[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v2 for-2.5 05/12] tcg/optimize: track const/copy
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH v2 for-2.5 05/12] tcg/optimize: track const/copy status separately |
Date: |
Mon, 27 Jul 2015 15:40:32 +0200 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On 2015-07-27 13:26, Paolo Bonzini wrote:
>
>
> On 27/07/2015 12:56, Aurelien Jarno wrote:
> > temps[dst].next_copy = temps[src].next_copy;
> > temps[dst].prev_copy = src;
> > temps[temps[dst].next_copy].prev_copy = dst;
> > temps[src].next_copy = dst;
Note that the patch doesn't change this part, it's already there in the
original code.
> This is:
>
> dst->next = src->next;
> dst->prev = src;
> dst->next->prev = dst;
> src->next = dst;
>
> which seems weird. I think it should be one of
>
> /* splice src after dst */
> dst->next->prev = src->prev;
> src->prev->next = dst->next;
> dst->next = src;
> src->prev = dst;
>
> or
>
> /* splice src before dst */
> last = src->prev;
> dst->prev->next = src;
> src->prev = dst->prev;
> last->next = dst;
> dst->prev = last;
>
> (written as pointer manipulations for clarity).
>
> Maybe I'm missing the obvious, but if it's a problem it's better to fix
> it before the links are used more pervasively.
I think your code is the generic for inserting a circular linked list
into another. Here we just want to insert one element, and thus before
the insertion we have dst->next = dst->prev = dst.
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
address@hidden http://www.aurel32.net
- [Qemu-devel] [PATCH v2 for-2.5 00/12] tcg: improve optimizer, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 08/12] tcg: don't abuse TCG type in tcg_gen_trunc_shr_i64_i32, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 12/12] tcg: update README about size changing ops, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 10/12] tcg/optimize: add optimizations for ext_i32_i64 and extu_i32_i64 ops, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 03/12] tcg/optimize: optimize temps tracking, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 11/12] tcg/optimize: do not remember garbage high bits for 32-bit ops, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 07/12] tcg: rename trunc_shr_i32 into trunc_shr_i64_i32, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 09/12] tcg: implement real ext_i32_i64 and extu_i32_i64 ops, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 04/12] tcg/optimize: add temp_is_const and temp_is_copy functions, Aurelien Jarno, 2015/07/27