1. Add default ISA level selection in non-multiarch/rtld
implementations.
2. Add ISA level build guards to different implementations.
- I.e strcpy-avx2.S which is ISA level 3 will only build if
compiled ISA level <= 3. Otherwise there is no reason to
include it as we will always use one of the ISA level 4
implementations (strcpy-evex.S).
3. Refactor the ifunc selector and ifunc implementation list to use
the ISA level aware wrapper macros that allow functions below the
compiled ISA level (with a guranteed replacement) to be skipped.
Tested with and without multiarch on x86_64 for ISA levels:
{generic, x86-64-v2, x86-64-v3, x86-64-v4}
And m32 with and without multiarch.
This commit doesn't affect libc.so.6, its just housekeeping to prepare
for adding explicit ISA level support.
Tested build on x86_64 and x86_32 with/without multiarch.
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 7061 files FOO.
I then removed trailing white space from math/tgmath.h,
support/tst-support-open-dev-null-range.c, and
sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following
obscure pre-commit check failure diagnostics from Savannah. I don't
know why I run into these diagnostics whereas others evidently do not.
remote: *** 912-#endif
remote: *** 913:
remote: *** 914-
remote: *** error: lines with trailing whitespace found
...
remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master
Implement strcpy family IFUNC selectors in C.
All internal calls within libc.so can use IFUNC on x86-64 since unlike
x86, x86-64 supports PC-relative addressing to access the GOT entry so
that it can call via PLT without using an extra register. For libc.a,
we can't use IFUNC for functions which are called before IFUNC has been
initialized. Use IFUNC internally reduces the icache footprint since
libc.so and other codes in the process use the same implementations.
This patch uses IFUNC for strcpy family functions within libc.
* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
strcpy-sse2 and stpcpy-sse2.
* sysdeps/x86_64/multiarch/ifunc-unaligned-ssse3.h: New file.
* sysdeps/x86_64/multiarch/stpcpy-sse2.S: Likewise.
* sysdeps/x86_64/multiarch/stpcpy.c: Likewise.
* sysdeps/x86_64/multiarch/stpncpy.c: Likewise.
* sysdeps/x86_64/multiarch/strcpy-sse2.S: Likewise.
* sysdeps/x86_64/multiarch/strcpy.c: Likewise.
* sysdeps/x86_64/multiarch/strncpy.c: Likewise.
* sysdeps/x86_64/multiarch/stpcpy.S: Removed.
* sysdeps/x86_64/multiarch/stpncpy.S: Likewise.
* sysdeps/x86_64/multiarch/strcpy.S: Likewise.
* sysdeps/x86_64/multiarch/strncpy.S: Likewise.
* sysdeps/x86_64/multiarch/stpncpy-c.c (weak_alias): New.
(libc_hidden_def): Always defined as empty.
* sysdeps/x86_64/multiarch/strncpy-c.c (libc_hidden_builtin_def):
Always Defined as empty.
