Commit 3f0b969772cf3056ed54349bfe6837d9de2995ea

Add the aligned versions of qMalloc/qRealloc/qFree
src/corelib/global/qglobal.h
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20652065Q_CORE_EXPORT void *qMalloc(size_t size);
20662066Q_CORE_EXPORT void qFree(void *ptr);
20672067Q_CORE_EXPORT void *qRealloc(void *ptr, size_t size);
2068Q_CORE_EXPORT void *qMallocAligned(size_t size, size_t alignment);
2069Q_CORE_EXPORT void *qReallocAligned(void *ptr, size_t size, size_t oldsize, size_t alignment);
2070Q_CORE_EXPORT void qFreeAligned(void *ptr);
20682071Q_CORE_EXPORT void *qMemCopy(void *dest, const void *src, size_t n);
20692072Q_CORE_EXPORT void *qMemSet(void *dest, int c, size_t n);
20702073
src/corelib/global/qmalloc.cpp
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4242#include "qplatformdefs.h"
4343
4444#include <stdlib.h>
45#include <malloc.h>
4546
4647/*
4748 Define the container allocation functions in a separate file, so that our
……
6464void *qRealloc(void *ptr, size_t size)
6565{
6666 return ::realloc(ptr, size);
67}
68
69#if ((defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L) || (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 600))
70# define HAVE_POSIX_MEMALIGN
71#endif
72
73void *qMallocAligned(size_t size, size_t alignment)
74{
75#if defined(Q_OS_WIN)
76 return _aligned_malloc(size, alignment);
77#elif defined(HAVE_POSIX_MEMALIGN)
78 if (alignment <= sizeof(void*))
79 return qMalloc(size);
80
81 // we have posix_memalign
82 void *ptr = 0;
83 if (posix_memalign(&ptr, alignment, size) == 0)
84 return ptr;
85 return 0;
86#else
87 return qReallocAligned(0, size, 0, alignment);
88#endif
89}
90
91void *qReallocAligned(void *oldptr, size_t newsize, size_t oldsize, size_t alignment)
92{
93#if defined(Q_OS_WIN)
94 Q_UNUSED(oldsize);
95 return _aligned_realloc(oldptr, newsize, alignment);
96#elif defined(HAVE_POSIX_MEMALIGN)
97 if (alignment <= sizeof(void*))
98 return qRealloc(oldptr, newsize);
99
100 void *newptr = qMallocAligned(newsize, alignment);
101 if (!newptr)
102 return 0;
103 qMemCopy(newptr, oldptr, qMin(oldsize, newsize));
104 qFree(oldptr);
105 return newptr;
106#else
107 // fake an aligned allocation
108 Q_UNUSED(oldsize);
109
110 void *actualptr = oldptr ? static_cast<void **>(oldptr)[-1] : 0;
111 if (alignment <= sizeof(void*)) {
112 // special, fast case
113 void **newptr = static_cast<void **>(qRealloc(actualptr, newsize + sizeof(void*)));
114 if (!newptr)
115 return 0;
116 if (newptr == actualptr) {
117 // realloc succeeded without reallocating
118 return oldptr;
119 }
120
121 *newptr = newptr;
122 return newptr + 1;
123 }
124
125 union { void *ptr; void **pptr; quintptr n; } real, faked;
126
127 // qMalloc returns pointers aligned at least at sizeof(size_t) boundaries
128 // but usually more (8- or 16-byte boundaries).
129 // So we overallocate by alignment-sizeof(size_t) bytes, so we're guaranteed to find a
130 // somewhere within the first alignment-sizeof(size_t) that is properly aligned.
131
132 // However, we need to store the actual pointer, so we need to allocate actually size +
133 // alignment anyway.
134
135 real.ptr = qRealloc(actualptr, newsize + alignment);
136 if (!real.ptr)
137 return 0;
138
139 faked.n = real.n + alignment;
140 faked.n &= ~(alignment - 1);
141
142 // now save the value of the real pointer at faked-sizeof(void*)
143 // by construction, alignment > sizeof(void*) and is a power of 2, so
144 // faked-sizeof(void*) is properly aligned for a pointer
145 faked.pptr[-1] = real.ptr;
146
147 // and save the actual size just before the pointer
148 //reinterpret_cast<size_t *>(faked.pptr - 1)[-1] = size;
149
150 return faked.ptr;
151#endif
152}
153
154void qFreeAligned(void *ptr)
155{
156#if defined(Q_OS_WIN)
157 _aligned_free(ptr);
158#elif defined(HAVE_POSIX_MEMALIGN)
159 ::free(ptr);
160#else
161 if (!ptr)
162 return;
163 void **ptr2 = static_cast<void **>(ptr);
164 free(ptr2[-1]);
165#endif
67166}
68167
69168QT_END_NAMESPACE