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ValueFlow: avoid unnecessary ValuePtr and Value copies #4845

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d135695
ValueFlow: avoid unnecessary `ValuePtr` and `Value` copies [skip ci]
firewave Feb 28, 2023
8b49f67
infer [skip ci]
firewave Jan 26, 2025
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12 changes: 6 additions & 6 deletions lib/forwardanalyzer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -47,8 +47,8 @@
namespace {
struct ForwardTraversal {
enum class Progress : std::uint8_t { Continue, Break, Skip };
ForwardTraversal(const ValuePtr<Analyzer>& analyzer, const TokenList& tokenList, ErrorLogger& errorLogger, const Settings& settings)
: analyzer(analyzer), tokenList(tokenList), errorLogger(errorLogger), settings(settings)
ForwardTraversal(ValuePtr<Analyzer> analyzer, const TokenList& tokenList, ErrorLogger& errorLogger, const Settings& settings)
: analyzer(std::move(analyzer)), tokenList(tokenList), errorLogger(errorLogger), settings(settings)
{}
ValuePtr<Analyzer> analyzer;
const TokenList& tokenList;
Expand Down Expand Up @@ -900,24 +900,24 @@ namespace {
};
}

Analyzer::Result valueFlowGenericForward(Token* start, const Token* end, const ValuePtr<Analyzer>& a, const TokenList& tokenList, ErrorLogger& errorLogger, const Settings& settings)
Analyzer::Result valueFlowGenericForward(Token* start, const Token* end, ValuePtr<Analyzer> a, const TokenList& tokenList, ErrorLogger& errorLogger, const Settings& settings)
{
if (a->invalid())
return Analyzer::Result{Analyzer::Action::None, Analyzer::Terminate::Bail};
ForwardTraversal ft{a, tokenList, errorLogger, settings};
ForwardTraversal ft{std::move(a), tokenList, errorLogger, settings};
if (start)
ft.analyzer->updateState(start);
ft.updateRange(start, end);
return Analyzer::Result{ ft.actions, ft.terminate };
}

Analyzer::Result valueFlowGenericForward(Token* start, const ValuePtr<Analyzer>& a, const TokenList& tokenList, ErrorLogger& errorLogger, const Settings& settings)
Analyzer::Result valueFlowGenericForward(Token* start, ValuePtr<Analyzer> a, const TokenList& tokenList, ErrorLogger& errorLogger, const Settings& settings)
{
if (Settings::terminated())
throw TerminateException();
if (a->invalid())
return Analyzer::Result{Analyzer::Action::None, Analyzer::Terminate::Bail};
ForwardTraversal ft{a, tokenList, errorLogger, settings};
ForwardTraversal ft{std::move(a), tokenList, errorLogger, settings};
(void)ft.updateRecursive(start);
return Analyzer::Result{ ft.actions, ft.terminate };
}
7 changes: 3 additions & 4 deletions lib/forwardanalyzer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -20,20 +20,19 @@
#define forwardanalyzerH

#include "analyzer.h"
#include "valueptr.h"

class ErrorLogger;
class Settings;
class Token;
class TokenList;
template<class T> class ValuePtr;

Analyzer::Result valueFlowGenericForward(Token* start,
const Token* end,
const ValuePtr<Analyzer>& a,
const Token* end,ValuePtr<Analyzer> a,
const TokenList& tokenList,
ErrorLogger& errorLogger,
const Settings& settings);

Analyzer::Result valueFlowGenericForward(Token* start, const ValuePtr<Analyzer>& a, const TokenList& tokenList, ErrorLogger& errorLogger, const Settings& settings);
Analyzer::Result valueFlowGenericForward(Token* start, ValuePtr<Analyzer> a, const TokenList& tokenList, ErrorLogger& errorLogger, const Settings& settings);

#endif
20 changes: 10 additions & 10 deletions lib/reverseanalyzer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -37,8 +37,8 @@

