whytofly
/
qt6-bb10
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Optimize code in QTaggedPointer 

Don't execute instructions that will never do anything.

Directly add the tag to the pointer in the constructor to avoid
additional masking operations, and avoid a masking op that is in
practice a no-op in setTag().

Do the same optimization in QTagPreservingPointerToPointer.

Change-Id: Ia364f89cbe6ccc876ec9bda0c239fc4f57c10501
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit 2721728c9056b442c0281f20792f19eb6a491aa0)
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
bb10
Lars Knoll 2020-11-25 11:36:24 +01:00 committed by Fabian Kosmale
parent de4a73ebd6
commit 1181286d43
2 changed files with 6 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/corelib/kernel/qpropertyprivate.h
View File

@ -283,7 +283,7 @@ public:
void setPointer(T *ptr)
{
*d = (reinterpret_cast<quintptr>(ptr) & QTaggedPointer<T, Tag>::pointerMask()) | (*d & QTaggedPointer<T, Tag>::tagMask());
*d = reinterpret_cast<quintptr>(ptr) | (*d & QTaggedPointer<T, Tag>::tagMask());
}
T *get() const

11
src/corelib/tools/qtaggedpointer.h
View File

@ -83,14 +83,13 @@ public:
constexpr QTaggedPointer(std::nullptr_t) noexcept : QTaggedPointer() {}
explicit QTaggedPointer(T *pointer, Tag tag = Tag()) noexcept
: d(quintptr(pointer))
: d(quintptr(pointer) | quintptr(tag))
{
static_assert(sizeof(Type*) == sizeof(QTaggedPointer));
Q_ASSERT_X((quintptr(pointer) & tagMask()) == 0,
"QTaggedPointer<T, Tag>", "Pointer is not aligned");
setTag(tag);
Q_ASSERT_X((quintptr(pointer) & tagMask()) == 0, "QTaggedPointer<T, Tag>", "Pointer is not aligned");
Q_ASSERT_X((static_cast<typename QtPrivate::TagInfo<T>::TagType>(tag) & pointerMask()) == 0,
"QTaggedPointer<T, Tag>::setTag", "Tag is larger than allowed by number of available tag bits");
}
Type &operator*() const noexcept
@ -125,7 +124,7 @@ public:
Q_ASSERT_X((static_cast<typename QtPrivate::TagInfo<T>::TagType>(tag) & pointerMask()) == 0,
"QTaggedPointer<T, Tag>::setTag", "Tag is larger than allowed by number of available tag bits");
d = (d & pointerMask()) | (static_cast<typename QtPrivate::TagInfo<T>::TagType>(tag) & tagMask());
d = (d & pointerMask()) | static_cast<quintptr>(tag);
}
Tag tag() const noexcept