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Fix memory alignment on 32-bit Windows. #1885

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Fix memory alignment on 32-bit Windows. #1885

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13 changes: 11 additions & 2 deletions include/godot_cpp/core/memory.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -64,7 +64,16 @@ class Memory {
Memory();

public:
// Alignment: ↓ max_align_t ↓ uint64_t ↓ max_align_t
#if defined(__MINGW32__) && !defined(__MINGW64__)
// Note: Using hardcoded value, since the value can end up different in different compile units on 32-bit windows
// due to a compiler bug (see GH-113145)
static constexpr size_t MAX_ALIGN = 16;
static_assert(MAX_ALIGN % alignof(max_align_t) == 0);
#else
static constexpr size_t MAX_ALIGN = alignof(max_align_t);
#endif

// Alignment: ↓ max_align_t ↓ uint64_t ↓ MAX_ALIGN
// ┌─────────────────┬──┬────────────────┬──┬───────────...
// │ uint64_t │░░│ uint64_t │░░│ T[]
// │ alloc size │░░│ element count │░░│ data
Expand All @@ -74,7 +83,7 @@ class Memory {

static constexpr size_t SIZE_OFFSET = 0;
static constexpr size_t ELEMENT_OFFSET = ((SIZE_OFFSET + sizeof(uint64_t)) % alignof(uint64_t) == 0) ? (SIZE_OFFSET + sizeof(uint64_t)) : ((SIZE_OFFSET + sizeof(uint64_t)) + alignof(uint64_t) - ((SIZE_OFFSET + sizeof(uint64_t)) % alignof(uint64_t)));
static constexpr size_t DATA_OFFSET = ((ELEMENT_OFFSET + sizeof(uint64_t)) % alignof(max_align_t) == 0) ? (ELEMENT_OFFSET + sizeof(uint64_t)) : ((ELEMENT_OFFSET + sizeof(uint64_t)) + alignof(max_align_t) - ((ELEMENT_OFFSET + sizeof(uint64_t)) % alignof(max_align_t)));
static constexpr size_t DATA_OFFSET = ((ELEMENT_OFFSET + sizeof(uint64_t)) % MAX_ALIGN == 0) ? (ELEMENT_OFFSET + sizeof(uint64_t)) : ((ELEMENT_OFFSET + sizeof(uint64_t)) + MAX_ALIGN - ((ELEMENT_OFFSET + sizeof(uint64_t)) % MAX_ALIGN));

static void *alloc_static(size_t p_bytes, bool p_pad_align = false);
static void *realloc_static(void *p_memory, size_t p_bytes, bool p_pad_align = false);
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4 changes: 2 additions & 2 deletions include/godot_cpp/templates/cowdata.hpp
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Expand Up @@ -97,7 +97,7 @@ class CowData {
return ++x;
}

// Alignment: ↓ max_align_t ↓ USize ↓ max_align_t
// Alignment: ↓ max_align_t ↓ USize ↓ MAX_ALIGN
// ┌────────────────────┬──┬─────────────┬──┬───────────...
// │ SafeNumeric<USize> │░░│ USize │░░│ T[]
// │ ref. count │░░│ data size │░░│ data
Expand All @@ -106,7 +106,7 @@ class CowData {

static constexpr size_t REF_COUNT_OFFSET = 0;
static constexpr size_t SIZE_OFFSET = ((REF_COUNT_OFFSET + sizeof(SafeNumeric<USize>)) % alignof(USize) == 0) ? (REF_COUNT_OFFSET + sizeof(SafeNumeric<USize>)) : ((REF_COUNT_OFFSET + sizeof(SafeNumeric<USize>)) + alignof(USize) - ((REF_COUNT_OFFSET + sizeof(SafeNumeric<USize>)) % alignof(USize)));
static constexpr size_t DATA_OFFSET = ((SIZE_OFFSET + sizeof(USize)) % alignof(max_align_t) == 0) ? (SIZE_OFFSET + sizeof(USize)) : ((SIZE_OFFSET + sizeof(USize)) + alignof(max_align_t) - ((SIZE_OFFSET + sizeof(USize)) % alignof(max_align_t)));
static constexpr size_t DATA_OFFSET = ((SIZE_OFFSET + sizeof(USize)) % Memory::MAX_ALIGN == 0) ? (SIZE_OFFSET + sizeof(USize)) : ((SIZE_OFFSET + sizeof(USize)) + Memory::MAX_ALIGN - ((SIZE_OFFSET + sizeof(USize)) % Memory::MAX_ALIGN));

mutable T *_ptr = nullptr;

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