Chris Lattner 6d71b7fb95 Improve ValueAlreadyLiveAtInst with a cheap and dirty, but effective ... heuristic: the value is already live at the new memory operation if it is used by some other instruction in the memop's block. This is cheap and simple to compute (moreso than full liveness). This improves the new heuristic even more. For example, it cuts two out of three new instructions out of 255.vortex:DbmFileInGrpHdr, which is one of the functions that the heuristic regressed. This overall eliminates another 40 instructions from 403.gcc and visibly reduces register pressure in 255.vortex (though this only actually ends up saving the 2 instructions from the whole program). llvm-svn: 60084		2008-11-26 03:20:37 +00:00
clang	Revert 60071, depends on uncommitted LLVM changes.	2008-11-26 02:18:33 +00:00
llvm	Improve ValueAlreadyLiveAtInst with a cheap and dirty, but effective	2008-11-26 03:20:37 +00:00