mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-21 00:32:23 +00:00
360 lines
12 KiB
C
360 lines
12 KiB
C
|
//===-- RegAllocSolver.h - Heuristic PBQP Solver for reg alloc --*- C++ -*-===//
|
||
|
|
//
|
||
|
|
// The LLVM Compiler Infrastructure
|
||
|
|
//
|
||
|
|
// This file is distributed under the University of Illinois Open Source
|
||
|
|
// License. See LICENSE.TXT for details.
|
||
|
|
//
|
||
|
|
//===----------------------------------------------------------------------===//
|
||
|
|
//
|
||
|
|
// Heuristic PBQP solver for register allocation problems. This solver uses a
|
||
|
|
// graph reduction approach. Nodes of degree 0, 1 and 2 are eliminated with
|
||
|
|
// optimality-preserving rules (see ReductionRules.h). When no low-degree (<3)
|
||
|
|
// nodes are present, a heuristic derived from Brigg's graph coloring approach
|
||
|
|
// is used.
|
||
|
|
//
|
||
|
|
//===----------------------------------------------------------------------===//
|
||
|
|
|
||
|
|
#ifndef LLVM_CODEGEN_PBQP_REGALLOCSOLVER_H
|
||
|
|
#define LLVM_CODEGEN_PBQP_REGALLOCSOLVER_H
|
||
|
|
|
||
|
|
#include "CostAllocator.h"
|
||
|
|
#include "Graph.h"
|
||
|
|
#include "ReductionRules.h"
|
||
|
|
#include "Solution.h"
|
||
|
|
#include "llvm/Support/ErrorHandling.h"
|
||
|
|
#include <limits>
|
||
|
|
#include <vector>
|
||
|
|
|
||
|
|
namespace PBQP {
|
||
|
|
|
||
|
|
namespace RegAlloc {
|
||
|
|
|
||
|
|
/// \brief Metadata to speed allocatability test.
|
||
|
|
///
|
||
|
|
/// Keeps track of the number of infinities in each row and column.
|
||
|
|
class MatrixMetadata {
|
||
|
|
private:
|
||
|
|
MatrixMetadata(const MatrixMetadata&);
|
||
|
|
void operator=(const MatrixMetadata&);
|
||
|
|
public:
|
||
|
|
MatrixMetadata(const PBQP::Matrix& m)
|
||
|
|
: worstRow(0), worstCol(0),
|
||
|
|
unsafeRows(new bool[m.getRows() - 1]()),
|
||
|
|
unsafeCols(new bool[m.getCols() - 1]()) {
|
||
|
|
|
||
|
|
unsigned* colCounts = new unsigned[m.getCols() - 1]();
|
||
|
|
|
||
|
|
for (unsigned i = 1; i < m.getRows(); ++i) {
|
||
|
|
unsigned rowCount = 0;
|
||
|
|
for (unsigned j = 1; j < m.getCols(); ++j) {
|
||
|
|
if (m[i][j] == std::numeric_limits<PBQP::PBQPNum>::infinity()) {
|
||
|
|
++rowCount;
|
||
|
|
++colCounts[j - 1];
|
||
|
|
unsafeRows[i - 1] = true;
|
||
|
|
unsafeCols[j - 1] = true;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
worstRow = std::max(worstRow, rowCount);
|
||
|
|
}
|
||
|
|
unsigned worstColCountForCurRow =
|
||
|
|
*std::max_element(colCounts, colCounts + m.getCols() - 1);
|
||
|
|
worstCol = std::max(worstCol, worstColCountForCurRow);
|
||
|
|
delete[] colCounts;
|
||
|
|
}
|
||
|
|
|
||
|
|
~MatrixMetadata() {
|
||
|
|
delete[] unsafeRows;
