[clang] [libcxx] [clang & libcxx] constexpr pointer tagging (DO NOT MERGE) (PR #111861)
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Thu Oct 10 08:51:20 PDT 2024
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<summary>
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``````````bash
git-clang-format --diff 545e0593f8c59376a7ec8c6eb558babf6c9f93c1 6679082fa13048516a2b1ea27edf8de4cecb6f07 --extensions ,cpp,h -- libcxx/include/__memory/tagged_ptr.h clang/include/clang/AST/APValue.h clang/lib/AST/APValue.cpp clang/lib/AST/ExprConstant.cpp clang/lib/CodeGen/CGBuiltin.cpp clang/lib/CodeGen/CodeGenFunction.h libcxx/include/memory
``````````
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<summary>
View the diff from clang-format here.
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``````````diff
diff --git a/clang/include/clang/AST/APValue.h b/clang/include/clang/AST/APValue.h
index 278cf61dd5..da6f23d36a 100644
--- a/clang/include/clang/AST/APValue.h
+++ b/clang/include/clang/AST/APValue.h
@@ -198,6 +198,7 @@ public:
/// The QualType, if this is a DynamicAllocLValue.
void *DynamicAllocType;
};
+
public:
uint64_t Metadata{0};
};
@@ -530,7 +531,7 @@ public:
const LValueBase getLValueBase() const;
uint64_t getLValueMetadata() const;
- uint64_t & getLValueMetadata();
+ uint64_t &getLValueMetadata();
CharUnits &getLValueOffset();
const CharUnits &getLValueOffset() const {
return const_cast<APValue*>(this)->getLValueOffset();
diff --git a/clang/lib/AST/APValue.cpp b/clang/lib/AST/APValue.cpp
index 02ba5cf51d..72704459a9 100644
--- a/clang/lib/AST/APValue.cpp
+++ b/clang/lib/AST/APValue.cpp
@@ -980,7 +980,7 @@ uint64_t APValue::getLValueMetadata() const {
return ((const LV *)(const void *)&Data)->Base.Metadata;
}
-uint64_t & APValue::getLValueMetadata() {
+uint64_t &APValue::getLValueMetadata() {
assert(isLValue() && "Invalid accessor");
return ((LV *)(void *)&Data)->Base.Metadata;
}
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index ed7eeeba20..3a83aedff1 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -4498,7 +4498,7 @@ handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, QualType Type,
bool WantObjectRepresentation = false) {
if (LVal.Designator.Invalid)
return false;
-
+
if (LVal.Base.Metadata != 0) {
Info.FFDiag(Conv, diag::note_constexpr_dereferencing_tagged_pointer);
return false;
@@ -9741,27 +9741,29 @@ bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
switch (BuiltinOp) {
// emulation of pointer tagging without actually touching pointer value
- // as there is no such thing as address here, so tag is stored as a metadata in lvalue base
- case Builtin::BI__builtin_tag_pointer_mask_or: {
- APSInt Value, Mask;
- if (!evaluatePointer(E->getArg(0), Result))
- return Error(E);
-
- if (!EvaluateInteger(E->getArg(1), Value, Info))
- return Error(E);
-
- if (!EvaluateInteger(E->getArg(2), Mask, Info))
- return Error(E);
-
- if (Mask.getLimitedValue() == 0) {
- CCEDiag(E->getArg(2), diag::note_constexpr_tagging_with_empty_mask);
- return false;
- }
-
- Result.Base.Metadata = (Result.Base.Metadata & ~Mask.getLimitedValue()) | (Value.getLimitedValue() & Mask.getLimitedValue());
- return true;
+ // as there is no such thing as address here, so tag is stored as a metadata
+ // in lvalue base
+ case Builtin::BI__builtin_tag_pointer_mask_or: {
+ APSInt Value, Mask;
+ if (!evaluatePointer(E->getArg(0), Result))
+ return Error(E);
+
+ if (!EvaluateInteger(E->getArg(1), Value, Info))
+ return Error(E);
+
+ if (!EvaluateInteger(E->getArg(2), Mask, Info))
+ return Error(E);
+
+ if (Mask.getLimitedValue() == 0) {
+ CCEDiag(E->getArg(2), diag::note_constexpr_tagging_with_empty_mask);
+ return false;
}
+ Result.Base.Metadata = (Result.Base.Metadata & ~Mask.getLimitedValue()) |
+ (Value.getLimitedValue() & Mask.getLimitedValue());
+ return true;
+ }
+
// alternative approach to tagging which shifts pointer
// here we are only shifting metadata
case Builtin::BI__builtin_tag_pointer_shift_or: {
@@ -9780,45 +9782,50 @@ bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
return false;
}
- const uint64_t Mask = (1ull << static_cast<uint64_t>(Shift.getLimitedValue())) - 1ull;
- Result.Base.Metadata = (Result.Base.Metadata << static_cast<uint64_t>(Shift.getLimitedValue())) | (Value.getLimitedValue() & Mask);
+ const uint64_t Mask =
+ (1ull << static_cast<uint64_t>(Shift.getLimitedValue())) - 1ull;
+ Result.Base.Metadata = (Result.Base.Metadata
+ << static_cast<uint64_t>(Shift.getLimitedValue())) |
+ (Value.getLimitedValue() & Mask);
return true;
}
-
+
// recover pointer by masking metadata
// exprconstant allows dereferencing only metadata == 0 pointer
case Builtin::BI__builtin_tag_pointer_mask: {
APSInt Mask;
if (!evaluatePointer(E->getArg(0), Result))
- return Error(E);
