Add Mozilla division bug

Author: kgryte

docs/native_math_bugs.md

@@ -43,9 +43,9 @@
 * [WebKit 32-bit Math bug][@bug:webkit:40367]
 * [Mozilla optimizations break commutativity][@bug:mozilla:969203]
 * [Mozilla debate on speed versus precision][@bug:mozilla:967709]
+* [Mozilla division bug to due C library delegation][@bug:mozilla:948321]
 
 
-* [Division bug to due C library delegation][29]
 * [Fixit to unify Math implementations in Chrome][30]
 * [Fixit to unify Math.pow implementation in Chrome][31]
 
@@ -100,14 +100,14 @@
 [@bug:webkit:40367]: https://bugs.webkit.org/show_bug.cgi?id=40367
 [@bug:mozilla:969203]: https://bugzilla.mozilla.org/show_bug.cgi?id=969203#c8
 [@bug:mozilla:967709]: https://bugzilla.mozilla.org/show_bug.cgi?id=967709
+[@bug:mozilla:948321]: https://bugzilla.mozilla.org/show_bug.cgi?id=948321
 
 
 [v8-issue-tracker]: https://bugs.chromium.org/p/v8/issues/list?can=1&q=math&colspec=ID%20Type%20Status%20Priority%20Owner%20Summary%20HW%20OS%20Component%20Stars&num=100&start=100
 [webkit-issue-tracker]: https://bugs.webkit.org/buglist.cgi?quicksearch=math
 [mozilla-issue-tracker]: https://bugzilla.mozilla.org/buglist.cgi?quicksearch=math
 
 
-[29]: https://bugzilla.mozilla.org/show_bug.cgi?id=948321
 [30]: https://bugs.chromium.org/p/v8/issues/detail?id=5086
 [31]: https://bugs.chromium.org/p/v8/issues/detail?id=5157
 

docs/references/bugs.bib

@@ -344,3 +344,12 @@ @misc{bug:mozilla:967709
 	year = {2014}
 }
 
+@misc{bug:mozilla:948321,
+	abstract = {fdiv is part of the x87 instruction set that's much older than SSE2/divsd. x87 has its own stack and is a pain to use compared to SSE; we try to avoid it as much as possible. We do use it for the fisttp instruction for instance because there's no SSE equivalent on x86. Unfortunately, fdiv uses 80-bit double-extended precision and divsd/SSE2 uses 64-bit double precision. That's probably causing the difference here. This sucks because it's not very easy to work around I'm afraid. For differential testing we could try to use a compiler switch so that it's free to emit SSE2+ instructions; maybe that will keep it from emitting fdiv, or maybe it won't.. Is this also a problem with 64-bit builds?},
+	keywords = {math, firefox, mozilla, divide, division},
+	notes = {},
+	title = {{Differential Testing: Different division results on x86 platforms}},
+	url = {https://bugzilla.mozilla.org/show_bug.cgi?id=948321},
+	year = {2013}
+}
+