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 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 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 55 public: 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