f824216cdb
I finally got around to trying out the define_subst approach for PR target/99195. The problem we have is that many Advanced SIMD instructions have 64-bit vector variants that clear the top half of the 128-bit Q register. This would allow the compiler to avoid generating explicit zeroing instructions to concat the 64-bit result with zeroes for code like: vcombine_u16(vadd_u16(a, b), vdup_n_u16(0)) We've been getting user reports of GCC missing this optimisation in real world code, so it's worth doing something about it. The straightforward approach that we've been taking so far is adding extra patterns in aarch64-simd.md that match the 64-bit result in a vec_concat with zeroes. Unfortunately for big-endian the vec_concat operands to match have to be the other way around, so we would end up adding two extra define_insns. This would lead to too much bloat in aarch64-simd.md This patch defines a pair of define_subst constructs that allow us to annotate patterns in aarch64-simd.md with the <vczle> and <vczbe> subst_attrs and the compiler will automatically produce the vec_concat widening patterns, properly gated for BYTES_BIG_ENDIAN when needed. This seems like the least intrusive way to describe the extra zeroing semantics. I've had a look at the generated insn-*.cc files in the build directory and it seems that define_subst does what we want it to do when applied multiple times on a pattern in terms of insn conditions and modes. This patch adds the define_subst machinery and adds the annotations to some of the straightforward binary and unary integer operations. Many more such annotations are possible and I aim add them in future patches if this approach is acceptable. Bootstrapped and tested on aarch64-none-linux-gnu and on aarch64_be-none-elf. gcc/ChangeLog: PR target/99195 * config/aarch64/aarch64-simd.md (add_vec_concat_subst_le): Define. (add_vec_concat_subst_be): Likewise. (vczle): Likewise. (vczbe): Likewise. (add<mode>3): Rename to... (add<mode>3<vczle><vczbe>): ... This. (sub<mode>3): Rename to... (sub<mode>3<vczle><vczbe>): ... This. (mul<mode>3): Rename to... (mul<mode>3<vczle><vczbe>): ... This. (and<mode>3): Rename to... (and<mode>3<vczle><vczbe>): ... This. (ior<mode>3): Rename to... (ior<mode>3<vczle><vczbe>): ... This. (xor<mode>3): Rename to... (xor<mode>3<vczle><vczbe>): ... This. * config/aarch64/iterators.md (VDZ): Define. gcc/testsuite/ChangeLog: PR target/99195 * gcc.target/aarch64/simd/pr99195_1.c: New test. |
||
|---|---|---|
| c++tools | ||
| config | ||
| contrib | ||
| fixincludes | ||
| gcc | ||
| gnattools | ||
| gotools | ||
| include | ||
| INSTALL | ||
| intl | ||
| libada | ||
| libatomic | ||
| libbacktrace | ||
| libcc1 | ||
| libcody | ||
| libcpp | ||
| libdecnumber | ||
| libffi | ||
| libgcc | ||
| libgfortran | ||
| libgm2 | ||
| libgo | ||
| libgomp | ||
| libiberty | ||
| libitm | ||
| libobjc | ||
| libphobos | ||
| libquadmath | ||
| libsanitizer | ||
| libssp | ||
| libstdc++-v3 | ||
| libvtv | ||
| lto-plugin | ||
| maintainer-scripts | ||
| zlib | ||
| .dir-locals.el | ||
| .gitattributes | ||
| .gitignore | ||
| ABOUT-NLS | ||
| ar-lib | ||
| 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 | ||
| multilib.am | ||
| README | ||
| symlink-tree | ||
| test-driver | ||
| 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.