[LLVMdev] LoopInfo are not able to identify some natural loops?

Bo Wu bwu at cs.wm.edu
Fri Apr 29 19:43:49 PDT 2011


I found that some loops can not be identified by LoopInfo pass. For example,
the loop at line 3094 of rdopt.c of benchmark 464.h264ref from spec cpu2006
is not a loop or a child (pr grandchild) of any loop in the loop list
generated by LoopInfo pass. The documentation of LoopInfo says that it
identifies natural loops, who have exactly one entry point. But the IR of
this loops shows that it's header only has one BB in preds. Does that mean
LoopInfo can not identify some natural loops?


Bo Wu

Ph.D. student
CAPS group
Computer Science Department
The College of William & Mary
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