infinite loop in ARM Constant Island pass

[llvmbot]

Bugzilla Link	1300
Resolution	FIXED
Resolved on	Feb 22, 2010 12:56
Version	1.0
OS	All
Attachments	RestoreMV8x8.bc
Reporter	LLVM Bugzilla Contributor

Extended Description

I think the ARM Constant Island pass algorithm doesn't converge to a solution in
some rare cases. This bug makes the lencod test never finish.

[lattner]

Dale, can you take a look please?

[llvmbot]

Sure. I can say lencod worked the last time I tried it, though.

[llvmbot]

Lencod worked before the last time I tried it.
I think this bug only occurs on rare situation. Unrelated changes can make it
doesn't occur. It doesn't occur on HEAD cvs version, but can be reproduced using
the version of April, 1 (cvs update -D 2007-04-01).

[lattner]

does it reproduce with the attached .bc file?

[llvmbot]

yes, I can reproduce and see what the problem is, should have a fix shortly.

[llvmbot]

does it reproduce with the attached .bc file?
Yes. It can be reproduced using "llc RestoreMV8x8.bc" with llvm of April, 1.

[llvmbot]

Fixed here.
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20070402/046683.html

[llvmbot]

The .ll form of the input is 63MB, so I think I won't put it in the test suite. Running lencod should exercise
the code in question.

[lattner]

sounds good to me, thanks dale!