project-base/server-skynet-source-3rd-jemalloc
2
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Add (x != 0) assertion to lg_floor(x).

Browse Source 
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
include/jemalloc/internal/util.h
View File

@ -136,14 +136,14 @@ JEMALLOC_ALWAYS_INLINE int
jemalloc_ffsl(long bitmap) jemalloc_ffsl(long bitmap)
{ {
return (JEMALLOC_INTERNAL_FFSL(bitmap)); return (JEMALLOC_INTERNAL_FFSL(bitmap));
} }
JEMALLOC_ALWAYS_INLINE int JEMALLOC_ALWAYS_INLINE int
jemalloc_ffs(int bitmap) jemalloc_ffs(int bitmap)
{ {
return (JEMALLOC_INTERNAL_FFS(bitmap)); return (JEMALLOC_INTERNAL_FFS(bitmap));
} }
/* Compute the smallest power of 2 that is >= x. */ /* Compute the smallest power of 2 that is >= x. */
@ -170,6 +170,8 @@ lg_floor(size_t x)
{ {
size_t ret; size_t ret;
assert(x != 0);
asm ("bsr %1, %0" asm ("bsr %1, %0"
: "=r"(ret) // Outputs. : "=r"(ret) // Outputs.
: "r"(x) // Inputs. : "r"(x) // Inputs.
@ -180,22 +182,26 @@ lg_floor(size_t x)
JEMALLOC_INLINE size_t JEMALLOC_INLINE size_t
lg_floor(size_t x) lg_floor(size_t x)
{ {
unsigned long ret; unsigned long ret;
assert(x != 0);
#if (LG_SIZEOF_PTR == 3) #if (LG_SIZEOF_PTR == 3)
_BitScanReverse64(&ret, x); _BitScanReverse64(&ret, x);
#elif (LG_SIZEOF_PTR == 2) #elif (LG_SIZEOF_PTR == 2)
_BitScanReverse(&ret, x); _BitScanReverse(&ret, x);
#else #else
# error "Unsupported type sizes for lg_floor()" # error "Unsupported type sizes for lg_floor()"
#endif #endif
return (ret); return (ret);
} }
#elif (defined(JEMALLOC_HAVE_BUILTIN_CLZ)) #elif (defined(JEMALLOC_HAVE_BUILTIN_CLZ))
JEMALLOC_INLINE size_t JEMALLOC_INLINE size_t
lg_floor(size_t x) lg_floor(size_t x)
{ {
assert(x != 0);
#if (LG_SIZEOF_PTR == LG_SIZEOF_INT) #if (LG_SIZEOF_PTR == LG_SIZEOF_INT)
return (((8 << LG_SIZEOF_PTR) - 1) - __builtin_clz(x)); return (((8 << LG_SIZEOF_PTR) - 1) - __builtin_clz(x));
#elif (LG_SIZEOF_PTR == LG_SIZEOF_LONG) #elif (LG_SIZEOF_PTR == LG_SIZEOF_LONG)
@ -209,6 +215,8 @@ JEMALLOC_INLINE size_t
lg_floor(size_t x) lg_floor(size_t x)
{ {
assert(x != 0);
x |= (x >> 1); x |= (x >> 1);
x |= (x >> 2); x |= (x >> 2);
x |= (x >> 4); x |= (x >> 4);