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PointerIntPair: Avoid an (academic) case of undefined behavior in the DenseMapInfo specialization.

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If we use a pair with an enum type this could create values outside
of the enum range. Avoid it by creating the bit pattern directly.
While there turn a dynamic assert into a static one. No functionality
change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204010 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2014-03-15 18:10:49 +00:00
parent 14029414f5
commit 80d3b1e708
1 changed files with 5 additions and 5 deletions
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10
include/llvm/ADT/PointerIntPair.h
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@ -45,6 +45,8 @@ class PointerIntPair {
static_assert(PtrTraits::NumLowBitsAvailable <
std::numeric_limits<uintptr_t>::digits,
"cannot use a pointer type that has all bits free");
static_assert(IntBits <= PtrTraits::NumLowBitsAvailable,
"PointerIntPair with integer size too large for pointer");
enum : uintptr_t {
/// PointerBitMask - The bits that come from the pointer.
PointerBitMask =
@ -63,8 +65,6 @@ class PointerIntPair {
public:
PointerIntPair() : Value(0) {}
PointerIntPair(PointerTy PtrVal, IntType IntVal) {
assert(IntBits <= PtrTraits::NumLowBitsAvailable &&
"PointerIntPair formed with integer size too large for pointer");
setPointerAndInt(PtrVal, IntVal);
}
explicit PointerIntPair(PointerTy PtrVal) {
@ -162,13 +162,13 @@ struct DenseMapInfo<PointerIntPair<PointerTy, IntBits, IntType> > {
typedef PointerIntPair<PointerTy, IntBits, IntType> Ty;
static Ty getEmptyKey() {
uintptr_t Val = static_cast<uintptr_t>(-1);
Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable;
return Ty(reinterpret_cast<PointerTy>(Val), IntType((1 << IntBits)-1));
Val <<= PointerLikeTypeTraits<Ty>::NumLowBitsAvailable;
return Ty::getFromOpaqueValue(reinterpret_cast<void *>(Val));
}
static Ty getTombstoneKey() {
uintptr_t Val = static_cast<uintptr_t>(-2);
Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable;
return Ty(reinterpret_cast<PointerTy>(Val), IntType(0));
return Ty::getFromOpaqueValue(reinterpret_cast<void *>(Val));
}
static unsigned getHashValue(Ty V) {
uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue());