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- Fixed some priority calculation bugs that were causing bug 478. Among them:

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a predecessor appearing more than once in the operand list was counted as
  multiple predecessor; priority1 should be updated during scheduling;
  CycleBound was updated after the node is inserted into priority queue; one
  of the tie breaking condition was flipped.
- Take into consideration of two address opcodes. If a predecessor is a def&use
  operand, it should have a higher priority.
- Scheduler should also favor floaters, i.e. nodes that do not have real
  predecessors such as MOV32ri.
- The scheduling fixes / tweaks fixed bug 478:
        .text
        .align  4
        .globl  _f
_f:
        movl 4(%esp), %eax
        movl 8(%esp), %ecx
        movl %eax, %edx
        imull %ecx, %edx
        imull %eax, %eax
        imull %ecx, %ecx
        addl %eax, %ecx
        leal (%ecx,%edx,2), %eax
        ret

  It is also a slight performance win (1% - 3%) for most tests.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26470 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2006-03-02 21:38:29 +00:00
parent db3f873bd8
commit 86ec7d1d07
1 changed files with 98 additions and 64 deletions
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162
lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp
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@ -21,8 +21,9 @@
#include "llvm/Support/Debug.h"
#include <climits>
#include <iostream>
#include <memory>
#include <queue>
#include <set>
#include <vector>
using namespace llvm;
namespace {
@ -32,14 +33,17 @@ namespace {
struct SUnit {
SDNode *Node; // Representative node.
std::vector<SDNode*> FlaggedNodes; // All nodes flagged to Node.
std::vector<SUnit*> Preds; // All real predecessors.
std::vector<SUnit*> ChainPreds; // All chain predecessors.
std::vector<SUnit*> Succs; // All real successors.
std::vector<SUnit*> ChainSuccs; // All chain successors.
std::set<SUnit*> Preds; // All real predecessors.
std::set<SUnit*> ChainPreds; // All chain predecessors.
std::set<SUnit*> Succs; // All real successors.
std::set<SUnit*> ChainSuccs; // All chain successors.
int NumPredsLeft; // # of preds not scheduled.
int NumSuccsLeft; // # of succs not scheduled.
int NumChainPredsLeft; // # of chain preds not scheduled.
int NumChainSuccsLeft; // # of chain succs not scheduled.
int Priority1; // Scheduling priority 1.
int Priority2; // Scheduling priority 2.
bool isDefNUseOperand; // Is a def&use operand.
unsigned Latency; // Node latency.
unsigned CycleBound; // Upper/lower cycle to be scheduled at.
unsigned Slot; // Cycle node is scheduled at.
@ -47,8 +51,9 @@ struct SUnit {
SUnit(SDNode *node)
: Node(node), NumPredsLeft(0), NumSuccsLeft(0),
Priority1(INT_MIN), Priority2(INT_MIN), Latency(0),
CycleBound(0), Slot(0), Next(NULL) {}
NumChainPredsLeft(0), NumChainSuccsLeft(0),
Priority1(INT_MIN), Priority2(INT_MIN), isDefNUseOperand(false),
Latency(0), CycleBound(0), Slot(0), Next(NULL) {}
void dump(const SelectionDAG *G, bool All=true) const;
};
@ -66,37 +71,43 @@ void SUnit::dump(const SelectionDAG *G, bool All) const {
}
if (All) {
std::cerr << "# preds left : " << NumPredsLeft << "\n";
std::cerr << "# succs left : " << NumSuccsLeft << "\n";
std::cerr << "Latency : " << Latency << "\n";
std::cerr << "Priority : " << Priority1 << " , " << Priority2 << "\n";
std::cerr << "# preds left : " << NumPredsLeft << "\n";
std::cerr << "# succs left : " << NumSuccsLeft << "\n";
std::cerr << "# chain preds left : " << NumChainPredsLeft << "\n";
std::cerr << "# chain succs left : " << NumChainSuccsLeft << "\n";
std::cerr << "Latency : " << Latency << "\n";
std::cerr << "Priority : " << Priority1 << " , " << Priority2 << "\n";
if (Preds.size() != 0) {
std::cerr << "Predecessors :\n";
for (unsigned i = 0, e = Preds.size(); i != e; i++) {
for (std::set<SUnit*>::iterator I = Preds.begin(),
E = Preds.end(); I != E; ++I) {
std::cerr << " ";
Preds[i]->dump(G, false);
(*I)->dump(G, false);
}
}
if (ChainPreds.size() != 0) {
std::cerr << "Chained Preds :\n";
for (unsigned i = 0, e = ChainPreds.size(); i != e; i++) {
for (std::set<SUnit*>::iterator I = ChainPreds.begin(),
E = ChainPreds.end(); I != E; ++I) {
std::cerr << " ";
ChainPreds[i]->dump(G, false);
(*I)->dump(G, false);
}
}
if (Succs.size() != 0) {
std::cerr << "Successors :\n";
for (unsigned i = 0, e = Succs.size(); i != e; i++) {
for (std::set<SUnit*>::iterator I = Succs.begin(),
E = Succs.end(); I != E; ++I) {
std::cerr << " ";
Succs[i]->dump(G, false);
(*I)->dump(G, false);
}
}
if (ChainSuccs.size() != 0) {
std::cerr << "Chained succs :\n";
for (unsigned i = 0, e = ChainSuccs.size(); i != e; i++) {
for (std::set<SUnit*>::iterator I = ChainSuccs.begin(),
E = ChainSuccs.end(); I != E; ++I) {
std::cerr << " ";
ChainSuccs[i]->dump(G, false);
(*I)->dump(G, false);
}
}
}
@ -105,24 +116,30 @@ void SUnit::dump(const SelectionDAG *G, bool All) const {
/// Sorting functions for the Available queue.
