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RESOLVED FIXED
174034
B3ReduceDoubleToFloat incorrectly reduces operations over two double constants
https://bugs.webkit.org/show_bug.cgi?id=174034
Summary
B3ReduceDoubleToFloat incorrectly reduces operations over two double constants
Saam Barati
Reported
2017-06-30 13:10:16 PDT
e.g, we'll change this program: a = DoubleConst(c1) b = DoubleConst(c2) c = EqualOrUnordered(@a, @b) into: a = FloatConst(static_cast<float>(c1)) b = FloatConst(static_cast<float>(c2)) c = EqualOrUnordered(@a, @b) Which is clearly wrong. The example program where this goes wrong is for a denormal negative zero. We have this comparison: a = DoubleConst(0x8000000000000001) b = DoubleConst(0x0000000000000000) c = EqualOrUnordered(@a, @b) into: a = FloatConst(0x80000000) b = FloatConst(0x00000000) c = EqualOrUnordered(@a, @b) And this will produce different program behavior.
Attachments
patch
(5.95 KB, patch)
2017-06-30 14:17 PDT
,
Saam Barati
no flags
Details
Formatted Diff
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proposed patch, testcase, etc.
Saam Barati
Comment 1
2017-06-30 14:09:33 PDT
<
rdar://problem/30793007
>
Saam Barati
Comment 2
2017-06-30 14:17:54 PDT
Created
attachment 314289
[details]
patch
WebKit Commit Bot
Comment 3
2017-06-30 16:37:04 PDT
Comment on
attachment 314289
[details]
patch Clearing flags on attachment: 314289 Committed
r219026
: <
http://trac.webkit.org/changeset/219026
>
WebKit Commit Bot
Comment 4
2017-06-30 16:37:06 PDT
All reviewed patches have been landed. Closing bug.
Csaba Osztrogonác
Comment 5
2017-06-30 22:52:03 PDT
(In reply to WebKit Commit Bot from
comment #3
)
> Comment on
attachment 314289
[details]
> patch > > Clearing flags on attachment: 314289 > > Committed
r219026
: <
http://trac.webkit.org/changeset/219026
>
It broke the GCC build, see build.webkit.org for details, for example the GTK bots and AArch64 bot.
Csaba Osztrogonác
Comment 6
2017-06-30 22:52:54 PDT
https://build.webkit.org/builders/GTK%20Linux%2064-bit%20Release%20Ubuntu%20LTS%20%28Build%29/builds/3368
Yusuke Suzuki
Comment 7
2017-07-01 02:36:41 PDT
Committed
r219047
: <
http://trac.webkit.org/changeset/219047
>
Saam Barati
Comment 8
2017-07-01 13:49:04 PDT
(In reply to Yusuke Suzuki from
comment #7
)
> Committed
r219047
: <
http://trac.webkit.org/changeset/219047
>
Thanks!
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