|
||
|
|
delete[] unsafeCols;
|
||
|
|
}
|
||
|
|
|
||
|
|
unsigned getWorstRow() const { return worstRow; }
|
||
|
|
unsigned getWorstCol() const { return worstCol; }
|
||
|
|
const bool* getUnsafeRows() const { return unsafeRows; }
|
||
|
|
const bool* getUnsafeCols() const { return unsafeCols; }
|
||
|
|
|
||
|
|
private:
|
||
|
|
unsigned worstRow, worstCol;
|
||
|
|
bool* unsafeRows;
|
||
|
|
bool* unsafeCols;
|
||
|
|
};
|
||
|
|
|
||
|
|
class NodeMetadata {
|
||
|
|
public:
|
||
|
|
typedef enum { Unprocessed,
|
||
|
|
OptimallyReducible,
|
||
|
|
ConservativelyAllocatable,
|
||
|
|
NotProvablyAllocatable } ReductionState;
|
||
|
|
|
||
|
|
NodeMetadata() : rs(Unprocessed), deniedOpts(0), optUnsafeEdges(0) {}
|
||
|
|
~NodeMetadata() { delete[] optUnsafeEdges; }
|
||
|
|
|
||
|
|
void setup(const Vector& costs) {
|
||
|
|
numOpts = costs.getLength() - 1;
|
||
|
|
optUnsafeEdges = new unsigned[numOpts]();
|
||
|
|
}
|
||
|
|
|
||
|
|
ReductionState getReductionState() const { return rs; }
|
||
|
|
void setReductionState(ReductionState rs) { this->rs = rs; }
|
||
|
|
|
||
|
|
void handleAddEdge(const MatrixMetadata& md, bool transpose) {
|
||
|
|
deniedOpts += transpose ? md.getWorstCol() : md.getWorstRow();
|
||
|
|
const bool* unsafeOpts =
|
||
|
|
transpose ? md.getUnsafeCols() : md.getUnsafeRows();
|
||
|
|
for (unsigned i = 0; i < numOpts; ++i)
|
||
|
|
optUnsafeEdges[i] += unsafeOpts[i];
|
||
|
|
}
|
||
|
|
|
||
|
|
void handleRemoveEdge(const MatrixMetadata& md, bool transpose) {
|
||
|
|
deniedOpts -= transpose ? md.getWorstCol() : md.getWorstRow();
|
||
|
|
const bool* unsafeOpts =
|
||
|
|
transpose ? md.getUnsafeCols() : md.getUnsafeRows();
|
||
|
|
for (unsigned i = 0; i < numOpts; ++i)
|
||
|
|
optUnsafeEdges[i] -= unsafeOpts[i];
|
||
|
|
}
|
||
|
|
|
||
|
|
bool isConservativelyAllocatable() const {
|
||
|
|
return (deniedOpts < numOpts) ||
|
||
|
|
(std::find(optUnsafeEdges, optUnsafeEdges + numOpts, 0) !=
|
||
|
|
optUnsafeEdges + numOpts);
|
||
|
|
}
|
||
|
|
|
||
|
|
private:
|
||
|
|
ReductionState rs;
|
||
|
|
unsigned numOpts;
|
||
|
|
unsigned deniedOpts;
|
||
|
|
unsigned* optUnsafeEdges;
|
||
|
|
};
|
||
|
|
|
||
|
|
class RegAllocSolverImpl {
|
||
|
|
private:
|
||
|
|
typedef PBQP::MDMatrix<MatrixMetadata> RAMatrix;
|
||
|
|
public:
|
||
|
|
typedef PBQP::Vector RawVector;
|
||
|
|
typedef PBQP::Matrix RawMatrix;
|
||
|
|
typedef PBQP::Vector Vector;
|
||
|
|
typedef RAMatrix Matrix;
|
||
|
|
typedef PBQP::PoolCostAllocator<
|
||
|
|
Vector, PBQP::VectorComparator,
|
||
|
|
Matrix, PBQP::MatrixComparator> CostAllocator;
|
||
|
|
|
||
|
|
typedef PBQP::GraphBase::NodeId NodeId;
|
||
|
|
typedef PBQP::GraphBase::EdgeId EdgeId;
|
||
|
