diff options
Diffstat (limited to 'lib/CodeGen/ScheduleDAGInstrs.cpp')
| -rw-r--r-- | lib/CodeGen/ScheduleDAGInstrs.cpp | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/lib/CodeGen/ScheduleDAGInstrs.cpp b/lib/CodeGen/ScheduleDAGInstrs.cpp index ef33b12367..ebb80a736d 100644 --- a/lib/CodeGen/ScheduleDAGInstrs.cpp +++ b/lib/CodeGen/ScheduleDAGInstrs.cpp @@ -765,6 +765,7 @@ void ScheduleDAGInstrs::buildSchedGraph(AliasAnalysis *AA, assert(SU && "No SUnit mapped to this MI"); // Add register-based dependencies (data, anti, and output). + bool HasVRegDef = false; for (unsigned j = 0, n = MI->getNumOperands(); j != n; ++j) { const MachineOperand &MO = MI->getOperand(j); if (!MO.isReg()) continue; @@ -775,12 +776,26 @@ void ScheduleDAGInstrs::buildSchedGraph(AliasAnalysis *AA, addPhysRegDeps(SU, j); else { assert(!IsPostRA && "Virtual register encountered!"); - if (MO.isDef()) + if (MO.isDef()) { + HasVRegDef = true; addVRegDefDeps(SU, j); + } else if (MO.readsReg()) // ignore undef operands addVRegUseDeps(SU, j); } } + // If we haven't seen any uses in this scheduling region, create a + // dependence edge to ExitSU to model the live-out latency. This is required + // for vreg defs with no in-region use, and prefetches with no vreg def. + // + // FIXME: NumDataSuccs would be more precise than NumSuccs here. This + // check currently relies on being called before adding chain deps. + if (SU->NumSuccs == 0 && SU->Latency > 1 + && (HasVRegDef || MI->mayLoad())) { + SDep Dep(SU, SDep::Artificial); + Dep.setLatency(SU->Latency - 1); + ExitSU.addPred(Dep); + } // Add chain dependencies. // Chain dependencies used to enforce memory order should have |