-
+ return Error(E);
+
if (!EvaluateInteger(E->getArg(1), Mask, Info))
return Error(E);
-
+
if (Mask.getLimitedValue() == 0) {
CCEDiag(E->getArg(2), diag::note_constexpr_tagging_with_empty_mask);
return false;
}
-
+
Result.Base.Metadata = (Result.Base.Metadata & Mask.getLimitedValue());
return true;
}
- // shifting back pointer (also can convert tagged pointer back to normal pointer)
+ // shifting back pointer (also can convert tagged pointer back to normal
+ // pointer)
case Builtin::BI__builtin_tag_pointer_unshift: {
APSInt Shift;
if (!evaluatePointer(E->getArg(0), Result))
- return Error(E);
-
+ return Error(E);
+
if (!EvaluateInteger(E->getArg(1), Shift, Info))
return Error(E);
-
+
if (Shift.getLimitedValue() == 0) {
CCEDiag(E->getArg(2), diag::note_constexpr_tagging_with_shift_zero);
return false;
}
-
- Result.Base.Metadata = (Result.Base.Metadata >> static_cast<uint64_t>(Shift.getLimitedValue()));
+
+ Result.Base.Metadata = (Result.Base.Metadata >>
+ static_cast<uint64_t>(Shift.getLimitedValue()));
return true;
}
case Builtin::BIaddressof:
@@ -12751,19 +12758,20 @@ bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
case Builtin::BI__builtin_tag_pointer_mask_as_int: {
LValue Pointer;
APSInt Mask;
-
+
if (!EvaluatePointer(E->getArg(0), Pointer, Info))
return Error(E);
if (!EvaluateInteger(E->getArg(1), Mask, Info))
return Error(E);
-
+
if (Mask.getLimitedValue() == 0) {
CCEDiag(E->getArg(2), diag::note_constexpr_tagging_with_empty_mask);
return false;
}
-
- const uint64_t Result = Pointer.Base.Metadata & (static_cast<uint64_t>(Mask.getLimitedValue()));
+
+ const uint64_t Result =
+ Pointer.Base.Metadata & (static_cast<uint64_t>(Mask.getLimitedValue()));
return Success(Result, E);
}
@@ -14324,13 +14332,13 @@ EvaluateComparisonBinaryOperator(EvalInfo &Info, const BinaryOperator *E,
return Success(CmpResult::Less, E);
if (CompareLHS > CompareRHS)
return Success(CmpResult::Greater, E);
-
+
// this makes tagged pointer not equal to original pointer
if (LHSValue.Base.Metadata < RHSValue.Base.Metadata)
return Success(CmpResult::Less, E);
if (LHSValue.Base.Metadata > RHSValue.Base.Metadata)
return Success(CmpResult::Greater, E);
-
+
return Success(CmpResult::Equal, E);
}
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 4ac09e7a31..14519d0ecd 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -5320,7 +5320,7 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
return RValue::get(Carry);
}
-
+
// support for pointer tagging
case Builtin::BI__builtin_tag_pointer_mask_or:
return EmitBuiltinTagPointerMaskOr(E);
@@ -21260,93 +21260,112 @@ Value *CodeGenFunction::EmitNVPTXBuiltinExpr(unsigned BuiltinID,
/// Generate (x & ~mask) | (value & mask).
RValue CodeGenFunction::EmitBuiltinTagPointerMaskOr(const CallExpr *E) {
- llvm::Value * Ptr = EmitScalarExpr(E->getArg(0));
- llvm::Value * Value = EmitScalarExpr(E->getArg(1));
- llvm::Value * Mask = EmitScalarExpr(E->getArg(2));
-
- llvm::IntegerType * IntType = IntegerType::get(getLLVMContext(), CGM.getDataLayout().getIndexTypeSizeInBits(Ptr->getType()));
-
+ llvm::Value *Ptr = EmitScalarExpr(E->getArg(0));
+ llvm::Value *Value = EmitScalarExpr(E->getArg(1));
+ llvm::Value *Mask = EmitScalarExpr(E->getArg(2));
+
+ llvm::IntegerType *IntType = IntegerType::get(
+ getLLVMContext(),
+ CGM.getDataLayout().getIndexTypeSizeInBits(Ptr->getType()));
+
// TODO: avoid using bitcast and go path of ptr.tag (mirror to ptr.mask)
- // to keep pointer's provenance, but this turns out a bit harder to do as it touches
- // a lot of places in llvm
- llvm::Value * PointerInt = Builder.CreateBitOrPointerCast(Ptr, IntType, "pointer_int");
- llvm::Value * InvertedMask = Builder.CreateNot(Mask, "inverted_mask");
-
- llvm::Value * MaskedPtr = Builder.CreateAnd(PointerInt, InvertedMask, "masked_ptr");
- llvm::Value * MaskedValue = Builder.CreateAnd(Value, Mask, "masked_value");
-
- llvm::Value * ResultInt = Builder.CreateOr(MaskedPtr, MaskedValue, "result_int");
- llvm::Value * Result = Builder.CreateBitOrPointerCast(ResultInt, Ptr->getType(), "result_ptr");
-
+ // to keep pointer's provenance, but this turns out a bit harder to do as it
+ // touches a lot of places in llvm
+ llvm::Value *PointerInt =
+ Builder.CreateBitOrPointerCast(Ptr, IntType, "pointer_int");
+ llvm::Value *InvertedMask = Builder.CreateNot(Mask, "inverted_mask");
+
+ llvm::Value *MaskedPtr =
+ Builder.CreateAnd(PointerInt, InvertedMask, "masked_ptr");
+ llvm::Value *MaskedValue = Builder.CreateAnd(Value, Mask, "masked_value");
+
+ llvm::Value *ResultInt =
+ Builder.CreateOr(MaskedPtr, MaskedValue, "result_int");
+ llvm::Value *Result =
+ Builder.CreateBitOrPointerCast(ResultInt, Ptr->getType(), "result_ptr");
+
return RValue::get(Result);
}
/// Generate (x << shift) | (value & ((1 << shift) - 1)).
