Experimental post-pass scheduling support. Post-pass scheduling
is currently off by default, and can be enabled with
-disable-post-RA-scheduler=false.
This doesn't have a significant impact on most code yet because it doesn't
yet do anything to address anti-dependencies and it doesn't attempt to
disambiguate memory references. Also, several popular targets
don't have pipeline descriptions yet.
The majority of the changes here are splitting the SelectionDAG-specific
code out of ScheduleDAG, so that ScheduleDAG can be moved to
libLLVMCodeGen.a. The interface between ScheduleDAG-using code and
the rest of the scheduling code is somewhat rough and will evolve.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59676 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ScheduleDAG.cpp b/lib/CodeGen/ScheduleDAG.cpp
new file mode 100644
index 0000000..e6a8d13
--- /dev/null
+++ b/lib/CodeGen/ScheduleDAG.cpp
@@ -0,0 +1,210 @@
+//===---- ScheduleDAG.cpp - Implement the ScheduleDAG class ---------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This implements the ScheduleDAG class, which is a base class used by
+// scheduling implementation classes.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "pre-RA-sched"
+#include "llvm/CodeGen/ScheduleDAG.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Support/Debug.h"
+using namespace llvm;
+
+ScheduleDAG::ScheduleDAG(SelectionDAG *dag, MachineBasicBlock *bb,
+ const TargetMachine &tm)
+ : DAG(dag), BB(bb), TM(tm), MRI(BB->getParent()->getRegInfo()) {
+ TII = TM.getInstrInfo();
+ MF = BB->getParent();
+ TRI = TM.getRegisterInfo();
+ TLI = TM.getTargetLowering();
+ ConstPool = MF->getConstantPool();
+}
+
+ScheduleDAG::~ScheduleDAG() {}
+
+/// CalculateDepths - compute depths using algorithms for the longest
+/// paths in the DAG
+void ScheduleDAG::CalculateDepths() {
+ unsigned DAGSize = SUnits.size();
+ std::vector<SUnit*> WorkList;
+ WorkList.reserve(DAGSize);
+
+ // Initialize the data structures
+ for (unsigned i = 0, e = DAGSize; i != e; ++i) {
+ SUnit *SU = &SUnits[i];
+ unsigned Degree = SU->Preds.size();
+ // Temporarily use the Depth field as scratch space for the degree count.
+ SU->Depth = Degree;
+
+ // Is it a node without dependencies?
+ if (Degree == 0) {
+ assert(SU->Preds.empty() && "SUnit should have no predecessors");
+ // Collect leaf nodes
+ WorkList.push_back(SU);
+ }
+ }
+
+ // Process nodes in the topological order
+ while (!WorkList.empty()) {
+ SUnit *SU = WorkList.back();
+ WorkList.pop_back();
+ unsigned SUDepth = 0;
+
+ // Use dynamic programming:
+ // When current node is being processed, all of its dependencies
+ // are already processed.
+ // So, just iterate over all predecessors and take the longest path
+ for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+ I != E; ++I) {
+ unsigned PredDepth = I->Dep->Depth;
+ if (PredDepth+1 > SUDepth) {
+ SUDepth = PredDepth + 1;
+ }
+ }
+
+ SU->Depth = SUDepth;
+
+ // Update degrees of all nodes depending on current SUnit
+ for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+ I != E; ++I) {
+ SUnit *SU = I->Dep;
+ if (!--SU->Depth)
+ // If all dependencies of the node are processed already,
+ // then the longest path for the node can be computed now
+ WorkList.push_back(SU);
+ }
+ }
+}
+
+/// CalculateHeights - compute heights using algorithms for the longest
+/// paths in the DAG
+void ScheduleDAG::CalculateHeights() {
+ unsigned DAGSize = SUnits.size();
+ std::vector<SUnit*> WorkList;
+ WorkList.reserve(DAGSize);
+
+ // Initialize the data structures
+ for (unsigned i = 0, e = DAGSize; i != e; ++i) {
+ SUnit *SU = &SUnits[i];
+ unsigned Degree = SU->Succs.size();
+ // Temporarily use the Height field as scratch space for the degree count.
+ SU->Height = Degree;
+
+ // Is it a node without dependencies?
+ if (Degree == 0) {
+ assert(SU->Succs.empty() && "Something wrong");
+ assert(WorkList.empty() && "Should be empty");
+ // Collect leaf nodes
+ WorkList.push_back(SU);
+ }
+ }
+
+ // Process nodes in the topological order
+ while (!WorkList.empty()) {
+ SUnit *SU = WorkList.back();
+ WorkList.pop_back();
+ unsigned SUHeight = 0;
+
+ // Use dynamic programming:
+ // When current node is being processed, all of its dependencies
+ // are already processed.
+ // So, just iterate over all successors and take the longest path
+ for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+ I != E; ++I) {
+ unsigned SuccHeight = I->Dep->Height;
+ if (SuccHeight+1 > SUHeight) {
+ SUHeight = SuccHeight + 1;
+ }
+ }
+
+ SU->Height = SUHeight;
+
+ // Update degrees of all nodes depending on current SUnit
+ for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+ I != E; ++I) {
+ SUnit *SU = I->Dep;
+ if (!--SU->Height)
+ // If all dependencies of the node are processed already,
+ // then the longest path for the node can be computed now
+ WorkList.push_back(SU);
+ }
+ }
+}
+
+/// dump - dump the schedule.
+void ScheduleDAG::dumpSchedule() const {
+ for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
+ if (SUnit *SU = Sequence[i])
+ SU->dump(this);
+ else
+ cerr << "**** NOOP ****\n";
+ }
+}
+
+
+/// Run - perform scheduling.
+///
+void ScheduleDAG::Run() {
+ Schedule();
+
+ DOUT << "*** Final schedule ***\n";
+ DEBUG(dumpSchedule());
+ DOUT << "\n";
+}
+
+/// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
+/// a group of nodes flagged together.
+void SUnit::dump(const ScheduleDAG *G) const {
+ cerr << "SU(" << NodeNum << "): ";
+ G->dumpNode(this);
+}
+
+void SUnit::dumpAll(const ScheduleDAG *G) const {
+ dump(G);
+
+ cerr << " # preds left : " << NumPredsLeft << "\n";
+ cerr << " # succs left : " << NumSuccsLeft << "\n";
+ cerr << " Latency : " << Latency << "\n";
+ cerr << " Depth : " << Depth << "\n";
+ cerr << " Height : " << Height << "\n";
+
+ if (Preds.size() != 0) {
+ cerr << " Predecessors:\n";
+ for (SUnit::const_succ_iterator I = Preds.begin(), E = Preds.end();
+ I != E; ++I) {
+ if (I->isCtrl)
+ cerr << " ch #";
+ else
+ cerr << " val #";
+ cerr << I->Dep << " - SU(" << I->Dep->NodeNum << ")";
+ if (I->isSpecial)
+ cerr << " *";
+ cerr << "\n";
+ }
+ }
+ if (Succs.size() != 0) {
+ cerr << " Successors:\n";
+ for (SUnit::const_succ_iterator I = Succs.begin(), E = Succs.end();
+ I != E; ++I) {
+ if (I->isCtrl)
+ cerr << " ch #";
+ else
+ cerr << " val #";
+ cerr << I->Dep << " - SU(" << I->Dep->NodeNum << ")";
+ if (I->isSpecial)
+ cerr << " *";
+ cerr << "\n";
+ }
+ }
+ cerr << "\n";
+}