Add Om1 lowering with no optimizations

src/IceInst.h

 //===- subzero/src/IceInst.h - High-level instructions ----------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares the Inst class and its target-independent
@@ skipping 29 matching lines @@
     Br,
     Call,
     Cast,
     Fcmp,
     Icmp,
     Load,
     Phi,
     Ret,
     Select,
     Store,
-    Switch
+    Switch,
+    FakeDef,  // not part of LLVM/PNaCl bitcode
+    FakeUse,  // not part of LLVM/PNaCl bitcode
+    FakeKill, // not part of LLVM/PNaCl bitcode
+    Target    // target-specific low-level ICE
+              // Anything >= Target is an InstTarget subclass.
   };
   InstKind getKind() const { return Kind; }
 
   int32_t getNumber() const { return Number; }
 
   bool isDeleted() const { return Deleted; }
   void setDeleted() { Deleted = true; }
 
   bool hasSideEffects() const { return HasSideEffects; }
 
@@ skipping 15 matching lines @@
         "getTerminatorEdges() called on a non-terminator instruction");
     return NodeList();
   }
 
   // Updates the status of the Variables contained within the
   // instruction.  In particular, it marks where the Dest variable is
   // first assigned, and it tracks whether variables are live across
   // basic blocks, i.e. used in a different block from their definition.
   void updateVars(CfgNode *Node);
 
+  virtual void emit(const Cfg *Func) const;
   virtual void dump(const Cfg *Func) const;
   void dumpDecorated(const Cfg *Func) const;
+  void emitSources(const Cfg *Func) const;
   void dumpSources(const Cfg *Func) const;
   void dumpDest(const Cfg *Func) const;
+  virtual bool isRedundantAssign() const { return false; }
 
   virtual ~Inst() {}
 
 protected:
   Inst(Cfg *Func, InstKind Kind, SizeT MaxSrcs, Variable *Dest);
   void addSource(Operand *Src) {
     assert(Src);
     assert(NumSrcs < MaxSrcs);
     Srcs[NumSrcs++] = Src;
   }
@@ skipping 47 matching lines @@
 
 // Binary arithmetic instruction.  The source operands are captured in
 // getSrc(0) and getSrc(1).
 class InstArithmetic : public Inst {
 public:
   enum OpKind {
 #define X(tag, str, commutative) tag,
     ICEINSTARITHMETIC_TABLE
 #undef X
   };
+
   static InstArithmetic *create(Cfg *Func, OpKind Op, Variable *Dest,
                                 Operand *Source1, Operand *Source2) {
     return new (Func->allocateInst<InstArithmetic>())
         InstArithmetic(Func, Op, Dest, Source1, Source2);
   }
   OpKind getOp() const { return Op; }
   bool isCommutative() const;
   virtual void dump(const Cfg *Func) const;
   static bool classof(const Inst *Inst) {
     return Inst->getKind() == Arithmetic;
@@ skipping 105 matching lines @@
 };
 
 // Cast instruction (a.k.a. conversion operation).
 class InstCast : public Inst {
 public:
   enum OpKind {
 #define X(tag, str) tag,
     ICEINSTCAST_TABLE
 #undef X
   };
+
   static InstCast *create(Cfg *Func, OpKind CastKind, Variable *Dest,
                           Operand *Source) {
     return new (Func->allocateInst<InstCast>())
         InstCast(Func, CastKind, Dest, Source);
   }
   OpKind getCastKind() const { return CastKind; }
   virtual void dump(const Cfg *Func) const;
   static bool classof(const Inst *Inst) { return Inst->getKind() == Cast; }
 
 private:
   InstCast(Cfg *Func, OpKind CastKind, Variable *Dest, Operand *Source);
   InstCast(const InstCast &) LLVM_DELETED_FUNCTION;
   InstCast &operator=(const InstCast &) LLVM_DELETED_FUNCTION;
   virtual ~InstCast() {}
   const OpKind CastKind;
 };
 
