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 | |
16 | namespace llvm { |
17 | |
18 | class raw_ostream; |
19 | class Value; |
20 | |
21 | namespace safestack { |
22 | |
23 | /// Compute the layout of an unsafe stack frame. |
24 | class 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 | |
54 | public: |
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 | |