Subzero: Allow delaying Phi lowering until after register allocation.

src/IceOperand.cpp

 //===- subzero/src/IceOperand.cpp - High-level operand implementation -----===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the Operand class and its target-independent
@@ skipping 302 matching lines @@
   // Mark implicit args as being used in the entry node.
   for (Variable *Var : Func->getImplicitArgs()) {
     const Inst *NoInst = NULL;
     const CfgNode *EntryNode = Func->getEntryNode();
     const bool IsFromDef = false;
     const bool IsImplicit = true;
     Metadata[Var->getIndex()]
         .markUse(Kind, NoInst, EntryNode, IsFromDef, IsImplicit);
   }
 
-  for (CfgNode *Node : Func->getNodes()) {
-    for (Inst *I : Node->getInsts()) {
-      if (I->isDeleted())
-        continue;
-      if (InstFakeKill *Kill = llvm::dyn_cast<InstFakeKill>(I)) {
-        // A FakeKill instruction indicates certain Variables (usually
-        // physical scratch registers) are redefined, so we register
-        // them as defs.
-        for (SizeT SrcNum = 0; SrcNum < I->getSrcSize(); ++SrcNum) {
-          Variable *Var = llvm::cast<Variable>(I->getSrc(SrcNum));
-          SizeT VarNum = Var->getIndex();
-          assert(VarNum < Metadata.size());
-          Metadata[VarNum].markDef(Kind, Kill, Node);
-        }
-        continue; // no point in executing the rest
-      }
-      if (Variable *Dest = I->getDest()) {
-        SizeT DestNum = Dest->getIndex();
-        assert(DestNum < Metadata.size());
-        Metadata[DestNum].markDef(Kind, I, Node);
-      }
-      for (SizeT SrcNum = 0; SrcNum < I->getSrcSize(); ++SrcNum) {
-        Operand *Src = I->getSrc(SrcNum);
-        SizeT NumVars = Src->getNumVars();
-        for (SizeT J = 0; J < NumVars; ++J) {
-          const Variable *Var = Src->getVar(J);
-          SizeT VarNum = Var->getIndex();
-          assert(VarNum < Metadata.size());
-          const bool IsFromDef = false;
-          const bool IsImplicit = false;
-          Metadata[VarNum].markUse(Kind, I, Node, IsFromDef, IsImplicit);
-        }
+  for (CfgNode *Node : Func->getNodes())
+    addNode(Node);
+}
+
+void VariablesMetadata::addNode(CfgNode *Node) {
+  if (Func->getNumVariables() >= Metadata.size())
+    Metadata.resize(Func->getNumVariables());
+
+  for (InstPhi *I : Node->getPhis()) {
+    if (I->isDeleted())
+      continue;
+    if (Variable *Dest = I->getDest()) {
+      SizeT DestNum = Dest->getIndex();
+      assert(DestNum < Metadata.size());
+      Metadata[DestNum].markDef(Kind, I, Node);
+    }
+    for (SizeT SrcNum = 0; SrcNum < I->getSrcSize(); ++SrcNum) {
+      if (const Variable *Var = llvm::dyn_cast<Variable>(I->getSrc(SrcNum))) {
+        SizeT VarNum = Var->getIndex();
+        assert(VarNum < Metadata.size());
+        const bool IsFromDef = false;
+        const bool IsImplicit = false;
+        Metadata[VarNum].markUse(Kind, I, Node, IsFromDef, IsImplicit);
       }
     }
   }
+
+  for (Inst *I : Node->getInsts()) {
+    if (I->isDeleted())
+      continue;
+    if (InstFakeKill *Kill = llvm::dyn_cast<InstFakeKill>(I)) {
+      // A FakeKill instruction indicates certain Variables (usually
+      // physical scratch registers) are redefined, so we register
+      // them as defs.
+      for (SizeT SrcNum = 0; SrcNum < I->getSrcSize(); ++SrcNum) {
+        Variable *Var = llvm::cast<Variable>(I->getSrc(SrcNum));
+        SizeT VarNum = Var->getIndex();
+        assert(VarNum < Metadata.size());
+        Metadata[VarNum].markDef(Kind, Kill, Node);
+      }
+      continue; // no point in executing the rest
+    }
+    if (Variable *Dest = I->getDest()) {
+      SizeT DestNum = Dest->getIndex();
+      assert(DestNum < Metadata.size());
+      Metadata[DestNum].markDef(Kind, I, Node);
+    }
+    for (SizeT SrcNum = 0; SrcNum < I->getSrcSize(); ++SrcNum) {
+      Operand *Src = I->getSrc(SrcNum);
+      SizeT NumVars = Src->getNumVars();
+      for (SizeT J = 0; J < NumVars; ++J) {
+        const Variable *Var = Src->getVar(J);
+        SizeT VarNum = Var->getIndex();
+        assert(VarNum < Metadata.size());
+        const bool IsFromDef = false;
+        const bool IsImplicit = false;
+        Metadata[VarNum].markUse(Kind, I, Node, IsFromDef, IsImplicit);
+      }
+    }
+  }
 }
 
 bool VariablesMetadata::isMultiDef(const Variable *Var) const {
   assert(Kind != VMK_Uses);
   if (Var->getIsArg())
     return false;
   if (!isTracked(Var))
     return true; // conservative answer
   SizeT VarNum = Var->getIndex();
   // Conservatively return true if the state is unknown.
@@ skipping 119 matching lines @@
 
 Ostream &operator<<(Ostream &Str, const RegWeight &W) {
   if (W.getWeight() == RegWeight::Inf)
     Str << "Inf";
   else
     Str << W.getWeight();
   return Str;
 }
 
 } // end of namespace Ice