282 lines
11 KiB
C++
282 lines
11 KiB
C++
#include "reverseanalyzer.h"
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#include "analyzer.h"
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#include "astutils.h"
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#include "forwardanalyzer.h"
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#include "settings.h"
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#include "symboldatabase.h"
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#include "token.h"
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#include "valueptr.h"
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#include <algorithm>
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#include <functional>
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struct ReverseTraversal {
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ReverseTraversal(const ValuePtr<Analyzer>& analyzer, const Settings* settings)
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: analyzer(analyzer), settings(settings)
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{}
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ValuePtr<Analyzer> analyzer;
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const Settings* settings;
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std::pair<bool, bool> evalCond(const Token* tok) {
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std::vector<int> result = analyzer->evaluate(tok);
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// TODO: We should convert to bool
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bool checkThen = std::any_of(result.begin(), result.end(), [](int x) {
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return x == 1;
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});
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bool checkElse = std::any_of(result.begin(), result.end(), [](int x) {
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return x == 0;
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});
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return std::make_pair(checkThen, checkElse);
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}
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bool update(Token* tok) {
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Analyzer::Action action = analyzer->analyze(tok, Analyzer::Direction::Reverse);
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if (!action.isNone())
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analyzer->update(tok, action, Analyzer::Direction::Reverse);
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if (action.isInconclusive() && !analyzer->lowerToInconclusive())
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return false;
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if (action.isInvalid())
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return false;
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return true;
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}
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bool updateRecursive(Token* start) {
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bool continueB = true;
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visitAstNodes(start, [&](Token* tok) {
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continueB &= update(tok);
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if (continueB)
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return ChildrenToVisit::op1_and_op2;
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else
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return ChildrenToVisit::done;
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});
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return continueB;
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}
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Analyzer::Action analyzeRecursive(const Token* start) {
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Analyzer::Action result = Analyzer::Action::None;
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visitAstNodes(start, [&](const Token* tok) {
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result |= analyzer->analyze(tok, Analyzer::Direction::Reverse);
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if (result.isModified())
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return ChildrenToVisit::done;
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return ChildrenToVisit::op1_and_op2;
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});
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return result;
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}
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Analyzer::Action analyzeRange(const Token* start, const Token* end) {
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Analyzer::Action result = Analyzer::Action::None;
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for (const Token* tok = start; tok && tok != end; tok = tok->next()) {
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Analyzer::Action action = analyzer->analyze(tok, Analyzer::Direction::Reverse);
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if (action.isModified())
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return action;
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result |= action;
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}
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return result;
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}
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Token* isDeadCode(Token* tok) {
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int opSide = 0;
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for (; tok && tok->astParent(); tok = tok->astParent()) {
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Token* parent = tok->astParent();
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if (tok != parent->astOperand2())
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continue;
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if (Token::simpleMatch(parent, ":")) {
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if (astIsLHS(tok))
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opSide = 1;
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else if (astIsRHS(tok))
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opSide = 2;
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else
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opSide = 0;
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}
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if (!Token::Match(parent, "%oror%|&&|?"))
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continue;
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Token* condTok = parent->astOperand1();
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if (!condTok)
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continue;
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bool checkThen, checkElse;
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std::tie(checkThen, checkElse) = evalCond(condTok);
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if (!checkThen && !checkElse) {
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Analyzer::Action action = analyzeRecursive(condTok);
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if (action.isRead() || action.isModified())
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return parent;
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}
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if (parent->str() == "?") {
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if (!checkElse && opSide == 1)
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return parent;
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if (!checkThen && opSide == 2)
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return parent;
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}
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if (!checkThen && parent->str() == "&&")
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return parent;
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if (!checkElse && parent->str() == "||")
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return parent;
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}
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return nullptr;
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}
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void traverse(Token* start) {
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for (Token* tok = start->previous(); tok; tok = tok->previous()) {
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if (tok == start || (tok->str() == "{" && (tok->scope()->type == Scope::ScopeType::eFunction ||
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tok->scope()->type == Scope::ScopeType::eLambda))) {
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break;
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}
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if (Token::Match(tok, "return|break|continue"))
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break;
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if (Token::Match(tok, "%name% :"))
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break;
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// Evaluate LHS of assignment before RHS
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if (Token* assignTok = assignExpr(tok)) {
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Token* assignTop = assignTok;
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bool continueB = true;
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while (assignTop->isAssignmentOp()) {
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if (!Token::Match(assignTop->astOperand1(), "%assign%")) {
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continueB &= updateRecursive(assignTop->astOperand1());
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}
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if (!assignTop->astParent())
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break;
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assignTop = assignTop->astParent();
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}
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// Is assignment in dead code
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if (Token* parent = isDeadCode(assignTok)) {
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tok = parent;
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continue;
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}
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// Simple assign
