[Bug tree-optimization/56490] [4.6/4.7/4.8 Regression] -Wall triggering infinite loop
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56490 Richard Biener rguenth at gcc dot gnu.org changed: What|Removed |Added Known to work|4.8.0 | Summary|[4.6/4.7 Regression] -Wall |[4.6/4.7/4.8 Regression] |triggering infinite loop|-Wall triggering infinite ||loop Known to fail||4.8.0 --- Comment #4 from Richard Biener rguenth at gcc dot gnu.org 2013-03-08 16:03:30 UTC --- Clearly the limiting is bougs ... the issue is with large fanout BBs we recurse in compute_control_dep_chain which leads to exponential complexity. Limiting that to 8^5 isn't really a fix ... (yes, you can call that O(1)). compute_control_dep_chain is called 65 million times(!) for the testcase after the patch. There has to be a better algorithmic way of implementing this. IMHO still not fixed in 4.8.
[Bug tree-optimization/56490] [4.6/4.7/4.8 Regression] -Wall triggering infinite loop
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56490 --- Comment #5 from davidxl xinliangli at gmail dot com 2013-03-08 16:21:13 UTC --- (In reply to comment #4) Clearly the limiting is bougs ... the issue is with large fanout BBs we recurse in compute_control_dep_chain which leads to exponential complexity. Limiting that to 8^5 isn't really a fix ... (yes, you can call that O(1)). compute_control_dep_chain is called 65 million times(!) for the testcase after the patch. There has to be a better algorithmic way of implementing this. IMHO still not fixed in 4.8. Right. However for on demand computation like this, limiting is still needed. For this particular case, limiting the depth to 3 (or may be smaller) won't cause any regressions.
