Recently I noticed this odd assembler warning when compiling using my
good old cross
toolchain based on gcc version 4.1.2 20061115 (prerelease) (Ubuntu 4.1.1-21):
CC fs/ext4/extents_status.o
{standard input}: Assembler messages:
{standard input}:666: Warning: expression out of range: defaulting to 0
The offending line is:
bfins %d1,-8(%fp){#4:#60} | tmp63, newes.es_pblk,,
where the "#60" is invalid, as bitfield widths are limited to 32 bits.
This was generated from the 64-bit mask operation in the following C code:
static inline void ext4_es_store_pblock(struct extent_status *es,
ext4_fsblk_t pb)
{
ext4_fsblk_t block; /* unsigned long long */
block = (pb & ~EXTENT_STATUS_FLAGS) |
(es->es_pblk & EXTENT_STATUS_FLAGS);
es->es_pblk = block;
}
Using gcc 4.6.3, the bug is not present, as it avoids emitting bfins
instructions.
JFYI, gcc 4.6.3 generates bigger code than 4.1.2:
-Linux version 3.9.0-rc5-atari-00740-gbb55db0-dirty (geert@ayla) (gcc version 4.
1.2 20061115 (prerelease) (Ubuntu 4.1.1-21)) #1048 Sat Apr 6 13:37:34 CEST 2013
+Linux version 3.9.0-rc5-atari-00741-gcfb7cca-dirty (geert@ayla) (gcc version 4.
6.3 (GCC) ) #1050 Sat Apr 6 21:15:54 CEST 2013
-Memory: 268464k/268464k available (2728k kernel code, 5152k data, 144k init)
+Memory: 268348k/268348k available (2864k kernel code, 5144k data, 132k init)
Virtual kernel memory layout:
- vector : 0x0036ce8c - 0x0036d28c ( 1 KiB)
+ vector : 0x0038ce2c - 0x0038d22c ( 1 KiB)
kmap : 0xd0000000 - 0xf0000000 ( 512 MiB)
vmalloc : 0x11800000 - 0xd0000000 (3048 MiB)
lowmem : 0x00000000 - 0x11000000 ( 272 MiB)
- .init : 0x00393000 - 0x003b7000 ( 144 KiB)
- .text : 0x00001000 - 0x002aa9d4 (2727 KiB)
- .data : 0x002ad7a8 - 0x00392148 ( 915 KiB)
- .bss : 0x0036cc60 - 0x00392148 ( 150 KiB)
+ .init : 0x003b3000 - 0x003d4000 ( 132 KiB)
+ .text : 0x00001000 - 0x002cc08e (2861 KiB)
+ .data : 0x002ceef8 - 0x003b20e8 ( 909 KiB)
+ .bss : 0x0038cc00 - 0x003b20e8 ( 150 KiB)
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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