go/src/cmd/compile/internal/ssa/cse.go

// cse does common-subexpression elimination on the Function.
// Values are just relinked, nothing is deleted. A subsequent deadcode
// pass is required to actually remove duplicate expressions.
func cse(f *Func) { … }

type eqclass …

// partitionValues partitions the values into equivalence classes
// based on having all the following features match:
//   - opcode
//   - type
//   - auxint
//   - aux
//   - nargs
//   - block # if a phi op
//   - first two arg's opcodes and auxint
//   - NOT first two arg's aux; that can break CSE.
//
// partitionValues returns a list of equivalence classes, each
// being a sorted by ID list of *Values. The eqclass slices are
// backed by the same storage as the input slice.
// Equivalence classes of size 1 are ignored.
func partitionValues(a []*Value, auxIDs auxmap) []eqclass { … }

func lt2Cmp(isLt bool) types.Cmp { … }

type auxmap …

func cmpVal(v, w *Value, auxIDs auxmap) types.Cmp { … }