struct ls_rr_sort : public std::binary_function<SUnit*, SUnit*, bool> {
bool operator()(const SUnit* left, const SUnit* right) const {
if (left->Priority1 > right->Priority1) {
bool LFloater = (left ->Preds.size() == 0);
bool RFloater = (right->Preds.size() == 0);
int LBonus = (int)left ->isDefNUseOperand;
int RBonus = (int)right->isDefNUseOperand;
int LPriority1 = left ->Priority1 - LBonus;
int RPriority1 = right->Priority1 - RBonus;
int LPriority2 = left ->Priority2 + LBonus;
int RPriority2 = right->Priority2 + RBonus;
// Favor floaters (i.e. node with no non-passive predecessors):
// e.g. MOV32ri.
if (!LFloater && RFloater)
return true;
} else if (left->Priority1 == right->Priority1) {
unsigned lf = left->FlaggedNodes.size();
unsigned rf = right->FlaggedNodes.size();
if (lf > rf)
else if (LFloater == RFloater)
if (LPriority1 > RPriority1)
return true;
else if (lf == rf) {
if (left->Priority2 > right->Priority2)
else if (LPriority1 == RPriority1)
if (LPriority2 < RPriority2)
return true;
else if (left->Priority2 == right->Priority2) {
else if (LPriority1 == RPriority1)
if (left->CycleBound > right->CycleBound)
return true;
else
return left->Node->getNodeDepth() < right->Node->getNodeDepth();
}
}
}
return false;
}
@ -163,7 +180,7 @@ public:
private:
SUnit *NewSUnit(SDNode *N);
void ReleasePred(SUnit *PredSU);
void ReleasePred(SUnit *PredSU, bool isChain = false);
void ScheduleNode(SUnit *SU);
int CalcNodePriority(SUnit *SU);
void CalculatePriorities();
@ -189,11 +206,21 @@ SUnit *ScheduleDAGList::NewSUnit(SDNode *N) {
/// ReleasePred - Decrement the NumSuccsLeft count of a predecessor. Add it to
/// the Available queue is the count reaches zero. Also update its cycle bound.
void ScheduleDAGList::ReleasePred(SUnit *PredSU) {
void ScheduleDAGList::ReleasePred(SUnit *PredSU, bool isChain) {
SDNode *PredNode = PredSU->Node;
PredSU->NumSuccsLeft--;
if (PredSU->NumSuccsLeft == 0) {
// FIXME: the distance between two nodes is not always == the predecessor's
// latency. For example, the reader can very well read the register written
// by the predecessor later than the issue cycle. It also depends on the
// interrupt model (drain vs. freeze).
PredSU->CycleBound = std::max(PredSU->CycleBound, CurrCycle + PredSU->Latency);
if (!isChain) {
PredSU->NumSuccsLeft--;
PredSU->Priority1++;
} else
PredSU->NumChainSuccsLeft--;
if (PredSU->NumSuccsLeft == 0 && PredSU->NumChainSuccsLeft == 0) {
// EntryToken has to go last!
if (PredNode->getOpcode() != ISD::EntryToken)
Available.push(PredSU);
@ -205,12 +232,6 @@ void ScheduleDAGList::ReleasePred(SUnit *PredSU) {
assert(0);
#endif
}
// FIXME: the distance between two nodes is not always == the predecessor's
// latency. For example, the reader can very well read the register written
// by the predecessor later than the issue cycle. It also depends on the
// interrupt model (drain vs. freeze).
