[Webkit-unassigned] [Bug 179446] New: [JSC][MIPS] Use fcsr to check the validity of the result of trunc.w.d
bugzilla-daemon at webkit.org
bugzilla-daemon at webkit.org
Wed Nov 8 14:11:41 PST 2017
https://bugs.webkit.org/show_bug.cgi?id=179446
Bug ID: 179446
Summary: [JSC][MIPS] Use fcsr to check the validity of the
result of trunc.w.d
Product: WebKit
Version: Other
Hardware: Other
OS: Linux
Status: NEW
Severity: Normal
Priority: P2
Component: JavaScriptCore
Assignee: webkit-unassigned at lists.webkit.org
Reporter: guijemont at igalia.com
The trunc.w.d mips instruction should give a 0x7fffffff result when the source value is Infinity, NaN, or rounds to an integer outside the range -2^31 to 2^31 -1. This is what branchTruncateDoubleToInt32() and branchTruncateDoubleToUInt32() have been relying on. It turns out that this assumption is not true on some CPUs, including on the ci20 on which we run the testbot (we get 0x80000000 instead). We should the invalid operation cause bit instead to check whether the source value could be properly truncated. This requires the addition of the cfc1 instruction, as well as the special registers that can be used with it (control registers of CP1).
--
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.webkit.org/pipermail/webkit-unassigned/attachments/20171108/ee54fb64/attachment.html>
More information about the webkit-unassigned
mailing list