Bug 10887 - Both left and right shift of BigInteger are buggy
Summary: Both left and right shift of BigInteger are buggy
Alias: None
Product: Class Libraries
Classification: Mono
Component: System ()
Version: 2.10.x
Hardware: PC Linux
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on:
Reported: 2013-03-04 15:47 UTC by gentlebeldin
Modified: 2013-06-10 18:37 UTC (History)
2 users (show)

Is this bug a regression?: ---
Last known good build:

Demo of the bug (506 bytes, text/x-csharp)
2013-03-04 15:47 UTC, gentlebeldin

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Description gentlebeldin 2013-03-04 15:47:17 UTC
Created attachment 3533 [details]
Demo of the bug

Both << and >> of a BigInteger may give incorrect results, if the BigInteger occupies more than one uint, and the shift is a multiple of 32. The bug is shown by a simple program I'll attach: a left shift of 32 bits, followed by division by Pow(2, 32), should leave a number unchanged, and also a multiplication by Pow(2, 32), followed by a right shift of 32 bits. 
The bug shows up both in Mono (Debian and in Mono JIT compiler version 2.10.11 (mono-2-10/2baeee2 Wed Jan 16 16:40:16 EST 2013) on my iMac.
Comment 1 Rodrigo Kumpera 2013-06-10 18:37:02 UTC
Thanks for the test case. This has been fixed on mono 3.0 and will be part of the next release there.