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Re: [Qemu-ppc] [PATCH] target/ppc: fix compilation breakage on windows
From: |
David Gibson |
Subject: |
Re: [Qemu-ppc] [PATCH] target/ppc: fix compilation breakage on windows |
Date: |
Mon, 17 Dec 2018 15:50:22 +1100 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
On Sat, Dec 15, 2018 at 07:42:22PM +0100, Cédric Le Goater wrote:
> Fix the PPC_BIT definitions to use ULL instead in UL and replace
> __builtin_ffssl() by the equivalent ctz routines.
>
> Signed-off-by: Cédric Le Goater <address@hidden>
> ---
>
> Compile tested with --cross-prefix=x86_64-w64-mingw32-. When I have
> some more time, I might try runtime on windows also.
Which version of the mingw compiler do you have? As I've noted
elsewhere, I haven't been able to reproduce the problem with the mingw
in Fedora 29.
> The PPC compile failures have been there for a while (pre 2.12) and
> the MASK_TO_LSH macro was not used until the XIVE definitions were
> introduced.
>
> I let you guys decide on how you want to proceed, but I think it is
> safe to merge this patch as a prereq of the pull request.
>
> Thanks,
>
> C.
>
> target/ppc/cpu.h | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index ab68abe8a23c..a3d3e91eb4ce 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -70,18 +70,18 @@
> #define PPC_ELF_MACHINE EM_PPC
> #endif
>
> -#define PPC_BIT(bit) (0x8000000000000000UL >> (bit))
> -#define PPC_BIT32(bit) (0x80000000UL >> (bit))
> -#define PPC_BIT8(bit) (0x80UL >> (bit))
> +#define PPC_BIT(bit) (0x8000000000000000ULL >> (bit))
> +#define PPC_BIT32(bit) (0x80000000ULL >> (bit))
> +#define PPC_BIT8(bit) (0x80ULL >> (bit))
We shouldn't need the ULL for the 32-bit and (especially) 8-bit
versions.
> #define PPC_BITMASK(bs, be) ((PPC_BIT(bs) - PPC_BIT(be)) | PPC_BIT(bs))
> #define PPC_BITMASK32(bs, be) ((PPC_BIT32(bs) - PPC_BIT32(be)) | \
> PPC_BIT32(bs))
> #define PPC_BITMASK8(bs, be) ((PPC_BIT8(bs) - PPC_BIT8(be)) |
> PPC_BIT8(bs))
>
> #if HOST_LONG_BITS == 32
> -# define MASK_TO_LSH(m) (__builtin_ffsll(m) - 1)
> +# define MASK_TO_LSH(m) ctz32(m)
> #elif HOST_LONG_BITS == 64
> -# define MASK_TO_LSH(m) (__builtin_ffsl(m) - 1)
> +# define MASK_TO_LSH(m) ctz64(m)
Having another look at this, this seems bogus: we're defining an
interface that's only correct on a *host long*. But when we use it
we're almost certain to be working on guest values with a fixed size,
so using this wrapper just adds confusion.
I'm not really seeing any reason to use MASK_TO_LSH() rather than
using ctz32() and ctz64() explicitly.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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