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From: "matz at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/96895] ABI of returning V1DF differs between GCC and clang
Date: Wed, 02 Sep 2020 12:14:26 +0000	[thread overview]
Message-ID: <bug-96895-4-6KvesQqrig@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-96895-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96895

--- Comment #2 from Michael Matz <matz at gcc dot gnu.org> ---
The psABI doesn't say anything about such types, no.  Maybe it could in some
additional info pages, but it's always a problem to codify behaviour
retroactively
in it, when conflicting implementations already exist.  It is about extension
types, though, so we might be fine.

FWIW, even ignoring the obvious relation of v1Xf to Xf, GCC behaviour for float
and clang behaviour for double is the most logical one: this extended type is
most
similar to a struct containing one float/double, and such are passed in XMM
registers per psABI.  As this is also consistent with how a single
top-level float is passed, this choice is the most consistent one.  This is
also
what the psABI _would_ say, if we had written it into it, so at least both
compilers would need a change to implement it.

  parent reply	other threads:[~2020-09-02 12:14 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-02  8:24 [Bug target/96895] New: " rguenth at gcc dot gnu.org
2020-09-02  8:29 ` [Bug target/96895] " rguenth at gcc dot gnu.org
2020-09-02 12:14 ` matz at gcc dot gnu.org [this message]
2020-09-02 12:15 ` hjl.tools at gmail dot com
2020-09-02 12:18 ` hjl.tools at gmail dot com
2020-09-02 14:08 ` rguenth at gcc dot gnu.org
2020-09-02 14:16 ` rguenth at gcc dot gnu.org
2020-09-02 14:28 ` matz at gcc dot gnu.org
2023-12-04 10:18 ` egallager at gcc dot gnu.org

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