Bug 23964

Summary: Use __uint128_t if available (gcc)
Product: cairo Reporter: Sebastian Dröge (slomo) <slomo>
Component: generalAssignee: Carl Worth <cworth>
Status: RESOLVED FIXED QA Contact: cairo-bugs mailing list <cairo-bugs>
Severity: trivial    
Priority: medium    
Version: 1.9.3   
Hardware: Other   
OS: All   
Whiteboard:
i915 platform: i915 features:
Attachments: 0001-Use-__uint128_t-and-__int128_t-if-available.patch

Description Sebastian Dröge (slomo) 2009-09-15 08:52:46 UTC 
Created attachment 29568 [details] [review]
0001-Use-__uint128_t-and-__int128_t-if-available.patch

Hi,
the attached patch changes configure to also check for __uint128_t, which is the new name of uint128_t from gcc. It is only available on architectures that provide instructions for 128 bit integers.

(I had to move some code in cairo-wideint.c because apparently nobody compiled with a gcc that has uint128_t since a very long time and macros/functions were not defined)
Comment 1 Sebastian Dröge (slomo) 2009-09-15 10:13:08 UTC 
Ok, this doesn't make anything much faster.

without __uint128_t:
[ # ]  backend                         test   min(s) median(s) stddev. count
[  0]     xlib         firefox-planet-gnome   89.557   89.572   0.29%    3/3
[  1]     xlib            firefox-talos-gfx  105.301  106.202   0.91%    3/3
[  2]     xlib            firefox-talos-svg   85.503   85.971   0.85%    3/3

with __uint128_t:
[ # ]  backend                         test   min(s) median(s) stddev. count
[  0]     xlib         firefox-planet-gnome   89.414   89.497   0.32%    3/3
[  1]     xlib            firefox-talos-gfx  104.758  105.281   0.60%    3/3
[  2]     xlib            firefox-talos-svg   85.359   86.239   0.74%    3/3
Comment 2 Chris Wilson 2009-09-15 10:22:04 UTC 
Actually it does have a significant impact on other workloads:

commit 56c9b2de7a2b93b2e0c59cf98326d8c0d4d508ba
Author: Sebastian Dröge <sebastian.droege@collabora.co.uk>
Date:   Tue Sep 15 17:26:59 2009 +0200

    Use __uint128_t and __int128_t if available
    
    GCC uses a peculiar name for a real 128-bit integer on x86-64.
    
    Speedups, xlib on a gm45
    ========================
    poppler        41246.56 -> 35102.82: 1.18x speedup
    swfdec-youtube 12623.01 -> 11936.79: 1.06x speedup
    
Pushed, thanks.

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