1 //===-- llvm/Target/TargetFrameInfo.h ---------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // 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 /// Information about stack frame layout on the target. It holds the direction
22 /// of stack growth, the known stack alignment on entry to each function, and
23 /// the offset to the locals area.
25 /// The offset to the local area is the offset from the stack pointer on
26 /// function entry to the first location where function data (local variables,
27 /// spill locations) can be stored.
28 class TargetFrameInfo {
31 StackGrowsUp, // Adding to the stack increases the stack address
32 StackGrowsDown // Adding to the stack decreases the stack address
35 // Maps a callee saved register to a stack slot with a fixed offset.
38 int Offset; // Offset relative to stack pointer on function entry.
41 StackDirection StackDir;
42 unsigned StackAlignment;
43 unsigned TransientStackAlignment;
46 TargetFrameInfo(StackDirection D, unsigned StackAl, int LAO,
48 : StackDir(D), StackAlignment(StackAl), TransientStackAlignment(TransAl),
49 LocalAreaOffset(LAO) {}
51 virtual ~TargetFrameInfo();
53 // These methods return information that describes the abstract stack layout
54 // of the target machine.
56 /// getStackGrowthDirection - Return the direction the stack grows
58 StackDirection getStackGrowthDirection() const { return StackDir; }
60 /// getStackAlignment - This method returns the number of bytes to which the
61 /// stack pointer must be aligned on entry to a function. Typically, this
62 /// is the largest alignment for any data object in the target.
64 unsigned getStackAlignment() const { return StackAlignment; }
66 /// getTransientStackAlignment - This method returns the number of bytes to
67 /// which the stack pointer must be aligned at all times, even between
70 unsigned getTransientStackAlignment() const {
71 return TransientStackAlignment;
74 /// getOffsetOfLocalArea - This method returns the offset of the local area
75 /// from the stack pointer on entrance to a function.
77 int getOffsetOfLocalArea() const { return LocalAreaOffset; }
79 /// getCalleeSavedSpillSlots - This method returns a pointer to an array of
80 /// pairs, that contains an entry for each callee saved register that must be
81 /// spilled to a particular stack location if it is spilled.
83 /// Each entry in this array contains a <register,offset> pair, indicating the
84 /// fixed offset from the incoming stack pointer that each register should be
85 /// spilled at. If a register is not listed here, the code generator is
86 /// allowed to spill it anywhere it chooses.
88 virtual const SpillSlot *
89 getCalleeSavedSpillSlots(unsigned &NumEntries) const {
95 } // End llvm namespace