2 Commits

Author	SHA1	Message	Date
Evan Cheng	d89d5180d1	Add comment; refactor; avoid pulling in DT if it's not used. ... git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93306 91177308-0d34-0410-b5e6-96231b3b80d8	2010-01-13 07:59:13 +00:00
Evan Cheng	7da9ecf967	Add a quick pass to optimize sign / zero extension instructions. For targets where the pre-extension values are available in the subreg of the result of the extension, replace the uses of the pre-extension value with the result + extract_subreg. ... For now, this pass is fairly conservative. It only perform the replacement when both the pre- and post- extension values are used in the block. It will miss cases where the post-extension values are live, but not used. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93278 91177308-0d34-0410-b5e6-96231b3b80d8	2010-01-13 00:30:23 +00:00