From: "vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
To: dwz@sourceware.org
Subject: [Bug default/25231] Reuse checksums
Date: Tue, 01 Jan 2019 00:00:00 -0000 [thread overview]
Message-ID: <bug-25231-11298-BkxNn76YJW@http.sourceware.org/bugzilla/> (raw)
In-Reply-To: <bug-25231-11298@http.sourceware.org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=25231
--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #0)
> That difference is caused by handling of DW_FORM_strp, which is encoded into
> the checksum using the index to the string table rather than the string
> contents, which is a speed optimization for regular-mode (but which assumes
> that the input file is optimally encoded, in the sense that each unique
> string is encoded either using DW_FORM_strp, or DW_FORM_string, but not
> both).
FTR, naively disabling this optimization makes no difference in the result for
cc1 and comes at a 5% execution time penalty:
...
series: 5630 5502 5510 5502 5521 5517 5521 5517 5486 5525
mean: 5523.10 (100%)
stddev: 39.37
series: 5877 5794 5832 5780 5811 5802 5769 5812 5845 5788
mean: 5811.00 (105.21%)
stddev: 32.62
user:
series: 5321 5326 5274 5258 5305 5319 5292 5300 5285 5299
mean: 5297.90 (100%)
stddev: 21.57
series: 5560 5546 5655 5531 5595 5554 5564 5568 5616 5555
mean: 5574.40 (105.22%)
stddev: 37.25
sys:
series: 308 176 236 244 216 196 228 216 200 224
mean: 224.40 (100%)
stddev: 35.60
series: 316 248 176 248 216 248 204 244 228 232
mean: 236.00 (105.17%)
stddev: 36.51
...
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prev parent reply other threads:[~2019-11-29 12:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-01 0:00 [Bug default/25231] New: " vries at gcc dot gnu.org
2019-01-01 0:00 ` vries at gcc dot gnu.org [this message]
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