[RDF] Differentiate between defining and clobbering nodes

Defining nodes should not alias with one another, while clobbering
nodes can. When pushing defs on stacks, push clobbers first, link
non-clobbering defs, then push the defs.

The data flow in a statement is now: uses -> clobbers -> defs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295356 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/Hexagon/HexagonOptAddrMode.cpp b/lib/Target/Hexagon/HexagonOptAddrMode.cpp
index 73fa0b3e5a3ddd0a91779cddaa8c6446ef2cc5fa..49d5cb34a0d17b5be707970591998d40f8257fc8 100644 (file)
--- a/lib/Target/Hexagon/HexagonOptAddrMode.cpp
+++ b/lib/Target/Hexagon/HexagonOptAddrMode.cpp
@@ -617,7 +617,7 @@ bool HexagonOptAddrMode::constructDefMap(MachineBasicBlock *B) {
 
   for (NodeAddr<InstrNode *> IA : BA.Addr->members(*DFG)) {
     updateMap(IA);
-    DFG->pushDefs(IA, DefM);
+    DFG->pushAllDefs(IA, DefM);
   }
 
   MachineDomTreeNode *N = MDT->getNode(B);

diff --git a/lib/Target/Hexagon/RDFCopy.cpp b/lib/Target/Hexagon/RDFCopy.cpp
index 392871628d98a4ac1669e687a1ab5d98bfad698a..392ab7af6c2572e0e02045a0bd9ed6b43a8766cf 100644 (file)
--- a/lib/Target/Hexagon/RDFCopy.cpp
+++ b/lib/Target/Hexagon/RDFCopy.cpp
@@ -104,7 +104,7 @@ bool CopyPropagation::scanBlock(MachineBasicBlock *B) {
     }
 
     updateMap(IA);
-    DFG.pushDefs(IA, DefM);
+    DFG.pushAllDefs(IA, DefM);
   }
 
   MachineDomTreeNode *N = MDT.getNode(B);

diff --git a/lib/Target/Hexagon/RDFGraph.cpp b/lib/Target/Hexagon/RDFGraph.cpp
index 600a516319668537b13e420f3014f3bd285edda0..f3ef6207a80f52ba2861a191db099d7fc41834a7 100644 (file)
--- a/lib/Target/Hexagon/RDFGraph.cpp
+++ b/lib/Target/Hexagon/RDFGraph.cpp
@@ -617,8 +617,12 @@ bool TargetOperandInfo::isPreserving(const MachineInstr &In, unsigned OpNum)
 // Check if the definition of RR produces an unspecified value.
 bool TargetOperandInfo::isClobbering(const MachineInstr &In, unsigned OpNum)
       const {
+  const MachineOperand &Op = In.getOperand(OpNum);
+  if (Op.isRegMask())
+    return true;
+  assert(Op.isReg());
   if (In.isCall())
-    if (In.getOperand(OpNum).isImplicit())
+    if (Op.isDef() && Op.isDead())
       return true;
   return false;
 }
@@ -1022,13 +1026,63 @@ void DataFlowGraph::releaseBlock(NodeId B, DefStackMap &DefM) {
   }
 }
 
