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//===-- llvm/Target/TargetFrameInfo.h ---------------------------*- 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.
//
//===----------------------------------------------------------------------===//
//
// Interface to describe the layout of a stack frame on the target machine.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TARGET_TARGETFRAMEINFO_H
#define LLVM_TARGET_TARGETFRAMEINFO_H
#include <utility>
namespace llvm {
class MachineFunction;
/// Information about stack frame layout on the target. It holds the direction
/// of stack growth, the known stack alignment on entry to each function, and
/// the offset to the locals area.
///
/// The offset to the local area is the offset from the stack pointer on
/// function entry to the first location where function data (local variables,
/// spill locations) can be stored.
class TargetFrameInfo {
public:
enum StackDirection {
StackGrowsUp, // Adding to the stack increases the stack address
StackGrowsDown // Adding to the stack decreases the stack address
};
private:
StackDirection StackDir;
unsigned StackAlignment;
int LocalAreaOffset;
public:
TargetFrameInfo(StackDirection D, unsigned StackAl, int LAO)
: StackDir(D), StackAlignment(StackAl), LocalAreaOffset(LAO) {}
virtual ~TargetFrameInfo();
// These methods return information that describes the abstract stack layout
// of the target machine.
/// getStackGrowthDirection - Return the direction the stack grows
///
StackDirection getStackGrowthDirection() const { return StackDir; }
/// getStackAlignment - This method returns the number of bytes that the stack
/// pointer must be aligned to. Typically, this is the largest alignment for
/// any data object in the target.
///
unsigned getStackAlignment() const { return StackAlignment; }
/// getOffsetOfLocalArea - This method returns the offset of the local area
/// from the stack pointer on entrance to a function.
///
int getOffsetOfLocalArea() const { return LocalAreaOffset; }
/// getCalleeSavedSpillSlots - This method returns a pointer to an array of
/// pairs, that contains an entry for each callee saved register that must be
/// spilled to a particular stack location if it is spilled.
///
/// Each entry in this array contains a <register,offset> pair, indicating the
/// fixed offset from the incoming stack pointer that each register should be
/// spilled at. If a register is not listed here, the code generator is
/// allowed to spill it anywhere it chooses.
///
virtual const std::pair<unsigned, int> *
getCalleeSavedSpillSlots(unsigned &NumEntries) const {
NumEntries = 0;
return 0;
}
};
} // End llvm namespace
#endif
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