diff --git a/src/cmd/compile/internal/ssa/schedule.go b/src/cmd/compile/internal/ssa/schedule.go index de0b4acbf4..cf5f872e0f 100644 --- a/src/cmd/compile/internal/ssa/schedule.go +++ b/src/cmd/compile/internal/ssa/schedule.go @@ -89,9 +89,21 @@ func schedule(f *Func) { // Force the control value to be scheduled at the end, // unless it is a phi value (which must be first). score[b.Control.ID] = 4 - // TODO: some times control values are used by other values - // in the block. So the control value will not appear at - // the very end. Decide if this is a problem or not. + + // Schedule values dependent on the control value at the end. + // This reduces the number of register spills. We don't find + // all values that depend on the control, just values with a + // direct dependency. This is cheaper and in testing there + // was no difference in the number of spills. + for _, v := range b.Values { + if v.Op != OpPhi { + for _, a := range v.Args { + if a == b.Control { + score[v.ID] = 4 + } + } + } + } } // Initialize priority queue with schedulable values.