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