External/pugixml
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Optimize compact_pointer_parent

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We now no longer need the compact_alignment type so replace it with a
constant.
This commit is contained in:
Arseny Kapoulkine 2014-10-08 08:42:37 -07:00
parent 80d6f5a7d0
commit 58282fd36f
1 changed files with 20 additions and 30 deletions
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50
src/pugixml.cpp
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@ -640,15 +640,14 @@ PUGI__NS_BEGIN
}; };
static const unsigned int compact_alignment_log2 = 2; static const unsigned int compact_alignment_log2 = 2;
static const unsigned int compact_alignment = 1 << compact_alignment_log2;
typedef uint32_t compact_alignment;
class compact_header class compact_header
{ {
public: public:
compact_header(xml_memory_page* page, unsigned int flags) compact_header(xml_memory_page* page, unsigned int flags)
{ {
ptrdiff_t page_offset = reinterpret_cast<compact_alignment*>(this) - reinterpret_cast<compact_alignment*>(page); ptrdiff_t page_offset = (reinterpret_cast<char*>(this) - reinterpret_cast<char*>(page)) >> compact_alignment_log2;
assert(page_offset >= 0 && page_offset < (1 << 16)); assert(page_offset >= 0 && page_offset < (1 << 16));
this->page0 = static_cast<unsigned char>(page_offset); this->page0 = static_cast<unsigned char>(page_offset);
@ -675,7 +674,7 @@ PUGI__NS_BEGIN
{ {
unsigned int page_offset = page0 + (page1 << 8); unsigned int page_offset = page0 + (page1 << 8);
return const_cast<xml_memory_page*>(reinterpret_cast<const xml_memory_page*>(reinterpret_cast<const compact_alignment*>(this) - page_offset)); return const_cast<xml_memory_page*>(reinterpret_cast<const xml_memory_page*>(reinterpret_cast<const char*>(this) - (page_offset << compact_alignment_log2)));
} }
private: private:
@ -716,7 +715,7 @@ PUGI__NS_BEGIN
{ {
if (value) if (value)
{ {
ptrdiff_t offset = ((reinterpret_cast<char*>(value) - reinterpret_cast<char*>(this) + int(sizeof(compact_alignment) - 1)) >> compact_alignment_log2) - start; ptrdiff_t offset = ((reinterpret_cast<char*>(value) - reinterpret_cast<char*>(this) + int(compact_alignment - 1)) >> compact_alignment_log2) - start;
if (static_cast<uintptr_t>(offset) <= 253) if (static_cast<uintptr_t>(offset) <= 253)
_data = static_cast<unsigned char>(offset + 1); _data = static_cast<unsigned char>(offset + 1);
@ -737,7 +736,7 @@ PUGI__NS_BEGIN
{ {
if (_data < 255) if (_data < 255)
{ {
uintptr_t base = reinterpret_cast<uintptr_t>(this) & ~(sizeof(compact_alignment) - 1); uintptr_t base = reinterpret_cast<uintptr_t>(this) & ~(compact_alignment - 1);
return reinterpret_cast<T*>(base + ((_data - (1 - start)) << compact_alignment_log2)); return reinterpret_cast<T*>(base + ((_data - (1 - start)) << compact_alignment_log2));
} }
@ -769,31 +768,27 @@ PUGI__NS_BEGIN
*this = rhs + 0; *this = rhs + 0;
} }
void operator=(T* value_) void operator=(T* value)
{ {
if (value_) if (value)
{ {
compact_alignment* base = get_base(); ptrdiff_t offset = ((reinterpret_cast<char*>(value) - reinterpret_cast<char*>(this) + int(compact_alignment - 1)) >> compact_alignment_log2) + 253;
compact_alignment* value = reinterpret_cast<compact_alignment*>(value_);
if (value <= base && value >= base - 252) if (static_cast<uintptr_t>(offset) <= 253)
_data = static_cast<unsigned char>((base - value) + 1); _data = static_cast<unsigned char>(offset + 1);
else else
{ {
xml_memory_page* page = compact_get_page(this, header_offset); xml_memory_page* page = compact_get_page(this, header_offset);
if (page->compact_parent == 0) if (page->compact_parent == 0)
{
page->compact_parent = value; page->compact_parent = value;
if (page->compact_parent == value)
_data = 254; _data = 254;
}
else if (page->compact_parent == value)
{
_data = 254;
}
else else
{ {
compact_set_value<header_offset, tag>(this, value); compact_set_value<header_offset, tag>(this, value);
_data = 255; _data = 255;
} }
} }
@ -806,16 +801,16 @@ PUGI__NS_BEGIN
{ {
if (_data) if (_data)
{ {
if (_data == 255) if (_data < 254)
return compact_get_value<header_offset, T>(this); {
uintptr_t base = reinterpret_cast<uintptr_t>(this) & ~(compact_alignment - 1);
return reinterpret_cast<T*>(base + ((_data - (1 + 253)) << compact_alignment_log2));
}
else if (_data == 254) else if (_data == 254)
return static_cast<T*>(compact_get_page(this, header_offset)->compact_parent); return static_cast<T*>(compact_get_page(this, header_offset)->compact_parent);
else else
{ return compact_get_value<header_offset, T>(this);
compact_alignment* base = get_base();
return reinterpret_cast<T*>(base - (_data - 1));
}
} }
else else
return 0; return 0;
@ -828,11 +823,6 @@ PUGI__NS_BEGIN
private: private:
unsigned char _data; unsigned char _data;
compact_alignment* get_base() const
{
return reinterpret_cast<compact_alignment*>(reinterpret_cast<uintptr_t>(this) & ~(sizeof(compact_alignment) - 1));
}
}; };
template <int header_offset, int tag> class compact_string template <int header_offset, int tag> class compact_string