namespace {
struct ReverseTraversal {
ReverseTraversal(const ValuePtr<Analyzer>& analyzer, const TokenList& tokenlist, ErrorLogger& errorLogger, const Settings& settings)
: analyzer(analyzer), tokenlist(tokenlist), errorLogger(errorLogger), settings(settings)
ReverseTraversal(ValuePtr<Analyzer> analyzer, const TokenList& tokenlist, ErrorLogger& errorLogger, const Settings& settings)
: analyzer(std::move(analyzer)), tokenlist(tokenlist), errorLogger(errorLogger), settings(settings)
{}
ValuePtr<Analyzer> analyzer;
const TokenList& tokenlist;
Expand Down Expand Up @@ -251,7 +251,7 @@ namespace {
if (a) {
valueFlowGenericForward(nextAfterAstRightmostLeaf(assignTok->astOperand2()),
assignTok->astOperand2()->scope()->bodyEnd,
a,
std::move(a),
tokenlist,
errorLogger,
settings);
Expand All @@ -265,11 +265,11 @@ namespace {
if (a) {
valueFlowGenericForward(nextAfterAstRightmostLeaf(assignTok->astOperand2()),
assignTok->astOperand2()->scope()->bodyEnd,
a,
std::move(a),
tokenlist,
errorLogger,
settings);
valueFlowGenericReverse(assignTok->astOperand1()->previous(), end, a, tokenlist, errorLogger, settings);
valueFlowGenericReverse(assignTok->astOperand1()->previous(), end, std::move(a), tokenlist, errorLogger, settings);
}
}
}
Expand Down Expand Up @@ -302,7 +302,7 @@ namespace {
break;
if (condAction.isModified())
break;
valueFlowGenericForward(condTok, analyzer, tokenlist, errorLogger, settings);
valueFlowGenericForward(condTok, std::move(analyzer), tokenlist, errorLogger, settings);
}
Token* thenEnd;
const bool hasElse = Token::simpleMatch(tok->link()->tokAt(-2), "} else {");
Expand Down Expand Up @@ -331,7 +331,7 @@ namespace {
break;

if (!thenAction.isModified() && !elseAction.isModified())
valueFlowGenericForward(condTok, analyzer, tokenlist, errorLogger, settings);
valueFlowGenericForward(condTok, std::move(analyzer), tokenlist, errorLogger, settings);
else if (condAction.isRead())
break;
// If the condition modifies the variable then bail
Expand All @@ -350,7 +350,7 @@ namespace {
}
Token* condTok = getCondTokFromEnd(tok->link());
if (condTok) {
Analyzer::Result r = valueFlowGenericForward(condTok, analyzer, tokenlist, errorLogger, settings);
Analyzer::Result r = valueFlowGenericForward(condTok, std::move(analyzer), tokenlist, errorLogger, settings);
if (r.action.isModified())
break;
}
Expand Down Expand Up @@ -403,10 +403,10 @@ namespace {
};
}

void valueFlowGenericReverse(Token* start, const Token* end, const ValuePtr<Analyzer>& a, const TokenList& tokenlist, ErrorLogger& errorLogger, const Settings& settings)
void valueFlowGenericReverse(Token* start, const Token* end, ValuePtr<Analyzer> a, const TokenList& tokenlist, ErrorLogger& errorLogger, const Settings& settings)
{
if (a->invalid())
return;
ReverseTraversal rt{a, tokenlist, errorLogger, settings};
ReverseTraversal rt{std::move(a), tokenlist, errorLogger, settings};
rt.traverse(start, end);
}
6 changes: 3 additions & 3 deletions lib/reverseanalyzer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -19,14 +19,14 @@
#ifndef reverseanalyzerH
#define reverseanalyzerH

#include "valueptr.h"

struct Analyzer;
class ErrorLogger;
class Settings;
class Token;
class TokenList;
template<class T>
class ValuePtr;

void valueFlowGenericReverse(Token* start, const Token* end, const ValuePtr<Analyzer>& a, const TokenList& tokenlist, ErrorLogger& errorLogger, const Settings& settings);
void valueFlowGenericReverse(Token* start, const Token* end, ValuePtr<Analyzer> a, const TokenList& tokenlist, ErrorLogger& errorLogger, const Settings& settings);

#endif
20 changes: 10 additions & 10 deletions lib/valueflow.cpp
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Expand Up @@ -3362,14 +3362,14 @@ static void valueFlowConditionExpressions(const TokenList& tokenlist,
condTok2,
makeConditionValue(1, condTok2, /*assume*/ true, !isBool, settings),
settings); // don't set '1' for non-boolean expressions
valueFlowGenericForward(startTok, startTok->link(), a1, tokenlist, errorLogger, settings);
valueFlowGenericForward(startTok, startTok->link(), std::move(a1), tokenlist, errorLogger, settings);
}

auto a2 = makeOppositeExpressionAnalyzer(true,
condTok2,
makeConditionValue(0, condTok2, true, false, settings),
settings);
valueFlowGenericForward(startTok, startTok->link(), a2, tokenlist, errorLogger, settings);
valueFlowGenericForward(startTok, startTok->link(), std::move(a2), tokenlist, errorLogger, settings);
}
}

