Bikramjeet Vig created IMPALA-5980: -------------------------------------- Summary: Upgrade to LLVM 4 and migrate to NewGVN for improved optimization perf Key: IMPALA-5980 URL: https://issues.apache.org/jira/browse/IMPALA-5980 Project: IMPALA Issue Type: Improvement Components: Backend Reporter: Bikramjeet Vig
As a part of IMPALA-5907 it was identified that the GVN optimization pass is slow for large cases, specifically when huge expression trees are passed to it. This slow GVN pass problem is a known issue (https://groups.google.com/forum/#!msg/llvm-dev/ozsAceDmOuA/2O_QC6EiDgAJ) that has motivated the llvm devs to develop a new GVN pass which is claimed to be faster and is available in LLVM 4. Therefore after upgrading to LLVM 4 we should try moving to the NewGVN pass and figure out if it is helpful by doing a perf analysis. -- This message was sent by Atlassian JIRA (v6.4.14#64029)