RValue CodeGenFunction::EmitBuiltinTagPointerShiftOr(const CallExpr *E) {
- llvm::Value * Ptr = EmitScalarExpr(E->getArg(0));
- llvm::Value * Value = EmitScalarExpr(E->getArg(1));
- llvm::Value * Shift = EmitScalarExpr(E->getArg(2));
-
- llvm::IntegerType * IntType = IntegerType::get(getLLVMContext(), CGM.getDataLayout().getIndexTypeSizeInBits(Ptr->getType()));
-
+ llvm::Value *Ptr = EmitScalarExpr(E->getArg(0));
+ llvm::Value *Value = EmitScalarExpr(E->getArg(1));
+ llvm::Value *Shift = EmitScalarExpr(E->getArg(2));
+
+ llvm::IntegerType *IntType = IntegerType::get(
+ getLLVMContext(),
+ CGM.getDataLayout().getIndexTypeSizeInBits(Ptr->getType()));
+
// TODO: again, for now a bitcast, later ptr.shift_tag
- llvm::Value * PointerInt = Builder.CreateBitOrPointerCast(Ptr, IntType, "pointer_int");
- llvm::Value * ShiftedPointerInt = Builder.CreateShl(PointerInt, Shift);
-
+ llvm::Value *PointerInt =
+ Builder.CreateBitOrPointerCast(Ptr, IntType, "pointer_int");
+ llvm::Value *ShiftedPointerInt = Builder.CreateShl(PointerInt, Shift);
+
auto *One = llvm::ConstantInt::get(IntType, 1);
-
- llvm::Value * Mask = Builder.CreateSub(Builder.CreateShl(One, Shift), One, "mask");
- llvm::Value * MaskedValue = Builder.CreateAdd(Value, Mask, "masked_value");
- llvm::Value * PointerWithTag = Builder.CreateOr(ShiftedPointerInt, MaskedValue, "pointer_with_tag_int");
-
- llvm::Value * Result = Builder.CreateBitOrPointerCast(PointerWithTag, Ptr->getType(), "result_ptr");
+
+ llvm::Value *Mask =
+ Builder.CreateSub(Builder.CreateShl(One, Shift), One, "mask");
+ llvm::Value *MaskedValue = Builder.CreateAdd(Value, Mask, "masked_value");
+ llvm::Value *PointerWithTag =
+ Builder.CreateOr(ShiftedPointerInt, MaskedValue, "pointer_with_tag_int");
+
+ llvm::Value *Result = Builder.CreateBitOrPointerCast(
+ PointerWithTag, Ptr->getType(), "result_ptr");
return RValue::get(Result);
}
/// Generate (x >> shift)
RValue CodeGenFunction::EmitBuiltinTagPointerUnshift(const CallExpr *E) {
- llvm::Value * Ptr = EmitScalarExpr(E->getArg(0));
- llvm::Value * Shift = EmitScalarExpr(E->getArg(1));
-
- llvm::IntegerType * IntType = IntegerType::get(getLLVMContext(), CGM.getDataLayout().getIndexTypeSizeInBits(Ptr->getType()));
-
+ llvm::Value *Ptr = EmitScalarExpr(E->getArg(0));
+ llvm::Value *Shift = EmitScalarExpr(E->getArg(1));
+
+ llvm::IntegerType *IntType = IntegerType::get(
+ getLLVMContext(),
+ CGM.getDataLayout().getIndexTypeSizeInBits(Ptr->getType()));
+
// for now I'm going path of bitcast
- llvm::Value * PointerInt = Builder.CreateBitOrPointerCast(Ptr, IntType, "pointer_int");
- llvm::Value * UnShiftedPointerInt = Builder.CreateAShr(PointerInt, Shift, "unshifted_pointer_int");
-
- llvm::Value * Result = Builder.CreateBitOrPointerCast(UnShiftedPointerInt, Ptr->getType(), "result_ptr");
+ llvm::Value *PointerInt =
+ Builder.CreateBitOrPointerCast(Ptr, IntType, "pointer_int");
+ llvm::Value *UnShiftedPointerInt =
+ Builder.CreateAShr(PointerInt, Shift, "unshifted_pointer_int");
+
+ llvm::Value *Result = Builder.CreateBitOrPointerCast(
+ UnShiftedPointerInt, Ptr->getType(), "result_ptr");
return RValue::get(Result);
}
/// Generate (x & mask).
RValue CodeGenFunction::EmitBuiltinTagPointerMask(const CallExpr *E) {
- llvm::Value * Ptr = EmitScalarExpr(E->getArg(0));
- llvm::Value * Mask = EmitScalarExpr(E->getArg(1));
-
+ llvm::Value *Ptr = EmitScalarExpr(E->getArg(0));
+ llvm::Value *Mask = EmitScalarExpr(E->getArg(1));
+
llvm::Value *Result = Builder.CreateIntrinsic(
- Intrinsic::ptrmask, {Ptr->getType(), Mask->getType()},
- {Ptr, Mask}, nullptr, "result");
-
+ Intrinsic::ptrmask, {Ptr->getType(), Mask->getType()}, {Ptr, Mask},
+ nullptr, "result");
+
return RValue::get(Result);
}
/// Generate (x & mask) (but return it as number).