 // Floating-point comparison instruction.  The source operands are
 // captured in getSrc(0) and getSrc(1).
 class InstFcmp : public Inst {
 public:
   enum FCond {
 #define X(tag, str) tag,
     ICEINSTFCMP_TABLE
 #undef X
   };
+
   static InstFcmp *create(Cfg *Func, FCond Condition, Variable *Dest,
                           Operand *Source1, Operand *Source2) {
     return new (Func->allocateInst<InstFcmp>())
         InstFcmp(Func, Condition, Dest, Source1, Source2);
   }
   FCond getCondition() const { return Condition; }
   virtual void dump(const Cfg *Func) const;
   static bool classof(const Inst *Inst) { return Inst->getKind() == Fcmp; }
 
 private:
   InstFcmp(Cfg *Func, FCond Condition, Variable *Dest, Operand *Source1,
            Operand *Source2);
   InstFcmp(const InstFcmp &) LLVM_DELETED_FUNCTION;
   InstFcmp &operator=(const InstFcmp &) LLVM_DELETED_FUNCTION;
   virtual ~InstFcmp() {}
   const FCond Condition;
 };
 
 // Integer comparison instruction.  The source operands are captured
 // in getSrc(0) and getSrc(1).
 class InstIcmp : public Inst {
 public:
   enum ICond {
 #define X(tag, str) tag,
     ICEINSTICMP_TABLE
 #undef X
   };
+
   static InstIcmp *create(Cfg *Func, ICond Condition, Variable *Dest,
                           Operand *Source1, Operand *Source2) {
     return new (Func->allocateInst<InstIcmp>())
         InstIcmp(Func, Condition, Dest, Source1, Source2);
   }
   ICond getCondition() const { return Condition; }
   virtual void dump(const Cfg *Func) const;
   static bool classof(const Inst *Inst) { return Inst->getKind() == Icmp; }
 
 private:
@@ skipping 24 matching lines @@
 };
 
 // Phi instruction.  For incoming edge I, the node is Labels[I] and
 // the Phi source operand is getSrc(I).
 class InstPhi : public Inst {
 public:
   static InstPhi *create(Cfg *Func, SizeT MaxSrcs, Variable *Dest) {
     return new (Func->allocateInst<InstPhi>()) InstPhi(Func, MaxSrcs, Dest);
   }
   void addArgument(Operand *Source, CfgNode *Label);
+  Operand *getOperandForTarget(CfgNode *Target) const;
+  Inst *lower(Cfg *Func, CfgNode *Node);
   virtual void dump(const Cfg *Func) const;
   static bool classof(const Inst *Inst) { return Inst->getKind() == Phi; }
 
 private:
   InstPhi(Cfg *Func, SizeT MaxSrcs, Variable *Dest);
   InstPhi(const InstPhi &) LLVM_DELETED_FUNCTION;
   InstPhi &operator=(const InstPhi &) LLVM_DELETED_FUNCTION;
   virtual void destroy(Cfg *Func) {
     Func->deallocateArrayOf<CfgNode *>(Labels);
     Inst::destroy(Func);
@@ skipping 126 matching lines @@
     return Inst->getKind() == Unreachable;
   }
 
 private:
   InstUnreachable(Cfg *Func);
   InstUnreachable(const InstUnreachable &) LLVM_DELETED_FUNCTION;
   InstUnreachable &operator=(const InstUnreachable &) LLVM_DELETED_FUNCTION;
   virtual ~InstUnreachable() {}
 };
 
