58c2ad42a8
A customer reported the following missed opportunities to combine a couple
instructions into a sbfiz.
int sbfiz32 (int x)
{
return x << 29 >> 10;
}
long sbfiz64 (long x)
{
return x << 58 >> 20;
}
This gets converted to the following pattern:
(set (reg:SI 98)
(ashift:SI (sign_extend:SI (reg:HI 0 x0 [ xD.3334 ]))
(const_int 6 [0x6])))
Currently, gcc generates the following:
sbfiz32:
lsl x0, x0, 29
asr x0, x0, 10
ret
sbfiz64:
lsl x0, x0, 58
asr x0, x0, 20
ret
It could generate this instead:
sbfiz32:
sbfiz w0, w0, 19, 3
ret
sbfiz64::
sbfiz x0, x0, 38, 6
ret
The unsigned versions already generate ubfiz for the same code, so the lack of
a sbfiz pattern may have been an oversight.
This particular sbfiz pattern shows up in both CPU2006 (~ 80 hits) and
CPU2017 (~ 280 hits). It's not a lot, but seems beneficial in any case. No
significant performance differences, probably due to the small number of
occurrences or cases outside hot areas.
gcc/ChangeLog:
2018-05-22 Luis Machado <luis.machado@linaro.org>
gcc/
* config/aarch64/aarch64.md (*ashift<mode>_extv_bfiz): New pattern.
gcc/testsuite/ChangeLog:
2018-05-22 Luis Machado <luis.machado@linaro.org>
gcc/testsuite/
* gcc.target/aarch64/lsl_asr_sbfiz.c: New test.
From-SVN: r260546
|
||
|---|---|---|
| config | ||
| contrib | ||
| fixincludes | ||
| gcc | ||
| gnattools | ||
| gotools | ||
| include | ||
| INSTALL | ||
| intl | ||
| libada | ||
| libatomic | ||
| libbacktrace | ||
| libcc1 | ||
| libcpp | ||
| libdecnumber | ||
| libffi | ||
| libgcc | ||
| libgfortran | ||
| libgo | ||
| libgomp | ||
| libhsail-rt | ||
| libiberty | ||
| libitm | ||
| libmpx | ||
| libobjc | ||
| liboffloadmic | ||
| libquadmath | ||
| libsanitizer | ||
| libssp | ||
| libstdc++-v3 | ||
| libvtv | ||
| lto-plugin | ||
| maintainer-scripts | ||
| zlib | ||
| .dir-locals.el | ||
| .gitattributes | ||
| .gitignore | ||
| ABOUT-NLS | ||
| ChangeLog | ||
| ChangeLog.jit | ||
| ChangeLog.tree-ssa | ||
| compile | ||
| config-ml.in | ||
| config.guess | ||
| config.rpath | ||
| config.sub | ||
| configure | ||
| configure.ac | ||
| COPYING | ||
| COPYING.LIB | ||
| COPYING.RUNTIME | ||
| COPYING3 | ||
| COPYING3.LIB | ||
| depcomp | ||
| install-sh | ||
| libtool-ldflags | ||
| libtool.m4 | ||
| ltgcc.m4 | ||
| ltmain.sh | ||
| ltoptions.m4 | ||
| ltsugar.m4 | ||
| ltversion.m4 | ||
| lt~obsolete.m4 | ||
| MAINTAINERS | ||
| Makefile.def | ||
| Makefile.in | ||
| Makefile.tpl | ||
| missing | ||
| mkdep | ||
| mkinstalldirs | ||
| move-if-change | ||
| README | ||
| symlink-tree | ||
| ylwrap | ||
This directory contains the GNU Compiler Collection (GCC). The GNU Compiler Collection is free software. See the files whose names start with COPYING for copying permission. The manuals, and some of the runtime libraries, are under different terms; see the individual source files for details. The directory INSTALL contains copies of the installation information as HTML and plain text. The source of this information is gcc/doc/install.texi. The installation information includes details of what is included in the GCC sources and what files GCC installs. See the file gcc/doc/gcc.texi (together with other files that it includes) for usage and porting information. An online readable version of the manual is in the files gcc/doc/gcc.info*. See http://gcc.gnu.org/bugs/ for how to report bugs usefully. Copyright years on GCC source files may be listed using range notation, e.g., 1987-2012, indicating that every year in the range, inclusive, is a copyrightable year that could otherwise be listed individually.