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Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation.
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation. |
Date: |
Wed, 26 Jan 2011 07:50:12 -0800 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101209 Fedora/3.1.7-0.35.b3pre.fc14 Thunderbird/3.1.7 |
On 01/26/2011 01:23 AM, Alexander Graf wrote:
> address@hidden:/studio/s390/qemu-s390> grep deposit target-s390x/translate.c
> tcg_gen_deposit_i64(regs[reg], regs[reg], tmp, 0, 32);
> tcg_gen_deposit_i64(regs[reg], regs[reg], v, 0, 32);
> tcg_gen_deposit_i64(regs[reg], regs[reg], tmp, 0, 16);
> tcg_gen_deposit_i64(regs[reg], regs[reg], v, 0, 8);
> tcg_gen_deposit_i64(regs[r1], regs[r1], tmp, 48, 16);
> tcg_gen_deposit_i64(regs[r1], regs[r1], tmp, 32, 16);
>
> The 0, 32 and 0, 16 versions should get accelerated pretty well while
> the 32, 16 and 48, 16 are not I assume?
No, only the 0,16 and 0,8 deposits correspond to a hardware insn on x86.
Given that the 0,32 lowpart writeback is almost certainly the most common
operation for s390x, I doubt the deposit patch will help with an x86 host.
Have you thought about buffering the lowpart writeback in the translator?
I.e. when a 32-bit insn writes to a register, remember that value without
writing it back. If the next insn in the TB is also 32-bit, reuse the
saved value, etc. Only perform the writeback for 64-bit insns using the
register as a source, end of TB, and places that can take an exception.
r~
- Re: [Qemu-devel] [PATCH 1/7] tcg: Define "deposit" as an optional operation., (continued)
- [Qemu-devel] [PATCH 3/7] tcg-hppa: Implement deposit operation., Richard Henderson, 2011/01/10
- [Qemu-devel] [PATCH 4/7] tcg-ia64: Implement deposit operation., Richard Henderson, 2011/01/10
- [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Richard Henderson, 2011/01/10
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Edgar E. Iglesias, 2011/01/25
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Richard Henderson, 2011/01/25
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Edgar E. Iglesias, 2011/01/25
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Richard Henderson, 2011/01/25
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Edgar E. Iglesias, 2011/01/26
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Alexander Graf, 2011/01/26
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation.,
Richard Henderson <=
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Alexander Graf, 2011/01/26
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Avi Kivity, 2011/01/26
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Richard Henderson, 2011/01/26
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Alexander Graf, 2011/01/26
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Richard Henderson, 2011/01/26
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Alexander Graf, 2011/01/26
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Richard Henderson, 2011/01/26
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Alexander Graf, 2011/01/26
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Richard Henderson, 2011/01/26
- Re: [Qemu-devel] [PATCH 5/7] tcg-i386: Implement deposit operation., Alexander Graf, 2011/01/26