+// Push all definitions from the instruction node IA to an appropriate
+// stack in DefM.
+void DataFlowGraph::pushAllDefs(NodeAddr<InstrNode*> IA, DefStackMap &DefM) {
+  pushClobbers(IA, DefM);
+  pushDefs(IA, DefM);
+}
+
+// Push all definitions from the instruction node IA to an appropriate
+// stack in DefM.
+void DataFlowGraph::pushClobbers(NodeAddr<InstrNode*> IA, DefStackMap &DefM) {
+  NodeSet Visited;
+  std::set<RegisterId> Defined;
+
+  // The important objectives of this function are:
+  // - to be able to handle instructions both while the graph is being
+  //   constructed, and after the graph has been constructed, and
+  // - maintain proper ordering of definitions on the stack for each
+  //   register reference:
+  //   - if there are two or more related defs in IA (i.e. coming from
+  //     the same machine operand), then only push one def on the stack,
+  //   - if there are multiple unrelated defs of non-overlapping
+  //     subregisters of S, then the stack for S will have both (in an
+  //     unspecified order), but the order does not matter from the data-
+  //     -flow perspective.
+
+  for (NodeAddr<DefNode*> DA : IA.Addr->members_if(IsDef, *this)) {
+    if (Visited.count(DA.Id))
+      continue;
+    if (!(DA.Addr->getFlags() & NodeAttrs::Clobbering))
+      continue;
+
+    NodeList Rel = getRelatedRefs(IA, DA);
+    NodeAddr<DefNode*> PDA = Rel.front();
+    RegisterRef RR = PDA.Addr->getRegRef(*this);
+
+    // Push the definition on the stack for the register and all aliases.
+    // The def stack traversal in linkNodeUp will check the exact aliasing.
+    DefM[RR.Reg].push(DA);
+    Defined.insert(RR.Reg);
+    for (RegisterId A : PRI.getAliasSet(RR.Reg)) {
+      // Check that we don't push the same def twice.
+      assert(A != RR.Reg);
+      if (!Defined.count(A))
+        DefM[A].push(DA);
+    }
+    // Mark all the related defs as visited.
+    for (NodeAddr<NodeBase*> T : Rel)
+      Visited.insert(T.Id);
+  }
+}
+
 // Push all definitions from the instruction node IA to an appropriate
 // stack in DefM.
 void DataFlowGraph::pushDefs(NodeAddr<InstrNode*> IA, DefStackMap &DefM) {
-  NodeList Defs = IA.Addr->members_if(IsDef, *this);
   NodeSet Visited;
 #ifndef NDEBUG
-  RegisterSet Defined;
+  std::set<RegisterId> Defined;
 #endif
 
   // The important objectives of this function are:
@@ -1043,9 +1097,11 @@ void DataFlowGraph::pushDefs(NodeAddr<InstrNode*> IA, DefStackMap &DefM) {
   //     unspecified order), but the order does not matter from the data-
   //     -flow perspective.
 
-  for (NodeAddr<DefNode*> DA : Defs) {
+  for (NodeAddr<DefNode*> DA : IA.Addr->members_if(IsDef, *this)) {
     if (Visited.count(DA.Id))
       continue;
+    if (DA.Addr->getFlags() & NodeAttrs::Clobbering)
+      continue;
 
     NodeList Rel = getRelatedRefs(IA, DA);
     NodeAddr<DefNode*> PDA = Rel.front();
@@ -1053,7 +1109,7 @@ void DataFlowGraph::pushDefs(NodeAddr<InstrNode*> IA, DefStackMap &DefM) {
 #ifndef NDEBUG
     // Assert if the register is defined in two or more unrelated defs.
     // This could happen if there are two or more def operands defining it.
-    if (!Defined.insert(RR).second) {
+    if (!Defined.insert(RR.Reg).second) {
       MachineInstr *MI = NodeAddr<StmtNode*>(IA).Addr->getCode();
       dbgs() << "Multiple definitions of register: "
              << Print<RegisterRef>(RR, *this) << " in\n  " << *MI
@@ -1611,13 +1667,15 @@ void DataFlowGraph::linkRefUp(NodeAddr<InstrNode*> IA, NodeAddr<T> TA,
 }
 
 // Create data-flow links for all reference nodes in the statement node SA.
-void DataFlowGraph::linkStmtRefs(DefStackMap &DefM, NodeAddr<StmtNode*> SA) {
+template <typename Predicate>
+void DataFlowGraph::linkStmtRefs(DefStackMap &DefM, NodeAddr<StmtNode*> SA,
+      Predicate P) {
 #ifndef NDEBUG
   RegisterSet Defs;
 #endif
 
