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Re: [Qemu-devel] Arm emulation tweak
From: |
Jamie Lokier |
Subject: |
Re: [Qemu-devel] Arm emulation tweak |
Date: |
Tue, 18 Aug 2009 17:14:24 +0100 |
User-agent: |
Mutt/1.5.13 (2006-08-11) |
Nigel Horne wrote:
> This small patch reduces (on my machine) the call to new_tmp by 16
> bytes, which may not sound much, but it's called so often that it makes
> a nice speed up of Arm emulation:
> if (GET_TCGV_I32(temps[num_temps]))
> return temps[num_temps++];
>
> ! tmp = tcg_temp_new_i32();
> ! temps[num_temps++] = tmp;
> ! return tmp;
> }
becomes
> if (GET_TCGV_I32(temps[num_temps]))
> return temps[num_temps++];
>
> ! return temps[num_temps++] = tcg_temp_new_i32();
> }
That's pretty tragic if GCC fails to compile them to identical code,
assuming you had optimisation turned on.
Have you tried building with -Os, -O2 etc. to see if that makes a
difference?
Which GCC version are you using?
-- Jamie