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430d275a39
kernel_optimize_test/lib
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Peter Lund 430d275a39 avoid negative (and full-width) shifts in radix-tree.c 
Negative shifts are not allowed in C (the result is undefined).  Same thing
with full-width shifts.

It works on most platforms but not on the VAX with gcc 4.0.1 (it results in an
"operand reserved" fault).

Shifting by more than the width of the value on the left is also not
allowed.  I think the extra '>> 1' tacked on at the end in the original
code was an attempt to work around that.  Getting rid of that is an extra
feature of this patch.

Here's the chapter and verse, taken from the final draft of the C99
standard ("6.5.7 Bitwise shift operators", paragraph 3):

  "The integer promotions are performed on each of the operands. The
  type of the result is that of the promoted left operand. If the
  value of the right operand is negative or is greater than or equal
  to the width of the promoted left operand, the behavior is
  undefined."

Thank you to Jan-Benedict Glaw, Christoph Hellwig, Maciej Rozycki, Pekka
Enberg, Andreas Schwab, and Christoph Lameter for review.  Special thanks
to Andreas for spotting that my fix only removed half the undefined
behaviour.

Signed-off-by: Peter Lund <firefly@vax64.dk>
Christoph Lameter <clameter@sgi.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Andreas Schwab <schwab@suse.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: WU Fengguang <wfg@mail.ustc.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-17 08:42:56 -07:00
..
lzo lzo: add some missing casts 2007-07-31 15:39:37 -07:00
reed_solomon [RSLIB] Support non-canonical GF representations 2007-05-02 11:56:33 +01:00
zlib_deflate [PATCH] zlib_inflate: Upgrade library code to a recent version 2006-06-22 15:05:58 -07:00
zlib_inflate [ZLIB]: Fix external builds of zlib_inflate code. 2007-10-11 22:17:20 -07:00
.gitignore Add some basic .gitignore files 2005-10-18 08:26:15 -07:00
argv_split.c argv_split: allow argv_split to handle NULL pointer in argcp parameter gracefully 2007-10-17 08:42:50 -07:00
audit.c [PATCH] audit signal recipients 2007-05-11 05:38:25 -04:00
bitmap.c [PATCH] kernel-doc fixes for 2.6.20-git15 (non-drivers) 2007-03-01 14:53:37 -08:00
bitrev.c [PATCH] add MODULE_* attributes to bit reversal library 2006-12-10 10:07:52 -08:00
bug.c generic bug: use show_regs() instead of dump_stack() 2007-07-16 09:05:51 -07:00
bust_spinlocks.c handle recursive calls to bust_spinlocks() 2007-10-17 08:42:56 -07:00
check_signature.c uninline check_signature() 2007-07-16 09:05:50 -07:00
cmdline.c [PATCH] Numerous fixes to kernel-doc info in source files. 2007-02-11 10:51:32 -08:00
cpumask.c Safer nr_node_ids and nr_node_ids determination and initial values 2007-05-07 12:12:51 -07:00
crc-ccitt.c [PATCH] kernel-doc for lib/crc*.c 2006-06-25 10:01:20 -07:00
crc-itu-t.c CRC ITU-T V.41 2007-05-10 18:24:13 +02:00
crc7.c CRC7 support 2007-07-17 10:23:04 -07:00
crc16.c [PATCH] kernel-doc for lib/crc*.c 2006-06-25 10:01:20 -07:00
crc32.c [PATCH] crc32: replace bitreverse by bitrev32 2006-12-08 08:28:39 -08:00
crc32defs.h
ctype.c
debug_locks.c [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
dec_and_lock.c [PATCH] atomic: dec_and_lock use atomic primitives 2006-01-08 20:13:48 -08:00
devres.c iomap: implement pcim_iounmap_regions() 2007-04-28 14:15:58 -04:00
div64.c [S390]: Fix build on 31-bit. 2007-04-25 22:28:53 -07:00
dump_stack.c
extable.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
fault-inject.c fault_inject: silence a warning 2007-07-24 12:24:59 -07:00
find_next_bit.c [PATCH] bitops: generic ext2_{set,clear,test,find_first_zero,find_next_zero}_bit() 2006-03-26 08:57:11 -08:00
gen_crc32table.c
genalloc.c Slab allocators: Replace explicit zeroing with __GFP_ZERO 2007-07-17 10:23:02 -07:00
halfmd4.c
hexdump.c hex_dump: add missing "const" qualifiers 2007-08-11 15:47:41 -07:00
hweight.c [PATCH] optimize hweight64 for x86_64 2006-09-26 10:52:38 +02:00
idr.c Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
