Add capability to scheduler to commute nodes for profit.
If a two-address code whose first operand has uses below, it should be commuted
when possible.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28230 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
index 4a9b9c7..e05d9d7 100644
--- a/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
@@ -120,13 +120,10 @@
if (MainNode->isTargetOpcode()) {
unsigned Opc = MainNode->getTargetOpcode();
- if (TII->isTwoAddrInstr(Opc)) {
+ if (TII->isTwoAddrInstr(Opc))
SU->isTwoAddress = true;
- SDNode *OpN = MainNode->getOperand(0).Val;
- SUnit *OpSU = SUnitMap[OpN];
- if (OpSU)
- OpSU->isDefNUseOperand = true;
- }
+ if (TII->isCommutableInstr(Opc))
+ SU->isCommutable = true;
}
// Find all predecessors and successors of the group.
@@ -391,7 +388,18 @@
// instruction as appropriate.
for (unsigned i = 0; i != NodeOperands; ++i)
AddOperand(MI, Node->getOperand(i), i+NumResults, &II, VRBaseMap);
-
+
+ // Commute node if it has been determined to be profitable.
+ if (CommuteSet.count(Node)) {
+ MachineInstr *NewMI = TII->commuteInstruction(MI);
+ if (NewMI == 0)
+ DEBUG(std::cerr << "Sched: COMMUTING FAILED!\n");
+ else {
+ DEBUG(std::cerr << "Sched: COMMUTED TO: " << *NewMI);
+ MI = NewMI;
+ }
+ }
+
// Now that we have emitted all operands, emit this instruction itself.
if ((II.Flags & M_USES_CUSTOM_DAG_SCHED_INSERTION) == 0) {
BB->insert(BB->end(), MI);