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

source code of llvm/lib/CodeGen/SafeStackLayout.h