4 Commits

Author	SHA1	Message	Date
Evan Cheng	bf43525a29	Do not extend extension results beyond the use of a PHI instruction at the start of a use block. A PHI use is expected to kill its source values. ... llvm-svn: 93895	2010-01-19 19:45:51 +00:00
Evan Cheng	af0ad65ff2	Commit some changes I had managed to lose last night while refactoring the code. Avoid change use of PHI instructions because it's not legal to insert any instructions before them. ... This fixes PR6027. llvm-svn: 93335	2010-01-13 19:16:39 +00:00
Evan Cheng	957b8beaaa	Add comment; refactor; avoid pulling in DT if it's not used. ... llvm-svn: 93306	2010-01-13 07:59:13 +00:00
Evan Cheng	30bebff456	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. llvm-svn: 93278	2010-01-13 00:30:23 +00:00