From: Richard Henderson <rth@twiddle.net>
To: Aurelien Jarno <aurelien@aurel32.net>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
qemu-devel@nongnu.org, anthony@codemonkey.ws
Subject: Re: [Qemu-devel] [PULL 5/7] tcg: Add mmu helpers that take a return address argument
Date: Tue, 27 Aug 2013 07:53:56 -0700 [thread overview]
Message-ID: <521CBD84.1040508@twiddle.net> (raw)
In-Reply-To: <20130827104647.GA5908@ohm.aurel32.net>
On 08/27/2013 03:46 AM, Aurelien Jarno wrote:
> On the other hand calling the helper is the exception more than the
> rule (that's why they have been moved at the end of the TB), so we
> should not look to much at generating fast code, but rather small code
> in order to use the caches (both TB and CPU caches) more efficiently.
>
> Therefore even on x86, if we move the -1 at the helper level, it should
> be possible to use a tail call for the stores, something like:
>
> mov %r14,%rdi
> mov %ebx,%edx
> xor %ecx,%ecx
> lea -0x10f(%rip),%r8 # 0x7f2541a6f69a
> pushq %r8
> jmpq 0x7f25526757a0
>
> Instead of:
>
> mov %r14,%rdi
> mov %ebx,%edx
> xor %ecx,%ecx
> lea -0x10f(%rip),%r8 # 0x7f2541a6f69a
> callq 0x7f25526757a0
> jmpq 0x7f2541a6f69b
Fair enough. I'll have a go at some follow-ups then.
r~
next prev parent reply other threads:[~2013-08-27 14:54 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-26 21:00 [Qemu-devel] [PULL 0/7] Improve tcg ldst optimization Richard Henderson
2013-08-26 21:00 ` [Qemu-devel] [PULL 1/7] tcg: Tidy generated code for tcg_outN Richard Henderson
2013-08-26 21:00 ` [Qemu-devel] [PULL 2/7] tcg-i386: Add and use tcg_out64 Richard Henderson
2013-08-26 21:00 ` [Qemu-devel] [PULL 3/7] tcg-i386: Try pc-relative lea for constant formation Richard Henderson
2013-08-26 21:00 ` [Qemu-devel] [PULL 4/7] tcg-i386: Tidy qemu_ld/st slow path Richard Henderson
2013-08-26 21:00 ` [Qemu-devel] [PULL 5/7] tcg: Add mmu helpers that take a return address argument Richard Henderson
2013-08-26 22:26 ` Paolo Bonzini
2013-08-26 22:34 ` Richard Henderson
2013-08-27 10:46 ` Aurelien Jarno
2013-08-27 14:53 ` Richard Henderson [this message]
2013-08-27 15:43 ` Aurelien Jarno
2013-08-27 15:53 ` Richard Henderson
2013-08-26 23:26 ` Peter Maydell
2013-08-27 10:47 ` Aurelien Jarno
2013-08-26 21:00 ` [Qemu-devel] [PULL 6/7] tcg: Tidy softmmu_template.h Richard Henderson
2013-08-26 21:00 ` [Qemu-devel] [PULL 7/7] tcg-i386: Use new return-argument ld/st helpers Richard Henderson
2013-08-28 22:55 ` Richard W.M. Jones
2013-08-29 15:21 ` [Qemu-devel] [PATCH] tcg-i386: Remove abort from GETPC_LDST Richard Henderson
2013-08-29 15:28 ` Paolo Bonzini
2013-08-29 15:32 ` Richard Henderson
2013-08-29 15:50 ` Richard W.M. Jones
2013-08-29 19:13 ` Aurelien Jarno
2013-08-27 21:30 ` [Qemu-devel] [PULL 0/7] Improve tcg ldst optimization Aurelien Jarno
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