[git commit ldso-future] Fix malloc alignment
Bernd Schmidt
bernds at codesourcery.com
Tue Apr 12 11:23:14 UTC 2011
commit: http://git.uclibc.org/uClibc/commit/?id=eff2d0ba5890b517ef5bc9d0269d6149556c12c8
branch: http://git.uclibc.org/uClibc/commit/?id=refs/heads/ldso-future
In commit 3e0a1f388, Richard tried to fix malloc alignments by using
alignof (double __attribute_aligned__(sizeof (size_t))).
This doesn't work, since attribute_aligned overrides the alignment
rather than providing a minimum. On C6X, malloc returns four-byte
aligned values rather than the necessary eight-byte alignment.
It's simpler to use a comparison and pick the bigger of the two values,
so that's what I've done.
Signed-off-by: Bernd Schmidt <bernds at codesourcery.com>
---
libc/stdlib/malloc/heap.h | 6 ++++--
libc/stdlib/malloc/malloc.h | 2 +-
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/libc/stdlib/malloc/heap.h b/libc/stdlib/malloc/heap.h
index 3038079..2f06ab1 100644
--- a/libc/stdlib/malloc/heap.h
+++ b/libc/stdlib/malloc/heap.h
@@ -29,8 +29,10 @@
/* The heap allocates in multiples of, and aligned to, HEAP_GRANULARITY.
HEAP_GRANULARITY must be a power of 2. Malloc depends on this being the
same as MALLOC_ALIGNMENT. */
-#define HEAP_GRANULARITY_TYPE double __attribute_aligned__ (sizeof (size_t))
-#define HEAP_GRANULARITY (__alignof__ (HEAP_GRANULARITY_TYPE))
+#define HEAP_GRANULARITY_TYPE double __attribute_aligned__ (HEAP_GRANULARITY)
+#define HEAP_GRANULARITY \
+ (__alignof__ (double) > sizeof (size_t) ? __alignof__ (double) : sizeof (size_t))
+
/* The HEAP_INIT macro can be used as a static initializer for a heap
diff --git a/libc/stdlib/malloc/malloc.h b/libc/stdlib/malloc/malloc.h
index 0a4b43b..25f7409 100644
--- a/libc/stdlib/malloc/malloc.h
+++ b/libc/stdlib/malloc/malloc.h
@@ -17,7 +17,7 @@
alignment can be a significant win on targets like m68k and Coldfire,
where __alignof__(double) == 2. */
#define MALLOC_ALIGNMENT \
- __alignof__ (double __attribute_aligned__ (sizeof (size_t)))
+ (__alignof__ (double) > sizeof (size_t) ? __alignof__ (double) : sizeof (size_t))
/* The system pagesize... */
extern size_t __pagesize;
--
1.7.3.4
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