ghidra/Ghidra/Features/Decompiler/src/decompile/cpp/variable.hh
2021-01-04 14:34:04 -05:00

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C++

/* ###
* IP: GHIDRA
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/// \file variable.hh
/// \brief Definitions for high-level variables
#ifndef __CPUI_TYPEVAR__
#define __CPUI_TYPEVAR__
#include "varnode.hh"
class Symbol;
/// \brief A high-level variable modeled as a list of low-level variables, each written once
///
/// In the Static Single Assignment (SSA) representation of a function's data-flow, the Varnode
/// object represents a variable node. This is a \b low-level \b variable: it is written to
/// at most once, and there is 1 or more reads. A \b high-level \b variable, in the source
/// language may be written to multiple times. We model this idea as a list of Varnode objects, where
/// a different Varnode holds the value of the variable for different parts of the code. The range(s)
/// of code for which a single Varnode holds the high-level variable's value is the \b cover or \b range
/// of that Varnode and is modeled by the class Cover. Within a high-level variable, HighVariable,
/// the covers of member Varnode objects should not intersect, as that represents the variable holding
/// two or more different values at the same place in the code. The HighVariable inherits a cover
/// which is the union of the covers of its Varnodes.
class HighVariable {
public:
/// \brief Dirtiness flags for a HighVariable
///
/// The HighVariable inherits its Cover, its data-type, and other boolean properties from its Varnodes.
/// The object holds these explicitly, but the values may become stale as the data-flow transforms.
/// So we keep track of when these inherited values are \e dirty
enum {
flagsdirty = 1, ///< Boolean properties for the HighVariable are dirty
namerepdirty = 2, ///< The name representative for the HighVariable is dirty
typedirty = 4, ///< The data-type for the HighVariable is dirty
coverdirty = 8, ///< The cover for the HighVariable is dirty
symboldirty = 0x10, ///< The symbol attachment is dirty
copy_in1 = 0x20, ///< There exists at least 1 COPY into \b this HighVariable from other HighVariables
copy_in2 = 0x40, ///< There exists at least 2 COPYs into \b this HighVariable from other HighVariables
type_finalized = 0x80, ///< Set if a final data-type is locked in and dirtying is disabled
unmerged = 0x100 ///< Set if part of a multi-entry Symbol but did not get merged with other SymbolEntrys
};
private:
friend class Varnode;
friend class Merge;
vector<Varnode *> inst; ///< The member Varnode objects making up \b this HighVariable
int4 numMergeClasses; ///< Number of different speculative merge classes in \b this
mutable uint4 highflags; ///< Dirtiness flags
mutable uint4 flags; ///< Boolean properties inherited from Varnode members
mutable Datatype *type; ///< The data-type for \b this
mutable Varnode *nameRepresentative; ///< The storage location used to generate a Symbol name
mutable Cover wholecover; ///< The ranges of code addresses covered by this HighVariable
mutable Symbol *symbol; ///< The Symbol \b this HighVariable is tied to
mutable int4 symboloffset; ///< -1=perfect symbol match >=0, offset
int4 instanceIndex(const Varnode *vn) const; ///< Find the index of a specific Varnode member
void updateFlags(void) const; ///< (Re)derive boolean properties of \b this from the member Varnodes
void updateCover(void) const; ///< (Re)derive the cover of \b this from the member Varnodes
void updateType(void) const; ///< (Re)derive the data-type for \b this from the member Varnodes
void updateSymbol(void) const; ///< (Re)derive the Symbol and offset for \b this from member Varnodes
void setCopyIn1(void) const { highflags |= copy_in1; } ///< Mark the existence of one COPY into \b this
void setCopyIn2(void) const { highflags |= copy_in2; } ///< Mark the existence of two COPYs into \b this
void clearCopyIns(void) const { highflags &= ~(copy_in1 | copy_in2); } ///< Clear marks indicating COPYs into \b this
bool hasCopyIn1(void) const { return ((highflags&copy_in1)!=0); } ///< Is there at least one COPY into \b this
bool hasCopyIn2(void) const { return ((highflags&copy_in2)!=0); } ///< Is there at least two COPYs into \b this
void remove(Varnode *vn); ///< Remove a member Varnode from \b this
void merge(HighVariable *tv2,bool isspeculative); ///< Merge another HighVariable into \b this
void setSymbol(Varnode *vn) const; ///< Update Symbol information for \b this from the given member Varnode
void setSymbolReference(Symbol *sym,int4 off); ///< Attach a reference to a Symbol to \b this
void flagsDirty(void) const { highflags |= flagsdirty | namerepdirty; } ///< Mark the boolean properties as \e dirty
void coverDirty(void) const { highflags |= coverdirty; } ///< Mark the cover as \e dirty
