public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug target/95471] New: vrndvq_f32 not supported on armv8
@ 2020-06-02 1:50 evan@coeus-group.com
2020-06-02 8:43 ` [Bug target/95471] " ktkachov at gcc dot gnu.org
2020-06-02 17:50 ` evan@coeus-group.com
0 siblings, 2 replies; 3+ messages in thread
From: evan@coeus-group.com @ 2020-06-02 1:50 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95471
Bug ID: 95471
Summary: vrndvq_f32 not supported on armv8
Product: gcc
Version: 9.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: evan@coeus-group.com
Target Milestone: ---
With -march=armv8-a -mfpu=neon, arm_neon.h exposes vrndnq_f32, but the
intrinsic used to implement it (__builtin_neon_vrintnv4sf) emits an "error:
this builtin is not supported for this target".
Here is a trivial test case:
#include <arm_neon.h>
#if defined(__ARM_NEON)
float32x4_t foo(float32x4_t a) {
return vrndnq_f32(a);
}
#endif
On Compiler Explorer: https://godbolt.org/z/ThfJQe
Relevant documentation from ARM:
<https://developer.arm.com/architectures/instruction-sets/simd-isas/neon/intrinsics?search=vrndnq_f32>.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug target/95471] vrndvq_f32 not supported on armv8
2020-06-02 1:50 [Bug target/95471] New: vrndvq_f32 not supported on armv8 evan@coeus-group.com
@ 2020-06-02 8:43 ` ktkachov at gcc dot gnu.org
2020-06-02 17:50 ` evan@coeus-group.com
1 sibling, 0 replies; 3+ messages in thread
From: ktkachov at gcc dot gnu.org @ 2020-06-02 8:43 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95471
ktkachov at gcc dot gnu.org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |INVALID
CC| |ktkachov at gcc dot gnu.org
--- Comment #1 from ktkachov at gcc dot gnu.org ---
-mfpu=neon doesn't support the Neon features from Armv8-A.
The recommended way is to use -mfpu=auto and use an appropriate -mcpu or -march
option.
In this case, using -march=armv8-a+simd -mfpu=auto generates the instruction.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug target/95471] vrndvq_f32 not supported on armv8
2020-06-02 1:50 [Bug target/95471] New: vrndvq_f32 not supported on armv8 evan@coeus-group.com
2020-06-02 8:43 ` [Bug target/95471] " ktkachov at gcc dot gnu.org
@ 2020-06-02 17:50 ` evan@coeus-group.com
1 sibling, 0 replies; 3+ messages in thread
From: evan@coeus-group.com @ 2020-06-02 17:50 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95471
--- Comment #2 from Evan Nemerson <evan@coeus-group.com> ---
In that case shouldn't the header be adjusted to not define the vrndvq_f32
function unless it is enabled?
It is already guarded by a check for __ARM_ARCH >= 8 (see
<https://github.com/gcc-mirror/gcc/blob/95827968e5f3e472bbef0ad8b65b0a7537c9cee3/gcc/config/arm/arm_neon.h#L1757>,
but obviously that isn't sufficient. If nothing else it would help document
the actual requirements, which would be great since the flags and macros on ARM
are a bit of a mess.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-06-02 17:50 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-06-02 1:50 [Bug target/95471] New: vrndvq_f32 not supported on armv8 evan@coeus-group.com
2020-06-02 8:43 ` [Bug target/95471] " ktkachov at gcc dot gnu.org
2020-06-02 17:50 ` evan@coeus-group.com
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).