From 80d6f5a7d0e1e60b928573d783192186613a42a8 Mon Sep 17 00:00:00 2001
From: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Date: Tue, 7 Oct 2014 20:16:32 -0700
Subject: [PATCH] Rework compact_pointer implementation
Split the implementation into a generic one with adjustable range and a
special implementation for parent (may need to use 2 bytes on that one
later).
Optimize compact_string and compact_pointer to use minimal amount of math
and move slow hash paths into no-inline functions so that compiler can
inline the fast-paths.
Merge compact_pointer_generic and compact_pointer_forward and optimize.
---
src/pugixml.cpp | 186 +++++++++++++++++++++++++++---------------------
1 file changed, 103 insertions(+), 83 deletions(-)
diff --git a/src/pugixml.cpp b/src/pugixml.cpp
index 9d75b20e..bdb84257 100644
--- a/src/pugixml.cpp
+++ b/src/pugixml.cpp
@@ -639,6 +639,8 @@ PUGI__NS_BEGIN
}
};
+ static const unsigned int compact_alignment_log2 = 2;
+
typedef uint32_t compact_alignment;
class compact_header
@@ -681,14 +683,24 @@ PUGI__NS_BEGIN
unsigned char flags;
};
- xml_memory_page* compact_get_page(const void* object, int header_offset)
+ PUGI__FN xml_memory_page* compact_get_page(const void* object, int header_offset)
{
const compact_header* header = reinterpret_cast<const compact_header*>(static_cast<const char*>(object) - header_offset);
return header->get_page();
}
- template <typename T, int header_offset, int direction, int tag> class compact_pointer
+ template <int header_offset, typename T> PUGI__FN_NO_INLINE T* compact_get_value(const void* object)
+ {
+ return static_cast<T*>(*compact_get_page(object, header_offset)->allocator->_hash->find(object));
+ }
+
+ template <int header_offset, int tag, typename T> PUGI__FN_NO_INLINE void compact_set_value(const void* object, T* value)
+ {
+ *compact_get_page(object, header_offset)->allocator->_hash->insert(object, tag) = value;
+ }
+
+ template <typename T, int header_offset, int tag, int start = -126> class compact_pointer
{
public:
compact_pointer(): _data(0)
@@ -700,6 +712,63 @@ PUGI__NS_BEGIN
*this = rhs + 0;
}
+ void operator=(T* value)
+ {
+ if (value)
+ {
+ ptrdiff_t offset = ((reinterpret_cast<char*>(value) - reinterpret_cast<char*>(this) + int(sizeof(compact_alignment) - 1)) >> compact_alignment_log2) - start;
+
+ if (static_cast<uintptr_t>(offset) <= 253)
+ _data = static_cast<unsigned char>(offset + 1);
+ else
+ {
+ compact_set_value<header_offset, tag>(this, value);
+
+ _data = 255;
+ }
+ }
+ else
+ _data = 0;
+ }
+
+ operator T* const() const
+ {
+ if (_data)
+ {
+ if (_data < 255)
+ {
+ uintptr_t base = reinterpret_cast<uintptr_t>(this) & ~(sizeof(compact_alignment) - 1);
+
+ return reinterpret_cast<T*>(base + ((_data - (1 - start)) << compact_alignment_log2));
+ }
+ else
+ return compact_get_value<header_offset, T>(this);
+ }
+ else
+ return 0;
+ }
+
+ T* operator->() const
+ {
+ return operator T* const();
+ }
+
+ private:
+ unsigned char _data;
+ };
+
+ template <typename T, int header_offset, int tag> class compact_pointer_parent
+ {
+ public:
+ compact_pointer_parent(): _data(0)
+ {
+ }
+
+ void operator=(const compact_pointer_parent& rhs)
+ {
+ *this = rhs + 0;
+ }
+
void operator=(T* value_)
{
if (value_)
@@ -707,49 +776,24 @@ PUGI__NS_BEGIN
compact_alignment* base = get_base();
compact_alignment* value = reinterpret_cast<compact_alignment*>(value_);
- if (direction > 0)
+ if (value <= base && value >= base - 252)
+ _data = static_cast<unsigned char>((base - value) + 1);
+ else
{
- if (value >= base && value <= base + 253)
- _data = static_cast<unsigned char>((value - base) + 1);
- else
- {
- *compact_get_page(this, header_offset)->allocator->_hash->insert(this, tag) = value;
+ xml_memory_page* page = compact_get_page(this, header_offset);
- _data = 255;
+ if (page->compact_parent == 0)
+ {
+ page->compact_parent = value;
+ _data = 254;
}
- }
- else if (direction < 0)
- {
- if (value <= base && value >= base - 252)
- _data = static_cast<unsigned char>((base - value) + 1);
- else
+ else if (page->compact_parent == value)
{
- xml_memory_page* page = compact_get_page(this, header_offset);
-
- if (page->compact_parent == 0)
- {
- page->compact_parent = value;
- _data = 254;
- }
- else if (page->compact_parent == value)
- {
- _data = 254;
- }
- else
- {
- *page->allocator->_hash->insert(this, tag) = value;
- _data = 255;
- }
+ _data = 254;
}
- }
- else
- {
- if (value >= base - 126 && value <= base + 127)
