project-base/server-skynet-source-3rd-jemalloc
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Add (x != 0) assertion to lg_floor(x).

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lg_floor(0) is undefined, but depending on compiler options may not
cause a crash.  This assertion makes it harder to accidentally abuse
lg_floor().
This commit is contained in:
Jason Evans 2015-02-04 16:41:55 -08:00
parent f500a10b2e
commit c810fcea1f
1 changed files with 14 additions and 6 deletions
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20
include/jemalloc/internal/util.h
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@ -136,14 +136,14 @@ JEMALLOC_ALWAYS_INLINE int
jemalloc_ffsl(long bitmap)
{
return (JEMALLOC_INTERNAL_FFSL(bitmap));
return (JEMALLOC_INTERNAL_FFSL(bitmap));
}
JEMALLOC_ALWAYS_INLINE int
jemalloc_ffs(int bitmap)
{
return (JEMALLOC_INTERNAL_FFS(bitmap));
return (JEMALLOC_INTERNAL_FFS(bitmap));
}
/* Compute the smallest power of 2 that is >= x. */
@ -170,6 +170,8 @@ lg_floor(size_t x)
{
size_t ret;
assert(x != 0);
asm ("bsr %1, %0"
: "=r"(ret) // Outputs.
: "r"(x) // Inputs.
@ -180,22 +182,26 @@ lg_floor(size_t x)
JEMALLOC_INLINE size_t
lg_floor(size_t x)
{
unsigned long ret;
unsigned long ret;
assert(x != 0);
#if (LG_SIZEOF_PTR == 3)
_BitScanReverse64(&ret, x);
_BitScanReverse64(&ret, x);
#elif (LG_SIZEOF_PTR == 2)
_BitScanReverse(&ret, x);
_BitScanReverse(&ret, x);
#else
# error "Unsupported type sizes for lg_floor()"
#endif
return (ret);
return (ret);
}
#elif (defined(JEMALLOC_HAVE_BUILTIN_CLZ))
JEMALLOC_INLINE size_t
lg_floor(size_t x)
{
assert(x != 0);
#if (LG_SIZEOF_PTR == LG_SIZEOF_INT)
return (((8 << LG_SIZEOF_PTR) - 1) - __builtin_clz(x));
#elif (LG_SIZEOF_PTR == LG_SIZEOF_LONG)
@ -209,6 +215,8 @@ JEMALLOC_INLINE size_t
lg_floor(size_t x)
{
assert(x != 0);
x |= (x >> 1);
x |= (x >> 2);
x |= (x >> 4);