PredSU->CycleBound = std::max(PredSU->CycleBound, CurrCycle + PredSU->Latency);
}
/// ScheduleNode - Add the node to the schedule. Decrement the pending count of
@ -221,10 +242,15 @@ void ScheduleDAGList::ScheduleNode(SUnit *SU) {
SU->Slot = CurrCycle;
// Bottom up: release predecessors
for (unsigned i = 0, e = SU->Preds.size(); i != e; i++)
ReleasePred(SU->Preds[i]);
for (unsigned i = 0, e = SU->ChainPreds.size(); i != e; i++)
ReleasePred(SU->ChainPreds[i]);
for (std::set<SUnit*>::iterator I1 = SU->Preds.begin(),
E1 = SU->Preds.end(); I1 != E1; ++I1) {
ReleasePred(*I1);
SU->NumPredsLeft--;
SU->Priority1--;
}
for (std::set<SUnit*>::iterator I2 = SU->ChainPreds.begin(),
E2 = SU->ChainPreds.end(); I2 != E2; ++I2)
ReleasePred(*I2, true);
CurrCycle++;
}
@ -272,7 +298,7 @@ void ScheduleDAGList::ListSchedule() {
#ifndef NDEBUG
bool AnyNotSched = false;
for (SUnit *SU = HeadSUnit; SU != NULL; SU = SU->Next) {
if (SU->NumSuccsLeft != 0) {
if (SU->NumSuccsLeft != 0 || SU->NumChainSuccsLeft != 0) {
if (!AnyNotSched)
std::cerr << "*** List scheduling failed! ***\n";
SU->dump(&DAG);
@ -292,22 +318,24 @@ void ScheduleDAGList::ListSchedule() {
DEBUG(std::cerr << "\n");
}
/// CalcNodePriority - Priority 1 is just the number of live range genned - number
/// of live range killed. Priority 2 is the Sethi Ullman number. It returns
/// priority 2 since it is calculated recursively.
/// Smaller number is the higher priority in both cases.
/// CalcNodePriority - Priority1 is just the number of live range genned -
/// number of live range killed. Priority2 is the Sethi Ullman number. It
/// returns Priority2 since it is calculated recursively.
/// Smaller number is the higher priority for Priority2. Reverse is true for
/// Priority1.
int ScheduleDAGList::CalcNodePriority(SUnit *SU) {
if (SU->Priority2 != INT_MIN)
return SU->Priority2;
SU->Priority1 = SU->Preds.size() - SU->Succs.size();
SU->Priority1 = SU->NumPredsLeft - SU->NumSuccsLeft;
if (SU->Preds.size() == 0) {
SU->Priority2 = 1;
} else {
int Extra = 0;
for (unsigned i = 0, e = SU->Preds.size(); i != e; i++) {
SUnit *PredSU = SU->Preds[i];
for (std::set<SUnit*>::iterator I = SU->Preds.begin(),
E = SU->Preds.end(); I != E; ++I) {
SUnit *PredSU = *I;
int PredPriority = CalcNodePriority(PredSU);
if (PredPriority > SU->Priority2) {
SU->Priority2 = PredPriority;
@ -387,14 +415,16 @@ void ScheduleDAGList::BuildSchedUnits() {
assert(VT != MVT::Flag);
SUnit *OpSU = SUnitMap[OpN];
if (VT == MVT::Other) {
SU ->ChainPreds.push_back(OpSU);
OpSU->ChainSuccs.push_back(SU);
if (SU->ChainPreds.insert(OpSU).second)
SU->NumChainPredsLeft++;
if (OpSU->ChainSuccs.insert(SU).second)
OpSU->NumChainSuccsLeft++;
} else {
SU ->Preds.push_back(OpSU);
OpSU->Succs.push_back(SU);
if (SU->Preds.insert(OpSU).second)
SU->NumPredsLeft++;
if (OpSU->Succs.insert(SU).second)
OpSU->NumSuccsLeft++;
}
SU->NumPredsLeft++;
OpSU->NumSuccsLeft++;
}
}
} else {
@ -407,14 +437,18 @@ void ScheduleDAGList::BuildSchedUnits() {
assert(VT != MVT::Flag);
SUnit *OpSU = SUnitMap[OpN];
if (VT == MVT::Other) {
SU ->ChainPreds.push_back(OpSU);
OpSU->ChainSuccs.push_back(SU);
if (SU->ChainPreds.insert(OpSU).second)
SU->NumChainPredsLeft++;
if (OpSU->ChainSuccs.insert(SU).second)
OpSU->NumChainSuccsLeft++;
} else {
SU ->Preds.push_back(OpSU);
OpSU->Succs.push_back(SU);
if (SU->Preds.insert(OpSU).second)
SU->NumPredsLeft++;
if (OpSU->Succs.insert(SU).second)
OpSU->NumSuccsLeft++;
if (j == 0 && TII->isTwoAddrInstr(N->getTargetOpcode()))
OpSU->isDefNUseOperand = true;
}
SU->NumPredsLeft++;
OpSU->NumSuccsLeft++;
}
}
}