- _data = static_cast<unsigned char>((value - base) + 127);
else
{
- *compact_get_page(this, header_offset)->allocator->_hash->insert(this, tag) = value;
-
+ compact_set_value<header_offset, tag>(this, value);
_data = 255;
}
}
@@ -763,19 +807,14 @@ PUGI__NS_BEGIN
if (_data)
{
if (_data == 255)
- return static_cast<T*>(*compact_get_page(this, header_offset)->allocator->_hash->find(this));
- else if (direction < 0 && _data == 254)
+ return compact_get_value<header_offset, T>(this);
+ else if (_data == 254)
return static_cast<T*>(compact_get_page(this, header_offset)->compact_parent);
else
{
compact_alignment* base = get_base();
- if (direction > 0)
- return reinterpret_cast<T*>(base + (_data - 1));
- else if (direction < 0)
- return reinterpret_cast<T*>(base - (_data - 1));
- else
- return reinterpret_cast<T*>(base + (_data - 127));
+ return reinterpret_cast<T*>(base - (_data - 1));
}
}
else
@@ -792,10 +831,7 @@ PUGI__NS_BEGIN
compact_alignment* get_base() const
{
- if (direction > 0)
- return reinterpret_cast<compact_alignment*>((reinterpret_cast<uintptr_t>(this) + sizeof(compact_alignment)) & ~(sizeof(compact_alignment) - 1));
- else
- return reinterpret_cast<compact_alignment*>(reinterpret_cast<uintptr_t>(this) & ~(sizeof(compact_alignment) - 1));
+ return reinterpret_cast<compact_alignment*>(reinterpret_cast<uintptr_t>(this) & ~(sizeof(compact_alignment) - 1));
}
};
@@ -818,32 +854,20 @@ PUGI__NS_BEGIN
xml_memory_page* page = compact_get_page(this, header_offset);
if (page->compact_string_base == 0)
- {
page->compact_string_base = value;
- _data0 = 1;
- _data1 = 0;
- _data2 = 0;
- }
- else
- {
- ptrdiff_t offset = value - page->compact_string_base;
+ ptrdiff_t offset = value - page->compact_string_base;
- if (offset >= 0 && offset <= 1677213)
- {
- _data0 = static_cast<unsigned char>(offset + 1);
- _data1 = static_cast<unsigned char>((offset + 1) >> 8);
- _data2 = static_cast<unsigned char>((offset + 1) >> 16);
- }
- else
- {
- *page->allocator->_hash->insert(this, tag) = value;
+ if (static_cast<uintptr_t>(offset) >= 16777213)
+ {
+ compact_set_value<header_offset, tag>(this, value);
- _data0 = 255;
- _data1 = 255;
- _data2 = 255;
- }
+ offset = 16777214;
}
+
+ _data0 = static_cast<unsigned char>(offset + 1);
+ _data1 = static_cast<unsigned char>((offset + 1) >> 8);
+ _data2 = static_cast<unsigned char>((offset + 1) >> 16);
}
else
{
@@ -862,13 +886,9 @@ PUGI__NS_BEGIN
xml_memory_page* page = compact_get_page(this, header_offset);
if (data < 16777215)
- {
return page->compact_string_base + (data - 1);
- }
else
- {
- return static_cast<char_t*>(*page->allocator->_hash->find(this));
- }
+ return compact_get_value<header_offset, char_t>(this);
}
else
return 0;
@@ -904,8 +924,8 @@ namespace pugi
impl::compact_string<4, /*tag*/11> name; ///< Pointer to attribute name.
impl::compact_string<7, /*tag*/12> value; ///< Pointer to attribute value.
- impl::compact_pointer<xml_attribute_struct, 10, 0, /*tag*/13> prev_attribute_c; ///< Previous attribute (cyclic list)
- impl::compact_pointer<xml_attribute_struct, 11, +1, /*tag*/14> next_attribute; ///< Next attribute
+ impl::compact_pointer<xml_attribute_struct, 10, /*tag*/13> prev_attribute_c; ///< Previous attribute (cyclic list)
+ impl::compact_pointer<xml_attribute_struct, 11, /*tag*/14, 0> next_attribute; ///< Next attribute
};
/// An XML document tree node.
@@ -926,14 +946,14 @@ namespace pugi
impl::compact_string<4, /*tag*/21> contents; ///< Pointer to element name.
- impl::compact_pointer<xml_node_struct, 7, -1, /*tag*/22> parent; ///< Pointer to parent
+ impl::compact_pointer_parent<xml_node_struct, 7, /*tag*/22> parent; ///< Pointer to parent
- impl::compact_pointer<xml_node_struct, 8, +1, /*tag*/23> first_child; ///< First child
+ impl::compact_pointer<xml_node_struct, 8, /*tag*/23, 0> first_child; ///< First child
- impl::compact_pointer<xml_node_struct, 9, 0, /*tag*/24> prev_sibling_c; ///< Left brother (cyclic list)
- impl::compact_pointer<xml_node_struct, 10, +1, /*tag*/25> next_sibling; ///< Right brother
+ impl::compact_pointer<xml_node_struct, 9, /*tag*/24> prev_sibling_c; ///< Left brother (cyclic list)
+ impl::compact_pointer<xml_node_struct, 10, /*tag*/25, 0> next_sibling; ///< Right brother
- impl::compact_pointer<xml_attribute_struct, 11, +1, /*tag*/26> first_attribute; ///< First attribute
+ impl::compact_pointer<xml_attribute_struct, 11, /*tag*/26, 0> first_attribute; ///< First attribute
};
}
#else
--
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