|
|
||
|
|
typedef RegAlloc::NodeMetadata NodeMetadata;
|
||
|
|
|
||
|
|
struct EdgeMetadata { };
|
||
|
|
|
||
|
|
typedef PBQP::Graph<RegAllocSolverImpl> Graph;
|
||
|
|
|
||
|
|
RegAllocSolverImpl(Graph &G) : G(G) {}
|
||
|
|
|
||
|
|
Solution solve() {
|
||
|
|
G.setSolver(*this);
|
||
|
|
Solution S;
|
||
|
|
setup();
|
||
|
|
S = backpropagate(G, reduce());
|
||
|
|
G.unsetSolver();
|
||
|
|
return S;
|
||
|
|
}
|
||
|
|
|
||
|
|
void handleAddNode(NodeId NId) {
|
||
|
|
G.getNodeMetadata(NId).setup(G.getNodeCosts(NId));
|
||
|
|
}
|
||
|
|
void handleRemoveNode(NodeId NId) {}
|
||
|
|
void handleSetNodeCosts(NodeId NId, const Vector& newCosts) {}
|
||
|
|
|
||
|
|
void handleAddEdge(EdgeId EId) {
|
||
|
|
handleReconnectEdge(EId, G.getEdgeNode1Id(EId));
|
||
|
|
handleReconnectEdge(EId, G.getEdgeNode2Id(EId));
|
||
|
|
}
|
||
|
|
|
||
|
|
void handleRemoveEdge(EdgeId EId) {
|
||
|
|
handleDisconnectEdge(EId, G.getEdgeNode1Id(EId));
|
||
|
|
handleDisconnectEdge(EId, G.getEdgeNode2Id(EId));
|
||
|
|
}
|
||
|
|
|
||
|
|
void handleDisconnectEdge(EdgeId EId, NodeId NId) {
|
||
|
|
NodeMetadata& nMd = G.getNodeMetadata(NId);
|
||
|
|
const MatrixMetadata& mMd = G.getEdgeCosts(EId).getMetadata();
|
||
|
|
nMd.handleRemoveEdge(mMd, NId == G.getEdgeNode2Id(EId));
|
||
|
|
if (G.getNodeDegree(NId) == 3) {
|
||
|
|
// This node is becoming optimally reducible.
|
||
|
|
moveToOptimallyReducibleNodes(NId);
|
||
|
|
} else if (nMd.getReductionState() ==
|
||
|
|
NodeMetadata::NotProvablyAllocatable &&
|
||
|
|
nMd.isConservativelyAllocatable()) {
|
||
|
|
// This node just became conservatively allocatable.
|
||
|
|
moveToConservativelyAllocatableNodes(NId);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
void handleReconnectEdge(EdgeId EId, NodeId NId) {
|
||
|
|
NodeMetadata& nMd = G.getNodeMetadata(NId);
|
||
|
|
const MatrixMetadata& mMd = G.getEdgeCosts(EId).getMetadata();
|
||
|
|
nMd.handleAddEdge(mMd, NId == G.getEdgeNode2Id(EId));
|
||
|
|
}
|
||
|
|
|
||
|
|
void handleSetEdgeCosts(EdgeId EId, const Matrix& NewCosts) {
|
||
|
|
handleRemoveEdge(EId);
|
||
|
|
|
||
|
|
NodeId n1Id = G.getEdgeNode1Id(EId);
|
||
|
|
NodeId n2Id = G.getEdgeNode2Id(EId);
|
||
|
|
NodeMetadata& n1Md = G.getNodeMetadata(n1Id);
|
||
|
|
NodeMetadata& n2Md = G.getNodeMetadata(n2Id);
|
||
|
|
const MatrixMetadata& mMd = NewCosts.getMetadata();
|
||
|
|
n1Md.handleAddEdge(mMd, n1Id != G.getEdgeNode1Id(EId));
|
||
|
|
n2Md.handleAddEdge(mMd, n2Id != G.getEdgeNode1Id(EId));
|
||
|
|
}
|
||
|
|
|
||
|
|
private:
|
||
|
|
|
||
|
|
void removeFromCurrentSet(NodeId NId) {
|
||
|
|
switch (G.getNodeMetadata(NId).getReductionState()) {
|
||
|
|
case NodeMetadata::Unprocessed: break;
|
||
|
|
