First draft of a new Target interface

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19323 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Target/TargetLowering.h b/include/llvm/Target/TargetLowering.h
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+++ b/include/llvm/Target/TargetLowering.h
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+//===-- llvm/Target/TargetLowering.h - Target Lowering Info -----*- C++ -*-===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file describes how to lower LLVM code to machine code.  This has two
+// main components:
+//
+//  1. Which ValueTypes are natively supported by the target.
+//  2. Which operations are supported for supported ValueTypes.
+//
+// In addition it has a few other components, like information about FP
+// immediates.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TARGET_TARGETLOWERING_H
+#define LLVM_TARGET_TARGETLOWERING_H
+
+#include "llvm/Type.h"
+#include "llvm/CodeGen/ValueTypes.h"
+#include <vector>
+
+namespace llvm {
+  class Function;
+  class TargetMachine;
+  class TargetData;
+  class TargetRegisterClass;
+  class SDNode;
+  class SDOperand;
+  class SelectionDAG;
+
+//===----------------------------------------------------------------------===//
+/// TargetLowering - This class defines information used to lower LLVM code to
+/// legal SelectionDAG operators that the target instruction selector can accept
+/// natively.
+///
+/// This class also defines callbacks that targets must implement to lower
+/// target-specific constructs to SelectionDAG operators.
+///
+class TargetLowering {
+  TargetMachine &TM;
+  const TargetData &TD;
+  
+  MVT::ValueType PointerTy;
+  bool IsLittleEndian;
+  
+  /// RegClassForVT - This indicates the default register class to use for
+  /// each ValueType the target supports natively.
+  TargetRegisterClass *RegClassForVT[MVT::LAST_VALUETYPE];
+  unsigned char NumElementsForVT[MVT::LAST_VALUETYPE];
+  
+  unsigned short UnsupportedOps[128];
+  
+  std::vector<double> LegalFPImmediates;
+  
+  std::vector<std::pair<MVT::ValueType,
+                        TargetRegisterClass*> > AvailableRegClasses;
+public:
+  TargetLowering(TargetMachine &TM);
+  virtual ~TargetLowering() {}
+
+  TargetMachine &getTargetMachine() const { return TM; }
+  const TargetData &getTargetData() const { return TD; }
+  
+  bool isLittleEndian() const { return IsLittleEndian; }
+  MVT::ValueType getPointerTy() const { return PointerTy; }
+  
+  TargetRegisterClass *getRegClassFor(MVT::ValueType VT) {
+    TargetRegisterClass *RC = RegClassForVT[VT];
+    assert(RC && "This value type is not natively supported!");
+    return RC;
+  }
+  
+  /// hasNativeSupportFor 
+  bool hasNativeSupportFor(MVT::ValueType VT) {
+    return RegClassForVT[VT] != 0;
+  }
+  
+  typedef std::vector<double>::const_iterator legal_fpimm_iterator;
+  legal_fpimm_iterator legal_fpimm_begin() const {
+    return LegalFPImmediates.begin();
+  }
+  legal_fpimm_iterator legal_fpimm_end() const {
+    return LegalFPImmediates.end();
+  }
+  
+  bool isOperationSupported(unsigned Op, MVT::ValueType VT) {
+    return (UnsupportedOps[Op] & (1 << VT)) == 0;
+  }
+  
+  MVT::ValueType getValueType(const Type *Ty) {
+    switch (Ty->getTypeID()) {
+    default: assert(0 && "Unknown type!");
+    case Type::VoidTyID:    return MVT::isVoid;
+    case Type::BoolTyID:    return MVT::i1;
+    case Type::UByteTyID:
+    case Type::SByteTyID:   return MVT::i8;
+    case Type::ShortTyID:
+    case Type::UShortTyID:  return MVT::i16;
+    case Type::IntTyID:
+    case Type::UIntTyID:    return MVT::i32;
+    case Type::LongTyID:
+    case Type::ULongTyID:   return MVT::i64;
+    case Type::FloatTyID:   return MVT::f32;
+    case Type::DoubleTyID:  return MVT::f64;
+    case Type::PointerTyID: return PointerTy;
+    }
+  }
+  
+  /// getNumElements - Return the number of registers that this ValueType will
+  /// eventually require.  This is always one for all non-integer types, is
+  /// one for any types promoted to live in larger registers, but may be more
+  /// than one for types (like i64) that are split into pieces.
+  unsigned getNumElements(MVT::ValueType VT) const {
+    return NumElementsForVT[VT];
+  }
+
+  //===--------------------------------------------------------------------===//
+  // TargetLowering Configuration Methods - These methods should be invoked by
+  // the derived class constructor to configure this object for the target.
+  //
+
+protected:
+
+  /// addRegisterClass - Add the specified register class as an available
+  /// regclass for the specified value type.  This indicates the selector can
+  /// handle values of that class natively.
+  void addRegisterClass(MVT::ValueType VT, TargetRegisterClass *RC) {
+    AvailableRegClasses.push_back(std::make_pair(VT, RC));
+    RegClassForVT[VT] = RC;
+  }
+
+  /// computeRegisterProperties - Once all of the register classes are added,
+  /// this allows us to compute derived properties we expose.
+  void computeRegisterProperties();
+  
+
+  void setOperationUnsupported(unsigned Op, MVT::ValueType VT) {
+    assert(VT < 16 && "Too many value types!");
+    UnsupportedOps[Op] |= 1 << VT;
+  }
+
+  /// addLegalFPImmediate - Indicate that this target can instruction select
+  /// the specified FP immediate natively.
+  void addLegalFPImmediate(double Imm) {
+    LegalFPImmediates.push_back(Imm);
+  }
+  
+
+public:
+
+  //===--------------------------------------------------------------------===//
+  // Lowering methods - These methods must be implemented by targets so that
+  // the SelectionDAGLowering code knows how to lower these.
+  //
+
+  /// LowerArguments - This hook must be implemented to indicate how we should
+  /// lower the arguments for the specified function, into the specified DAG.
+  virtual std::vector<SDOperand>
+  LowerArguments(Function &F, SelectionDAG &DAG) = 0;
+
+  /// LowerCallTo - This hook lowers an abstract call to a function into an
+  /// actual call.
+  typedef std::vector<std::pair<SDOperand, const Type*> > ArgListTy;
+  virtual SDNode *LowerCallTo(const Type *RetTy, SDOperand Callee,
+                              ArgListTy &Args, SelectionDAG &DAG) = 0;
+};
+} // end llvm namespace
+
+#endif