From: Paolo Bonzini <pbonzini@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: kvm@vger.kernel.org
Subject: Re: [PATCH 0/8] Simplify byte/word opcode pair decode
Date: Mon, 23 Aug 2010 16:04:46 +0200 [thread overview]
Message-ID: <4C727FFE.8060806@redhat.com> (raw)
In-Reply-To: <4C727C1A.3080204@redhat.com>
On 08/23/2010 03:48 PM, Avi Kivity wrote:
> On 08/23/2010 04:29 PM, Paolo Bonzini wrote:
>> On 08/23/2010 01:06 PM, Avi Kivity wrote:
>>> Many x86 instructions come in pairs - byte and word variants where bit 0
>>> of the opcode determines operand size. Use this to simplify the decode
>>> tables.
>>
>> Many actually come in quadruples, bit 0 is the size and bit 1 says
>> which of ModRM and REG is the destination.
>>
>> example:
>>
>> D2bv(DstMem | SrcReg | ModRM | Lock), D2bv(DstReg | SrcMem | ModRM),
>>
>
> Right. We can't exploit those yet.
What about this? It wouldn't work for things such as SrcAcc, but it
would still reap most of the benefit:
#define D4modrm(x) \
D2bv(DstMem | SrcReg | ModRM | (x)), \
D2bv(DstReg | SrcMem | ModRM | ((x) & ~Lock))
e.g.
- ALU block -> D4modrm(Lock)
- 0x88-0x8b -> D4modrm(Mov)
Paolo
next prev parent reply other threads:[~2010-08-23 14:04 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-23 11:06 [PATCH 0/8] Simplify byte/word opcode pair decode Avi Kivity
2010-08-23 11:06 ` [PATCH 1/8] KVM: x86 emulator: support byte/word opcode pairs Avi Kivity
2010-08-23 11:06 ` [PATCH 2/8] KVM: x86 emulator: simplify ALU block (opcodes 00-3F) decode flags Avi Kivity
2010-08-25 19:39 ` Marcelo Tosatti
2010-08-26 8:26 ` Avi Kivity
2010-08-23 11:06 ` [PATCH 3/8] KVM: x86 emulator: simplify string instruction " Avi Kivity
2010-08-23 11:06 ` [PATCH 4/8] KVM: x86 emulator: simplify instruction decode flags for opcodes 80-8F Avi Kivity
2010-08-23 11:06 ` [PATCH 5/8] KVM: x86 emulator: simplify instruction decode flags for opcodes A0-AF Avi Kivity
2010-08-23 11:06 ` [PATCH 6/8] KVM: x86 emulator: simplify instruction decode flags for opcodes C0-DF Avi Kivity
2010-08-23 11:06 ` [PATCH 7/8] KVM: x86 emulator: simplify instruction decode flags for opcodes E0-FF Avi Kivity
2010-08-23 13:33 ` Gleb Natapov
2010-08-23 13:46 ` Avi Kivity
2010-08-23 13:56 ` Gleb Natapov
2010-08-23 11:06 ` [PATCH 8/8] KVM: x86 emulator: simplify instruction decode flags for opcodes 0F 00-FF Avi Kivity
2010-08-23 13:29 ` [PATCH 0/8] Simplify byte/word opcode pair decode Paolo Bonzini
2010-08-23 13:48 ` Avi Kivity
2010-08-23 14:04 ` Paolo Bonzini [this message]
2010-08-23 14:13 ` Avi Kivity
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