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Re: [Qemu-devel] [PATCH 3/3] tcg/aarch64: implement new TCG target for a
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH 3/3] tcg/aarch64: implement new TCG target for aarch64 |
Date: |
Tue, 14 May 2013 08:16:34 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130402 Thunderbird/17.0.5 |
On 05/14/2013 07:05 AM, Claudio Fontana wrote:
>> Conditional branch range is +-1MB. You'll never see a TB that large. You
>> don't need to emit a branch-across-branch.
>
> Is there maybe a way to do it right even in the corner case where we have
> a huge list of hundreds of thousands of instructions without jumps and then a
> conditional jump?
> Are we _guaranteed_ to never see that large a TB with some kind of define,
> similarly to MAX_CODE_GEN_BUFFER_SIZE?
There are three mechanisms that all limit TB size:
(1) OPC_MAX_SIZE, limiting the number of opcodes emitted,
(2) CF_COUNT_MASK, limiting the number of instructions translated,
(3) Instruction pointer crossing a page boundary, where we end a TB
and re-verify the page protection bits of the new page.
Nr 1 is probably the most significant, since it most directly relates to
the number of output instructions, and thus the resulting TB size.
r~
- Re: [Qemu-devel] [PATCH 2/3] include/elf.h: add aarch64 ELF machine and relocs, (continued)
- [Qemu-devel] [PATCH 3/3] tcg/aarch64: implement new TCG target for aarch64, Claudio Fontana, 2013/05/13
- Re: [Qemu-devel] [PATCH 3/3] tcg/aarch64: implement new TCG target for aarch64, Peter Maydell, 2013/05/13
- Re: [Qemu-devel] [PATCH 3/3] tcg/aarch64: implement new TCG target for aarch64, Claudio Fontana, 2013/05/14
- Re: [Qemu-devel] [PATCH 3/3] tcg/aarch64: implement new TCG target for aarch64, Peter Maydell, 2013/05/14
- Re: [Qemu-devel] [PATCH 3/3] tcg/aarch64: implement new TCG target for aarch64, Richard Henderson, 2013/05/14
- Re: [Qemu-devel] [PATCH 3/3] tcg/aarch64: implement new TCG target for aarch64, Laurent Desnogues, 2013/05/14
- Re: [Qemu-devel] [PATCH 3/3] tcg/aarch64: implement new TCG target for aarch64, Richard Henderson, 2013/05/13
- Re: [Qemu-devel] [PATCH 3/3] tcg/aarch64: implement new TCG target for aarch64, Claudio Fontana, 2013/05/14
- Re: [Qemu-devel] [PATCH 3/3] tcg/aarch64: implement new TCG target for aarch64,
Richard Henderson <=
- Re: [Qemu-devel] [PATCH 3/3] tcg/aarch64: implement new TCG target for aarch64, Richard Henderson, 2013/05/14
- [Qemu-devel] [PATCH 1/3] configure: permit compilation on arm aarch64, Claudio Fontana, 2013/05/13
- Re: [Qemu-devel] [PATCH 1/3] configure: permit compilation on arm aarch64, Peter Maydell, 2013/05/13
- Re: [Qemu-devel] [PATCH 1/3] configure: permit compilation on arm aarch64, Claudio Fontana, 2013/05/14
Re: [Qemu-devel] QEMU aarch64 TCG target - testing question about x86-64, Peter Maydell, 2013/05/06