Peculiar use of ‘unsigned’ indices in ‘PostRASchedulerList.cpp’

[danchr]

Bugzilla Link	3238
Resolution	FIXED
Resolved on	Mar 06, 2010 14:00
Version	trunk
OS	All
Attachments	Fix
CC	@asl,@sunfishcode

Extended Description

The file ‘lib/CodeGen/PostRASchedulerList.cpp’ contains two index arrays of unsigned type, where the value ‘-1u’ is used to invalidate an index. GCC 3.4.6 on RHEL5.2 issued warnings about this. To be honest, I know little about C++ or what exactly this code does; it's just that it feels very wrong to me to store -1 in a variable which is explicitly declared to not have that value.

The attached patch fixes this by using a signed integer for the index; I've had it in my local branch for a few days, and it seems to work fine :) If using a signed integer is unacceptable, perhaps using ~0 or UINT_MAX to designate an invalid index would be better?

[asl]

-1u there is perfectly allowed, so, it seems, that compiler is broken. What's the warning message you're seeing?

[sunfishcode]

-1u is idiomatic, but it's not difficult to change. Fixed here:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20081215/071374.html
I didn't test this on RHEL5.2; please reply if needed.