RValue CodeGenFunction::EmitBuiltinTagPointerMaskAsInt(const CallExpr *E) {
- llvm::Value * Ptr = EmitScalarExpr(E->getArg(0));
- llvm::Value * Mask = EmitScalarExpr(E->getArg(1));
-
- llvm::IntegerType * IntType = IntegerType::get(getLLVMContext(), CGM.getDataLayout().getIndexTypeSizeInBits(Ptr->getType()));
-
+ llvm::Value *Ptr = EmitScalarExpr(E->getArg(0));
+ llvm::Value *Mask = EmitScalarExpr(E->getArg(1));
+
+ llvm::IntegerType *IntType = IntegerType::get(
+ getLLVMContext(),
+ CGM.getDataLayout().getIndexTypeSizeInBits(Ptr->getType()));
+
llvm::Value *Result = Builder.CreateIntrinsic(
- Intrinsic::ptrmask, {Ptr->getType(), Mask->getType()},
- {Ptr, Mask}, nullptr, "result");
+ Intrinsic::ptrmask, {Ptr->getType(), Mask->getType()}, {Ptr, Mask},
+ nullptr, "result");
+
+ llvm::Value *IntResult =
+ Builder.CreateBitOrPointerCast(Result, IntType, "int_result");
- llvm::Value * IntResult = Builder.CreateBitOrPointerCast(Result, IntType, "int_result");
-
return RValue::get(IntResult);
}
-
namespace {
struct BuiltinAlignArgs {
llvm::Value *Src = nullptr;
diff --git a/libcxx/include/__memory/tagged_ptr.h b/libcxx/include/__memory/tagged_ptr.h
index 7c99d0e929..c11d9dacae 100644
--- a/libcxx/include/__memory/tagged_ptr.h
+++ b/libcxx/include/__memory/tagged_ptr.h
@@ -15,122 +15,142 @@
#endif
#if _LIBCPP_STD_VER >= 26
-
-#include <__config>
-#include <__type_traits/is_trivially_copyable.h>
-#include <__assert>
-#include "__bit/has_single_bit.h"
-#include <__type_traits/rank.h>
-#include "pointer_traits.h"
-#include <compare>
+
+# include "__bit/has_single_bit.h"
+# include "pointer_traits.h"
+# include <__assert>
+# include <__config>
+# include <__type_traits/is_trivially_copyable.h>
+# include <__type_traits/rank.h>
+# include <compare>
_LIBCPP_BEGIN_NAMESPACE_STD
-template <typename T, typename Y> concept convertible_to_from = std::convertible_to<Y, T> && std::convertible_to<T, Y>;
-
-template <typename T> concept pointer_tagging_schema = requires(T::dirty_pointer payload, T::clean_pointer clean, T::tag_type tag) {
- //requires convertible_to_from<typename T::tag_type, uintptr_t>;
+template <typename T, typename Y>
+concept convertible_to_from = std::convertible_to<Y, T> && std::convertible_to<T, Y>;
+
+template <typename T>
+concept pointer_tagging_schema = requires(T::dirty_pointer payload, T::clean_pointer clean, T::tag_type tag) {
+ // requires convertible_to_from<typename T::tag_type, uintptr_t>;
requires std::is_pointer_v<typename T::clean_pointer>;
-
+
{ T::encode_pointer_with_tag(clean, tag) } noexcept -> std::same_as<typename T::dirty_pointer>;
{ T::recover_pointer(payload) } noexcept -> std::same_as<typename T::clean_pointer>;
{ T::recover_value(payload) } noexcept -> std::same_as<typename T::tag_type>;
};
-template <typename T> concept pointer_tagging_schema_with_aliasing = pointer_tagging_schema<T> && requires(T::dirty_pointer payload) {
+template <typename T>
+concept pointer_tagging_schema_with_aliasing = pointer_tagging_schema<T> && requires(T::dirty_pointer payload) {
{ T::recover_aliasing_pointer(payload) } noexcept -> std::same_as<typename T::clean_pointer>;
};
struct no_tag {
- template <typename T, typename Tag> struct schema {
- using clean_pointer = T *;
- using dirty_pointer = void *;
- using tag_type = Tag;
-
- [[clang::always_inline]] static constexpr dirty_pointer encode_pointer_with_tag(clean_pointer _ptr, tag_type) noexcept {
+ template <typename T, typename Tag>
+ struct schema {
+ using clean_pointer = T*;
+ using dirty_pointer = void*;
+ using tag_type = Tag;
+
+ [[clang::always_inline]] static constexpr dirty_pointer
+ encode_pointer_with_tag(clean_pointer _ptr, tag_type) noexcept {
return (dirty_pointer)_ptr;
}
[[clang::always_inline]] static constexpr clean_pointer recover_pointer(dirty_pointer _ptr) noexcept {
return (clean_pointer)_ptr;
}
- [[clang::always_inline]] static constexpr tag_type recover_value(dirty_pointer) noexcept {
- return {};
- }
+ [[clang::always_inline]] static constexpr tag_type recover_value(dirty_pointer) noexcept { return {}; }
};
};
-template <uintptr_t Mask> struct bitmask_tag {
+template <uintptr_t Mask>
+struct bitmask_tag {
static constexpr uintptr_t _mask = Mask;
- template <typename T, typename Tag> struct schema {
- using clean_pointer = T *;
- using dirty_pointer = void *;
- using tag_type = Tag;
+ template <typename T, typename Tag>
+ struct schema {
+ using clean_pointer = T*;
+ using dirty_pointer = void*;
+ using tag_type = Tag;
- [[clang::always_inline]] static constexpr dirty_pointer encode_pointer_with_tag(clean_pointer _ptr, tag_type _value) noexcept {
- return static_cast<dirty_pointer>(__builtin_tag_pointer_mask_or((void *)(_ptr), static_cast<uintptr_t>(_value), _mask));
+ [[clang::always_inline]] static constexpr dirty_pointer
+ encode_pointer_with_tag(clean_pointer _ptr, tag_type _value) noexcept {
+ return static_cast<dirty_pointer>(
+ __builtin_tag_pointer_mask_or((void*)(_ptr), static_cast<uintptr_t>(_value), _mask));
}
[[clang::always_inline]] static constexpr clean_pointer recover_pointer(dirty_pointer _ptr) noexcept {
- return static_cast<clean_pointer>(__builtin_tag_pointer_mask((void *)_ptr, ~_mask));
+ return static_cast<clean_pointer>(__builtin_tag_pointer_mask((void*)_ptr, ~_mask));
}
[[clang::always_inline]] static constexpr tag_type recover_value(dirty_pointer _ptr) noexcept {
