llvm-6502/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
Andrew Trick 92e946630d Introducing a new method of tracking register pressure. We can't
precisely track pressure on a selection DAG, but we can at least keep
it balanced. This design accounts for various interesting aspects of
selection DAGS: register and subregister copies, glued nodes, dead
nodes, unused registers, etc.

Added SUnit::NumRegDefsLeft and ScheduleDAGSDNodes::RegDefIter.

Note: I disabled PrescheduleNodesWithMultipleUses when register
pressure is enabled, based on no evidence other than I don't think it
makes sense to have both enabled.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124853 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-04 03:18:17 +00:00

152 lines
5.3 KiB
C++

//===---- ScheduleDAGSDNodes.h - SDNode Scheduling --------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the ScheduleDAGSDNodes class, which implements
// scheduling for an SDNode-based dependency graph.
//
//===----------------------------------------------------------------------===//
#ifndef SCHEDULEDAGSDNODES_H
#define SCHEDULEDAGSDNODES_H
#include "llvm/CodeGen/ScheduleDAG.h"
#include "llvm/CodeGen/SelectionDAG.h"
namespace llvm {
/// ScheduleDAGSDNodes - A ScheduleDAG for scheduling SDNode-based DAGs.
///
/// Edges between SUnits are initially based on edges in the SelectionDAG,
/// and additional edges can be added by the schedulers as heuristics.
/// SDNodes such as Constants, Registers, and a few others that are not
/// interesting to schedulers are not allocated SUnits.
///
/// SDNodes with MVT::Glue operands are grouped along with the flagged
/// nodes into a single SUnit so that they are scheduled together.
///
/// SDNode-based scheduling graphs do not use SDep::Anti or SDep::Output
/// edges. Physical register dependence information is not carried in
/// the DAG and must be handled explicitly by schedulers.
///
class ScheduleDAGSDNodes : public ScheduleDAG {
public:
SelectionDAG *DAG; // DAG of the current basic block
const InstrItineraryData *InstrItins;
explicit ScheduleDAGSDNodes(MachineFunction &mf);
virtual ~ScheduleDAGSDNodes() {}
/// Run - perform scheduling.
///
void Run(SelectionDAG *dag, MachineBasicBlock *bb,
MachineBasicBlock::iterator insertPos);
/// isPassiveNode - Return true if the node is a non-scheduled leaf.
///
static bool isPassiveNode(SDNode *Node) {
if (isa<ConstantSDNode>(Node)) return true;
if (isa<ConstantFPSDNode>(Node)) return true;
if (isa<RegisterSDNode>(Node)) return true;
if (isa<GlobalAddressSDNode>(Node)) return true;
if (isa<BasicBlockSDNode>(Node)) return true;
if (isa<FrameIndexSDNode>(Node)) return true;
if (isa<ConstantPoolSDNode>(Node)) return true;
if (isa<JumpTableSDNode>(Node)) return true;
if (isa<ExternalSymbolSDNode>(Node)) return true;
if (isa<BlockAddressSDNode>(Node)) return true;
if (Node->getOpcode() == ISD::EntryToken ||
isa<MDNodeSDNode>(Node)) return true;
return false;
}
/// NewSUnit - Creates a new SUnit and return a ptr to it.
///
SUnit *NewSUnit(SDNode *N);
/// Clone - Creates a clone of the specified SUnit. It does not copy the
/// predecessors / successors info nor the temporary scheduling states.
///
SUnit *Clone(SUnit *N);
/// BuildSchedGraph - Build the SUnit graph from the selection dag that we
/// are input. This SUnit graph is similar to the SelectionDAG, but
/// excludes nodes that aren't interesting to scheduling, and represents
/// flagged together nodes with a single SUnit.
virtual void BuildSchedGraph(AliasAnalysis *AA);
/// InitNumRegDefsLeft - Determine the # of regs defined by this node.
///
void InitNumRegDefsLeft(SUnit *SU);
/// ComputeLatency - Compute node latency.
///
virtual void ComputeLatency(SUnit *SU);
/// ComputeOperandLatency - Override dependence edge latency using
/// operand use/def information
///
virtual void ComputeOperandLatency(SUnit *Def, SUnit *Use,
SDep& dep) const { }
virtual void ComputeOperandLatency(SDNode *Def, SDNode *Use,
unsigned OpIdx, SDep& dep) const;
virtual MachineBasicBlock *EmitSchedule();
/// Schedule - Order nodes according to selected style, filling
/// in the Sequence member.
///
virtual void Schedule() = 0;
virtual void dumpNode(const SUnit *SU) const;
virtual std::string getGraphNodeLabel(const SUnit *SU) const;
virtual void getCustomGraphFeatures(GraphWriter<ScheduleDAG*> &GW) const;
/// RegDefIter - In place iteration over the values defined by an
/// SUnit. This does not need copies of the iterator or any other STLisms.
/// The iterator creates itself, rather than being provided by the SchedDAG.
class RegDefIter {
const ScheduleDAGSDNodes *SchedDAG;
const SDNode *Node;
unsigned DefIdx;
unsigned NodeNumDefs;
EVT ValueType;
public:
RegDefIter(const SUnit *SU, const ScheduleDAGSDNodes *SD);
bool IsValid() const { return Node != NULL; }
EVT GetValue() const {
assert(IsValid() && "bad iterator");
return ValueType;
}
void Advance();
private:
void InitNodeNumDefs();
};
private:
/// ClusterNeighboringLoads - Cluster loads from "near" addresses into
/// combined SUnits.
void ClusterNeighboringLoads(SDNode *Node);
/// ClusterNodes - Cluster certain nodes which should be scheduled together.
///
void ClusterNodes();
/// BuildSchedUnits, AddSchedEdges - Helper functions for BuildSchedGraph.
void BuildSchedUnits();
void AddSchedEdges();
};
}
#endif