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if (assignTok->astParent() == assignTop || assignTok == assignTop) {
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Analyzer::Action rhsAction =
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analyzer->analyze(assignTok->astOperand2(), Analyzer::Direction::Reverse);
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Analyzer::Action lhsAction =
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analyzer->analyze(assignTok->astOperand1(), Analyzer::Direction::Reverse);
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// Assignment from
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if (rhsAction.isRead()) {
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const std::string info = "Assignment from '" + assignTok->expressionString() + "'";
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ValuePtr<Analyzer> a = analyzer->reanalyze(assignTok->astOperand1(), info);
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if (a) {
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valueFlowGenericForward(nextAfterAstRightmostLeaf(assignTok->astOperand2()),
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assignTok->astOperand2()->scope()->bodyEnd,
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a,
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settings);
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}
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// Assignment to
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} else if (lhsAction.matches() && !assignTok->astOperand2()->hasKnownValue()) {
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const std::string info = "Assignment to '" + assignTok->expressionString() + "'";
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ValuePtr<Analyzer> a = analyzer->reanalyze(assignTok->astOperand2(), info);
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if (a) {
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valueFlowGenericForward(nextAfterAstRightmostLeaf(assignTok->astOperand2()),
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assignTok->astOperand2()->scope()->bodyEnd,
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a,
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settings);
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valueFlowGenericReverse(assignTok->astOperand1()->previous(), a, settings);
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}
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}
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}
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if (!continueB)
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break;
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valueFlowGenericForward(assignTop->astOperand2(), analyzer, settings);
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tok = previousBeforeAstLeftmostLeaf(assignTop)->next();
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continue;
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}
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if (tok->str() == "}") {
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Token* condTok = getCondTokFromEnd(tok);
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if (!condTok)
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break;
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Analyzer::Action condAction = analyzeRecursive(condTok);
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const bool inLoop = condTok->astTop() && Token::Match(condTok->astTop()->previous(), "for|while (");
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// Evaluate condition of for and while loops first
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if (inLoop) {
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if (condAction.isModified())
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break;
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valueFlowGenericForward(condTok, analyzer, settings);
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}
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Token* thenEnd;
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const bool hasElse = Token::simpleMatch(tok->link()->tokAt(-2), "} else {");
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if (hasElse) {
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thenEnd = tok->link()->tokAt(-2);
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} else {
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thenEnd = tok;
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}
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Analyzer::Action thenAction = analyzeRange(thenEnd->link(), thenEnd);
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Analyzer::Action elseAction = Analyzer::Action::None;
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if (hasElse) {
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elseAction = analyzeRange(tok->link(), tok);
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}
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if (thenAction.isModified() && inLoop)
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break;
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else if (thenAction.isModified() && !elseAction.isModified())
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analyzer->assume(condTok, hasElse, condTok);
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else if (elseAction.isModified() && !thenAction.isModified())
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analyzer->assume(condTok, !hasElse, condTok);
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// Bail if one of the branches are read to avoid FPs due to over constraints
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else if (thenAction.isIdempotent() || elseAction.isIdempotent() || thenAction.isRead() ||
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elseAction.isRead())
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break;
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if (thenAction.isInvalid() || elseAction.isInvalid())
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break;
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if (!thenAction.isModified() && !elseAction.isModified())
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valueFlowGenericForward(condTok, analyzer, settings);
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else if (condAction.isRead())
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break;
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// If the condition modifies the variable then bail
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if (condAction.isModified())
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break;
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tok = condTok->astTop()->previous();
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continue;
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}
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if (tok->str() == "{") {
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if (tok->previous() &&
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(Token::simpleMatch(tok->previous(), "do") ||
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(tok->strAt(-1) == ")" && Token::Match(tok->linkAt(-1)->previous(), "for|while (")))) {
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Analyzer::Action action = analyzeRange(tok, tok->link());
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if (action.isModified())
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break;
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}
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if (Token::simpleMatch(tok->tokAt(-2), "} else {"))
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tok = tok->linkAt(-2);
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if (Token::simpleMatch(tok->previous(), ") {"))
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tok = tok->previous()->link();
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continue;
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}
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if (Token* next = isUnevaluated(tok)) {
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tok = next;
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continue;
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}
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if (Token* parent = isDeadCode(tok)) {
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tok = parent;
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continue;
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}
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if (!update(tok))
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break;
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}
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}
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static Token* assignExpr(Token* tok) {
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while (tok->astParent() && (astIsRHS(tok) || !tok->astParent()->isBinaryOp())) {
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if (tok->astParent()->isAssignmentOp())
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return tok->astParent();
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tok = tok->astParent();
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}
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return nullptr;
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}
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static Token* isUnevaluated(Token* tok) {
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if (Token::Match(tok, ")|>") && tok->link()) {
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Token* start = tok->link();
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if (Token::Match(start->previous(), "sizeof|decltype ("))
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return start->previous();
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if (Token::simpleMatch(start, "<"))
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return start;
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}
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return nullptr;
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}
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};
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void valueFlowGenericReverse(Token* start, const ValuePtr<Analyzer>& a, const Settings* settings)
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{
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ReverseTraversal rt{a, settings};
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rt.traverse(start);
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}
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