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Lift self-copy protection up to the header file and add self-move

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protection to the same layer.

This is in line with Howard's advice on how best to handle self-move
assignment as he explained on SO[1]. It also ensures that implementing
swap with move assignment continues to work in the case of self-swap.

[1]: http://stackoverflow.com/questions/9322174/move-assignment-operator-and-if-this-rhs

llvm-svn: 195705
This commit is contained in:
Chandler Carruth 2013-11-26 00:54:44 +00:00
parent 9233af88ac
commit dc82f92af7
2 changed files with 7 additions and 4 deletions
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6
include/llvm/ADT/SmallPtrSet.h
View File

@ -293,14 +293,16 @@ public:
SmallPtrSet<PtrType, SmallSize> & SmallPtrSet<PtrType, SmallSize> &
operator=(const SmallPtrSet<PtrType, SmallSize> &RHS) { operator=(const SmallPtrSet<PtrType, SmallSize> &RHS) {
CopyFrom(RHS); if (&RHS != this)
CopyFrom(RHS);
return *this; return *this;
} }
#if LLVM_HAS_RVALUE_REFERENCES #if LLVM_HAS_RVALUE_REFERENCES
SmallPtrSet<PtrType, SmallSize>& SmallPtrSet<PtrType, SmallSize>&
operator=(SmallPtrSet<PtrType, SmallSize> &&RHS) { operator=(SmallPtrSet<PtrType, SmallSize> &&RHS) {
MoveFrom(SmallSizePowTwo, std::move(RHS)); if (&RHS != this)
MoveFrom(SmallSizePowTwo, std::move(RHS));
return *this; return *this;
} }
#endif #endif

5
lib/Support/SmallPtrSet.cpp
View File

@ -218,8 +218,7 @@ SmallPtrSetImpl::SmallPtrSetImpl(const void **SmallStorage, unsigned SmallSize,
/// CopyFrom - implement operator= from a smallptrset that has the same pointer /// CopyFrom - implement operator= from a smallptrset that has the same pointer
/// type, but may have a different small size. /// type, but may have a different small size.
void SmallPtrSetImpl::CopyFrom(const SmallPtrSetImpl &RHS) { void SmallPtrSetImpl::CopyFrom(const SmallPtrSetImpl &RHS) {
if (&RHS == this) assert(&RHS != this && "Self-copy should be handled by the caller.");
return;
if (isSmall() && RHS.isSmall()) if (isSmall() && RHS.isSmall())
assert(CurArraySize == RHS.CurArraySize && assert(CurArraySize == RHS.CurArraySize &&
@ -256,6 +255,8 @@ void SmallPtrSetImpl::CopyFrom(const SmallPtrSetImpl &RHS) {
#if LLVM_HAS_RVALUE_REFERENCES #if LLVM_HAS_RVALUE_REFERENCES
void SmallPtrSetImpl::MoveFrom(unsigned SmallSize, SmallPtrSetImpl &&RHS) { void SmallPtrSetImpl::MoveFrom(unsigned SmallSize, SmallPtrSetImpl &&RHS) {
assert(&RHS != this && "Self-move should be handled by the caller.");
if (!isSmall()) if (!isSmall())
free(CurArray); free(CurArray);