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Re: [Qemu-arm] [PATCH v6 00/35] target/arm SVE patches
From: |
Peter Maydell |
Subject: |
Re: [Qemu-arm] [PATCH v6 00/35] target/arm SVE patches |
Date: |
Thu, 28 Jun 2018 15:55:10 +0100 |
On 28 June 2018 at 15:12, Peter Maydell <address@hidden> wrote:
> On 28 June 2018 at 12:30, Alex Bennée <address@hidden> wrote:
>> loading test image
>> address@hidden/insn_sdiv_z_p_zz___INC.risu.bin...
>> starting apprentice image at 0x4000801000
>> starting image
>> fish: “../qemu.git/aarch64-linux-user/…” terminated by signal SIGFPE
>> (Floating point exception)
>
> Do you have the insn that it's barfing on? In particular,
> I'm guessing from the test name that this is for something
> covered by one of the SDIV_zpzz lines in sve.decode, which
> is already in master rather than in this test series.
> If that's true, then it shouldn't block applying this set...
Further discussion on IRC suggests that this is failing on
MININT idiv -1, which is an annoying special case that x86
happens to generate SIGFPE for. Compare our HELPER(sdiv) code:
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;
}
with what we do for SVE:
#define DO_DIV(N, M) (M ? N / M : 0)
This is OK for unsigned division, but signed division needs to
special case INT_MIN / -1.
In any case, this is in an existing insn, so I'm going to apply
this series to target-arm.next (fixing up the patch 5 comment
typo).
thanks
-- PMM
- [Qemu-arm] [PATCH v6 31/35] target/arm: Implement SVE fp complex multiply add (indexed), (continued)
- [Qemu-arm] [PATCH v6 31/35] target/arm: Implement SVE fp complex multiply add (indexed), Richard Henderson, 2018/06/27
- [Qemu-arm] [PATCH v6 33/35] target/arm: Implement SVE dot product (indexed), Richard Henderson, 2018/06/27
- [Qemu-arm] [PATCH v6 34/35] target/arm: Enable SVE for aarch64-linux-user, Richard Henderson, 2018/06/27
- [Qemu-arm] [PATCH v6 35/35] target/arm: Implement ARMv8.2-DotProd, Richard Henderson, 2018/06/27
- Re: [Qemu-arm] [PATCH v6 00/35] target/arm SVE patches, Alex Bennée, 2018/06/28
- Re: [Qemu-arm] [PATCH v6 00/35] target/arm SVE patches, Alex Bennée, 2018/06/28