- return static_cast<tag_type>(__builtin_tag_pointer_mask_as_int((void *)_ptr, _mask));
+ return static_cast<tag_type>(__builtin_tag_pointer_mask_as_int((void*)_ptr, _mask));
}
};
};
-template <unsigned Alignment> struct custom_alignment_tag {
+template <unsigned Alignment>
+struct custom_alignment_tag {
static constexpr uintptr_t mask = (static_cast<uintptr_t>(1u) << static_cast<uintptr_t>(Alignment)) - 1ull;
- template <typename T, typename Tag> using schema = typename bitmask_tag<mask>::template schema<T, Tag>;
+ template <typename T, typename Tag>
+ using schema = typename bitmask_tag<mask>::template schema<T, Tag>;
};
struct alignment_low_bits_tag {
- template <typename T> static constexpr unsigned alignment = alignof(T);
- template <typename T, typename Tag> using schema = typename custom_alignment_tag<alignment<T>>::template schema<T, Tag>;
+ template <typename T>
+ static constexpr unsigned alignment = alignof(T);
+ template <typename T, typename Tag>
+ using schema = typename custom_alignment_tag<alignment<T>>::template schema<T, Tag>;
};
-template <unsigned Bits> struct shift_tag {
+template <unsigned Bits>
+struct shift_tag {
static constexpr unsigned _shift = Bits;
static constexpr uintptr_t _mask = (uintptr_t{1u} << _shift) - 1u;
- template <typename T, typename Tag> struct schema {
- using clean_pointer = T *;
- using dirty_pointer = void *;
- using tag_type = Tag;
+ template <typename T, typename Tag>
+ struct schema {
+ using clean_pointer = T*;
+ using dirty_pointer = void*;
+ using tag_type = Tag;
- [[clang::always_inline]] static constexpr dirty_pointer encode_pointer_with_tag(clean_pointer _ptr, tag_type _value) noexcept {
- return static_cast<dirty_pointer>(__builtin_tag_pointer_shift_or((void *)(_ptr), (uintptr_t)_value, _shift));
+ [[clang::always_inline]] static constexpr dirty_pointer
+ encode_pointer_with_tag(clean_pointer _ptr, tag_type _value) noexcept {
+ return static_cast<dirty_pointer>(__builtin_tag_pointer_shift_or((void*)(_ptr), (uintptr_t)_value, _shift));
}
[[clang::always_inline]] static constexpr clean_pointer recover_pointer(dirty_pointer _ptr) noexcept {
- return static_cast<clean_pointer>(__builtin_tag_pointer_unshift((void *)_ptr, _shift));
+ return static_cast<clean_pointer>(__builtin_tag_pointer_unshift((void*)_ptr, _shift));
}
[[clang::always_inline]] static constexpr tag_type recover_value(dirty_pointer _ptr) noexcept {
- return static_cast<tag_type>(__builtin_tag_pointer_mask_as_int((void *)_ptr, _mask));
+ return static_cast<tag_type>(__builtin_tag_pointer_mask_as_int((void*)_ptr, _mask));
}
};
};
struct low_byte_tag {
- template <typename T, typename Tag> using schema = typename shift_tag<8>::template schema<T, Tag>;
+ template <typename T, typename Tag>
+ using schema = typename shift_tag<8>::template schema<T, Tag>;
};
struct upper_byte_tag {
- template <typename T> static constexpr unsigned _shift = sizeof(T *) * 8ull - 8ull;
- template <typename T> static constexpr uintptr_t _mask = 0b1111'1111ull << _shift<T>;
-
- template <typename T, typename Tag> using schema = typename bitmask_tag<_mask<T>>::template schema<T, Tag>;
+ template <typename T>
+ static constexpr unsigned _shift = sizeof(T*) * 8ull - 8ull;
+ template <typename T>
+ static constexpr uintptr_t _mask = 0b1111'1111ull << _shift<T>;
+
+ template <typename T, typename Tag>
+ using schema = typename bitmask_tag<_mask<T>>::template schema<T, Tag>;
};
-struct upper_byte_shifted_tag: upper_byte_tag {
- template <typename T, typename Tag> struct schema {
- using _underlying_schema = typename upper_byte_tag::template schema<T, uintptr_t>;
+struct upper_byte_shifted_tag : upper_byte_tag {
+ template <typename T, typename Tag>
+ struct schema {
+ using _underlying_schema = typename upper_byte_tag::template schema<T, uintptr_t>;
static constexpr unsigned _shift = upper_byte_tag::template _shift<T>;
-
- using clean_pointer = T *;
- using dirty_pointer = void *;
- using tag_type = Tag;
-
- [[clang::always_inline]] static constexpr dirty_pointer encode_pointer_with_tag(clean_pointer _ptr, tag_type _value) noexcept {
+
+ using clean_pointer = T*;
+ using dirty_pointer = void*;
+ using tag_type = Tag;
+
+ [[clang::always_inline]] static constexpr dirty_pointer
+ encode_pointer_with_tag(clean_pointer _ptr, tag_type _value) noexcept {
return _underlying_schema::encode_pointer_with_tag(_ptr, static_cast<uintptr_t>(_value) << _shift);
}
[[clang::always_inline]] static constexpr clean_pointer recover_pointer(dirty_pointer _ptr) noexcept {
@@ -142,213 +162,218 @@ struct upper_byte_shifted_tag: upper_byte_tag {
};
};
-
-
// forward declaration
-template <typename _T, typename _Tag = uintptr_t, typename _Schema = alignment_low_bits_tag> class tagged_ptr;
-
+template <typename _T, typename _Tag = uintptr_t, typename _Schema = alignment_low_bits_tag>
+class tagged_ptr;
-template <typename _Schema, typename _T, typename _Tag = uintptr_t> constexpr auto tag_ptr(_T * _ptr, _Tag _tag = {}) noexcept {
+template <typename _Schema, typename _T, typename _Tag = uintptr_t>
+constexpr auto tag_ptr(_T* _ptr, _Tag _tag = {}) noexcept {
return tagged_ptr<_T, _Tag, _Schema>{_ptr, _tag};
}
-template <typename _T, typename _Tag, typename _Schema = alignment_low_bits_tag> constexpr auto tagged_pointer_cast(typename _Schema::template schema<_T, _Tag>::dirty_pointer _ptr) noexcept -> tagged_ptr<_T, _Tag, _Schema> {