inflate.c [PATCH] x86-64: deflate inflate_dynamic too 2007-05-02 19:27:15 +02:00
int_sqrt.c [PATCH] lib: Fix bug in int_sqrt() for 64 bit longs 2006-02-03 08:32:08 -08:00
iomap_copy.c [PATCH] add __iowrite64_copy 2006-06-20 20:24:58 -07:00
iomap.c PCI: Document pci_iomap() 2007-08-22 14:48:40 -07:00
ioremap.c lib/ioremap.c should #include <linux/io.h> 2007-10-17 08:42:50 -07:00
irq_regs.c [PATCH] irq_reqs: export __irq_regs 2006-10-06 08:53:40 -07:00
kasprintf.c lib: move kasprintf to a separate file 2007-07-31 15:39:39 -07:00
Kconfig Introduce CONFIG_CHECK_SIGNATURE 2007-08-22 19:52:45 -07:00
Kconfig.debug slow down printk during boot 2007-10-16 09:42:49 -07:00
kernel_lock.c [PATCH] lockdep: prove spinlock rwlock locking correctness 2006-07-03 15:27:04 -07:00
klist.c Driver core: Don't call put methods while holding a spinlock 2006-09-25 21:08:40 -07:00
kobject_uevent.c Driver core: kerneldoc - kobject_uevent_env is not "usually KOBJ_MOVE" 2007-10-12 14:51:06 -07:00
kobject.c kobject: update the copyrights 2007-10-12 14:51:12 -07:00
kref.c kref: fix CPU ordering with respect to krefs 2007-04-27 10:57:29 -07:00
libcrc32c.c [PATCH] constify libcrc32c table 2006-06-25 10:01:09 -07:00
list_debug.c [PATCH] More list debugging context 2006-12-07 08:39:35 -08:00
locking-selftest-hardirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-mutex.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-rlock-hardirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-rlock-softirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-rlock.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-rsem.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-softirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-spin-hardirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-spin-softirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-spin.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-wlock-hardirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-wlock-softirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-wlock.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-wsem.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest.c [PATCH] lockdep: show more details about self-test failures 2006-12-07 08:39:43 -08:00
Makefile lib: floating proportions 2007-10-17 08:42:45 -07:00
parser.c [AFS]: Make the match_*() functions take const options. 2007-05-03 03:10:39 -07:00
percpu_counter.c lib: percpu_counter_init_irq 2007-10-17 08:42:44 -07:00
plist.c [PATCH] pi-futex: add plist implementation 2006-06-27 17:32:46 -07:00
prio_tree.c
proportions.c lib: floating proportions 2007-10-17 08:42:45 -07:00
radix-tree.c avoid negative (and full-width) shifts in radix-tree.c 2007-10-17 08:42:56 -07:00
random32.c [PATCH] severing module.h->sched.h 2006-12-04 02:00:22 -05:00
rbtree.c [PATCH] rbtree: fixed reversed RB_EMPTY_NODE and rb_next/prev 2006-09-30 20:26:56 +02:00
reciprocal_div.c [PATCH] SLAB: use a multiply instead of a divide in obj_to_index() 2006-12-13 09:05:49 -08:00
rwsem-spinlock.c Lockdep: add lockdep_set_class_and_subclass() and lockdep_set_subclass() 2006-10-11 01:45:14 -04:00
rwsem.c Lockdep: add lockdep_set_class_and_subclass() and lockdep_set_subclass() 2006-10-11 01:45:14 -04:00
semaphore-sleepers.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
sha1.c [PATCH] Numerous fixes to kernel-doc info in source files. 2007-02-11 10:51:32 -08:00
smp_processor_id.c [PATCH] fix missing includes 2005-10-30 17:37:32 -08:00
sort.c lib/sort.c optimization 2007-10-17 08:42:52 -07:00
spinlock_debug.c [PATCH] x86: all cpu backtrace 2006-12-07 02:14:01 +01:00
string.c [STRING]: Move strcasecmp/strncasecmp to lib/string.c 2007-04-26 01:54:39 -07:00
swiotlb.c swiotlb: sg chaining support 2007-10-16 11:26:01 +02:00
textsearch.c Various typo fixes. 2007-02-17 19:07:33 +01:00
ts_bm.c [TEXTSEARCH]: Fix Boyer Moore initialization bug 2006-08-22 14:33:58 -07:00
ts_fsm.c [PATCH] lib/ts_fsm.c: constify structs 2006-09-29 09:18:23 -07:00
ts_kmp.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
vsprintf.c lib: move kasprintf to a separate file 2007-07-31 15:39:39 -07:00