https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81949
Bug ID: 81949 Summary: DOM fails to simplify conditional Product: gcc Version: 6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: law at redhat dot com Target Milestone: --- DOM fails to simplify the 3rd conditional in the test 20030922-2.c. This is by current design and the test is xfailed. This is a regression relative to gcc-7 and earlier. So solve this within the DOM framework we'd need to build unwindable equivalence classes from the conditional equivalences. Given those classes, we could then iterate over the items within the equivalence class for each use operand to see if using an equivalent SSA_NAME allows a given statement to simplify (not just propagate, but truly simplify).