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CPlusPlus: Do not needlessly allocate space for a vector

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It's not a rare ocurrence that the vector will stay empty, so let's not
reserve memory unconditionally.

Task-number: QTCREATORBUG-26841
Change-Id: I842620cfa1fd0571691829401e4ccc162ab61d7b
Reviewed-by: hjk <hjk@qt.io>
This commit is contained in:
Christian Kandeler
2022-01-12 13:51:52 +01:00
parent 9056d708fa
commit 0326bbdc81
1 changed files with 13 additions and 8 deletions
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21
src/libs/cplusplus/pp-engine.cpp
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@@ -1147,7 +1147,12 @@ bool Preprocessor::handleFunctionLikeMacro(const Macro *macro,
unsigned baseLine)
{
QVector<PPToken> expanded;
expanded.reserve(MAX_TOKEN_EXPANSION_COUNT);
const auto addToken = [&expanded](PPToken &&tok) {
if (expanded.isEmpty())
expanded.reserve(50);
expanded.push_back(std::move(tok));
};
const size_t bodySize = body.size();
for (size_t i = 0; i < bodySize && expanded.size() < MAX_TOKEN_EXPANSION_COUNT;
@@ -1189,10 +1194,10 @@ bool Preprocessor::handleFunctionLikeMacro(const Macro *macro,
enclosedString.replace("\\", "\\\\");
enclosedString.replace("\"", "\\\"");
expanded.push_back(generateToken(T_STRING_LITERAL,
enclosedString.constData(),
enclosedString.size(),
lineno, true));
addToken(generateToken(T_STRING_LITERAL,
enclosedString.constData(),
enclosedString.size(),
lineno, true));
} else {
for (int k = 0; k < actualsSize; ++k) {
// Mark the actual tokens (which are the replaced version of the
@@ -1202,9 +1207,9 @@ bool Preprocessor::handleFunctionLikeMacro(const Macro *macro,
actual.f.expanded = true;
if (k == 0)
actual.f.whitespace = bodyTk.whitespace();
expanded += actual;
if (k == actualsSize - 1)
lineno = actual.lineno;
addToken(std::move(actual));
}
}
@@ -1219,12 +1224,12 @@ bool Preprocessor::handleFunctionLikeMacro(const Macro *macro,
// No formal macro parameter for this identifier in the body.
bodyTk.f.generated = true;
bodyTk.lineno = baseLine;
expanded.push_back(std::move(bodyTk));
addToken(std::move(bodyTk));
}
} else if (bodyTk.isNot(T_POUND) && bodyTk.isNot(T_POUND_POUND)) {
bodyTk.f.generated = true;
bodyTk.lineno = baseLine;
expanded.push_back(std::move(bodyTk));
addToken(std::move(bodyTk));
}
if (i > 1 && body[int(i) - 1].is(T_POUND_POUND)) {