void typeDirty(void) const { highflags |= typedirty; } ///< Mark the data-type as \e dirty
void setUnmerged(void) const { highflags |= unmerged; } ///< Mark \b this as having merge problems
public:
HighVariable(Varnode *vn); ///< Construct a HighVariable with a single member Varnode
Datatype *getType(void) const { updateType(); return type; } ///< Get the data-type
Symbol *getSymbol(void) const { updateSymbol(); return symbol; } ///< Get the Symbol associated with \b this or null
SymbolEntry *getSymbolEntry(void) const; /// Get the SymbolEntry mapping to \b this or null
int4 getSymbolOffset(void) const { return symboloffset; } ///< Get the Symbol offset associated with \b this
int4 numInstances(void) const { return inst.size(); } ///< Get the number of member Varnodes \b this has
Varnode *getInstance(int4 i) const { return inst[i]; } ///< Get the i-th member Varnode
void finalizeDatatype(Datatype *tp); ///< Set a final datatype for \b this variable
/// \brief Print details of the cover for \b this (for debug purposes)
///
/// \param s is the output stream
void printCover(ostream &s) const { if ((highflags&HighVariable::coverdirty)==0) wholecover.print(s); else s << "Cover dirty"; }
void printInfo(ostream &s) const; ///< Print information about \b this HighVariable to stream
bool hasName(void) const; ///< Check if \b this HighVariable can be named
Varnode *getTiedVarnode(void) const; ///< Find the first address tied member Varnode
Varnode *getInputVarnode(void) const; ///< Find (the) input member Varnode
Varnode *getTypeRepresentative(void) const; ///< Get a member Varnode with the strongest data-type
Varnode *getNameRepresentative(void) const; ///< Get a member Varnode that dictates the naming of \b this HighVariable
int4 getNumMergeClasses(void) const { return numMergeClasses; } ///< Get the number of speculative merges for \b this
bool isMapped(void) const { updateFlags(); return ((flags&Varnode::mapped)!=0); } ///< Return \b true if \b this is mapped
bool isPersist(void) const { updateFlags(); return ((flags&Varnode::persist)!=0); } ///< Return \b true if \b this is a global variable
bool isAddrTied(void) const { updateFlags(); return ((flags&Varnode::addrtied)!=0); } ///< Return \b true if \b this is \e address \e ties
bool isInput(void) const { updateFlags(); return ((flags&Varnode::input)!=0); } ///< Return \b true if \b this is an input variable
bool isImplied(void) const { updateFlags(); return ((flags&Varnode::implied)!=0); } ///< Return \b true if \b this is an implied variable
bool isSpacebase(void) const { updateFlags(); return ((flags&Varnode::spacebase)!=0); } ///< Return \b true if \b this is a \e spacebase
bool isConstant(void) const { updateFlags(); return ((flags&Varnode::constant)!=0); } ///< Return \b true if \b this is a constant
bool isUnaffected(void) const { updateFlags(); return ((flags&Varnode::unaffected)!=0); } ///< Return \b true if \b this is an \e unaffected register
bool isExtraOut(void) const { updateFlags(); return ((flags&(Varnode::indirect_creation|Varnode::addrtied))==Varnode::indirect_creation); } ///< Return \b true if \b this is an extra output
void setMark(void) const { flags |= Varnode::mark; } ///< Set the mark on this variable
void clearMark(void) const { flags &= ~Varnode::mark; } ///< Clear the mark on this variable
bool isMark(void) const { return ((flags&Varnode::mark)!=0); } ///< Return \b true if \b this is marked
bool isUnmerged(void) const { return ((highflags&unmerged)!=0); } ///< Return \b true if \b this has merge problems
/// \brief Determine if \b this HighVariable has an associated cover.
///
/// Constant and annotation variables do not have a cover
/// \return \b true if \b this has a cover
bool hasCover(void) const {
updateFlags();
return ((flags&(Varnode::constant|Varnode::annotation|Varnode::insert))==Varnode::insert); }
bool isUnattached(void) const { return inst.empty(); } ///< Return \b true if \b this has no member Varnode
bool isTypeLock(void) const { updateType(); return ((flags & Varnode::typelock)!=0); } ///< Return \b true if \b this is \e typelocked
bool isNameLock(void) const { updateFlags(); return ((flags & Varnode::namelock)!=0); } ///< Return \b true if \b this is \e namelocked
void saveXml(ostream &s) const; ///< Save the variable to stream as an XML \<high\> tag
#ifdef MERGEMULTI_DEBUG
void verifyCover(void) const;
#endif
// Varnode *findGlobalRep(void) const;
static bool compareName(Varnode *vn1,Varnode *vn2); ///< Determine which given Varnode is most nameable
static bool compareJustLoc(const Varnode *a,const Varnode *b); ///< Compare based on storage location
static int4 markExpression(Varnode *vn,vector<HighVariable *> &highList); ///< Mark and collect variables in expression
};
#endif