From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51998) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VELQg-00020M-EW for qemu-devel@nongnu.org; Tue, 27 Aug 2013 11:43:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VELQf-0007bY-26 for qemu-devel@nongnu.org; Tue, 27 Aug 2013 11:43:38 -0400 Received: from hall.aurel32.net ([2001:470:1f0b:4a8::1]:56600) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VELQe-0007bR-Qt for qemu-devel@nongnu.org; Tue, 27 Aug 2013 11:43:36 -0400 Date: Tue, 27 Aug 2013 17:43:32 +0200 From: Aurelien Jarno Message-ID: <20130827154332.GA4219@hall.aurel32.net> References: <1377550812-908-1-git-send-email-rth@twiddle.net> <1377550812-908-6-git-send-email-rth@twiddle.net> <521BD62A.50203@redhat.com> <521BD7E7.9090107@twiddle.net> <20130827104647.GA5908@ohm.aurel32.net> <521CBD84.1040508@twiddle.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <521CBD84.1040508@twiddle.net> Sender: Aurelien Jarno Subject: Re: [Qemu-devel] [PULL 5/7] tcg: Add mmu helpers that take a return address argument List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Henderson Cc: Paolo Bonzini , qemu-devel@nongnu.org, anthony@codemonkey.ws On Tue, Aug 27, 2013 at 07:53:56AM -0700, Richard Henderson wrote: > 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. > I think this can also be done in a second time. Do you want to create a version 3, or should I just process the current pull request and you will provide additional patches later? -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurelien@aurel32.net http://www.aurel32.net