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llvm-mirror/unittests/ADT/PointerIntPairTest.cpp
Serge Guelton b20ef5f960 Replace llvm::isPodLike<...> by llvm::is_trivially_copyable<...>
As noted in https://bugs.llvm.org/show_bug.cgi?id=36651, the specialization for
isPodLike<std::pair<...>> did not match the expectation of
std::is_trivially_copyable which makes the memcpy optimization invalid.

This patch renames the llvm::isPodLike trait into llvm::is_trivially_copyable.
Unfortunately std::is_trivially_copyable is not portable across compiler / STL
versions. So a portable version is provided too.

Note that the following specialization were invalid:

    std::pair<T0, T1>
    llvm::Optional<T>

Tests have been added to assert that former specialization are respected by the
standard usage of llvm::is_trivially_copyable, and that when a decent version
of std::is_trivially_copyable is available, llvm::is_trivially_copyable is
compared to std::is_trivially_copyable.

As of this patch, llvm::Optional is no longer considered trivially copyable,
even if T is. This is to be fixed in a later patch, as it has impact on a
long-running bug (see r347004)

Note that GCC warns about this UB, but this got silented by https://reviews.llvm.org/D50296.

Differential Revision: https://reviews.llvm.org/D54472

llvm-svn: 351701
2019-01-20 21:19:56 +00:00

110 lines
3.3 KiB
C++

//===- llvm/unittest/ADT/PointerIntPairTest.cpp - 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/PointerIntPair.h"
#include "gtest/gtest.h"
#include <limits>
using namespace llvm;
namespace {
TEST(PointerIntPairTest, GetSet) {
struct S {
int i;
};
S s;
PointerIntPair<S *, 2> Pair(&s, 1U);
EXPECT_EQ(&s, Pair.getPointer());
EXPECT_EQ(1U, Pair.getInt());
Pair.setInt(2);
EXPECT_EQ(&s, Pair.getPointer());
EXPECT_EQ(2U, Pair.getInt());
Pair.setPointer(nullptr);
EXPECT_EQ(nullptr, Pair.getPointer());
EXPECT_EQ(2U, Pair.getInt());
Pair.setPointerAndInt(&s, 3U);
EXPECT_EQ(&s, Pair.getPointer());
EXPECT_EQ(3U, Pair.getInt());
// Make sure that we can perform all of our operations on enum classes.
//
// The concern is that enum classes are only explicitly convertible to
// integers. This means that if we assume in PointerIntPair this, a
// compilation error will result. This group of tests exercises the enum class
// code to make sure that we do not run into such issues in the future.
enum class E : unsigned {
Case1,
Case2,
Case3,
};
PointerIntPair<S *, 2, E> Pair2(&s, E::Case1);
EXPECT_EQ(&s, Pair2.getPointer());
EXPECT_EQ(E::Case1, Pair2.getInt());
Pair2.setInt(E::Case2);
EXPECT_EQ(&s, Pair2.getPointer());
EXPECT_EQ(E::Case2, Pair2.getInt());
Pair2.setPointer(nullptr);
EXPECT_EQ(nullptr, Pair2.getPointer());
EXPECT_EQ(E::Case2, Pair2.getInt());
Pair2.setPointerAndInt(&s, E::Case3);
EXPECT_EQ(&s, Pair2.getPointer());
EXPECT_EQ(E::Case3, Pair2.getInt());
static_assert(is_trivially_copyable<PointerIntPair<S *, 2, E>>::value,
"trivially copyable");
}
TEST(PointerIntPairTest, DefaultInitialize) {
PointerIntPair<float *, 2> Pair;
EXPECT_EQ(nullptr, Pair.getPointer());
EXPECT_EQ(0U, Pair.getInt());
}
TEST(PointerIntPairTest, ManyUnusedBits) {
// In real code this would be a word-sized integer limited to 31 bits.
struct Fixnum31 {
uintptr_t Value;
};
class FixnumPointerTraits {
public:
static inline void *getAsVoidPointer(Fixnum31 Num) {
return reinterpret_cast<void *>(Num.Value << NumLowBitsAvailable);
}
static inline Fixnum31 getFromVoidPointer(void *P) {
// In real code this would assert that the value is in range.
return { reinterpret_cast<uintptr_t>(P) >> NumLowBitsAvailable };
}
enum { NumLowBitsAvailable = std::numeric_limits<uintptr_t>::digits - 31 };
};
PointerIntPair<Fixnum31, 1, bool, FixnumPointerTraits> pair;
EXPECT_EQ((uintptr_t)0, pair.getPointer().Value);
EXPECT_FALSE(pair.getInt());
pair.setPointerAndInt({ 0x7FFFFFFF }, true );
EXPECT_EQ((uintptr_t)0x7FFFFFFF, pair.getPointer().Value);
EXPECT_TRUE(pair.getInt());
EXPECT_EQ(FixnumPointerTraits::NumLowBitsAvailable - 1,
PointerLikeTypeTraits<decltype(pair)>::NumLowBitsAvailable);
static_assert(
is_trivially_copyable<
PointerIntPair<Fixnum31, 1, bool, FixnumPointerTraits>>::value,
"trivially copyable");
}
} // end anonymous namespace