1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
|
//===-- llvm/Target/TargetFrameInfo.h ---------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file 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 {
/// 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
};
// Maps a callee saved register to a stack slot with a fixed offset.
struct SpillSlot {
unsigned Reg;
int Offset; // Offset relative to stack pointer on function entry.
};
private:
StackDirection StackDir;
unsigned StackAlignment;
unsigned TransientStackAlignment;
int LocalAreaOffset;
public:
TargetFrameInfo(StackDirection D, unsigned StackAl, int LAO,
unsigned TransAl = 1)
: StackDir(D), StackAlignment(StackAl), TransientStackAlignment(TransAl),
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 to which the
/// stack pointer must be aligned on entry to a function. Typically, this
/// is the largest alignment for any data object in the target.
///
unsigned getStackAlignment() const { return StackAlignment; }
/// getTransientStackAlignment - This method returns the number of bytes to
/// which the stack pointer must be aligned at all times, even between
/// calls.
///
unsigned getTransientStackAlignment() const {
return TransientStackAlignment;
}
/// 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 SpillSlot *
getCalleeSavedSpillSlots(unsigned &NumEntries) const {
NumEntries = 0;
return 0;
}
};
} // End llvm namespace
#endif
|