case NodeMetadata::OptimallyReducible:
|
||
|
|
assert(OptimallyReducibleNodes.find(NId) !=
|
||
|
|
OptimallyReducibleNodes.end() &&
|
||
|
|
"Node not in optimally reducible set.");
|
||
|
|
OptimallyReducibleNodes.erase(NId);
|
||
|
|
break;
|
||
|
|
case NodeMetadata::ConservativelyAllocatable:
|
||
|
|
assert(ConservativelyAllocatableNodes.find(NId) !=
|
||
|
|
ConservativelyAllocatableNodes.end() &&
|
||
|
|
"Node not in conservatively allocatable set.");
|
||
|
|
ConservativelyAllocatableNodes.erase(NId);
|
||
|
|
break;
|
||
|
|
case NodeMetadata::NotProvablyAllocatable:
|
||
|
|
assert(NotProvablyAllocatableNodes.find(NId) !=
|
||
|
|
NotProvablyAllocatableNodes.end() &&
|
||
|
|
"Node not in not-provably-allocatable set.");
|
||
|
|
NotProvablyAllocatableNodes.erase(NId);
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
void moveToOptimallyReducibleNodes(NodeId NId) {
|
||
|
|
removeFromCurrentSet(NId);
|
||
|
|
OptimallyReducibleNodes.insert(NId);
|
||
|
|
G.getNodeMetadata(NId).setReductionState(
|
||
|
|
NodeMetadata::OptimallyReducible);
|
||
|
|
}
|
||
|
|
|
||
|
|
void moveToConservativelyAllocatableNodes(NodeId NId) {
|
||
|
|
removeFromCurrentSet(NId);
|
||
|
|
ConservativelyAllocatableNodes.insert(NId);
|
||
|
|
G.getNodeMetadata(NId).setReductionState(
|
||
|
|
NodeMetadata::ConservativelyAllocatable);
|
||
|
|
}
|
||
|
|
|
||
|
|
void moveToNotProvablyAllocatableNodes(NodeId NId) {
|
||
|
|
removeFromCurrentSet(NId);
|
||
|
|
NotProvablyAllocatableNodes.insert(NId);
|
||
|
|
G.getNodeMetadata(NId).setReductionState(
|
||
|
|
NodeMetadata::NotProvablyAllocatable);
|
||
|
|
}
|
||
|
|
|
||
|
|
void setup() {
|
||
|
|
// Set up worklists.
|
||
|
|
for (auto NId : G.nodeIds()) {
|
||
|
|
if (G.getNodeDegree(NId) < 3)
|
||
|
|
moveToOptimallyReducibleNodes(NId);
|
||
|
|
else if (G.getNodeMetadata(NId).isConservativelyAllocatable())
|
||
|
|
moveToConservativelyAllocatableNodes(NId);
|
||
|
|
else
|
||
|
|
moveToNotProvablyAllocatableNodes(NId);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// Compute a reduction order for the graph by iteratively applying PBQP
|
||
|
|
// reduction rules. Locally optimal rules are applied whenever possible (R0,
|
||
|
|
// R1, R2). If no locally-optimal rules apply then any conservatively
|
||
|
|
// allocatable node is reduced. Finally, if no conservatively allocatable
|
||
|
|
// node exists then the node with the lowest spill-cost:degree ratio is
|
||
|
|
// selected.
|
||
|
|
std::vector<GraphBase::NodeId> reduce() {
|
||
|
|
assert(!G.empty() && "Cannot reduce empty graph.");
|
||
|
|
|
||
|
|
typedef GraphBase::NodeId NodeId;
|
||
|
|
std::vector<NodeId> NodeStack;
|
||
|
|
|
||
|
|
// Consume worklists.
