397 lines
13 KiB
C++
397 lines
13 KiB
C++
/*****************************************************************************
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* dcc project CFG related functions
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* (C) Cristina Cifuentes
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****************************************************************************/
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#include "graph.h"
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#include "msvc_fixes.h"
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#include "dcc.h"
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#include "project.h"
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#include <boost/range/rbegin.hpp>
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#include <boost/range/rend.hpp>
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#include <string.h>
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using namespace std;
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using namespace boost;
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//static BB * rmJMP(Function * pProc, int marker, BB * pBB);
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//static void mergeFallThrough(Function * pProc, BB * pBB);
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//static void dfsNumbering(BB * pBB, std::vector<BB*> &dfsLast, int *first, int *last);
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void Function::addOutEdgesForConditionalJump(BB * pBB,int next_ip, LLInst *ll)
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{
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pBB->addOutEdge(next_ip);
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/* This is checking for jumps off into nowhere */
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if ( not ll->testFlags(NO_LABEL) )
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pBB->addOutEdge(ll->src().getImm2());
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}
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/*****************************************************************************
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* createCFG - Create the basic control flow graph
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****************************************************************************/
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void Function::createCFG()
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{
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/* Splits Icode associated with the procedure into Basic Blocks.
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* The links between BBs represent the control flow graph of the
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* procedure.
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* A Basic Block is defined to end on one of the following instructions:
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* 1) Conditional and unconditional jumps
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* 2) CALL(F)
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* 3) RET(F)
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* 4) On the instruction before a join (a flagged TARGET)
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* 5) Repeated string instructions
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* 6) End of procedure
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*/
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BB * psBB;
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BB * pBB;
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iICODE pIcode = Icode.begin();
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stats.numBBbef = stats.numBBaft = 0;
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rICODE current_range=make_iterator_range(pIcode,++iICODE(pIcode));
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for (; pIcode!=Icode.end(); ++pIcode,current_range.advance_end(1))
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{
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iICODE nextIcode = ++iICODE(pIcode);
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pBB = nullptr;
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LLInst *ll = pIcode->ll();
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/* Only process icodes that have valid instructions */
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if(ll->testFlags(NO_CODE))
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continue;
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/* Stick a NOWHERE_NODE on the end if we terminate
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* with anything other than a ret, jump or terminate */
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if (nextIcode == Icode.end() and
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(not ll->testFlags(TERMINATES)) and
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(not ll->match(iJMP)) and (not ll->match(iJMPF)) and
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(not ll->match(iRET)) and (not ll->match(iRETF)))
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{
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pBB=BB::Create(current_range, NOWHERE_NODE, this);
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}
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else
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switch (ll->getOpcode()) {
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case iJB: case iJBE: case iJAE: case iJA:
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case iJL: case iJLE: case iJGE: case iJG:
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case iJE: case iJNE: case iJS: case iJNS:
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case iJO: case iJNO: case iJP: case iJNP:
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case iJCXZ:
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pBB = BB::Create(current_range, TWO_BRANCH, this);
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addOutEdgesForConditionalJump(pBB,nextIcode->loc_ip, ll);
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break;
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case iLOOP: case iLOOPE: case iLOOPNE:
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pBB = BB::Create(current_range, LOOP_NODE, this);
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addOutEdgesForConditionalJump(pBB,nextIcode->loc_ip, ll);
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break;
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case iJMPF: case iJMP:
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if (ll->testFlags(SWITCH))
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{
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pBB = BB::Create(current_range, MULTI_BRANCH, this);
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for (auto & elem : ll->caseTbl2)
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pBB->addOutEdge(elem);
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hasCase = true;
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}
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else if (ll->srcIsImmed() and not ll->testFlags(NO_LABEL)) //TODO: WHY NO_LABEL TESTIT
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{
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pBB = BB::Create(current_range, ONE_BRANCH, this);
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pBB->addOutEdge(ll->src().getImm2());
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}
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else
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pBB = BB::Create(current_range, NOWHERE_NODE, this);
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break;
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case iCALLF: case iCALL:
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{
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Function * p = ll->src().proc.proc;
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pBB = BB::Create(current_range, CALL_NODE, this);
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if (p and not ((p->flg) & TERMINATES) )
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pBB->addOutEdge(nextIcode->loc_ip);
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break;
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}
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case iRET: case iRETF:
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pBB = BB::Create(current_range, RETURN_NODE, this);
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break;
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default:
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/* Check for exit to DOS */
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if ( ll->testFlags(TERMINATES) )
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{
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pBB = BB::Create(current_range, TERMINATE_NODE, this);
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}
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/* Check for a fall through */
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else if (nextIcode != Icode.end())
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{
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if (nextIcode->ll()->testFlags(TARGET | CASE))
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{
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pBB = BB::Create(current_range, FALL_NODE, this);
