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//===- SafeStackLayout.h - SafeStack frame layout --------------*- C++ -*--===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_CODEGEN_SAFESTACKLAYOUT_H
#define LLVM_LIB_CODEGEN_SAFESTACKLAYOUT_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/StackLifetime.h"
namespace llvm {
class raw_ostream;
class Value;
namespace safestack {
/// Compute the layout of an unsafe stack frame.
class StackLayout {
unsigned MaxAlignment;
struct StackRegion {
unsigned Start;
unsigned End;
StackLifetime::LiveRange Range;
StackRegion(unsigned Start, unsigned End,
const StackLifetime::LiveRange &Range)
: Start(Start), End(End), Range(Range) {}
};
/// The list of current stack regions, sorted by StackRegion::Start.
SmallVector<StackRegion, 16> Regions;
struct StackObject {
const Value *Handle;
unsigned Size, Alignment;
StackLifetime::LiveRange Range;
};
SmallVector<StackObject, 8> StackObjects;
DenseMap<const Value *, unsigned> ObjectOffsets;
DenseMap<const Value *, unsigned> ObjectAlignments;
void layoutObject(StackObject &Obj);
public:
StackLayout(unsigned StackAlignment) : MaxAlignment(StackAlignment) {}
/// Add an object to the stack frame. Value pointer is opaque and used as a
/// handle to retrieve the object's offset in the frame later.
void addObject(const Value *V, unsigned Size, unsigned Alignment,
const StackLifetime::LiveRange &Range);
/// Run the layout computation for all previously added objects.
void computeLayout();
/// Returns the offset to the object start in the stack frame.
unsigned getObjectOffset(const Value *V) { return ObjectOffsets[V]; }
/// Returns the alignment of the object
unsigned getObjectAlignment(const Value *V) { return ObjectAlignments[V]; }
/// Returns the size of the entire frame.
unsigned getFrameSize() { return Regions.empty() ? 0 : Regions.back().End; }
/// Returns the alignment of the frame.
unsigned getFrameAlignment() { return MaxAlignment; }
void print(raw_ostream &OS);
};
} // end namespace safestack
} // end namespace llvm
#endif // LLVM_LIB_CODEGEN_SAFESTACKLAYOUT_H
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