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 #include "llvm/ADT/DenseMap.h"
15 #include "llvm/ADT/SmallVector.h"
16 
17 namespace llvm {
18 
19 class raw_ostream;
20 class Value;
21 
22 namespace safestack {
23 
24 /// Compute the layout of an unsafe stack frame.
25 class StackLayout {
26   unsigned MaxAlignment;
27 
28   struct StackRegion {
29     unsigned Start;
30     unsigned End;
31     StackColoring::LiveRange Range;
32 
StackRegionStackRegion33     StackRegion(unsigned Start, unsigned End,
34                 const StackColoring::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, Alignment;
44     StackColoring::LiveRange Range;
45   };
46 
47   SmallVector<StackObject, 8> StackObjects;
48 
49   DenseMap<const Value *, unsigned> ObjectOffsets;
50   DenseMap<const Value *, unsigned> ObjectAlignments;
51 
52   void layoutObject(StackObject &Obj);
53 
54 public:
StackLayout(unsigned StackAlignment)55   StackLayout(unsigned 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, unsigned Alignment,
60                  const StackColoring::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.
getObjectOffset(const Value * V)66   unsigned getObjectOffset(const Value *V) { return ObjectOffsets[V]; }
67 
68   /// Returns the alignment of the object
getObjectAlignment(const Value * V)69   unsigned getObjectAlignment(const Value *V) { return ObjectAlignments[V]; }
70 
71   /// Returns the size of the entire frame.
getFrameSize()72   unsigned getFrameSize() { return Regions.empty() ? 0 : Regions.back().End; }
73 
74   /// Returns the alignment of the frame.
getFrameAlignment()75   unsigned 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