Add a new MVT::untyped. This will be used in future work for modelling ISA features like register pairs and lists with "interesting" constraints (such as ARM NEON contiguous register lists or even-odd paired registers). We need to be able to generate these instructions (often from intrinsics), but don't want to have to assign a legal type to them. Instead, we'll use an "untyped" edge to bypass the type-checking and simply ensure that the register classes match.

llvm-svn: 133106

include/llvm/CodeGen/ValueTypes.h

@@ -83,7 +83,11 @@ namespace llvm {
 
       isVoid         =  35,   // This has no value
 
-      LAST_VALUETYPE =  36,   // This always remains at the end of the list.
+      untyped        = 36,    // This value takes a register, but has
+                              // unspecified type.  The register class
+                              // will be determined by the opcode.
+
+      LAST_VALUETYPE =  37,   // This always remains at the end of the list.
 
       // This is the current maximum for LAST_VALUETYPE.
       // MVT::MAX_ALLOWED_VALUETYPE is used for asserts and to size bit vectors

include/llvm/CodeGen/ValueTypes.td

@@ -58,6 +58,7 @@ def v4f64  : ValueType<256, 32>;   //  4 x f64 vector value
 def x86mmx : ValueType<64 , 33>;   // X86 MMX value
 def FlagVT : ValueType<0  , 34>;   // Pre-RA sched glue
 def isVoid : ValueType<0  , 35>;   // Produces no value
+def untyped : ValueType<8,36>;   // Produces an untyped value
 
 def MetadataVT: ValueType<0, 250>; // Metadata
 

lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp

@@ -276,6 +276,33 @@ private:
 };
 }  // end anonymous namespace
 
+/// GetCostForDef - Looks up the register class and cost for a given definition.
+/// Typically this just means looking up the representative register class,
+/// but for untyped values (MVT::untyped) it means inspecting the node's
+/// opcode to determine what register class is being generated.
+static void GetCostForDef(const ScheduleDAGSDNodes::RegDefIter &RegDefPos,
+                          const TargetLowering *TLI,
+                          const TargetInstrInfo *TII,
+                          const TargetRegisterInfo *TRI,
+                          unsigned &RegClass, unsigned &Cost) {
+  EVT VT = RegDefPos.GetValue();
+
+  // Special handling for untyped values.  These values can only come from
+  // the expansion of custom DAG-to-DAG patterns.
+  if (VT == MVT::untyped) {
+    unsigned Opcode = RegDefPos.GetNode()->getMachineOpcode();
+    unsigned Idx = RegDefPos.GetIdx();
+    const TargetInstrDesc Desc = TII->get(Opcode);
+    const TargetRegisterClass *RC = Desc.getRegClass(Idx, TRI);
+    RegClass = RC->getID();
+    // FIXME: Cost arbitrarily set to 1 because there doesn't seem to be a
+    // better way to determine it.
+    Cost = 1;
+  } else {
+    RegClass = TLI->getRepRegClassFor(VT)->getID();
+    Cost = TLI->getRepRegClassCostFor(VT);
+  }
+}
 
 /// Schedule - Schedule the DAG using list scheduling.
 void ScheduleDAGRRList::Schedule() {
@@ -1807,8 +1834,10 @@ bool RegReductionPQBase::HighRegPressure(const SUnit *SU) const {
     for (ScheduleDAGSDNodes::RegDefIter RegDefPos(PredSU, scheduleDAG);
          RegDefPos.IsValid(); RegDefPos.Advance()) {
       EVT VT = RegDefPos.GetValue();
-      unsigned RCId = TLI->getRepRegClassFor(VT)->getID();
-      unsigned Cost = TLI->getRepRegClassCostFor(VT);
+
+      unsigned RCId, Cost;
+      GetCostForDef(RegDefPos, TLI, TII, TRI, RCId, Cost);
+
       if ((RegPressure[RCId] + Cost) >= RegLimit[RCId])
         return true;
     }
@@ -1919,9 +1948,10 @@ void RegReductionPQBase::ScheduledNode(SUnit *SU) {
          RegDefPos.IsValid(); RegDefPos.Advance(), --SkipRegDefs) {
       if (SkipRegDefs)
         continue;
-      EVT VT = RegDefPos.GetValue();
-      unsigned RCId = TLI->getRepRegClassFor(VT)->getID();
-      RegPressure[RCId] += TLI->getRepRegClassCostFor(VT);
+
+      unsigned RCId, Cost;
+      GetCostForDef(RegDefPos, TLI, TII, TRI, RCId, Cost);
+      RegPressure[RCId] += Cost;
       break;
     }
   }
@@ -1934,16 +1964,16 @@ void RegReductionPQBase::ScheduledNode(SUnit *SU) {
        RegDefPos.IsValid(); RegDefPos.Advance(), --SkipRegDefs) {
     if (SkipRegDefs > 0)
       continue;
-    EVT VT = RegDefPos.GetValue();
-    unsigned RCId = TLI->getRepRegClassFor(VT)->getID();
-    if (RegPressure[RCId] < TLI->getRepRegClassCostFor(VT)) {
+    unsigned RCId, Cost;
+    GetCostForDef(RegDefPos, TLI, TII, TRI, RCId, Cost);
+    if (RegPressure[RCId] < Cost) {
       // Register pressure tracking is imprecise. This can happen. But we try
       // hard not to let it happen because it likely results in poor scheduling.
       DEBUG(dbgs() << "  SU(" << SU->NodeNum << ") has too many regdefs\n");
       RegPressure[RCId] = 0;
     }
     else {
-      RegPressure[RCId] -= TLI->getRepRegClassCostFor(VT);
+      RegPressure[RCId] -= Cost;
     }
   }
   dumpRegPressure();

lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h

@@ -135,6 +135,14 @@ namespace llvm {
         return ValueType;
       }
 
+      const SDNode *GetNode() const {
+        return Node;
+      }
+
+      unsigned GetIdx() const {
+        return DefIdx;
+      }
+
       void Advance();
     private:
       void InitNodeNumDefs();

utils/TableGen/CodeGenTarget.cpp

@@ -90,6 +90,7 @@ std::string llvm::getEnumName(MVT::SimpleValueType T) {
   case MVT::Metadata: return "MVT::Metadata";
   case MVT::iPTR:     return "MVT::iPTR";
   case MVT::iPTRAny:  return "MVT::iPTRAny";
+  case MVT::untyped: return "MVT::untyped";
   default: assert(0 && "ILLEGAL VALUE TYPE!"); return "";
   }
 }