Expand All @@ -3384,15 +3384,15 @@ static void valueFlowConditionExpressions(const TokenList& tokenlist,
auto a1 = makeSameExpressionAnalyzer(condTok2,
makeConditionValue(0, condTok2, false, false, settings),
settings);
valueFlowGenericForward(startTok, startTok->link(), a1, tokenlist, errorLogger, settings);
valueFlowGenericForward(startTok, startTok->link(), std::move(a1), tokenlist, errorLogger, settings);

if (is1) {
auto a2 =
makeOppositeExpressionAnalyzer(true,
condTok2,
makeConditionValue(isOp, condTok2, false, false, settings),
settings);
valueFlowGenericForward(startTok, startTok->link(), a2, tokenlist, errorLogger, settings);
valueFlowGenericForward(startTok, startTok->link(), std::move(a2), tokenlist, errorLogger, settings);
}
}
}
Expand All @@ -3410,7 +3410,7 @@ static void valueFlowConditionExpressions(const TokenList& tokenlist,
auto a1 = makeSameExpressionAnalyzer(condTok2,
makeConditionValue(0, condTok2, false, false, settings),
settings);
valueFlowGenericForward(startTok->link()->next(), scope2->bodyEnd, a1, tokenlist, errorLogger, settings);
valueFlowGenericForward(startTok->link()->next(), scope2->bodyEnd, std::move(a1), tokenlist, errorLogger, settings);

if (is1) {
auto a2 = makeOppositeExpressionAnalyzer(true,
Expand All @@ -3419,7 +3419,7 @@ static void valueFlowConditionExpressions(const TokenList& tokenlist,
settings);
valueFlowGenericForward(startTok->link()->next(),
scope2->bodyEnd,
a2,
std::move(a2),
tokenlist,
errorLogger,
settings);
Expand Down Expand Up @@ -3711,11 +3711,11 @@ static void valueFlowSymbolicInfer(const SymbolDatabase& symboldatabase, const S
std::vector<ValueFlow::Value> values;
{
SymbolicInferModel leftModel{tok->astOperand1()};
values = infer(leftModel, tok->str(), 0, tok->astOperand2()->values());
values = infer(std::move(leftModel), tok->str(), 0, tok->astOperand2()->values());
}
if (values.empty()) {
SymbolicInferModel rightModel{tok->astOperand2()};
values = infer(rightModel, tok->str(), tok->astOperand1()->values(), 0);
values = infer(std::move(rightModel), tok->str(), tok->astOperand1()->values(), 0);
}
for (ValueFlow::Value& value : values) {
setTokenValue(tok, std::move(value), settings);
Expand Down Expand Up @@ -5404,7 +5404,7 @@ static void valueFlowInjectParameter(const TokenList& tokenlist,
auto a = makeMultiValueFlowAnalyzer(arg, settings);
valueFlowGenericForward(const_cast<Token*>(functionScope->bodyStart),
functionScope->bodyEnd,
a,
std::move(a),
tokenlist,
errorLogger,
settings);
Expand Down Expand Up @@ -5932,7 +5932,7 @@ static void valueFlowUninit(TokenList& tokenlist, ErrorLogger& errorLogger, cons
}
auto partialReadsAnalyzer = std::make_shared<PartialReadContainer>();
auto analyzer = makeMemberExpressionAnalyzer(memVar.nameToken()->str(), tok, uninitValue, partialReadsAnalyzer, settings);
valueFlowGenericForward(start, tok->scope()->bodyEnd, analyzer, tokenlist, errorLogger, settings);
valueFlowGenericForward(start, tok->scope()->bodyEnd, std::move(analyzer), tokenlist, errorLogger, settings);

for (auto&& p : *partialReadsAnalyzer) {
Token* tok2 = p.first;
Expand Down
7 changes: 7 additions & 0 deletions lib/valueptr.h
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Expand Up @@ -32,6 +32,9 @@ class CPPCHECKLIB ValuePtr {
static T* apply(const T* x) {
return new U(*static_cast<const U*>(x));
}
static T* move(T* x) {
return new U(std::move(*static_cast<const U*>(x)));
}
};

public:
Expand All @@ -47,6 +50,10 @@ class CPPCHECKLIB ValuePtr {
ValuePtr(const U& value) : mPtr(cloner<U>::apply(&value)), mClone(&cloner<U>::apply)
{}

template<class U>
ValuePtr(U&& value) : mPtr(cloner<U>::move(&value)), mClone(&cloner<U>::apply)
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We should only move when its passed as an rvalue references, not for lvalue references. Also, this might be called for the copy constructor and move constructor, so it needs to be constrained.

    template<class U, REQUIRES("Must be rvalue", !is_lvalue_reference<U>), REQUIRES("Must not be ValuePtr", !std::is_base_of<ValuePtr, U>)>
    ValuePtr(U&& value) : mPtr(cloner<U>::move(&value)), mClone(&cloner<U>::apply)
    {}

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Thanks for the input. I need to check again what the actual impact of this was - probably not within the next few days.

I just pushed it again to clean up my local branches.

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One case where I came across this was makeAnalyzer. You would expect that it is being moved on return but it is copied so we essentially create it twice every time - with the destruction on top.

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This fails to compile when we generate copies. I wonder if this even needs to be copyable at all.

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The current code crashes. Will have a proper look in the next few days.

{}

ValuePtr(const ValuePtr& rhs) : mPtr(nullptr), mClone(rhs.mClone) {
if (rhs) {
mPtr.reset(mClone(rhs.get()));
Expand Down