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| author | Joseph Myers <joseph@codesourcery.com> | 2017-09-05 15:14:09 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2017-09-05 15:14:09 +0000 |
| commit | 99d6791899c43eb31b4d1896134501d814da7741 (patch) | |
| tree | ecc50e46abf386187fc9a5fbc2bad6faf296a68d | |
| parent | 3f802aeb3403a558426b50d42a50c6bfcc6cc425 (diff) | |
| download | glibc-99d6791899c43eb31b4d1896134501d814da7741.zip glibc-99d6791899c43eb31b4d1896134501d814da7741.tar.gz glibc-99d6791899c43eb31b4d1896134501d814da7741.tar.bz2 | |
Fix pcprofiledump cross-endian condition (bug 22086).
debug/pcprofiledump.c contains code that tries to handle other-endian
data. This uses a condition "(word & 0xfffffff0) == bswap_32
(0xdeb00000)". This condition is always false (the LHS always has the
low four bits zero, the RHS doesn't); a correct comparison would use
0x0fffffff. This results in -Werror=tautological-compare build
failures with the tile version of bits/byteswap.h and mainline GCC.
https://sourceware.org/ml/libc-testresults/2017-q3/msg00400.html
pcprofiledump.c: In function 'main':
pcprofiledump.c:118:39: error: bitwise comparison always evaluates to false
[-Werror=tautological-compare]
int must_swap = (word & 0xfffffff0) == bswap_32 (0xdeb00000);
^~
This patch fixes the condition. Tested for x86_64, and with
build-many-glibcs.py that it fixes the build for tilegx-linux-gnu.
(Note that I have not tested the actual pcprofiledump functionality,
native or cross endian, which lacks any testsuite coverage.)
[BZ #22086]
* debug/pcprofiledump.c (main): Use byte-swapped mask when
comparing word with byte-swapped constant.
| -rw-r--r-- | ChangeLog | 6 | ||||
| -rw-r--r-- | debug/pcprofiledump.c | 2 |
2 files changed, 7 insertions, 1 deletions
@@ -1,3 +1,9 @@ +2017-09-05 Joseph Myers <joseph@codesourcery.com> + + [BZ #22086] + * debug/pcprofiledump.c (main): Use byte-swapped mask when + comparing word with byte-swapped constant. + 2017-09-05 Chris Leonard <cjlhomeaddress@gmail.com> [BZ #20498] diff --git a/debug/pcprofiledump.c b/debug/pcprofiledump.c index a32cdef..6a9641e 100644 --- a/debug/pcprofiledump.c +++ b/debug/pcprofiledump.c @@ -115,7 +115,7 @@ main (int argc, char *argv[]) error (EXIT_FAILURE, errno, _("cannot read header")); /* Check whether we have to swap the byte order. */ - int must_swap = (word & 0xfffffff0) == bswap_32 (0xdeb00000); + int must_swap = (word & 0x0fffffff) == bswap_32 (0xdeb00000); if (must_swap) word = bswap_32 (word); |