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(uint64_t 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