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

// trim removes blocks with no code in them.
// These blocks were inserted to remove critical edges.
func trim(f *Func) { … }

// emptyBlock reports whether the block does not contain actual
// instructions.
func emptyBlock(b *Block) bool { … }

// trimmableBlock reports whether the block can be trimmed from the CFG,
// subject to the following criteria:
//   - it should not be the first block.
//   - it should be BlockPlain.
//   - it should not loop back to itself.
//   - it either is the single predecessor of the successor block or
//     contains no actual instructions.
func trimmableBlock(b *Block) bool { … }

// mergePhi adjusts the number of `v`s arguments to account for merge
// of `b`, which was `i`th predecessor of the `v`s block.
func mergePhi(v *Value, i int, b *Block) { … }