lib/CodeGen/SafeStackLayout.h

   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
  33     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:
  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.
  66   unsigned getObjectOffset(const Value *V) { return ObjectOffsets[V]; }
  67
  68   /// Returns the alignment of the object
  69   unsigned 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   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