On Fri, Nov 13, 2020 at 11:53:43AM -0700, Jeff Law via Gcc-patches wrote:
>
> On 5/1/20 6:06 PM, Seija Kijin via Gcc-patches wrote:
> > The original code in libiberty says "FIXME" and then says it has not been
> > validated to be ANSI compliant. However, this patch changes the function to
> > match implementations that ARE compliant, and such code is in the public
> > domain.
> >
> > I ran the test results, and there are no test failures.
>
> Thanks. This seems to be the standard "simple" strstr implementation.
> There's significantly faster implementations available, but I doubt it's
> worth the effort as the version in this file only gets used if there is
> no system strstr.c.
Except that PR109306 says the new version is non-compliant and
is certainly slower than what we used to have. The only problem I see
on the old version (sure, it is not very fast version) is that for
strstr ("abcd", "") it returned "abcd"+4 rather than "abcd" because
strchr in that case changed p to point to the last character and then
strncmp returned 0.
The question reported in PR109306 is whether memcmp is required not to
access characters beyond the first difference or not.
For all of memcmp/strcmp/strncmp, C17 says:
"The sign of a nonzero value returned by the comparison functions memcmp, strcmp, and strncmp
is determined by the sign of the difference between the values of the first pair of characters (both
interpreted as unsigned char) that differ in the objects being compared."
but then in memcmp description says:
"The memcmp function compares the first n characters of the object pointed to by s1 to the first n
characters of the object pointed to by s2."
rather than something similar to strncmp wording:
"The strncmp function compares not more than n characters (characters that follow a null character
are not compared) from the array pointed to by s1 to the array pointed to by
s2."
So, while for strncmp it seems clearly well defined when there is zero
terminator before reaching the n, for memcmp it is unclear if say
int
memcmp (const void *s1, const void *s2, size_t n)
{
int ret = 0;
size_t i;
const unsigned char *p1 = (const unsigned char *) s1;
const unsigned char *p2 = (const unsigned char *) s2;
for (i = n; i; i--)
if (p1[i - 1] != p2[i - 1])
ret = p1[i - 1] < p2[i - 1] ? -1 : 1;
return ret;
}
wouldn't be valid implementation (one which always compares all characters
and just returns non-zero from the first one that differs).
So, shouldn't we just revert and handle the len == 0 case correctly?
I think almost nothing really uses it, but still, the old version
at least worked nicer with a fast strchr.
Could as well strncmp (p + 1, s2 + 1, len - 1) if that is preferred
because strchr already compared the first character.
2023-04-02 Jakub Jelinek <jakub@redhat.com>
PR other/109306
* strstr.c (strstr): Return s1 if len is 0.
(cherry picked from commit 1719fa40c4)
Darwin provides an implementation of sbrk, which is detected by
the configuration process. However, it is deprecated which leads
to build warnings. The malloc-based implementation is more
suitable. This patch removes sbrk from the functions searched
for Darwin.
Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
libiberty/ChangeLog:
* configure: Regenerate.
* configure.ac: Do not search for sbrk on Darwin.
* xmalloc.c: Do not declare sbrk unless it has been found
by configure.
(cherry picked from commit fbb334a6ac)
We encapsulate streamed IR in three special sections with a table
that describes their entries. The table is expected to be written
with native endianness for the target, but for cross-endian cross-
compilation the swapping was omitted. Fixed thus.
Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
libiberty/ChangeLog:
* simple-object-mach-o.c (simple_object_mach_o_write_segment):
Arrange to swap the LTO index tables where needed.
(cherry picked from commit 220c410162)
On
#define A(n) int foo1##n(void) { return 1##n; }
#define B(n) A(n##0) A(n##1) A(n##2) A(n##3) A(n##4) A(n##5) A(n##6) A(n##7) A(n##8) A(n##9)
#define C(n) B(n##0) B(n##1) B(n##2) B(n##3) B(n##4) B(n##5) B(n##6) B(n##7) B(n##8) B(n##9)
#define D(n) C(n##0) C(n##1) C(n##2) C(n##3) C(n##4) C(n##5) C(n##6) C(n##7) C(n##8) C(n##9)
#define E(n) D(n##0) D(n##1) D(n##2) D(n##3) D(n##4) D(n##5) D(n##6) D(n##7) D(n##8) D(n##9)
E(0) E(1) E(2) D(30) D(31) C(320) C(321) C(322) C(323) C(324) C(325)
B(3260) B(3261) B(3262) B(3263) A(32640) A(32641) A(32642)
testcase with
./xgcc -B ./ -c -g -fpic -ffat-lto-objects -flto -O0 -o foo1.o foo1.c -ffunction-sections
./xgcc -B ./ -shared -g -fpic -flto -O0 -o foo1.so foo1.o
/tmp/ccTW8mBm.debug.temp.o: file not recognized: file format not recognized
(testcase too slow to be included into testsuite).
