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Re: [Qemu-devel] [PATCH v2 06/27] int128: Use complex numbers if advisab
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH v2 06/27] int128: Use complex numbers if advisable |
Date: |
Mon, 4 Jul 2016 13:07:55 +0100 |
On 1 July 2016 at 18:04, Richard Henderson <address@hidden> wrote:
> If __int128 is not supported, prefer a base type that is
> returned in registers rather than memory.
So which host architectures does this improve?
128 bit integers are nothing to do with complex numbers,
so we ought to have a strong justification for abusing
the _Complex type.
The ifdef suggests this only helps ppc and sparc, which
to my mind is not a sufficient justification.
If there's much benefit from doing this then it would be
better for the compiler on those architectures to support
int128 as a proper native type returned in registers.
> +#if defined(__GNUC__) \
> + && (defined(__powerpc__) || defined(__sparc__)) \
> + && !defined(CONFIG_TCG_INTERPRETER)
Why the CONFIG_TCG_INTERPRETER clause ?
thanks
-- PMM
- [Qemu-devel] [PATCH v2 04/27] int128: Use __int128 if available, (continued)
- [Qemu-devel] [PATCH v2 04/27] int128: Use __int128 if available, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 03/27] exec: Avoid direct references to Int128 parts, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 02/27] atomics: add atomic_op_fetch variants, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 08/27] HACK: Always enable parallel_cpus, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 01/27] atomics: add atomic_xor, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 11/27] target-i386: emulate LOCK'ed cmpxchg using cmpxchg helpers, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 06/27] int128: Use complex numbers if advisable, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 10/27] tcg: Add atomic128 helpers, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 07/27] tcg: Add EXCP_ATOMIC, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 13/27] target-i386: emulate LOCK'ed INC using atomic helper, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 09/27] tcg: Add atomic helpers, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 15/27] target-i386: emulate LOCK'ed NEG using cmpxchg helper, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 16/27] target-i386: emulate LOCK'ed XADD using atomic helper, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 12/27] target-i386: emulate LOCK'ed OP instructions using atomic helpers, Richard Henderson, 2016/07/01
- [Qemu-devel] [PATCH v2 14/27] target-i386: emulate LOCK'ed NOT using atomic helper, Richard Henderson, 2016/07/01