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Turn "label: goto label;" or "while(cond);" into assume #375

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Merged
kroening merged 1 commit into from
Apr 4, 2017
Merged

Turn "label: goto label;" or "while(cond);" into assume #375

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21 changes: 21 additions & 0 deletions src/goto-symex/symex_goto.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,27 @@ void goto_symext::symex_goto(statet &state)

if(!forward) // backwards?
{
// is it label: goto label; or while(cond); - popular in SV-COMP
if(goto_target==state.source.pc ||
(instruction.incoming_edges.size()==1 &&
*instruction.incoming_edges.begin()==goto_target))
{
// generate assume(false) or a suitable negation if this
// instruction is a conditional goto
exprt negated_cond;

if(new_guard.is_true())
negated_cond=false_exprt();
else
negated_cond=not_exprt(new_guard);

symex_assume(state, negated_cond);

// next instruction
state.source.pc++;
return;
}

unsigned &unwind=
frame.loop_iterations[goto_programt::loop_id(state.source.pc)].count;
unwind++;
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