The problem is clearly reported by readelf:
readelf: foo1.o.debug.temp.o: Warning: Section 2 has an out of range sh_link value of 65321
readelf: foo1.o.debug.temp.o: Warning: Section 5 has an out of range sh_link value of 65321
readelf: foo1.o.debug.temp.o: Warning: Section 10 has an out of range sh_link value of 65323
readelf: foo1.o.debug.temp.o: Warning: [ 2]: Link field (65321) should index a symtab section.
readelf: foo1.o.debug.temp.o: Warning: [ 5]: Link field (65321) should index a symtab section.
readelf: foo1.o.debug.temp.o: Warning: [10]: Link field (65323) should index a string section.
because simple_object_elf_copy_lto_debug_sections doesn't adjust sh_info and
sh_link fields in ElfNN_Shdr if they are in between SHN_{LO,HI}RESERVE
inclusive. Not adjusting those is incorrect though, SHN_{LO,HI}RESERVE
range is only relevant to the 16-bit fields, mainly st_shndx in ElfNN_Sym
where if one needs >= SHN_LORESERVE section number, SHN_XINDEX should be
used instead and .symtab_shndx section should contain the real section
index, and in ElfNN_Ehdr e_shnum and e_shstrndx fields, where if >=
SHN_LORESERVE value is needed it should put those into
Shdr[0].sh_{size,link}. But, sh_{link,info} are 32-bit fields which can
contain any section index.
Note, as simple-object-elf.c mentions, binutils from 2.12 to 2.18 (so before
2011) used to mishandle the > 63.75K sections case and assumed there is a
hole in between the sections, but what
simple_object_elf_copy_lto_debug_sections does wouldn't help in that case
for the debug temp object creation, we'd need to detect the case also in
that routine and take it into account in the remapping etc. I think
it is not worth it given that it is over 10 years, if somebody needs
63.75K or more sections, better use more recent binutils.
2022-02-22 Jakub Jelinek <jakub@redhat.com>
PR lto/104617
* simple-object-elf.c (simple_object_elf_match): Fix up URL
in comment.
(simple_object_elf_copy_lto_debug_sections): Remap sh_info and
sh_link even if they are in the SHN_LORESERVE .. SHN_HIRESERVE
range (inclusive).
(cherry picked from commit 2f59f06761)
readelf -S prints:
There are 81999 section headers, starting at offset 0x1f488060:
Section Headers:
[Nr] Name Type Address Off Size ES Flg Lk Inf Al
[ 0] NULL 0000000000000000 000000 01404f 00 81998 0 0
[ 1] .group GROUP 0000000000000000 000040 000008 04 81995 105027 4
...
[81995] .symtab SYMTAB 0000000000000000 d5d9298 2db310 18 81997 105026 8
[81996] .symtab_shndx SYMTAB SECTION INDICES 0000000000000000 d8b45a8 079dd8 04 81995 0 4
[81997] .strtab STRTAB 0000000000000000 d92e380 80460c 00 0 0 1
...
Looking at the documentation:
Table 7–15 ELF sh_link and sh_info Interpretation
sh_type - sh_link
SHT_SYMTAB - The section header index of the associated string table.
SHT_SYMTAB_SHNDX - The section header index of the associated symbol table.
As seen, sh_link of a SHT_SYMTAB always points to a .strtab and readelf
confirms that.
So we need to use reverse mapping taken from
[81996] .symtab_shndx SYMTAB SECTION INDICES 0000000000000000 d8b45a8 079dd8 04 81995 0 4
where sh_link points to 81995.
libiberty/ChangeLog:
PR lto/97290
* simple-object-elf.c (simple_object_elf_copy_lto_debug_sections):
Use sh_link of a .symtab_shndx section.
(cherry picked from commit 190c04ba36)
Unused global UNDEFs can have side-effects in some circumstances so
the following patch avoids them by treating them the same as other
to be discarded DEFs - make them local.
2020-08-03 Richard Biener <rguenther@suse.de>
PR lto/96385
libiberty/
* simple-object-elf.c
(simple_object_elf_copy_lto_debug_sections): Localize global
UNDEFs and reuse the prevailing name.
(cherry picked from commit b32c5d0b72)
Don't perform CET run-time check for host when cross compiling. Instead,
enable CET in cross compiler if possible so that it will run on both CET
and non-CET hosts.
config/
PR bootstrap/94998
* cet.m4 (GCC_CET_HOST_FLAGS): Enable CET in cross compiler if
possible.
libiberty/
PR bootstrap/94998
* configure: Regenerated.
lto-plugin/
PR bootstrap/94998
* configure: Regenerated.
(cherry picked from commit d17cdc17c9)
GCC_CET_HOST_FLAGS uses -Wl,-z,ibt,-z,shstk to check if Linux/x86 host
has Intel CET enabled by introducing an Intel CET violation on purpose.
To avoid false positive, check whether -Wl,-z,ibt,-z,shstk works first.
