1 //===-- llvm/Target/TargetFrameInfo.h ---------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Interface to describe the layout of a stack frame on the target machine.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_TARGET_TARGETFRAMEINFO_H
15 #define LLVM_TARGET_TARGETFRAMEINFO_H
21 class MachineFunction;
23 /// Information about stack frame layout on the target. It holds the direction
24 /// of stack growth, the known stack alignment on entry to each function, and
25 /// the offset to the locals area.
27 /// The offset to the local area is the offset from the stack pointer on
28 /// function entry to the first location where function data (local variables,
29 /// spill locations) can be stored.
30 class TargetFrameInfo {
33 StackGrowsUp, // Adding to the stack increases the stack address
34 StackGrowsDown // Adding to the stack decreases the stack address
37 StackDirection StackDir;
38 unsigned StackAlignment;
41 TargetFrameInfo(StackDirection D, unsigned StackAl, int LAO)
42 : StackDir(D), StackAlignment(StackAl), LocalAreaOffset(LAO) {}
44 virtual ~TargetFrameInfo();
46 // These methods return information that describes the abstract stack layout
47 // of the target machine.
49 /// getStackGrowthDirection - Return the direction the stack grows
51 StackDirection getStackGrowthDirection() const { return StackDir; }
53 /// getStackAlignment - This method returns the number of bytes that the stack
54 /// pointer must be aligned to. Typically, this is the largest alignment for
55 /// any data object in the target.
57 unsigned getStackAlignment() const { return StackAlignment; }
59 /// getOffsetOfLocalArea - This method returns the offset of the local area
60 /// from the stack pointer on entrance to a function.
62 int getOffsetOfLocalArea() const { return LocalAreaOffset; }
64 /// getCalleeSaveSpillSlots - This method returns a pointer to an array of
65 /// pairs, that contains an entry for each callee save register that must be
66 /// spilled to a particular stack location if it is spilled.
68 /// Each entry in this array contains a <register,offset> pair, indicating the
69 /// fixed offset from the incoming stack pointer that each register should be
70 /// spilled at. If a register is not listed here, the code generator is
71 /// allowed to spill it anywhere it chooses.
73 virtual const std::pair<unsigned, int> *
74 getCalleeSaveSpillSlots(unsigned &NumEntries) const {
80 } // End llvm namespace