aboutsummaryrefslogtreecommitdiffstats
path: root/lib/CodeGen/RegAllocPBQP.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'lib/CodeGen/RegAllocPBQP.cpp')
-rw-r--r--lib/CodeGen/RegAllocPBQP.cpp83
1 files changed, 71 insertions, 12 deletions
diff --git a/lib/CodeGen/RegAllocPBQP.cpp b/lib/CodeGen/RegAllocPBQP.cpp
index 77a42b3..eeff73d 100644
--- a/lib/CodeGen/RegAllocPBQP.cpp
+++ b/lib/CodeGen/RegAllocPBQP.cpp
@@ -178,8 +178,40 @@ class Interference : public PBQPRAConstraint {
private:
typedef const PBQP::RegAlloc::AllowedRegVector* AllowedRegVecPtr;
- typedef std::pair<AllowedRegVecPtr, AllowedRegVecPtr> IMatrixKey;
- typedef DenseMap<IMatrixKey, PBQPRAGraph::MatrixPtr> IMatrixCache;
+ typedef std::pair<AllowedRegVecPtr, AllowedRegVecPtr> IKey;
+ typedef DenseMap<IKey, PBQPRAGraph::MatrixPtr> IMatrixCache;
+ typedef DenseSet<IKey> DisjointAllowedRegsCache;
+ typedef std::pair<PBQP::GraphBase::NodeId, PBQP::GraphBase::NodeId> IEdgeKey;
+ typedef DenseSet<IEdgeKey> IEdgeCache;
+
+ bool haveDisjointAllowedRegs(const PBQPRAGraph &G, PBQPRAGraph::NodeId NId,
+ PBQPRAGraph::NodeId MId,
+ const DisjointAllowedRegsCache &D) const {
+ const auto *NRegs = &G.getNodeMetadata(NId).getAllowedRegs();
+ const auto *MRegs = &G.getNodeMetadata(MId).getAllowedRegs();
+
+ if (NRegs == MRegs)
+ return false;
+
+ if (NRegs < MRegs)
+ return D.count(IKey(NRegs, MRegs)) > 0;
+
+ return D.count(IKey(MRegs, NRegs)) > 0;
+ }
+
+ void setDisjointAllowedRegs(const PBQPRAGraph &G, PBQPRAGraph::NodeId NId,
+ PBQPRAGraph::NodeId MId,
+ DisjointAllowedRegsCache &D) {
+ const auto *NRegs = &G.getNodeMetadata(NId).getAllowedRegs();
+ const auto *MRegs = &G.getNodeMetadata(MId).getAllowedRegs();
+
+ assert(NRegs != MRegs && "AllowedRegs can not be disjoint with itself");
+
+ if (NRegs < MRegs)
+ D.insert(IKey(NRegs, MRegs));
+ else
+ D.insert(IKey(MRegs, NRegs));
+ }
// Holds (Interval, CurrentSegmentID, and NodeId). The first two are required
// for the fast interference graph construction algorithm. The last is there
@@ -247,6 +279,13 @@ public:
// and uniquing them.
IMatrixCache C;
+ // Finding an edge is expensive in the worst case (O(max_clique(G))). So
+ // cache locally edges we have already seen.
+ IEdgeCache EC;
+
+ // Cache known disjoint allowed registers pairs
+ DisjointAllowedRegsCache D;
+
typedef std::set<IntervalInfo, decltype(&lowestEndPoint)> IntervalSet;
typedef std::priority_queue<IntervalInfo, std::vector<IntervalInfo>,
decltype(&lowestStartPoint)> IntervalQueue;
@@ -290,14 +329,21 @@ public:
for (const auto &A : Active) {
PBQP::GraphBase::NodeId MId = getNodeId(A);
+ // Do not add an edge when the nodes' allowed registers do not
+ // intersect: there is obviously no interference.
+ if (haveDisjointAllowedRegs(G, NId, MId, D))
+ continue;
+
// Check that we haven't already added this edge
- // FIXME: findEdge is expensive in the worst case (O(max_clique(G))).
- // It might be better to replace this with a local bit-matrix.
- if (G.findEdge(NId, MId) != PBQPRAGraph::invalidEdgeId())
+ IEdgeKey EK(std::min(NId, MId), std::max(NId, MId));
+ if (EC.count(EK))
continue;
// This is a new edge - add it to the graph.
- createInterferenceEdge(G, NId, MId, C);
+ if (!createInterferenceEdge(G, NId, MId, C))
+ setDisjointAllowedRegs(G, NId, MId, D);
+ else
+ EC.insert(EK);
}
// Finally, add Cur to the Active set.
@@ -307,35 +353,48 @@ public:
private:
- void createInterferenceEdge(PBQPRAGraph &G, PBQPRAGraph::NodeId NId,
- PBQPRAGraph::NodeId MId, IMatrixCache &C) {
+ // Create an Interference edge and add it to the graph, unless it is
+ // a null matrix, meaning the nodes' allowed registers do not have any
+ // interference. This case occurs frequently between integer and floating
+ // point registers for example.
+ // return true iff both nodes interferes.
+ bool createInterferenceEdge(PBQPRAGraph &G,
+ PBQPRAGraph::NodeId NId, PBQPRAGraph::NodeId MId,
+ IMatrixCache &C) {
const TargetRegisterInfo &TRI =
*G.getMetadata().MF.getSubtarget().getRegisterInfo();
-
const auto &NRegs = G.getNodeMetadata(NId).getAllowedRegs();
const auto &MRegs = G.getNodeMetadata(MId).getAllowedRegs();
// Try looking the edge costs up in the IMatrixCache first.
- IMatrixKey K(&NRegs, &MRegs);
+ IKey K(&NRegs, &MRegs);
IMatrixCache::iterator I = C.find(K);
if (I != C.end()) {
G.addEdgeBypassingCostAllocator(NId, MId, I->second);
- return;
+ return true;
}
PBQPRAGraph::RawMatrix M(NRegs.size() + 1, MRegs.size() + 1, 0);
+ bool NodesInterfere = false;
for (unsigned I = 0; I != NRegs.size(); ++I) {
unsigned PRegN = NRegs[I];
for (unsigned J = 0; J != MRegs.size(); ++J) {
unsigned PRegM = MRegs[J];
- if (TRI.regsOverlap(PRegN, PRegM))
+ if (TRI.regsOverlap(PRegN, PRegM)) {
M[I + 1][J + 1] = std::numeric_limits<PBQP::PBQPNum>::infinity();
+ NodesInterfere = true;
+ }
}
}
+ if (!NodesInterfere)
+ return false;
+
PBQPRAGraph::EdgeId EId = G.addEdge(NId, MId, std::move(M));
C[K] = G.getEdgeCostsPtr(EId);
+
+ return true;
}
};