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Re: [PATCH 2/2] target/arm: Relax r13 restriction for ldrex/strex for v8
From: |
Richard Henderson |
Subject: |
Re: [PATCH 2/2] target/arm: Relax r13 restriction for ldrex/strex for v8.0 |
Date: |
Mon, 18 Nov 2019 21:02:17 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 |
On 11/18/19 6:53 PM, Peter Maydell wrote:
> On Mon, 18 Nov 2019 at 13:16, Richard Henderson
> <address@hidden> wrote:
>>
>> On 11/18/19 2:10 PM, Peter Maydell wrote:
>>>> /* We UNDEF for these UNPREDICTABLE cases. */
>>>> if (a->rn == 15 || a->rt == 15
>>>> - || (s->thumb && a->rt == 13)
>>>> + || (!ENABLE_ARCH_8 && s->thumb && a->rt == 13)
>>>> || (mop == MO_64
>>>> && (a->rt2 == 15 || a->rt == a->rt2
>>>> - || (s->thumb && a->rt2 == 13)))) {
>>>> + || (!ENABLE_ARCH_8 && s->thumb && a->rt2 == 13)))) {
>>>> unallocated_encoding(s);
>>>> return true;
>>>> }
>>>
>>> These cases for r13 are indeed no longer UNPREDICTABLE in
>>> v8A, but they are still marked as UNPREDICTABLE for v8M...
>>
>> Ho hum. I knew I should have looked at that doc as well...
>
> I would like to get this in for rc2 tomorrow, so I propose
> to squash in changes to give the following result (basically
> turning the ENABLE_ARCH_8 checks into checks on a new bool 'v8a'):
>
>
> diff --git a/target/arm/translate.c b/target/arm/translate.c
> index b285b23858e..4d5d4bd8886 100644
> --- a/target/arm/translate.c
> +++ b/target/arm/translate.c
> @@ -8927,15 +8927,17 @@ static bool trans_SWPB(DisasContext *s, arg_SWP *a)
> static bool op_strex(DisasContext *s, arg_STREX *a, MemOp mop, bool rel)
> {
> TCGv_i32 addr;
> + /* Some cases stopped being UNPREDICTABLE in v8A (but not v8M) */
> + bool v8a = ENABLE_ARCH_8 && !arm_dc_feature(s, ARM_FEATURE_M);
Sorry, I wrote the patch but got distracted with other bugs without getting
around to posting. I had solved this with a new ENABLE_ARCH_8A, but this
version works for me as well.
Thanks,
r~