|
||
|
|
while (true) {
|
||
|
|
if (!OptimallyReducibleNodes.empty()) {
|
||
|
|
NodeSet::iterator nItr = OptimallyReducibleNodes.begin();
|
||
|
|
NodeId NId = *nItr;
|
||
|
|
OptimallyReducibleNodes.erase(nItr);
|
||
|
|
NodeStack.push_back(NId);
|
||
|
|
switch (G.getNodeDegree(NId)) {
|
||
|
|
case 0:
|
||
|
|
break;
|
||
|
|
case 1:
|
||
|
|
applyR1(G, NId);
|
||
|
|
break;
|
||
|
|
case 2:
|
||
|
|
applyR2(G, NId);
|
||
|
|
break;
|
||
|
|
default: llvm_unreachable("Not an optimally reducible node.");
|
||
|
|
}
|
||
|
|
} else if (!ConservativelyAllocatableNodes.empty()) {
|
||
|
|
// Conservatively allocatable nodes will never spill. For now just
|
||
|
|
// take the first node in the set and push it on the stack. When we
|
||
|
|
// start optimizing more heavily for register preferencing, it may
|
||
|
|
// would be better to push nodes with lower 'expected' or worst-case
|
||
|
|
// register costs first (since early nodes are the most
|
||
|
|
// constrained).
|
||
|
|
NodeSet::iterator nItr = ConservativelyAllocatableNodes.begin();
|
||
|
|
NodeId NId = *nItr;
|
||
|
|
ConservativelyAllocatableNodes.erase(nItr);
|
||
|
|
NodeStack.push_back(NId);
|
||
|
|
G.disconnectAllNeighborsFromNode(NId);
|
||
|
|
|
||
|
|
} else if (!NotProvablyAllocatableNodes.empty()) {
|
||
|
|
NodeSet::iterator nItr =
|
||
|
|
std::min_element(NotProvablyAllocatableNodes.begin(),
|
||
|
|
NotProvablyAllocatableNodes.end(),
|
||
|
|
SpillCostComparator(G));
|
||
|
|
NodeId NId = *nItr;
|
||
|
|
NotProvablyAllocatableNodes.erase(nItr);
|
||
|
|
NodeStack.push_back(NId);
|
||
|
|
G.disconnectAllNeighborsFromNode(NId);
|
||
|
|
} else
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
|
||
|
|
return NodeStack;
|
||
|
|
}
|
||
|
|
|
||
|
|
class SpillCostComparator {
|
||
|
|
public:
|
||
|
|
SpillCostComparator(const Graph& G) : G(G) {}
|
||
|
|
bool operator()(NodeId N1Id, NodeId N2Id) {
|
||
|
|
PBQPNum N1SC = G.getNodeCosts(N1Id)[0] / G.getNodeDegree(N1Id);
|
||
|
|
PBQPNum N2SC = G.getNodeCosts(N2Id)[0] / G.getNodeDegree(N2Id);
|
||
|
|
return N1SC < N2SC;
|
||
|
|
}
|
||
|
|
private:
|
||
|
|
const Graph& G;
|
||
|
|
};
|
||
|
|
|
||
|
|
Graph& G;
|
||
|
|
typedef std::set<NodeId> NodeSet;
|
||
|
|
NodeSet OptimallyReducibleNodes;
|
||
|
|
NodeSet ConservativelyAllocatableNodes;
|
||
|
|
NodeSet NotProvablyAllocatableNodes;
|
||
|
|
};
|
||
|
|
|
||
|
|
typedef Graph<RegAllocSolverImpl> Graph;
|
||
|
|
|
||
|
|
Solution solve(Graph& G) {
|
||
|
|
if (G.empty())
|
||
|
|
return Solution();
|
||
|
|
RegAllocSolverImpl RegAllocSolver(G);
|
||
|
|
return RegAllocSolver.solve();
|
||
|
|
}
|
||
|
|
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif // LLVM_CODEGEN_PBQP_REGALLOCSOLVER_H
|