+// FakeDef instruction.  This creates a fake definition of a variable,
+// which is how we represent the case when an instruction produces
+// multiple results.  This doesn't happen with high-level ICE
+// instructions, but might with lowered instructions.  For example,
+// this would be a way to represent condition flags being modified by
+// an instruction.
+//
+// It's generally useful to set the optional source operand to be the
+// dest variable of the instruction that actually produces the FakeDef
+// dest.  Otherwise, the original instruction could be dead-code
+// eliminated if its dest operand is unused, and therefore the FakeDef
+// dest wouldn't be properly initialized.
+class InstFakeDef : public Inst {
+public:
+  static InstFakeDef *create(Cfg *Func, Variable *Dest, Variable *Src = NULL) {
+    return new (Func->allocateInst<InstFakeDef>()) InstFakeDef(Func, Dest, Src);
+  }
+  virtual void emit(const Cfg *Func) const;
+  virtual void dump(const Cfg *Func) const;
+  static bool classof(const Inst *Inst) { return Inst->getKind() == FakeDef; }
+
+private:
+  InstFakeDef(Cfg *Func, Variable *Dest, Variable *Src);
+  InstFakeDef(const InstFakeDef &) LLVM_DELETED_FUNCTION;
+  InstFakeDef &operator=(const InstFakeDef &) LLVM_DELETED_FUNCTION;
+  virtual ~InstFakeDef() {}
+};
+
+// FakeUse instruction.  This creates a fake use of a variable, to
+// keep the instruction that produces that variable from being
+// dead-code eliminated.  This is useful in a variety of lowering
+// situations.  The FakeUse instruction has no dest, so it can itself
+// never be dead-code eliminated.
+class InstFakeUse : public Inst {
+public:
+  static InstFakeUse *create(Cfg *Func, Variable *Src) {
+    return new (Func->allocateInst<InstFakeUse>()) InstFakeUse(Func, Src);
+  }
+  virtual void emit(const Cfg *Func) const;
+  virtual void dump(const Cfg *Func) const;
+  static bool classof(const Inst *Inst) { return Inst->getKind() == FakeUse; }
+
+private:
+  InstFakeUse(Cfg *Func, Variable *Src);
+  InstFakeUse(const InstFakeUse &) LLVM_DELETED_FUNCTION;
+  InstFakeUse &operator=(const InstFakeUse &) LLVM_DELETED_FUNCTION;
+  virtual ~InstFakeUse() {}
+};
+
+// FakeKill instruction.  This "kills" a set of variables by adding a
+// trivial live range at this instruction to each variable.  The
+// primary use is to indicate that scratch registers are killed after
+// a call, so that the register allocator won't assign a scratch
+// register to a variable whose live range spans a call.
+//
+// The FakeKill instruction also holds a pointer to the instruction
+// that kills the set of variables, so that if that linked instruction
+// gets dead-code eliminated, the FakeKill instruction will as well.
+class InstFakeKill : public Inst {
+public:
+  static InstFakeKill *create(Cfg *Func, const VarList &KilledRegs,
+                              const Inst *Linked) {
+    return new (Func->allocateInst<InstFakeKill>())
+        InstFakeKill(Func, KilledRegs, Linked);
+  }
+  const Inst *getLinked() const { return Linked; }
+  virtual void emit(const Cfg *Func) const;
+  virtual void dump(const Cfg *Func) const;
+  static bool classof(const Inst *Inst) { return Inst->getKind() == FakeKill; }
+
+private:
+  InstFakeKill(Cfg *Func, const VarList &KilledRegs, const Inst *Linked);
+  InstFakeKill(const InstFakeKill &) LLVM_DELETED_FUNCTION;
+  InstFakeKill &operator=(const InstFakeKill &) LLVM_DELETED_FUNCTION;
+  virtual ~InstFakeKill() {}
+
+  // This instruction is ignored if Linked->isDeleted() is true.
+  const Inst *Linked;
+};
+
+// The Target instruction is the base class for all target-specific
+// instructions.
+class InstTarget : public Inst {
+public:
+  virtual void emit(const Cfg *Func) const = 0;
+  virtual void dump(const Cfg *Func) const;
+  static bool classof(const Inst *Inst) { return Inst->getKind() >= Target; }
+
+protected:
+  InstTarget(Cfg *Func, InstKind Kind, SizeT MaxSrcs, Variable *Dest)
+      : Inst(Func, Kind, MaxSrcs, Dest) {
+    assert(Kind >= Target);
+  }
+  InstTarget(const InstTarget &) LLVM_DELETED_FUNCTION;
+  InstTarget &operator=(const InstTarget &) LLVM_DELETED_FUNCTION;
+  virtual ~InstTarget() {}
+};
+
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEINST_H