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on 64-bit systems, glibc's malloc returns 16-byte aligned ptrs, and we now take advantage of that.

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This commit is contained in:
Benoit Jacob 2010-02-28 10:10:53 -05:00
parent a480e7e60f
commit 9334ed4444
1 changed files with 27 additions and 9 deletions
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22
Eigen/src/Core/util/Memory.h
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@ -33,6 +33,20 @@
#ifndef EIGEN_MEMORY_H
#define EIGEN_MEMORY_H
// On 64-bit systems, glibc's malloc returns 16-byte-aligned pointers, see:
// http://www.gnu.org/s/libc/manual/html_node/Aligned-Memory-Blocks.html
// This is true at least since glibc 2.8.
// This leaves the question how to detect 64-bit. According to this document,
// http://gcc.fyxm.net/summit/2003/Porting%20to%2064%20bit.pdf
// page 114, "[The] LP64 model [...] is used by all 64-bit UNIX ports" so it's indeed
// quite safe, at least within the context of glibc, to equate 64-bit with LP64.
#if defined(__GLIBC__) && ((__GLIBC__>=2 && __GLIBC_MINOR__ >= 8) || __GLIBC__>2) \
&& __LP64__
#define EIGEN_GLIBC_MALLOC_ALREADY_ALIGNED 1
#else
#define EIGEN_GLIBC_MALLOC_ALREADY_ALIGNED 0
#endif
// FreeBSD 6 seems to have 16-byte aligned malloc
// See http://svn.freebsd.org/viewvc/base/stable/6/lib/libc/stdlib/malloc.c?view=markup
// FreeBSD 7 seems to have 16-byte aligned malloc except on ARM and MIPS architectures
@ -43,13 +57,17 @@
#define EIGEN_FREEBSD_MALLOC_ALREADY_ALIGNED 0
#endif
#if defined(__APPLE__) || defined(_WIN64) || EIGEN_FREEBSD_MALLOC_ALREADY_ALIGNED
#if defined(__APPLE__) \
|| defined(_WIN64) \
|| EIGEN_GLIBC_MALLOC_ALREADY_ALIGNED \
|| EIGEN_FREEBSD_MALLOC_ALREADY_ALIGNED
#define EIGEN_MALLOC_ALREADY_ALIGNED 1
#else
#define EIGEN_MALLOC_ALREADY_ALIGNED 0
#endif
#if ((defined _GNU_SOURCE) || ((defined _XOPEN_SOURCE) && (_XOPEN_SOURCE >= 600))) && (defined _POSIX_ADVISORY_INFO) && (_POSIX_ADVISORY_INFO > 0)
#if ((defined _GNU_SOURCE) || ((defined _XOPEN_SOURCE) && (_XOPEN_SOURCE >= 600))) \
&& (defined _POSIX_ADVISORY_INFO) && (_POSIX_ADVISORY_INFO > 0)
#define EIGEN_HAS_POSIX_MEMALIGN 1
#else
#define EIGEN_HAS_POSIX_MEMALIGN 0