-fcf-protection=none is added to avoid false negative when -fcf-protection
is enabled by default.
config/
PR bootstrap/94739
* cet.m4 (GCC_CET_HOST_FLAGS): Add -fcf-protection=none to
-Wl,-z,ibt,-z,shstk. Check whether -fcf-protection=none
-Wl,-z,ibt,-z,shstk works first.
libiberty/
PR bootstrap/94739
* configure: Regenerated.
lto-plugin/
PR bootstrap/94739
* configure: Regenerated.
Since ld is Intel CET enabled on Intel CET enabled host, dlopen fails on
liblto_plugin.so if it isn't Intel CET enabled. Add GCC_CET_HOST_FLAGS
to cet.m4, use it in libiberty and lto-plugin to always enable Intel
CET in liblto_plugin.so on Intel CET enabled host.
On Linux/x86 host, enable Intel CET by default if assembler and compiler
support Intel CET so that the generated liblto_plugin.so can be used on
both CET and non-CET machines. It is an error to disable Intel CET in
liblto_plugin.so on Intel CET enabled host.
config/
PR bootstrap/94739
* cet.m4 (GCC_CET_HOST_FLAGS): New.
libiberty/
PR bootstrap/94739
* Makefile.in (COMPILE.c): Add @CET_HOST_FLAGS@.
(configure_deps): Add $(srcdir)/../config/cet.m4 and
$(srcdir)/../config/enable.m4.
* aclocal.m4: Include ../config/cet.m4 and ../config/enable.m4.
* configure.ac: Add GCC_CET_HOST_FLAGS(CET_HOST_FLAGS) and
AC_SUBST(CET_HOST_FLAGS).
* configure: Regenerated.
lto-plugin/
PR bootstrap/94739
* Makefile.am (AM_CFLAGS): Add $(CET_HOST_FLAGS).
* configure.ac: Add GCC_CET_HOST_FLAGS(CET_HOST_FLAGS) and
AC_SUBST(CET_HOST_FLAGS).
* Makefile.in: Regenerated.
* aclocal.m4: Likewise.
* configure: Likewise.
When generating the separate file with LTO debug sections, we should
also copy .note.gnu.property section.
PR lto/93966
* simple-object.c (handle_lto_debug_sections): Also copy
.note.gnu.property section.
On bare-metal targets, I/O support is typically provided by a BSP and
requires a linker script and/or hosting library to be specified on the
linker command line. Linking an empty program with the default linker
script may succeed, however, which confuses libstdc++ configuration
when programs that probe for the presence of various I/O features fail
with link errors.
2020-02-12 Sandra Loosemore <sandra@codesourcery.com>
PR libstdc++/79193
PR libstdc++/88999
config/
* no-executables.m4: Use a non-empty program to test for linker
support.
libgcc/
* configure: Regenerated.
libgfortran/
* configure: Regenerated.
libiberty/
* configure: Regenerated.
libitm/
* configure: Regenerated.
libobjc/
* configure: Regenerated.
libquadmath/
* configure: Regenerated.
libssp/
* configure: Regenerated.
libstdc++v-3/
* configure: Regenerated.
Makes some parameters const in libiberty's hashtab library.
include/ChangeLog:
* hashtab.h (htab_remove_elt): Make a parameter const.
(htab_remove_elt_with_hash): Likewise.
libiberty/ChangeLog:
* hashtab.c (htab_remove_elt): Make a parameter const.
(htab_remove_elt_with_hash): Likewise.
writeargv writes out empty arguments in a way that expandargv skips
them instead of preserving them. Fixed by writing out a pair of
quotes for them.
for libiberty/ChangeLog
* argv.c (writeargv): Output empty args as "".
C++20 coroutines introduces a new operator with a mangling of 'aw'.
This patch adds that to libiberty's demangler.
libiberty/ChangeLog:
2020-01-18 Iain Sandoe <iain@sandoe.co.uk>
* cp-demangle.c (cplus_demangle_operators): Add the co_await
operator.
* testsuite/demangle-expected: Test co_await operator mangling.
* cp-demangle.c (d_print_mod): Add a space before printing `complex`
and `imaginary`, as opposed to after.
* testsuite/demangle-expected: Adjust test.
From-SVN: r277535
2019-08-27 Martin Liska <mliska@suse.cz>
PR lto/91478
* simple-object-elf.c (simple_object_elf_copy_lto_debug_sections):
First find a WEAK HIDDEN symbol in symbol table that will be
preserved. Later, use the symbol name for all removed symbols.
From-SVN: r274955
2019-07-22 Martin Liska <mliska@suse.cz>
* config/avr/avr.c (avr_asm_output_aligned_decl_common): Update
comment.
* toplev.c (compile_file): Do not emit __gnu_lto_v1 symbol.
2019-07-22 Martin Liska <mliska@suse.cz>
* config/pa/stublib.c: Remove stub symbol __gnu_lto_v1.
* config/pa/t-stublib: Likewise.
2019-07-22 Martin Liska <mliska@suse.cz>
* simple-object-elf.c (simple_object_elf_copy_lto_debug_sections):
Do not search for gnu_lto_v1, but search for first '\0'.
From-SVN: r273662
