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authorArseny Kapoulkine <arseny.kapoulkine@gmail.com>2015-05-02 15:57:46 -0700
committerArseny Kapoulkine <arseny.kapoulkine@gmail.com>2015-05-02 15:57:46 -0700
commit20e2041f14f8ebb842df4ebdac9ba3dc0955e670 (patch)
tree3cb000b8ba7be0a02fe0c708285653cda580d911 /src/pugixml.cpp
parentf8915c8eab0241d2a9621e28893518c010aa0cb5 (diff)
Reorder conditions in compact_string implementation
Now compact_string matches compact_pointer_parent. Turns out PUGI__UNLIKELY is good at reordering conditions but usually does not really affect performance. Since MSVC should treat "if" branches as taken and does not support branch probabilities, don't use them if we don't need to.
Diffstat (limited to 'src/pugixml.cpp')
-rw-r--r--src/pugixml.cpp58
1 files changed, 28 insertions, 30 deletions
diff --git a/src/pugixml.cpp b/src/pugixml.cpp
index 1a7acb3..568eb17 100644
--- a/src/pugixml.cpp
+++ b/src/pugixml.cpp
@@ -849,7 +849,7 @@ PUGI__NS_BEGIN
{
xml_memory_page* page = compact_get_page(this, header_offset);
- if (page->compact_shared_parent == 0)
+ if (PUGI__UNLIKELY(page->compact_shared_parent == 0))
page->compact_shared_parent = value;
if (page->compact_shared_parent == value)
@@ -872,17 +872,15 @@ PUGI__NS_BEGIN
operator T*() const
{
- int data = _data;
-
- if (data)
+ if (_data)
{
- if (data < 65534)
+ if (_data < 65534)
{
uintptr_t base = reinterpret_cast<uintptr_t>(this) & ~(compact_alignment - 1);
- return reinterpret_cast<T*>(base + ((data - 1 - 65533) << compact_alignment_log2));
+ return reinterpret_cast<T*>(base + ((_data - 1 - 65533) << compact_alignment_log2));
}
- else if (data == 65534)
+ else if (_data == 65534)
return static_cast<T*>(compact_get_page(this, header_offset)->compact_shared_parent);
else
return compact_get_value<header_offset, T>(this);
@@ -923,36 +921,36 @@ PUGI__NS_BEGIN
ptrdiff_t offset = value - page->compact_string_base;
- if (PUGI__UNLIKELY(static_cast<uintptr_t>(offset) >= (65535 << 7)))
- {
- compact_set_value<header_offset>(this, value);
-
- _data = 255;
- }
- else
+ if (static_cast<uintptr_t>(offset) < (65535 << 7))
{
uint16_t* base = reinterpret_cast<uint16_t*>(reinterpret_cast<char*>(this) - base_offset);
- if (PUGI__UNLIKELY(*base))
+ if (*base == 0)
+ {
+ *base = static_cast<uint16_t>((offset >> 7) + 1);
+ _data = static_cast<unsigned char>((offset & 127) + 1);
+ }
+ else
{
ptrdiff_t remainder = offset - ((*base - 1) << 7);
- if (PUGI__UNLIKELY(static_cast<uintptr_t>(remainder) >= 254))
+ if (static_cast<uintptr_t>(remainder) < 254)
{
- compact_set_value<header_offset>(this, value);
-
- _data = 255;
+ _data = static_cast<unsigned char>(remainder + 1);
}
else
{
- _data = static_cast<unsigned char>(remainder + 1);
+ compact_set_value<header_offset>(this, value);
+
+ _data = 255;
}
}
- else
- {
- *base = static_cast<uint16_t>((offset >> 7) + 1);
- _data = static_cast<unsigned char>((offset & 127) + 1);
- }
+ }
+ else
+ {
+ compact_set_value<header_offset>(this, value);
+
+ _data = 255;
}
}
else
@@ -965,11 +963,7 @@ PUGI__NS_BEGIN
{
if (_data)
{
- if (PUGI__UNLIKELY(_data == 255))
- {
- return compact_get_value<header_offset, char_t>(this);
- }
- else
+ if (_data < 255)
{
xml_memory_page* page = compact_get_page(this, header_offset);
@@ -980,6 +974,10 @@ PUGI__NS_BEGIN
return page->compact_string_base + offset;
}
+ else
+ {
+ return compact_get_value<header_offset, char_t>(this);
+ }
}
else
return 0;