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Re: [Qemu-devel] [PATCH v5 45/76] target/mips: Implement emulation of na
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH v5 45/76] target/mips: Implement emulation of nanoMIPS LLWP/SCWP pair |
Date: |
Thu, 2 Aug 2018 13:28:31 -0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
On 08/02/2018 08:29 AM, Aleksandar Markovic wrote:
> Hi, Richard,
>
> We are going to remove obsoleted helpers, that was just an honest mistake
> made in a rush.
>
> For unprotected access to gpr, we are going to insert if(reg1 != 0) in two
> places.
Be careful that you do not eliminate side effects in the process. This
includes things like check_dspr2, and any helper that sets overflow_flag or
carry_flag.
I cannot see how you will avoid that when adding only two if statements.
> However, it looks there is a bigger problem now in SCWP. QEMU crashes with
> this message:
>
> /qemu/tcg/tcg.c:2862: tcg fatal error
>
> This happens in user mode only, system mode case runs fine.
>
> the problem seems to appear as a consequence of using tcg_gen_brcond_*(().
>
> Do you have any idea what are we doing wrong here?
If you send me a binary that triggers this error, I'll look at it.
r~