+template <typename _T, typename _Tag, typename _Schema = alignment_low_bits_tag>
+constexpr auto tagged_pointer_cast(typename _Schema::template schema<_T, _Tag>::dirty_pointer _ptr) noexcept
+ -> tagged_ptr<_T, _Tag, _Schema> {
using result_type = tagged_ptr<_T, _Tag, _Schema>;
return result_type{typename result_type::already_tagged_tag{_ptr}};
}
-template <typename _Schema2, typename _T, typename _Tag, typename _Schema> constexpr auto scheme_pointer_cast(tagged_ptr<_T, _Tag, _Schema> in) noexcept {
+template <typename _Schema2, typename _T, typename _Tag, typename _Schema>
+constexpr auto scheme_pointer_cast(tagged_ptr<_T, _Tag, _Schema> in) noexcept {
return tagged_ptr<_T, _Tag, _Schema2>{in.pointer(), in.tag()};
}
-template <typename _Y, typename _T, typename _Tag, typename _Schema> constexpr auto const_pointer_cast(tagged_ptr<_T, _Tag, _Schema> in) noexcept {
+template <typename _Y, typename _T, typename _Tag, typename _Schema>
+constexpr auto const_pointer_cast(tagged_ptr<_T, _Tag, _Schema> in) noexcept {
// TODO we can just use native pointer here
return tagged_ptr<_Y, _Tag, _Schema>{const_cast<_Y*>(in.pointer()), in.tag()};
}
-template <typename _Y, typename _T, typename _Tag, typename _Schema> constexpr auto static_pointer_cast(tagged_ptr<_T, _Tag, _Schema> in) noexcept {
+template <typename _Y, typename _T, typename _Tag, typename _Schema>
+constexpr auto static_pointer_cast(tagged_ptr<_T, _Tag, _Schema> in) noexcept {
return tagged_ptr<_Y, _Tag, _Schema>{static_cast<_Y*>(in.pointer()), in.tag()};
}
-template <typename _Y, typename _T, typename _Tag, typename _Schema> constexpr auto dynamic_pointer_cast(tagged_ptr<_T, _Tag, _Schema> in) noexcept {
+template <typename _Y, typename _T, typename _Tag, typename _Schema>
+constexpr auto dynamic_pointer_cast(tagged_ptr<_T, _Tag, _Schema> in) noexcept {
return tagged_ptr<_Y, _Tag, _Schema>{dynamic_cast<_Y*>(in.pointer()), in.tag()};
}
-template <typename _Y, typename _T, typename _Tag, typename _Schema> auto reinterpret_pointer_cast(tagged_ptr<_T, _Tag, _Schema> in) noexcept {
+template <typename _Y, typename _T, typename _Tag, typename _Schema>
+auto reinterpret_pointer_cast(tagged_ptr<_T, _Tag, _Schema> in) noexcept {
return tagged_ptr<_Y, _Tag, _Schema>{reinterpret_cast<_Y*>(in.pointer()), in.tag()};
}
-
// wrapper class containing the pointer value and provides access
-template <typename _T, typename _Tag, typename _Schema> class tagged_ptr {
+template <typename _T, typename _Tag, typename _Schema>
+class tagged_ptr {
public:
- using schema = typename _Schema::template schema<_T, _Tag>;
+ using schema = typename _Schema::template schema<_T, _Tag>;
using dirty_pointer = typename schema::dirty_pointer;
using clean_pointer = typename schema::clean_pointer;
- using tag_type = typename schema::tag_type;
-
- using value_type = std::remove_cvref_t<decltype(*std::declval<clean_pointer>())>;
+ using tag_type = typename schema::tag_type;
+
+ using value_type = std::remove_cvref_t<decltype(*std::declval<clean_pointer>())>;
using difference_type = typename std::pointer_traits<clean_pointer>::difference_type;
-
-
- template <typename _Y> using rebind = tagged_ptr<_Y, _Tag, _Schema>;
-
+
+ template <typename _Y>
+ using rebind = tagged_ptr<_Y, _Tag, _Schema>;
+
private:
-
dirty_pointer _pointer{nullptr};
-
- friend constexpr auto tagged_pointer_cast<_T, _Tag, _Schema>(typename _Schema::template schema<_T, _Tag>::dirty_pointer ptr) noexcept -> tagged_ptr<_T, _Tag, _Schema>;
-
+
+ friend constexpr auto tagged_pointer_cast<_T, _Tag, _Schema>(
+ typename _Schema::template schema<_T, _Tag>::dirty_pointer ptr) noexcept -> tagged_ptr<_T, _Tag, _Schema>;
+
struct already_tagged_tag {
dirty_pointer _ptr;
};
-
+
// special hidden constructor to allow constructing unsafely
- [[clang::always_inline]] constexpr tagged_ptr(already_tagged_tag _in) noexcept: _pointer{_in._ptr} { }
-
- template <typename _Y, typename _T2, typename _Tag2, typename _Schema2> constexpr auto const_pointer_cast(tagged_ptr<_T2, _Tag2, _Schema2> in) noexcept -> rebind<_T>;
-
+ [[clang::always_inline]] constexpr tagged_ptr(already_tagged_tag _in) noexcept : _pointer{_in._ptr} {}
+
+ template <typename _Y, typename _T2, typename _Tag2, typename _Schema2>
+ constexpr auto const_pointer_cast(tagged_ptr<_T2, _Tag2, _Schema2> in) noexcept -> rebind<_T>;
+
public:
tagged_ptr() = default;
- consteval tagged_ptr(nullptr_t) noexcept: _pointer{nullptr} { }
- tagged_ptr(const tagged_ptr &) = default;
- tagged_ptr(tagged_ptr &&) = default;
- ~tagged_ptr() = default;
- tagged_ptr & operator=(const tagged_ptr &) = default;
- tagged_ptr & operator=(tagged_ptr &&) = default;
-
- [[clang::always_inline]] explicit constexpr tagged_ptr(clean_pointer _ptr, tag_type _tag = {}) noexcept: _pointer{schema::encode_pointer_with_tag(_ptr, _tag)} {
+ consteval tagged_ptr(nullptr_t) noexcept : _pointer{nullptr} {}
+ tagged_ptr(const tagged_ptr&) = default;
+ tagged_ptr(tagged_ptr&&) = default;
+ ~tagged_ptr() = default;
+ tagged_ptr& operator=(const tagged_ptr&) = default;
+ tagged_ptr& operator=(tagged_ptr&&) = default;
+
+ [[clang::always_inline]] explicit constexpr tagged_ptr(clean_pointer _ptr, tag_type _tag = {}) noexcept
+ : _pointer{schema::encode_pointer_with_tag(_ptr, _tag)} {
