Merge remote-tracking branch 'origin/ryan-reassoc' into grape-initial

hercules_ir/src/ir.rs

hercules_opt/src/lib.rs

hercules_opt/src/reassociate.rs

juno_samples/grape_reduction/src/grape.sch

juno_scheduler/src/compile.rs

juno_scheduler/src/ir.rs

juno_scheduler/src/pm.rs