move CC Lowering stuff to its own public interface

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34655 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/CallingConvLower.h

@@ -0,0 +1,149 @@
+//===-- llvm/CallingConvLower.h - Calling Conventions -----------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the CCState and CCValAssign classes, used for lowering
+// and implementing calling conventions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_CALLINGCONVLOWER_H
+#define LLVM_CODEGEN_CALLINGCONVLOWER_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/CodeGen/ValueTypes.h"
+
+namespace llvm {
+  class MRegisterInfo;
+  
+/// CCState - This class holds information needed while lowering arguments and
+/// return values.  It captures which registers are already assigned and which
+/// stack slots are used.  It provides accessors to allocate these values.
+class CCState {
+  unsigned StackOffset;
+  const MRegisterInfo &MRI;
+  SmallVector<uint32_t, 16> UsedRegs;
+public:
+  CCState(const MRegisterInfo &mri);
+  
+  unsigned getNextStackOffset() const { return StackOffset; }
+
+  /// isAllocated - Return true if the specified register (or an alias) is
+  /// allocated.
+  bool isAllocated(unsigned Reg) const {
+    return UsedRegs[Reg/32] & (1 << (Reg&31));
+  }
+
+  /// getFirstUnallocated - Return the first unallocated register in the set, or
+  /// NumRegs if they are all allocated.
+  unsigned getFirstUnallocated(const unsigned *Regs, unsigned NumRegs) const {
+    for (unsigned i = 0; i != NumRegs; ++i)
+      if (!isAllocated(Regs[i]))
+        return i;
+    return NumRegs;
+  }
+  
+  /// AllocateReg - Attempt to allocate one of the specified registers.  If none
+  /// are available, return zero.  Otherwise, return the first one available,
+  /// marking it and any aliases as allocated.
+  unsigned AllocateReg(const unsigned *Regs, unsigned NumRegs) {
+    unsigned FirstUnalloc = getFirstUnallocated(Regs, NumRegs);
+    if (FirstUnalloc == NumRegs)
+      return 0;    // Didn't find the reg.
+     
+    // Mark the register and any aliases as allocated.
+    unsigned Reg = Regs[FirstUnalloc];
+    MarkAllocated(Reg);
+    return Reg;
+  }
+  
+  /// AllocateStack - Allocate a chunk of stack space with the specified size
+  /// and alignment.
+  unsigned AllocateStack(unsigned Size, unsigned Align) {
+    assert(Align && ((Align-1) & Align) == 0); // Align is power of 2.
+    StackOffset = ((StackOffset + Align-1) & ~(Align-1));
+    unsigned Result = StackOffset;
+    StackOffset += Size;
+    return Result;
+  }
+private:
+  /// MarkAllocated - Mark a register and all of its aliases as allocated.
+  void MarkAllocated(unsigned Reg);
+};
+
+/// CCValAssign - Represent assignment of one arg/retval to a location.
+class CCValAssign {
+public:
+  enum LocInfo {
+    Full,   // The value fills the full location.
+    SExt,   // The value is sign extended in the location.
+    ZExt,   // The value is zero extended in the location.
+    AExt    // The value is extended with undefined upper bits.
+    // TODO: a subset of the value is in the location.
+  };
+private:
+  /// ValNo - This is the value number begin assigned (e.g. an argument number).
+  unsigned ValNo;
+  
+  /// Loc is either a stack offset or a register number.
+  unsigned Loc;
+  
+  /// isMem - True if this is a memory loc, false if it is a register loc.
+  bool isMem : 1;
+  
+  /// Information about how the value is assigned.
+  LocInfo HTP : 7;
+  
+  /// ValVT - The type of the value being assigned.
+  MVT::ValueType ValVT : 8;
+
+  /// LocVT - The type of the location being assigned to.
+  MVT::ValueType LocVT : 8;
+public:
+    
+  static CCValAssign getReg(unsigned ValNo, MVT::ValueType ValVT,
+                            unsigned RegNo, MVT::ValueType LocVT,
+                            LocInfo HTP) {
+    CCValAssign Ret;
+    Ret.ValNo = ValNo;
+    Ret.Loc = RegNo;
+    Ret.isMem = false;
+    Ret.HTP = HTP;
+    Ret.ValVT = ValVT;
+    Ret.LocVT = LocVT;
+    return Ret;
+  }
+  static CCValAssign getMem(unsigned ValNo, MVT::ValueType ValVT,
+                            unsigned Offset, MVT::ValueType LocVT,
+                            LocInfo HTP) {
+    CCValAssign Ret;
+    Ret.ValNo = ValNo;
+    Ret.Loc = Offset;
+    Ret.isMem = true;
+    Ret.HTP = HTP;
+    Ret.ValVT = ValVT;
+    Ret.LocVT = LocVT;
+    return Ret;
+  }
+  
+  unsigned getValNo() const { return ValNo; }
+  MVT::ValueType getValVT() const { return ValVT; }
+
+  bool isRegLoc() const { return !isMem; }
+  bool isMemLoc() const { return isMem; }
+  
+  unsigned getLocReg() const { assert(isRegLoc()); return Loc; }
+  unsigned getLocMemOffset() const { assert(isMemLoc()); return Loc; }
+  MVT::ValueType getLocVT() const { return LocVT; }
+  
+  LocInfo getLocInfo() const { return HTP; }
+};
+
+} // end namespace llvm
+
+#endif