diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/cmd/compile/internal/ssa/schedule.go | 14 |
1 files changed, 4 insertions, 10 deletions
diff --git a/src/cmd/compile/internal/ssa/schedule.go b/src/cmd/compile/internal/ssa/schedule.go index 7ef04b2c32..ebf84d59b3 100644 --- a/src/cmd/compile/internal/ssa/schedule.go +++ b/src/cmd/compile/internal/ssa/schedule.go @@ -155,16 +155,10 @@ func schedule(f *Func) { // VARDEF ops are scheduled before the corresponding LEA. score[v.ID] = ScoreMemory case v.Op == OpSelect0 || v.Op == OpSelect1 || v.Op == OpSelectN: - // Schedule the pseudo-op of reading part of a tuple - // immediately after the tuple-generating op, since - // this value is already live. This also removes its - // false dependency on the other part of the tuple. - // Also ensures tuple is never spilled. - if (v.Op == OpSelect1 || v.Op == OpSelect0) && v.Args[0].Op.isCarry() { - // Score tuple ops of carry ops later to ensure they do not - // delay scheduling the tuple-generating op. If such tuple ops - // are not placed more readily, unrelated carry clobbering ops - // may be placed inbetween two carry-dependent operations. + if (v.Op == OpSelect1 || v.Op == OpSelect0) && (v.Args[0].Op.isCarry() || v.Type.IsFlags()) { + // When the Select pseudo op is being used for a carry or flag from + // a tuple then score it as ScoreFlags so it happens later. This + // prevents the bit from being clobbered before it is used. score[v.ID] = ScoreFlags } else { score[v.ID] = ScoreReadTuple |