys> struct TotalSizeToAlloc {
static_assert(
std::is_same<Foo<TrailingTys...>, Foo<Tys...>>::value,
"Arguments to TotalSizeToAlloc do not match with TrailingObjects");
template <size_t... Counts> struct with_counts {
static_assert(sizeof...(TrailingTys) == sizeof...(Counts),
"Number of counts do not match number of types");
static const size_t value =
sizeof(BaseTy) +
ParentType::template AdditionalSizeToAllocImpl<0, Counts...>::value;
};
};
/// A type where its ::with_counts template member has a ::type member
/// suitable for use as uninitialized storage for an object with the given
/// trailing object counts. The template arguments are similar to those
@ -360,7 +404,9 @@ public:
/// \endcode
template <typename... Tys> struct FixedSizeStorage {
template <size_t... Counts> struct with_counts {
enum { Size = totalSizeToAlloc<Tys...>(Counts...) };
enum {
Size = TotalSizeToAlloc<Tys...>::template with_counts<Counts...>::value
};
typedef llvm::AlignedCharArray<
llvm::AlignOf<BaseTy>::Alignment, Size
> type;

47
unittests/Support/TrailingObjectsTest.cpp
View File

@ -41,6 +41,9 @@ public:
unsigned numShorts() const { return NumShorts; }
// Pull some protected members in as public, for testability.
template <typename... Ty>
using FixedSizeStorage = TrailingObjects::FixedSizeStorage<Ty...>;
using TrailingObjects::totalSizeToAlloc;
using TrailingObjects::additionalSizeToAlloc;
using TrailingObjects::getTrailingObjects;
@ -94,6 +97,9 @@ public:
}
// Pull some protected members in as public, for testability.
template <typename... Ty>
using FixedSizeStorage = TrailingObjects::FixedSizeStorage<Ty...>;
using TrailingObjects::totalSizeToAlloc;
using TrailingObjects::additionalSizeToAlloc;
using TrailingObjects::getTrailingObjects;
@ -106,7 +112,20 @@ TEST(TrailingObjects, OneArg) {
EXPECT_EQ(Class1::additionalSizeToAlloc<short>(1), sizeof(short));
EXPECT_EQ(Class1::additionalSizeToAlloc<short>(3), sizeof(short) * 3);
EXPECT_EQ(
llvm::alignOf<Class1>(),
llvm::alignOf<Class1::FixedSizeStorage<short>::with_counts<1>::type>());
EXPECT_EQ(sizeof(Class1::FixedSizeStorage<short>::with_counts<1>::type),
llvm::alignTo(Class1::totalSizeToAlloc<short>(1),
llvm::alignOf<Class1>()));
EXPECT_EQ(Class1::totalSizeToAlloc<short>(1), sizeof(Class1) + sizeof(short));
EXPECT_EQ(
llvm::alignOf<Class1>(),
llvm::alignOf<Class1::FixedSizeStorage<short>::with_counts<3>::type>());
EXPECT_EQ(sizeof(Class1::FixedSizeStorage<short>::with_counts<3>::type),
llvm::alignTo(Class1::totalSizeToAlloc<short>(3),
llvm::alignOf<Class1>()));
EXPECT_EQ(Class1::totalSizeToAlloc<short>(3),
sizeof(Class1) + sizeof(short) * 3);
@ -131,6 +150,14 @@ TEST(TrailingObjects, TwoArg) {
EXPECT_EQ((Class2::additionalSizeToAlloc<double, short>(3, 1)),
sizeof(double) * 3 + sizeof(short));
EXPECT_EQ(
llvm::alignOf<Class2>(),
(llvm::alignOf<
Class2::FixedSizeStorage<double, short>::with_counts<1, 1>::type>()));
EXPECT_EQ(
sizeof(Class2::FixedSizeStorage<double, short>::with_counts<1, 1>::type),
llvm::alignTo(Class2::totalSizeToAlloc<double, short>(1, 1),
llvm::alignOf<Class2>()));
EXPECT_EQ((Class2::totalSizeToAlloc<double, short>(1, 1)),
sizeof(Class2) + sizeof(double) + sizeof(short));
@ -165,6 +192,16 @@ TEST(TrailingObjects, ThreeArg) {
EXPECT_EQ((Class3::additionalSizeToAlloc<double, short, bool>(1, 1, 3)),
sizeof(double) + sizeof(short) + 3 * sizeof(bool));
EXPECT_EQ(sizeof(Class3), llvm::alignTo(1, llvm::alignOf<double>()));
EXPECT_EQ(llvm::alignOf<Class3>(),
(llvm::alignOf<Class3::FixedSizeStorage<
double, short, bool>::with_counts<1, 1, 3>::type>()));
EXPECT_EQ(
sizeof(Class3::FixedSizeStorage<double, short,
bool>::with_counts<1, 1, 3>::type),
llvm::alignTo(Class3::totalSizeToAlloc<double, short, bool>(1, 1, 3),
llvm::alignOf<Class3>()));
std::unique_ptr<char[]> P(new char[1000]);
Class3 *C = reinterpret_cast<Class3 *>(P.get());
EXPECT_EQ(C->getTrailingObjects<double>(), reinterpret_cast<double *>(C + 1));
@ -186,6 +223,16 @@ TEST(TrailingObjects, Realignment) {
EXPECT_EQ((Class4::additionalSizeToAlloc<char, long>(1, 1)),
llvm::alignTo(sizeof(long) + 1, llvm::alignOf<long>()));
EXPECT_EQ(sizeof(Class4), llvm::alignTo(1, llvm::alignOf<long>()));
EXPECT_EQ(
llvm::alignOf<Class4>(),
(llvm::alignOf<
Class4::FixedSizeStorage<char, long>::with_counts<1, 1>::type>()));
EXPECT_EQ(
sizeof(Class4::FixedSizeStorage<char, long>::with_counts<1, 1>::type),
llvm::alignTo(Class4::totalSizeToAlloc<char, long>(1, 1),
llvm::alignOf<Class4>()));
std::unique_ptr<char[]> P(new char[1000]);
Class4 *C = reinterpret_cast<Class4 *>(P.get());
EXPECT_EQ(C->getTrailingObjects<char>(), reinterpret_cast<char *>(C + 1));