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pBB->addOutEdge(nextIcode->loc_ip);
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}
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}
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break;
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}
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if(pBB!=nullptr) // created a new Basic block
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{
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// restart the range
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// end iterator will be updated by expression in for statement
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current_range=make_iterator_range(nextIcode,nextIcode);
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}
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if (nextIcode == Icode.end())
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break;
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}
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for (auto pr : m_ip_to_bb)
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{
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BB* pBB=pr.second;
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for (auto & elem : pBB->edges)
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{
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int32_t ip = elem.ip;
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if (ip >= SYNTHESIZED_MIN)
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{
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fatalError (INVALID_SYNTHETIC_BB);
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return;
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}
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auto iter2=m_ip_to_bb.find(ip);
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if(iter2==m_ip_to_bb.end())
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fatalError(NO_BB, ip, qPrintable(name));
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psBB = iter2->second;
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elem.BBptr = psBB;
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psBB->inEdges.push_back((BB *)nullptr);
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}
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}
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}
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void Function::markImpure()
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{
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PROG &prog(Project::get()->prog);
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for(ICODE &icod : Icode)
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{
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if ( not icod.ll()->testFlags(SYM_USE | SYM_DEF))
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continue;
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//assert that case tbl has less entries then symbol table ????
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//WARNING: Case entries are held in symbol table !
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assert(Project::get()->validSymIdx(icod.ll()->caseEntry));
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const SYM &psym(Project::get()->getSymByIdx(icod.ll()->caseEntry));
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for (int c = (int)psym.label; c < (int)psym.label+psym.size; c++)
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{
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if (BITMAP(c, BM_CODE))
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{
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icod.ll()->setFlags(IMPURE);
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flg |= IMPURE;
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break;
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}
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}
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}
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}
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/*****************************************************************************
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* freeCFG - Deallocates a cfg
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****************************************************************************/
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void Function::freeCFG()
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{
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for(auto p : m_ip_to_bb)
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{
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delete p.second;
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}
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m_ip_to_bb.clear();
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}
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/*****************************************************************************
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* compressCFG - Remove redundancies and add in-edge information
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****************************************************************************/
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void Function::compressCFG()
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{
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BB *pNxt;
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int ip, first=0, last;
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/* First pass over BB list removes redundant jumps of the form
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* (Un)Conditional -> Unconditional jump */
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for (BB *pBB : m_actual_cfg) //m_cfg
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{
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if(pBB->inEdges.empty() or (pBB->nodeType != ONE_BRANCH and pBB->nodeType != TWO_BRANCH))
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continue;
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for (TYPEADR_TYPE &edgeRef : pBB->edges)
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{
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ip = pBB->rbegin()->loc_ip;
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pNxt = edgeRef.BBptr->rmJMP(ip, edgeRef.BBptr);
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if (not pBB->edges.empty()) /* Might have been clobbered */
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{
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edgeRef.BBptr = pNxt;
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assert(pBB->back().loc_ip==ip);
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pBB->back().ll()->SetImmediateOp((uint32_t)pNxt->begin()->loc_ip);
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//Icode[ip].SetImmediateOp((uint32_t)pNxt->begin());
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}
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}
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}
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/* Next is a depth-first traversal merging any FALL_NODE or
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* ONE_BRANCH that fall through to a node with that as their only
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* in-edge. */
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m_actual_cfg.front()->mergeFallThrough(Icode);
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/* Remove redundant BBs created by the above compressions
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* and allocate in-edge arrays as required. */
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stats.numBBaft = stats.numBBbef;
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bool entry_node=true;
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for(BB *pBB : m_actual_cfg)
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{
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if (pBB->inEdges.empty())
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{
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if (entry_node) /* Init it misses out on */
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pBB->index = UN_INIT;
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else
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{
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delete pBB;
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stats.numBBaft--;
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}
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}
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else
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{
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pBB->inEdgeCount = pBB->inEdges.size();
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}
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entry_node=false;
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}
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/* Allocate storage for dfsLast[] array */
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numBBs = stats.numBBaft;
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m_dfsLast.resize(numBBs,nullptr); // = (BB **)allocMem(numBBs * sizeof(BB *))
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/* Now do a dfs numbering traversal and fill in the inEdges[] array */