   // Link all nodes (upwards in the data-flow) with their reaching defs.
-  for (NodeAddr<RefNode*> RA : SA.Addr->members(*this)) {
+  for (NodeAddr<RefNode*> RA : SA.Addr->members_if(P, *this)) {
     uint16_t Kind = RA.Addr->getKind();
     assert(Kind == NodeAttrs::Def || Kind == NodeAttrs::Use);
     RegisterRef RR = RA.Addr->getRegRef(*this);
@@ -1646,6 +1704,13 @@ void DataFlowGraph::linkBlockRefs(DefStackMap &DefM, NodeAddr<BlockNode*> BA) {
   // Push block delimiters.
   markBlock(BA.Id, DefM);
 
+  auto IsClobber = [this] (NodeAddr<RefNode*> RA) -> bool {
+    return IsDef(RA) && (RA.Addr->getFlags() & NodeAttrs::Clobbering);
+  };
+  auto IsNoClobber = [this] (NodeAddr<RefNode*> RA) -> bool {
+    return IsDef(RA) && !(RA.Addr->getFlags() & NodeAttrs::Clobbering);
+  };
+
   assert(BA.Addr && "block node address is needed to create a data-flow link");
   // For each non-phi instruction in the block, link all the defs and uses
   // to their reaching defs. For any member of the block (including phis),
@@ -1653,10 +1718,17 @@ void DataFlowGraph::linkBlockRefs(DefStackMap &DefM, NodeAddr<BlockNode*> BA) {
   for (NodeAddr<InstrNode*> IA : BA.Addr->members(*this)) {
     // Ignore phi nodes here. They will be linked part by part from the
     // predecessors.
-    if (IA.Addr->getKind() == NodeAttrs::Stmt)
-      linkStmtRefs(DefM, IA);
+    if (IA.Addr->getKind() == NodeAttrs::Stmt) {
+      linkStmtRefs(DefM, IA, IsUse);
+      linkStmtRefs(DefM, IA, IsClobber);
+    }
 
     // Push the definitions on the stack.
+    pushClobbers(IA, DefM);
+
+    if (IA.Addr->getKind() == NodeAttrs::Stmt)
+      linkStmtRefs(DefM, IA, IsNoClobber);
+
     pushDefs(IA, DefM);
   }
 

diff --git a/lib/Target/Hexagon/RDFGraph.h b/lib/Target/Hexagon/RDFGraph.h
index 92c317c4d3c59f4a9797ed5f8f02e5cf8d67570d..bf4018ba7fcd0e05a0eed3d10d5fa4e36b5a25e3 100644 (file)
--- a/lib/Target/Hexagon/RDFGraph.h
+++ b/lib/Target/Hexagon/RDFGraph.h
@@ -729,7 +729,7 @@ namespace rdf {
     typedef std::unordered_map<RegisterId,DefStack> DefStackMap;
 
     void build(unsigned Options = BuildOptions::None);
-    void pushDefs(NodeAddr<InstrNode*> IA, DefStackMap &DM);
+    void pushAllDefs(NodeAddr<InstrNode*> IA, DefStackMap &DM);
     void markBlock(NodeId B, DefStackMap &DefM);
     void releaseBlock(NodeId B, DefStackMap &DefM);
 
@@ -844,9 +844,12 @@ namespace rdf {
         NodeAddr<BlockNode*> BA);
     void removeUnusedPhis();
 
+    void pushClobbers(NodeAddr<InstrNode*> IA, DefStackMap &DM);
+    void pushDefs(NodeAddr<InstrNode*> IA, DefStackMap &DM);
     template <typename T> void linkRefUp(NodeAddr<InstrNode*> IA,
         NodeAddr<T> TA, DefStack &DS);
-    void linkStmtRefs(DefStackMap &DefM, NodeAddr<StmtNode*> SA);
+    template <typename Predicate> void linkStmtRefs(DefStackMap &DefM,
+        NodeAddr<StmtNode*> SA, Predicate P);
     void linkBlockRefs(DefStackMap &DefM, NodeAddr<BlockNode*> BA);
 
     void unlinkUseDF(NodeAddr<UseNode*> UA);