_LIBCPP_ASSERT_SEMANTIC_REQUIREMENT(pointer() == _ptr, "pointer must be recoverable after untagging");
- _LIBCPP_ASSERT_SEMANTIC_REQUIREMENT(tag() == _tag, "stored tag must be recoverable and within schema provided bit capacity");
- }
+ _LIBCPP_ASSERT_SEMANTIC_REQUIREMENT(
+ tag() == _tag, "stored tag must be recoverable and within schema provided bit capacity");
+ }
// accessors
- [[clang::always_inline]] constexpr decltype(auto) operator*() const noexcept {
- return *pointer();
- }
-
- [[clang::always_inline]] constexpr clean_pointer operator->() const noexcept {
- return pointer();
- }
-
- template <typename...Ts> [[clang::always_inline]] [[clang::always_inline]] constexpr decltype(auto) operator[](Ts... args) const noexcept requires std::is_array_v<value_type> && (sizeof...(Ts) == std::rank_v<value_type>) {
+ [[clang::always_inline]] constexpr decltype(auto) operator*() const noexcept { return *pointer(); }
+
+ [[clang::always_inline]] constexpr clean_pointer operator->() const noexcept { return pointer(); }
+
+ template <typename... Ts>
+ [[clang::always_inline]] [[clang::always_inline]] constexpr decltype(auto) operator[](Ts... args) const noexcept
+ requires std::is_array_v<value_type> && (sizeof...(Ts) == std::rank_v<value_type>)
+ {
return (*pointer())[args...];
}
-
- [[clang::always_inline]] constexpr decltype(auto) operator[](difference_type diff) const noexcept requires (!std::is_array_v<value_type>) {
+
+ [[clang::always_inline]] constexpr decltype(auto) operator[](difference_type diff) const noexcept
+ requires(!std::is_array_v<value_type>)
+ {
return *(pointer() + diff);
}
-
+
// swap
- [[clang::always_inline]] friend constexpr void swap(tagged_ptr & lhs, tagged_ptr & rhs) noexcept {
+ [[clang::always_inline]] friend constexpr void swap(tagged_ptr& lhs, tagged_ptr& rhs) noexcept {
std::swap(lhs._pointer, rhs._pointer);
}
-
+
// modifiers for tag
- [[clang::always_inline]] constexpr auto & set(tag_type new_tag) noexcept {
+ [[clang::always_inline]] constexpr auto& set(tag_type new_tag) noexcept {
// this is here so I can avoid checks
// TODO we should be able to check what bits available
_pointer = schema::encode_pointer_with_tag(pointer(), new_tag);
return *this;
}
-
- [[clang::always_inline]] constexpr auto & set_union(tag_type addition) noexcept {
- return set(tag() | addition);
- }
-
- [[clang::always_inline]] constexpr auto & set_difference(tag_type mask) noexcept {
+
+ [[clang::always_inline]] constexpr auto& set_union(tag_type addition) noexcept { return set(tag() | addition); }
+
+ [[clang::always_inline]] constexpr auto& set_difference(tag_type mask) noexcept {
return set(tag() & (~static_cast<uintptr_t>(mask)));
}
-
- [[clang::always_inline]] constexpr auto & set_intersection(tag_type mask) noexcept {
- return set(tag() & mask);
- }
-
- [[clang::always_inline]] constexpr auto & set_all() noexcept {
+
+ [[clang::always_inline]] constexpr auto& set_intersection(tag_type mask) noexcept { return set(tag() & mask); }
+
+ [[clang::always_inline]] constexpr auto& set_all() noexcept {
return set(static_cast<tag_type>(0xFFFFFFFF'FFFFFFFFull));
}
// modifiers for pointer
- [[clang::always_inline]] constexpr auto & operator++() noexcept {
- _pointer = tagged_ptr{pointer()+1u, tag()}._pointer;
+ [[clang::always_inline]] constexpr auto& operator++() noexcept {
+ _pointer = tagged_ptr{pointer() + 1u, tag()}._pointer;
return *this;
}
-
+
[[clang::always_inline]] constexpr auto operator++(int) noexcept {
auto copy = auto(*this);
this->operator++();
return copy;
}
-
- [[clang::always_inline]] constexpr auto & operator+=(difference_type diff) noexcept {
- _pointer = tagged_ptr{pointer()+diff, tag()}._pointer;
+
+ [[clang::always_inline]] constexpr auto& operator+=(difference_type diff) noexcept {
+ _pointer = tagged_ptr{pointer() + diff, tag()}._pointer;
return *this;
}
-
+
[[clang::always_inline]] friend constexpr auto operator+(tagged_ptr lhs, difference_type diff) noexcept {
lhs += diff;
return lhs;
}
-
+
[[clang::always_inline]] friend constexpr auto operator+(difference_type diff, tagged_ptr rhs) noexcept {
rhs += diff;
return rhs;
}
-
+
[[clang::always_inline]] friend constexpr auto operator-(tagged_ptr lhs, difference_type diff) noexcept {
lhs -= diff;
return lhs;
}
-
+
[[clang::always_inline]] friend constexpr auto operator-(difference_type diff, tagged_ptr rhs) noexcept {
rhs -= diff;
return rhs;
}
-
- [[clang::always_inline]] constexpr auto & operator-=(difference_type diff) noexcept {
- _pointer = tagged_ptr{pointer()-diff, tag()}._pointer;
+
+ [[clang::always_inline]] constexpr auto& operator-=(difference_type diff) noexcept {
+ _pointer = tagged_ptr{pointer() - diff, tag()}._pointer;
return *this;
}
-
- [[clang::always_inline]] constexpr auto & operator--() noexcept {
- _pointer = tagged_ptr{pointer()-1u, tag()}._pointer;
+
+ [[clang::always_inline]] constexpr auto& operator--() noexcept {
+ _pointer = tagged_ptr{pointer() - 1u, tag()}._pointer;
return *this;
}
-
+
[[clang::always_inline]] constexpr auto operator--(int) noexcept {
auto copy = auto(*this);
this->operator--();
return copy;
}
-
+
// observers
constexpr dirty_pointer unsafe_dirty_pointer() const noexcept {
// this function is not intentionally constexpr, as it is needed only to interact with
// existing runtime code
return _pointer;
- }
-
+ }
+
