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Reduce binary size of the Microsoft demangler #89454

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8f3933c
Reduce binary size of the microsoft demangler
apache-hb Apr 15, 2024
f970420
Update MicrosoftDemangle.h
apache-hb Apr 19, 2024
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56 changes: 23 additions & 33 deletions llvm/include/llvm/Demangle/MicrosoftDemangle.h
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,24 @@ class ArenaAllocator {
NewHead->Used = 0;
}

uint8_t *allocAlignedBuffer(size_t Size, size_t Align) {
assert(Head && Head->Buf);

size_t P = (size_t)Head->Buf + Head->Used;
uintptr_t AlignedP =
(((size_t)P + Align - 1) & ~(size_t)(Align - 1));
uint8_t *PP = (uint8_t *)AlignedP;
size_t Adjustment = AlignedP - P;

Head->Used += Size + Adjustment;
if (Head->Used <= Head->Capacity)
return PP;

addNode(std::max(AllocUnit, Size));
Head->Used = Size;
return Head->Buf;
}

public:
ArenaAllocator() { addNode(AllocUnit); }

Expand Down Expand Up @@ -69,42 +87,14 @@ class ArenaAllocator {
}

template <typename T, typename... Args> T *allocArray(size_t Count) {
size_t Size = Count * sizeof(T);
assert(Head && Head->Buf);

size_t P = (size_t)Head->Buf + Head->Used;
uintptr_t AlignedP =
(((size_t)P + alignof(T) - 1) & ~(size_t)(alignof(T) - 1));
uint8_t *PP = (uint8_t *)AlignedP;
size_t Adjustment = AlignedP - P;

Head->Used += Size + Adjustment;
if (Head->Used <= Head->Capacity)
return new (PP) T[Count]();

addNode(std::max(AllocUnit, Size));
Head->Used = Size;
return new (Head->Buf) T[Count]();
uint8_t *Data = allocAlignedBuffer(Count * sizeof(T), alignof(T));
return new (Data) T[Count]();
}

template <typename T, typename... Args> T *alloc(Args &&... ConstructorArgs) {
constexpr size_t Size = sizeof(T);
assert(Head && Head->Buf);

size_t P = (size_t)Head->Buf + Head->Used;
uintptr_t AlignedP =
(((size_t)P + alignof(T) - 1) & ~(size_t)(alignof(T) - 1));
uint8_t *PP = (uint8_t *)AlignedP;
size_t Adjustment = AlignedP - P;

Head->Used += Size + Adjustment;
if (Head->Used <= Head->Capacity)
return new (PP) T(std::forward<Args>(ConstructorArgs)...);

static_assert(Size < AllocUnit);
addNode(AllocUnit);
Head->Used = Size;
return new (Head->Buf) T(std::forward<Args>(ConstructorArgs)...);
static_assert(sizeof(T) < AllocUnit);
uint8_t *Data = allocAlignedBuffer(sizeof(T), alignof(T));
return new (Data) T(std::forward<Args>(ConstructorArgs)...);
}

private:
Expand Down