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Re: [RFC PATCH 02/13] target/riscv: Support UXL32 for branch instruction
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From: |
LIU Zhiwei |
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Subject: |
Re: [RFC PATCH 02/13] target/riscv: Support UXL32 for branch instructions |
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Date: |
Thu, 12 Aug 2021 13:03:07 +0800 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 |
On 2021/8/12 下午12:42, Richard Henderson wrote:
On 8/11/21 12:40 PM, LIU Zhiwei wrote:
If the software doesn't use the high part, who cares the really value
in high part? Do you know the benefit? Thanks again.
I do not.
I simply presume that they already have the hardware, in the form of
the addw instruction, etc.
The mistake, I think, was changing the definition of "add" in the
first place, which required the addition of a different opcode "addw",
which is then undefined for RV32.
Sorry, I don't get "the mistake" here. Do you think the specification is
not right.
Or the QEMU implementation of this patch set is not right?
Currently I don't know there is a 64-bit hardware which has done with
UXL32.
They should simply have had "addw" and "addq" as different opcodes
that didn't change behaviour. Etc.
I don't get this statement. Is it related to UXL32?
Best Regards,
Zhiwei
But what's done is done.
r~
- Re: [RFC PATCH 01/13] target/riscv: Add UXL to tb flags, (continued)
- [RFC PATCH 02/13] target/riscv: Support UXL32 for branch instructions, LIU Zhiwei, 2021/08/04
- Re: [RFC PATCH 02/13] target/riscv: Support UXL32 for branch instructions, Richard Henderson, 2021/08/05
- Re: [RFC PATCH 02/13] target/riscv: Support UXL32 for branch instructions, LIU Zhiwei, 2021/08/08
- Re: [RFC PATCH 02/13] target/riscv: Support UXL32 for branch instructions, Richard Henderson, 2021/08/09
- Re: [RFC PATCH 02/13] target/riscv: Support UXL32 for branch instructions, LIU Zhiwei, 2021/08/11
- Re: [RFC PATCH 02/13] target/riscv: Support UXL32 for branch instructions, Richard Henderson, 2021/08/11
- Re: [RFC PATCH 02/13] target/riscv: Support UXL32 for branch instructions, LIU Zhiwei, 2021/08/11
- Re: [RFC PATCH 02/13] target/riscv: Support UXL32 for branch instructions, Richard Henderson, 2021/08/12
- Re: [RFC PATCH 02/13] target/riscv: Support UXL32 for branch instructions,
LIU Zhiwei <=
- Re: [RFC PATCH 02/13] target/riscv: Support UXL32 for branch instructions, Richard Henderson, 2021/08/12
- Re: [RFC PATCH 02/13] target/riscv: Support UXL32 for branch instructions, LIU Zhiwei, 2021/08/12
[RFC PATCH 03/13] target/riscv: Support UXL32 on 64-bit cpu for load/store, LIU Zhiwei, 2021/08/04
[RFC PATCH 04/13] target/riscv: Support UXL32 for slit/sltiu, LIU Zhiwei, 2021/08/04
[RFC PATCH 05/13] target/riscv: Support UXL32 for shift instruction, LIU Zhiwei, 2021/08/04