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 "llvm/ADT/DenseMap.h"
13#include "llvm/ADT/SmallVector.h"
14#include "llvm/Analysis/StackLifetime.h"
15#include "llvm/Support/Alignment.h"
16
17namespace llvm {
18
19class raw_ostream;
20class Value;
21
22namespace safestack {
23
24/// Compute the layout of an unsafe stack frame.
25class StackLayout {
26 Align MaxAlignment;
27
28 struct StackRegion {
29 unsigned Start;
30 unsigned End;
31 StackLifetime::LiveRange Range;
32
33 StackRegion(unsigned Start, unsigned End,
34 const StackLifetime::LiveRange &Range)
35 : Start(Start), End(End), Range(Range) {}
36 };
37
38 /// The list of current stack regions, sorted by StackRegion::Start.
39 SmallVector<StackRegion, 16> Regions;
40
41 struct StackObject {
42 const Value *Handle;
43 unsigned Size;
44 Align Alignment;
45 StackLifetime::LiveRange Range;
46 };
47
48 SmallVector<StackObject, 8> StackObjects;
49
50 DenseMap<const Value *, unsigned> ObjectOffsets;
51 DenseMap<const Value *, Align> ObjectAlignments;
52
53 void layoutObject(StackObject &Obj);
54
55public:
56 StackLayout(Align StackAlignment) : MaxAlignment(StackAlignment) {}
57
58 /// Add an object to the stack frame. Value pointer is opaque and used as a
59 /// handle to retrieve the object's offset in the frame later.
60 void addObject(const Value *V, unsigned Size, Align Alignment,
61 const StackLifetime::LiveRange &Range);
62
63 /// Run the layout computation for all previously added objects.
64 void computeLayout();
65
66 /// Returns the offset to the object start in the stack frame.
67 unsigned getObjectOffset(const Value *V) { return ObjectOffsets[V]; }
68
69 /// Returns the alignment of the object
70 Align getObjectAlignment(const Value *V) { return ObjectAlignments[V]; }
71
72 /// Returns the size of the entire frame.
73 unsigned getFrameSize() { return Regions.empty() ? 0 : Regions.back().End; }
74
75 /// Returns the alignment of the frame.
76 Align getFrameAlignment() { return MaxAlignment; }
77
78 void print(raw_ostream &OS);
79};
80
81} // end namespace safestack
82
83} // end namespace llvm
84
85#endif // LLVM_LIB_CODEGEN_SAFESTACKLAYOUT_H
86