1//===- SafeStackLayout.h - SafeStack frame layout --------------*- C++ -*--===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_LIB_CODEGEN_SAFESTACKLAYOUT_H
10#define LLVM_LIB_CODEGEN_SAFESTACKLAYOUT_H
11
12#include "SafeStackColoring.h"
13#include "llvm/ADT/DenseMap.h"
14#include "llvm/ADT/SmallVector.h"
15
16namespace llvm {
17
18class raw_ostream;
19class Value;
20
21namespace safestack {
22
23/// Compute the layout of an unsafe stack frame.
24class StackLayout {
25  unsigned MaxAlignment;
26
27  struct StackRegion {
28    unsigned Start;
29    unsigned End;
30    StackColoring::LiveRange Range;
31
32    StackRegion(unsigned Start, unsigned End,
33                const StackColoring::LiveRange &Range)
34        : Start(Start), End(End), Range(Range) {}
35  };
36
37  /// The list of current stack regions, sorted by StackRegion::Start.
38  SmallVector<StackRegion, 16> Regions;
39
40  struct StackObject {
41    const Value *Handle;
42    unsigned Size, Alignment;
43    StackColoring::LiveRange Range;
44  };
45
46  SmallVector<StackObject, 8> StackObjects;
47
48  DenseMap<const Value *, unsigned> ObjectOffsets;
49  DenseMap<const Value *, unsigned> ObjectAlignments;
50
51  void layoutObject(StackObject &Obj);
52
53public:
54  StackLayout(unsigned StackAlignment) : MaxAlignment(StackAlignment) {}
55
56  /// Add an object to the stack frame. Value pointer is opaque and used as a
57  /// handle to retrieve the object's offset in the frame later.
58  void addObject(const Value *V, unsigned Size, unsigned Alignment,
59                 const StackColoring::LiveRange &Range);
60
61  /// Run the layout computation for all previously added objects.
62  void computeLayout();
63
64  /// Returns the offset to the object start in the stack frame.
65  unsigned getObjectOffset(const Value *V) { return ObjectOffsets[V]; }
66
67  /// Returns the alignment of the object
68  unsigned getObjectAlignment(const Value *V) { return ObjectAlignments[V]; }
69
70  /// Returns the size of the entire frame.
71  unsigned getFrameSize() { return Regions.empty() ? 0 : Regions.back().End; }
72
73  /// Returns the alignment of the frame.
74  unsigned getFrameAlignment() { return MaxAlignment; }
75
76  void print(raw_ostream &OS);
77};
78
79} // end namespace safestack
80
81} // end namespace llvm
82
83#endif // LLVM_LIB_CODEGEN_SAFESTACKLAYOUT_H
84