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last = numBBs - 1;
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m_actual_cfg.front()->dfsNumbering(m_dfsLast, &first, &last);
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}
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/****************************************************************************
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* rmJMP - If BB addressed is just a JMP it is replaced with its target
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***************************************************************************/
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BB *BB::rmJMP(int marker, BB * pBB)
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{
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marker += (int)DFS_JMP;
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while (pBB->nodeType == ONE_BRANCH and pBB->size() == 1)
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{
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if (pBB->traversed != marker)
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{
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pBB->traversed = (eDFS)marker;
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pBB->inEdges.pop_back();
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if (not pBB->inEdges.empty())
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{
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pBB->edges[0].BBptr->inEdges.push_back((BB *)nullptr);
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}
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else
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{
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pBB->front().ll()->setFlags(NO_CODE);
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pBB->front().invalidate(); //pProc->Icode.SetLlInvalid(pBB->begin(), true);
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}
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pBB = pBB->edges[0].BBptr;
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}
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else
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{
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/* We are going around in circles */
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pBB->nodeType = NOWHERE_NODE;
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pBB->front().ll()->replaceSrc(LLOperand::CreateImm2(pBB->front().loc_ip));
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//pBB->front().ll()->src.immed.op = pBB->front().loc_ip;
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do {
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pBB = pBB->edges[0].BBptr;
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pBB->inEdges.pop_back(); // was --numInedges
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if (not pBB->inEdges.empty())
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{
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pBB->front().ll()->setFlags(NO_CODE);
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pBB->front().invalidate();
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// pProc->Icode.setFlags(pBB->start, NO_CODE);
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// pProc->Icode.SetLlInvalid(pBB->start, true);
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}
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} while (pBB->nodeType != NOWHERE_NODE);
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pBB->edges.clear();
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}
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}
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return pBB;
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}
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/*****************************************************************************
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* mergeFallThrough
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****************************************************************************/
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void BB::mergeFallThrough( CIcodeRec &Icode)
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{
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BB * pChild;
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if (nullptr==this)
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{
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printf("mergeFallThrough on empty BB!\n");
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}
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while (nodeType == FALL_NODE or nodeType == ONE_BRANCH)
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{
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pChild = edges[0].BBptr;
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/* Jump to next instruction can always be removed */
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if (nodeType == ONE_BRANCH)
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{
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assert(Parent==pChild->Parent);
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if(back().loc_ip>pChild->front().loc_ip) // back edege
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break;
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auto iter=std::find_if(this->end(),pChild->begin(),[](ICODE &c)
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{return not c.ll()->testFlags(NO_CODE);});
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if (iter != pChild->begin())
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break;
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back().ll()->setFlags(NO_CODE);
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back().invalidate();
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nodeType = FALL_NODE;
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//instructions.advance_end(-1); //TODO: causes creation of empty BB
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}
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/* If there's no other edges into child can merge */
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if (pChild->inEdges.size() != 1)
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break;
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nodeType = pChild->nodeType;
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instructions = boost::make_iterator_range(begin(),pChild->end());
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pChild->front().ll()->clrFlags(TARGET);
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edges.swap(pChild->edges);
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pChild->inEdges.clear();
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pChild->edges.clear();
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}
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traversed = DFS_MERGE;
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/* Process all out edges recursively */
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for (auto & elem : edges)
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{
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if (elem.BBptr->traversed != DFS_MERGE)
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elem.BBptr->mergeFallThrough(Icode);
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}
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}
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/*****************************************************************************
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* dfsNumbering - Numbers nodes during first and last visits and determine
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* in-edges
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****************************************************************************/
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void BB::dfsNumbering(std::vector<BB *> &dfsLast, int *first, int *last)
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{
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BB * pChild;
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traversed = DFS_NUM;
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dfsFirstNum = (*first)++;
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/* index is being used as an index to inEdges[]. */
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// for (i = 0; i < edges.size(); i++)
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for(auto edge : edges)
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{
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pChild = edge.BBptr;
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pChild->inEdges[pChild->index++] = this;
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/* Is this the last visit? */
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if (pChild->index == int(pChild->inEdges.size()))
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pChild->index = UN_INIT;
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if (pChild->traversed != DFS_NUM)
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pChild->dfsNumbering(dfsLast, first, last);
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}
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dfsLastNum = *last;
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dfsLast[(*last)--] = this;
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}
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