[llvm-commits] CVS: llvm/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp ScheduleDAGRRList.cpp
Evan Cheng
evan.cheng at apple.com
Thu May 11 18:58:38 PDT 2006
Changes in directory llvm/lib/CodeGen/SelectionDAG:
ScheduleDAG.cpp updated: 1.87 -> 1.88
ScheduleDAGRRList.cpp updated: 1.1 -> 1.2
---
Log message:
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.
---
Diffs of the changes: (+61 -31)
ScheduleDAG.cpp | 22 ++++++++++-----
ScheduleDAGRRList.cpp | 70 ++++++++++++++++++++++++++++++++------------------
2 files changed, 61 insertions(+), 31 deletions(-)
Index: llvm/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp:1.87 llvm/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp:1.88
--- llvm/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp:1.87 Thu May 11 18:55:42 2006
+++ llvm/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp Thu May 11 20:58:24 2006
@@ -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);
Index: llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp:1.1 llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp:1.2
--- llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp:1.1 Thu May 11 18:55:42 2006
+++ llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp Thu May 11 20:58:24 2006
@@ -30,7 +30,7 @@
using namespace llvm;
namespace {
- cl::opt<bool> SchedLowerDefNUse("sched-lower-defnuse", cl::Hidden);
+ cl::opt<bool> SchedCommuteNodes("sched-commute-nodes", cl::Hidden);
}
namespace {
@@ -70,6 +70,7 @@
void ScheduleNodeTopDown(SUnit *SU, unsigned& CurCycle);
void ListScheduleTopDown();
void ListScheduleBottomUp();
+ void CommuteNodesToReducePressure();
};
} // end anonymous namespace
@@ -95,6 +96,9 @@
ListScheduleTopDown();
AvailableQueue->releaseState();
+
+ if (SchedCommuteNodes)
+ CommuteNodesToReducePressure();
DEBUG(std::cerr << "*** Final schedule ***\n");
DEBUG(dumpSchedule());
@@ -104,6 +108,41 @@
EmitSchedule();
}
+/// CommuteNodesToReducePressure - Is a node is two-address and commutable, and
+/// it is not the last use of its first operand, add it to the CommuteSet if
+/// possible. It will be commuted when it is translated to a MI.
+void ScheduleDAGRRList::CommuteNodesToReducePressure() {
+ std::set<SUnit *> OperandSeen;
+ for (unsigned i = Sequence.size()-1; i != 0; --i) { // Ignore first node.
+ SUnit *SU = Sequence[i];
+ if (!SU) continue;
+ if (SU->isTwoAddress && SU->isCommutable) {
+ SDNode *OpN = SU->Node->getOperand(0).Val;
+ SUnit *OpSU = SUnitMap[OpN];
+ if (OpSU && OperandSeen.count(OpSU) == 1) {
+ // Ok, so SU is not the last use of OpSU, but SU is two-address so
+ // it will clobber OpSU. Try to commute it if possible.
+ bool DoCommute = true;
+ for (unsigned j = 1, e = SU->Node->getNumOperands(); j != e; ++j) {
+ OpN = SU->Node->getOperand(j).Val;
+ OpSU = SUnitMap[OpN];
+ if (OpSU && OperandSeen.count(OpSU) == 1) {
+ DoCommute = false;
+ break;
+ }
+ }
+ if (DoCommute)
+ CommuteSet.insert(SU->Node);
+ }
+ }
+
+ for (std::set<std::pair<SUnit*, bool> >::iterator I = SU->Preds.begin(),
+ E = SU->Preds.end(); I != E; ++I) {
+ if (!I->second)
+ OperandSeen.insert(I->first);
+ }
+ }
+}
//===----------------------------------------------------------------------===//
// Bottom-Up Scheduling
@@ -436,8 +475,7 @@
void initNodes(const std::vector<SUnit> &sunits) {
SUnits = &sunits;
// Add pseudo dependency edges for two-address nodes.
- if (SchedLowerDefNUse)
- AddPseudoTwoAddrDeps();
+ AddPseudoTwoAddrDeps();
// Calculate node priorities.
CalculatePriorities();
}
@@ -513,23 +551,6 @@
if (RIsFloater)
RBonus += 2;
- if (!SchedLowerDefNUse) {
- // Special tie breaker: if two nodes share a operand, the one that use it
- // as a def&use operand is preferred.
- if (LIsTarget && RIsTarget) {
- if (left->isTwoAddress && !right->isTwoAddress) {
- SDNode *DUNode = left->Node->getOperand(0).Val;
- if (DUNode->isOperand(right->Node))
- LBonus += 2;
- }
- if (!left->isTwoAddress && right->isTwoAddress) {
- SDNode *DUNode = right->Node->getOperand(0).Val;
- if (DUNode->isOperand(left->Node))
- RBonus += 2;
- }
- }
- }
-
if (LPriority+LBonus < RPriority+RBonus)
return true;
else if (LPriority+LBonus == RPriority+RBonus)
@@ -602,16 +623,17 @@
continue;
if (SU->isTwoAddress) {
- unsigned Depth = SU->Node->getNodeDepth();
SUnit *DUSU = getDefUsePredecessor(SU);
if (!DUSU) continue;
for (std::set<std::pair<SUnit*, bool> >::iterator I = DUSU->Succs.begin(),
E = DUSU->Succs.end(); I != E; ++I) {
+ if (I->second) continue;
SUnit *SuccSU = I->first;
- if (SuccSU != SU && !canClobber(SuccSU, DUSU)) {
- if (SuccSU->Node->getNodeDepth() <= Depth+2 &&
- !isReachable(SuccSU, SU)) {
+ if (SuccSU != SU &&
+ (!canClobber(SuccSU, DUSU) ||
+ (SchedCommuteNodes && !SU->isCommutable && SuccSU->isCommutable))){
+ if (SuccSU->Depth <= SU->Depth+2 && !isReachable(SuccSU, SU)) {
DEBUG(std::cerr << "Adding an edge from SU # " << SU->NodeNum
<< " to SU #" << SuccSU->NodeNum << "\n");
if (SU->Preds.insert(std::make_pair(SuccSU, true)).second)
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