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Re: [Qemu-devel] [PATCH] disas/libvixl: Fix VIXL_FALLTHROUGH macro for Q
From: |
Stefan Weil |
Subject: |
Re: [Qemu-devel] [PATCH] disas/libvixl: Fix VIXL_FALLTHROUGH macro for QEMU |
Date: |
Tue, 15 May 2018 15:13:33 +0200 |
User-agent: |
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 |
Am 15.05.2018 um 14:13 schrieb Peter Maydell:
> On 13 May 2018 at 10:57, Stefan Weil <address@hidden> wrote:
>> Even with the above patch, disas/libvixl raises a compiler warning for a
>> fall through case. The patch below fixes that warning, but I am not sure
>> whether a fall through is correct there.
>>
>> Stefan
>>
>>
>> diff --git a/disas/libvixl/vixl/a64/disasm-a64.cc
>> b/disas/libvixl/vixl/a64/disasm-a64.cc
>> index 7a58a5c087..5481d94209 100644
>> --- a/disas/libvixl/vixl/a64/disasm-a64.cc
>> +++ b/disas/libvixl/vixl/a64/disasm-a64.cc
>> @@ -2986,6 +2986,7 @@ int Disassembler::SubstituteImmediateField(const
>> Instruction* instr,
>> return 3;
>> }
>> }
>> + VIXL_FALLTHROUGH(); // ???
>> }
>> case 'C': { // ICondB - Immediate Conditional Branch.
>> int64_t offset = instr->ImmCondBranch() << 2;
> This is fixed in upstream vixl, in fact:
>
> https://git.linaro.org/arm/vixl.git/commit/?id=de326f850f736c3a337fda52845ed3d2e620cc02
>
> thanks
> -- PMM
That fix will work for the moment, but is not sufficient for the future
because it only supports gcc 7.x, but not gcc 8.x or later:
+#elif __GNUC__ == 7
How do we proceed with the code in QEMU? Do you have a plan to update
the vixl code? As vixl is obviously no longer maintained on GitHub, I am
not sure whom I could contact.
And what about my other question / suggestion:
"I suggest to add and use a similar macro QEMU_FALLTHROUGH() for the
rest of the code and can provide a patch if that's fine for everyone."
gcc gives lots of fallthrough warnings, and many code locations don't contain a
comment stating that the fall through is fine.
Thanks
Stefan
- [Qemu-devel] [PATCH] disas/libvixl: Fix VIXL_FALLTHROUGH macro for QEMU, Stefan Weil, 2018/05/13
- Re: [Qemu-devel] [PATCH] disas/libvixl: Fix VIXL_FALLTHROUGH macro for QEMU, Stefan Weil, 2018/05/13
- Re: [Qemu-devel] [PATCH] disas/libvixl: Fix VIXL_FALLTHROUGH macro for QEMU, Peter Maydell, 2018/05/13
- Re: [Qemu-devel] [PATCH] disas/libvixl: Fix VIXL_FALLTHROUGH macro for QEMU, Peter Maydell, 2018/05/15
- Re: [Qemu-devel] [PATCH] disas/libvixl: Fix VIXL_FALLTHROUGH macro for QEMU,
Stefan Weil <=
- Re: [Qemu-devel] [PATCH] disas/libvixl: Fix VIXL_FALLTHROUGH macro for QEMU, Peter Maydell, 2018/05/15
- Re: [Qemu-devel] [PATCH] disas/libvixl: Fix VIXL_FALLTHROUGH macro for QEMU, Richard Henderson, 2018/05/15
- Re: [Qemu-devel] [PATCH] disas/libvixl: Fix VIXL_FALLTHROUGH macro for QEMU, Peter Maydell, 2018/05/15
- Re: [Qemu-devel] [PATCH] disas/libvixl: Fix VIXL_FALLTHROUGH macro for QEMU, Peter Maydell, 2018/05/18
- Re: [Qemu-devel] [PATCH] disas/libvixl: Fix VIXL_FALLTHROUGH macro for QEMU, Richard Henderson, 2018/05/18
- Re: [Qemu-devel] [PATCH] disas/libvixl: Fix VIXL_FALLTHROUGH macro for QEMU, Peter Maydell, 2018/05/17