On 11/24/2021 4:48 PM, Raoni Fassina Firmino via Gcc-patches wrote:
Changes since v6[6] and v5[5]:
- Based this version on the v5 one.
- Reworked all builtins back to the way they are in v5 and added the
following changes:
+ Added a test to target libc, only expanding with glibc as the
target libc.
+ Updated all three expanders header comment to reflect the added
behavior (fegetround got a full header as it had none).
+ Added extra documentation for the builtins on doc/extend.texi,
similar to v6 version, but only the introductory paragraph,
without a dedicated entry for each, since now they behavior and
signature match the C99 ones.
- Changed the description for the return operand in the RTL template
of the fegetround expander. Using "(set )", the same way as
rs6000_mffsl expander (this change was taken from v6).
- Updated the commit message mentioning the target libc restriction
and updated changelog.
Tested on top of master (9bf69a8558638ce0cdd69e83a68776deb9b8e053)
on the following plataforms with no regression:
- powerpc64le-linux-gnu (Power 9)
- powerpc64le-linux-gnu (Power 8)
- powerpc64-linux-gnu (Power 9, with 32 and 64 bits tests)
Also made a visual test comparing the generated assembly of a test
program built against glibc and musl (with -mmusl and with musl-gcc).
Documentation changes tested on x86_64-redhat-linux.
Well, turns out v6 was kind of a misstep[7]. But turns out the
solution was in my face the whole time and Joseph was kind enough to
spell it out to me. I should have known, one can check for the target
libc at runtime. It is a really simple addition to each expander, only
expanding for the libcs the expander know the FE_* and can handle it.
As Joseph mentioned on his review, with that the expander don't have
to always expand and everything is fine.
As I mentioned[8], musl and uclibc both uses the same values as glibc,
I could add then enabling the expanders for them, not sure about it.
I don't know if I should add something to the documentation, more
precisely on section "6.59 Other Built-in Functions Provided by GCC"
in doc/extend.text. Like I mentioned in v6 but I don't know if I'm
doing it right, especially changing such a front facing documentation,
but here it is.
I'm repeating the "changelog" from past versions here for convenience:
Changes since v5[5]:
- Reworked all builtins to accept the FE_* macros as parameters and
so be agnostic to libc implementations. Largely based of
fpclassify. To that end, there is some new files changed:
+ Change the argument list for the builtins declarations in
builtins.def
+ Added new types in builtin-types.def to use in the buitins
declarations.
+ Added extra documentation for the builtins on doc/extend.texi,
similar to fpclassify.
- Updated doc/md.texi documentation with the new optab behaviors.
- Updated comments to the expanders and expand handlers to try to
explain whats is going on.
- Changed the description for the return operand in the RTL template
of the fegetround expander. Using "(set )", the same way as
rs6000_mffsl expander.
- Updated testcases with helper macros with the new argument list.
Changes since v4[4]:
- Fixed more spelling and code style.
- Add more clarification on comments for feraiseexcept and
feclearexcept expands;
Changes since v3[3]:
- Fixed fegetround bug on powerpc64 (big endian) that Segher
spotted;
Changes since v2[2]:
- Added documentation for the new optabs;
- Remove use of non portable __builtin_clz;
- Changed feclearexcept and feraiseexcept to accept all 4 valid
flags at the same time and added more test for that case;
- Extended feclearexcept and feraiseexcept testcases to match
accepting multiple flags;
- Fixed builtin-feclearexcept-feraiseexcept-2.c testcase comparison
after feclearexcept tests;
- Updated commit message to reflect change in feclearexcept and
feraiseexcept from the glibc counterpart;
- Fixed English spelling and typos;
- Fixed code-style;
- Changed subject line tag to make clear it is not just rs6000 code.
Changes since v1[1]:
- Fixed English spelling;
- Fixed code-style;
- Changed match operand predicate in feclearexcept and feraiseexcept;
- Changed testcase options;
- Minor changes in test code to be C90 compatible;
- Other minor changes suggested by Segher;
- Changed subject line tag (not sure if I tagged correctly or should
include optabs: also)
[1] https://gcc.gnu.org/pipermail/gcc-patches/2020-August/552024.html
[2] https://gcc.gnu.org/pipermail/gcc-patches/2020-September/553297.html
[3] https://gcc.gnu.org/pipermail/gcc-patches/2020-October/557109.html
[4] https://gcc.gnu.org/pipermail/gcc-patches/2020-October/557349.html
[5] https://gcc.gnu.org/pipermail/gcc-patches/2020-November/557984.html
[6] https://gcc.gnu.org/pipermail/gcc-patches/2021-October/581837.html
[7] https://gcc.gnu.org/pipermail/gcc-patches/2021-October/581929.html
[8] https://gcc.gnu.org/pipermail/gcc-patches/2020-November/558070.html
---- 8< ----
This optimizations were originally in glibc, but was removed
and suggested that they were a good fit as gcc builtins[1].
feclearexcept and feraiseexcept were extended (in comparison to the
glibc version) to accept any combination of the accepted flags, not
limited to just one flag bit at a time anymore.
The builtin expanders needs knowledge of the target libc's FE_*
values, so they are limited to expand only to suitable libcs.
The associated bugreport: PR target/94193
[1] https://sourceware.org/legacy-ml/libc-alpha/2020-03/msg00047.html
https://sourceware.org/legacy-ml/libc-alpha/2020-03/msg00080.html
2020-08-13 Raoni Fassina Firmino <ra...@linux.ibm.com>
gcc/ChangeLog:
* builtins.c (expand_builtin_fegetround): New function.
(expand_builtin_feclear_feraise_except): New function.
(expand_builtin): Add cases for BUILT_IN_FEGETROUND,
BUILT_IN_FECLEAREXCEPT and BUILT_IN_FERAISEEXCEPT
* config/rs6000/rs6000.md (fegetroundsi): New pattern.
(feclearexceptsi): New Pattern.
(feraiseexceptsi): New Pattern.
* doc/extend.texi: Add a new introductory paragraph about the
new builtins.
* doc/md.texi: (fegetround@var{m}): Document new optab.
(feclearexcept@var{m}): Document new optab.
(feraiseexcept@var{m}): Document new optab.
* optabs.def (fegetround_optab): New optab.
(feclearexcept_optab): New optab.
(feraiseexcept_optab): New optab.
gcc/testsuite/ChangeLog:
* gcc.target/powerpc/builtin-feclearexcept-feraiseexcept-1.c: New test.
* gcc.target/powerpc/builtin-feclearexcept-feraiseexcept-2.c: New test.
* gcc.target/powerpc/builtin-fegetround.c: New test.
I think the generic parts are fine once Segher is happy with the rest of
the bits.
jeff
