Bug 10320 - Wrong results for some expressions with "(ulong)", "-" and ">>" operators
Summary: Wrong results for some expressions with "(ulong)", "-" and ">>" operators
Status: RESOLVED FIXED
Alias: None
Product: Runtime
Classification: Mono
Component: JIT ()
Version: unspecified
Hardware: All All
: --- normal
Target Milestone: ---
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2013-02-15 10:55 UTC by Rebex.NET
Modified: 2013-02-19 09:25 UTC (History)
3 users (show)

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

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Status:
RESOLVED FIXED

Description Rebex.NET 2013-02-15 10:55:15 UTC
Some expressions with unary '-' operator, bitwise shifting and conversion to ulong produce wrong results.

Test case #1:
  long a = 0x100000000;
  ulong b = (ulong) (a) >> 32;
  ulong c = (ulong) (-(-a)) >> 32; // this produces wrong result in Mono
  Console.WriteLine("{0}=={1}");

Excected output: "1==1" (just like in .NET).
However, the actual results are different in 32bit Mono:

Mono 2.10.9 (tarball Mon May 7 20:25:51 EDT 2012) - x86 - MacOS X 10.8.2:
  1==0

Mono 2.6.7 (Debian 2.6.7-5.1) - x86 - Debian 6.0:
  1==0
		 
Mono 2.10.8.1 (Debian 2.10.8.1-5) - x86 - Debian 7.0:
  1==0

Interestingly, 64bit version of Mono produces correct result (just like .NET):

Mono 2.10.9 (tarball Mon Nov 19 16:16:18 CET 2012) - amd64 - MacOS X 10.8.2:
  1==1

MS .NET 4.5 (64bit version) - Windows 8:
  1==1

MS .NET 4.5 (32bit version) - Windows 8:
  1==1

-----

Test case #2:
  long a = -1;
  ulong b = ((ulong)1) >> 32;
  ulong c = ((ulong)-a) >> 32; // this produces wrong result in Mono
  Console.WriteLine("{0}=={1}", b, c);

Expected output:
  0 == 0

Result on Mono 2.10.8.1 (Debian 2.10.8.1-5) - x86 - Debian 7.0:
  1 == 0
(have not tried the other platform)
Comment 1 Rebex.NET 2013-02-15 14:59:29 UTC
Sorry, there is an error in the test case #1 code - please use Console.WriteLine("{0}=={1}", b, c) instead of Console.WriteLine("{0}=={1}")
Comment 2 Zoltan Varga 2013-02-19 09:25:30 UTC
Fixed in master/2.10 branches. Thanks for the report.