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Re: [Qemu-devel] [PATCH] target-arm: fix sdiv helper
From: |
Laurent Desnogues |
Subject: |
Re: [Qemu-devel] [PATCH] target-arm: fix sdiv helper |
Date: |
Sun, 18 Oct 2009 16:29:00 +0200 |
On Thu, Oct 15, 2009 at 11:08 PM, Aurelien Jarno <address@hidden> wrote:
> (INT32_MIN / -1) triggers an overflow, and the result depends on the
> host architecture (INT32_MIN on arm, -1 on ppc, SIGFPE on x86). Use a
> test to output the correct value.
>
> Signed-off-by: Aurelien Jarno <address@hidden>
> ---
> target-arm/helper.c | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index 701629a..b3d6198 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -404,6 +404,8 @@ int32_t HELPER(sdiv)(int32_t num, int32_t den)
> {
> if (den == 0)
> return 0;
> + if (num == INT_MIN && den == -1)
> + return INT_MIN;
> return num / den;
> }
>
> --
> 1.6.1.3
Acked-by: Laurent Desnogues <address@hidden>
That is provided we accept the behaviour for division by zero is
not strictly conforming to what the ARM ARM says.
Also note this instruction is not available on v7-A CPU's (Cortex-A8
for instance). It's part of v7-R (Cortex R4).
Laurent