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Bring back APInt self-move assignment check for MSVC only

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Summary:
It was removed about a year ago in r300477. Bring it back, along with
its unittest, when the MSVC STL is in use. The MSVC STL performs
self-assignment in std::shuffle. These days, llvm::sort calls
std::shuffle when expensive checks are enabled to help find
non-determinism bugs.

Reviewers: craig.topper, chandlerc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D46028

llvm-svn: 330776
This commit is contained in:
Reid Kleckner 2018-04-24 21:41:50 +00:00
parent 8b4c489d56
commit 1df08a9be7
2 changed files with 37 additions and 0 deletions
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5
include/llvm/ADT/APInt.h
View File

@ -739,6 +739,11 @@ public:
/// @brief Move assignment operator.
APInt &operator=(APInt &&that) {
#ifdef _MSC_VER
// The MSVC std::shuffle implementation still does self-assignment.
if (this == &that)
return *this;
#endif
assert(this != &that && "Self-move not supported");
if (!isSingleWord())
delete[] U.pVal;

32
unittests/ADT/APIntTest.cpp
View File

@ -1659,6 +1659,38 @@ TEST(APIntTest, isShiftedMask) {
}
}
// Test that self-move works, but only when we're using MSVC.
#if defined(_MSC_VER)
#if defined(__clang__)
// Disable the pragma warning from versions of Clang without -Wself-move
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunknown-pragmas"
// Disable the warning that triggers on exactly what is being tested.
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wself-move"
#endif
TEST(APIntTest, SelfMoveAssignment) {
APInt X(32, 0xdeadbeef);
X = std::move(X);
EXPECT_EQ(32u, X.getBitWidth());
EXPECT_EQ(0xdeadbeefULL, X.getLimitedValue());
uint64_t Bits[] = {0xdeadbeefdeadbeefULL, 0xdeadbeefdeadbeefULL};
APInt Y(128, Bits);
Y = std::move(Y);
EXPECT_EQ(128u, Y.getBitWidth());
EXPECT_EQ(~0ULL, Y.getLimitedValue());
const uint64_t *Raw = Y.getRawData();
EXPECT_EQ(2u, Y.getNumWords());
EXPECT_EQ(0xdeadbeefdeadbeefULL, Raw[0]);
EXPECT_EQ(0xdeadbeefdeadbeefULL, Raw[1]);
}
#if defined(__clang__)
#pragma clang diagnostic pop
#pragma clang diagnostic pop
#endif
#endif // _MSC_VER
TEST(APIntTest, reverseBits) {
EXPECT_EQ(1, APInt(1, 1).reverseBits());
EXPECT_EQ(0, APInt(1, 0).reverseBits());