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* [Bug target/105359] New: _Float128 expanders and builtins disabled on ppc targets with 64-bit long double
@ 2022-04-23 13:49 aoliva at gcc dot gnu.org
2022-04-27 5:24 ` [Bug target/105359] " aoliva at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: aoliva at gcc dot gnu.org @ 2022-04-23 13:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105359
Bug ID: 105359
Summary: _Float128 expanders and builtins disabled on ppc
targets with 64-bit long double
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: aoliva at gcc dot gnu.org
Target Milestone: ---
Target: rs6000
As described elsewhere, some tests fail on targets with 64-bit long double,
because of patterns that (IMHO incorrectly) use TARGET_LONG_DOUBLE_128 in their
conditions, and because of type compatibility tests that only accept _Float128
types under the same condition.
https://gcc.gnu.org/pipermail/gcc-patches/2022-April/593257.html
https://gcc.gnu.org/pipermail/gcc-patches/2022-April/593515.html
There doesn't seem to be a reason for the patterns to conditioned on long
double being a 128-bit type: that's too strict. A laxer condition, covering
the requirements for _Float128 to be *supported*, ought to be enough.
Furthermore, there doesn't seem to be any reason for -mlong-double-64 to
disable those patterns even on target variants that use 128-bit long double.
It's too late to fix this for GCC 12, but hopefully some rs6000/powerpc
maintainer will agree that there's no reason to tie support for insn patterns
and builtins for _Float128 with long double's being the same type as _Float128.
It looks like all of the troublesome patterns have TARGET_HARD_FLOAT &&
TARGET_LONG_DOUBLE_128. I hope this problem could be fixed by replacing the
latter with TARGET_FLOAT128_TYPE, but I'll defer to more knowledgeable port
maintainers.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug target/105359] _Float128 expanders and builtins disabled on ppc targets with 64-bit long double
2022-04-23 13:49 [Bug target/105359] New: _Float128 expanders and builtins disabled on ppc targets with 64-bit long double aoliva at gcc dot gnu.org
@ 2022-04-27 5:24 ` aoliva at gcc dot gnu.org
2024-04-23 9:13 ` linkw at gcc dot gnu.org
2024-05-23 6:24 ` cvs-commit at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: aoliva at gcc dot gnu.org @ 2022-04-27 5:24 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105359
--- Comment #1 from Alexandre Oliva <aoliva at gcc dot gnu.org> ---
pr82748-1.c is another victim of this issue. do_copysign_ld needs to convert
between (64-bit) long double and __ieee128 for __builtin_copysignq, and since
the expanders for these conversions are conditioned on TARGET_LONG_DOUBLE_128,
we end up issuing libcalls, but the test doesn't want any 'bl' opcode.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug target/105359] _Float128 expanders and builtins disabled on ppc targets with 64-bit long double
2022-04-23 13:49 [Bug target/105359] New: _Float128 expanders and builtins disabled on ppc targets with 64-bit long double aoliva at gcc dot gnu.org
2022-04-27 5:24 ` [Bug target/105359] " aoliva at gcc dot gnu.org
@ 2024-04-23 9:13 ` linkw at gcc dot gnu.org
2024-05-23 6:24 ` cvs-commit at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: linkw at gcc dot gnu.org @ 2024-04-23 9:13 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105359
Kewen Lin <linkw at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2024-04-23
Keywords| |missed-optimization
Assignee|unassigned at gcc dot gnu.org |linkw at gcc dot gnu.org
CC| |linkw at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #2 from Kewen Lin <linkw at gcc dot gnu.org> ---
Thanks for reporting, I'll have a look.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug target/105359] _Float128 expanders and builtins disabled on ppc targets with 64-bit long double
2022-04-23 13:49 [Bug target/105359] New: _Float128 expanders and builtins disabled on ppc targets with 64-bit long double aoliva at gcc dot gnu.org
2022-04-27 5:24 ` [Bug target/105359] " aoliva at gcc dot gnu.org
2024-04-23 9:13 ` linkw at gcc dot gnu.org
@ 2024-05-23 6:24 ` cvs-commit at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2024-05-23 6:24 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105359
--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Alexandre Oliva <aoliva@gcc.gnu.org>:
https://gcc.gnu.org/g:dbdddc92a3b955fce71af47755c226132559eda2
commit r15-786-gdbdddc92a3b955fce71af47755c226132559eda2
Author: Alexandre Oliva <oliva@adacore.com>
Date: Thu May 23 03:20:19 2024 -0300
[testsuite] xfail pr79004 on longdouble64; drop long_double_64bit
Some of the asm opcodes expected by pr79004 depend on
-mlong-double-128 to be output. E.g., without this flag, the
conditions of patterns @extenddf<mode>2 and extendsf<mode>2 do not
hold, and so GCC resorts to libcalls instead of even trying
rs6000_expand_float128_convert.
Perhaps the conditions are too strict, and they could enable the use
of conversion insns involving __ieee128/_Float128 even with 64-bit
long doubles.
For now, xfail the opcodes that are not available on longdouble64.
While at that, drop long_double_64bit, since it's broken and sort of
redundant.
for gcc/testsuite/ChangeLog
PR target/105359
* gcc.target/powerpc/pr79004.c: Xfail opcodes not available on
longdouble64.
* lib/target-supports.exp
(check_effective_target_long_double_64bit): Drop.
(add_options_for_long_double_64bit): Likewise.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2022-04-23 13:49 [Bug target/105359] New: _Float128 expanders and builtins disabled on ppc targets with 64-bit long double aoliva at gcc dot gnu.org
2022-04-27 5:24 ` [Bug target/105359] " aoliva at gcc dot gnu.org
2024-04-23 9:13 ` linkw at gcc dot gnu.org
2024-05-23 6:24 ` cvs-commit at gcc dot gnu.org
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