static constexpr bool support_aliasing_masking = pointer_tagging_schema_with_aliasing<schema>;
-
+
[[clang::always_inline]] constexpr clean_pointer aliasing_pointer() const noexcept {
if constexpr (support_aliasing_masking) {
if !consteval {
return schema::recover_aliasing_pointer(_pointer);
}
}
-
+
return schema::recover_pointer(_pointer);
}
-
+
[[clang::always_inline]] constexpr clean_pointer pointer() const noexcept {
return schema::recover_pointer(_pointer);
}
-
- [[clang::always_inline]] constexpr tag_type tag() const noexcept {
- return schema::recover_value(_pointer);
- }
-
- template <std::size_t I> [[nodiscard, clang::always_inline]] friend constexpr decltype(auto) get(tagged_ptr _pair) noexcept {
+
+ [[clang::always_inline]] constexpr tag_type tag() const noexcept { return schema::recover_value(_pointer); }
+
+ template <std::size_t I>
+ [[nodiscard, clang::always_inline]] friend constexpr decltype(auto) get(tagged_ptr _pair) noexcept {
static_assert(I < 3);
if constexpr (I == 0) {
return _pair.pointer();
@@ -356,25 +381,23 @@ public:
return _pair.tag();
}
}
-
- [[clang::always_inline]] constexpr explicit operator bool() const noexcept {
- return pointer() != nullptr;
- }
-
+
+ [[clang::always_inline]] constexpr explicit operator bool() const noexcept { return pointer() != nullptr; }
+
[[clang::always_inline]] friend constexpr ptrdiff_t operator-(tagged_ptr lhs, tagged_ptr rhs) noexcept {
return lhs.pointer() - rhs.pointer();
}
-
+
// comparison operators
[[clang::always_inline]] friend bool operator==(tagged_ptr, tagged_ptr) = default;
-
+
struct _compare_object {
clean_pointer pointer;
tag_type tag;
-
+
friend auto operator<=>(_compare_object, _compare_object) = default;
};
-
+
[[clang::always_inline]] friend constexpr auto operator<=>(tagged_ptr lhs, tagged_ptr rhs) noexcept {
return _compare_object{lhs.pointer(), lhs.tag()} <=> _compare_object{rhs.pointer(), rhs.tag()};
}
@@ -390,7 +413,9 @@ public:
};
// to_address specialization
-template <typename _T, typename _Tag, typename _Schema> static constexpr auto to_address(tagged_ptr<_T, _Tag, _Schema> p) noexcept -> tagged_ptr<_T, _Tag, _Schema>::element_type * {
+template <typename _T, typename _Tag, typename _Schema>
+static constexpr auto
+to_address(tagged_ptr<_T, _Tag, _Schema> p) noexcept -> tagged_ptr<_T, _Tag, _Schema>::element_type* {
return p.pointer();
}
@@ -398,46 +423,47 @@ template <typename _T, typename _Tag, typename _Schema> static constexpr auto to
template <typename _T, typename _Tag, typename _Schema>
struct _LIBCPP_TEMPLATE_VIS iterator_traits<tagged_ptr<_T, _Tag, _Schema>> {
using _tagged_ptr = tagged_ptr<_T, _Tag, _Schema>;
-
+
using iterator_category = std::random_access_iterator_tag;
- using iterator_concept = std::contiguous_iterator_tag;
-
- using value_type = _tagged_ptr::value_type;
- using reference = value_type &;
- using pointer = _tagged_ptr::clean_pointer;
+ using iterator_concept = std::contiguous_iterator_tag;
+
+ using value_type = _tagged_ptr::value_type;
+ using reference = value_type&;
+ using pointer = _tagged_ptr::clean_pointer;
using difference_type = _tagged_ptr::difference_type;
};
// pointer traits
template <typename _T, typename _Tag, typename _Schema>
struct _LIBCPP_TEMPLATE_VIS pointer_traits<tagged_ptr<_T, _Tag, _Schema>> {
- using _tagged_ptr = tagged_ptr<_T, _Tag, _Schema>;
- using pointer = _tagged_ptr::clean_pointer;
- using element_type = _tagged_ptr::value_type;
+ using _tagged_ptr = tagged_ptr<_T, _Tag, _Schema>;
+ using pointer = _tagged_ptr::clean_pointer;
+ using element_type = _tagged_ptr::value_type;
using difference_type = _tagged_ptr::difference_type;
-
+
// what to do with this?
- template <typename _Up> using rebind = typename _tagged_ptr::template rebind<_Up>;
+ template <typename _Up>
+ using rebind = typename _tagged_ptr::template rebind<_Up>;
public:
- _LIBCPP_HIDE_FROM_ABI constexpr static pointer pointer_to(pointer ptr) _NOEXCEPT {
- return _tagged_ptr{ptr};
- }
+ _LIBCPP_HIDE_FROM_ABI constexpr static pointer pointer_to(pointer ptr) _NOEXCEPT { return _tagged_ptr{ptr}; }
};
// we are defaulting always to low_bits schema
-template <typename _T> tagged_ptr(_T *) -> tagged_ptr<_T>;
-template <typename _T, typename _Tag> tagged_ptr(_T *, _Tag) -> tagged_ptr<_T, _Tag>;
+template <typename _T>
+tagged_ptr(_T*) -> tagged_ptr<_T>;
+template <typename _T, typename _Tag>
+tagged_ptr(_T*, _Tag) -> tagged_ptr<_T, _Tag>;
// support for tuple protocol so we can split tagged pointer to structured bindings:
// auto [ptr, tag] = tagged_ptr
template <typename _T, typename _Tag, typename _Schema>
-struct tuple_size<tagged_ptr<_T, _Tag, _Schema>>: std::integral_constant<std::size_t, 2> {};
+struct tuple_size<tagged_ptr<_T, _Tag, _Schema>> : std::integral_constant<std::size_t, 2> {};
template <std::size_t I, typename _T, typename _Tag, typename _Schema>
struct tuple_element<I, tagged_ptr<_T, _Tag, _Schema>> {
using _pair_type = tagged_ptr<_T, _Tag, _Schema>;
- using type = std::conditional_t<I == 0, typename _pair_type::clean_pointer, typename _pair_type::tag_type>;
+ using type = std::conditional_t<I == 0, typename _pair_type::clean_pointer, typename _pair_type::tag_type>;
};
_LIBCPP_END_NAMESPACE_STD
``````````
</details>
https://github.com/llvm/llvm-project/pull/111861
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