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QString: optimize number() and setNum()

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Previously, number() was implemented in terms of setNum().

That makes no sense whatsoever. It creates a temporary
value which requires the function to have an exception
table and an unwinding trampoline. It also introduces
a default constructor (in number()) and a copy assignment
(in setNum()), which breaks the chain of RVOs originating
in the QLocaleData functions.

Instead, implement setNum() in terms of number().

This makes setNum() such a premature pessimisation that
it's probably best to deprecate it in the near future.
There are not many users of it in qtbase left, and it
just pollutes the QString interface.

Effects on Linux GCC 4.9 stripped release builds:
 text   -708B
 data    +-0B
 relocs  +-0

Change-Id: I015c9ddb1ba9c98c2c55e38e54ef7894954ac4ca
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
This commit is contained in:
Marc Mutz 2015-02-01 01:59:54 +01:00
parent 10d3f603f0
commit 08ab00e749
1 changed files with 46 additions and 63 deletions
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109
src/corelib/tools/qstring.cpp
View File

@ -6398,14 +6398,7 @@ float QString::toFloat(bool *ok) const
*/
QString &QString::setNum(qlonglong n, int base)
{
#if defined(QT_CHECK_RANGE)
if (base < 2 || base > 36) {
qWarning("QString::setNum: Invalid base (%d)", base);
base = 10;
}
#endif
*this = QLocaleData::c()->longLongToString(n, -1, base);
return *this;
return *this = number(n, base);
}
/*!
@ -6413,14 +6406,7 @@ QString &QString::setNum(qlonglong n, int base)
*/
QString &QString::setNum(qulonglong n, int base)
{
#if defined(QT_CHECK_RANGE)
if (base < 2 || base > 36) {
qWarning("QString::setNum: Invalid base (%d)", base);
base = 10;
}
#endif
*this = QLocaleData::c()->unsLongLongToString(n, -1, base);
return *this;
return *this = number(n, base);
}
/*! \fn QString &QString::setNum(short n, int base)
@ -6451,32 +6437,7 @@ QString &QString::setNum(qulonglong n, int base)
QString &QString::setNum(double n, char f, int prec)
{
QLocaleData::DoubleForm form = QLocaleData::DFDecimal;
uint flags = 0;
if (qIsUpper(f))
flags = QLocaleData::CapitalEorX;
f = qToLower(f);
switch (f) {
case 'f':
form = QLocaleData::DFDecimal;
break;
case 'e':
form = QLocaleData::DFExponent;
break;
case 'g':
form = QLocaleData::DFSignificantDigits;
break;
default:
#if defined(QT_CHECK_RANGE)
qWarning("QString::setNum: Invalid format char '%c'", f);
#endif
break;
}
*this = QLocaleData::c()->doubleToString(n, prec, form, -1, flags);
return *this;
return *this = number(n, f, prec);
}
/*!
@ -6514,9 +6475,7 @@ QString &QString::setNum(double n, char f, int prec)
QString QString::number(long n, int base)
{
QString s;
s.setNum(n, base);
return s;
return number(qlonglong(n), base);
}
/*!
@ -6526,9 +6485,7 @@ QString QString::number(long n, int base)
*/
QString QString::number(ulong n, int base)
{
QString s;
s.setNum(n, base);
return s;
return number(qulonglong(n), base);
}
/*!
@ -6536,9 +6493,7 @@ QString QString::number(ulong n, int base)
*/
QString QString::number(int n, int base)
{
QString s;
s.setNum(n, base);
return s;
return number(qlonglong(n), base);
}
/*!
@ -6546,9 +6501,7 @@ QString QString::number(int n, int base)
*/
QString QString::number(uint n, int base)
{
QString s;
s.setNum(n, base);
return s;
return number(qulonglong(n), base);
}
/*!
@ -6556,9 +6509,13 @@ QString QString::number(uint n, int base)
*/
QString QString::number(qlonglong n, int base)
{
QString s;
s.setNum(n, base);
return s;
#if defined(QT_CHECK_RANGE)
if (base < 2 || base > 36) {
qWarning("QString::setNum: Invalid base (%d)", base);
base = 10;
}
#endif
return QLocaleData::c()->longLongToString(n, -1, base);
}
/*!
@ -6566,9 +6523,13 @@ QString QString::number(qlonglong n, int base)
*/
QString QString::number(qulonglong n, int base)
{
QString s;
s.setNum(n, base);
return s;
#if defined(QT_CHECK_RANGE)
if (base < 2 || base > 36) {
qWarning("QString::setNum: Invalid base (%d)", base);
base = 10;
}
#endif
return QLocaleData::c()->unsLongLongToString(n, -1, base);
}
@ -6586,9 +6547,31 @@ QString QString::number(qulonglong n, int base)
*/
QString QString::number(double n, char f, int prec)
{
QString s;
s.setNum(n, f, prec);
return s;
QLocaleData::DoubleForm form = QLocaleData::DFDecimal;
uint flags = 0;
if (qIsUpper(f))
flags = QLocaleData::CapitalEorX;
f = qToLower(f);
switch (f) {
case 'f':
form = QLocaleData::DFDecimal;
break;
case 'e':
form = QLocaleData::DFExponent;
break;
case 'g':
form = QLocaleData::DFSignificantDigits;
break;
default:
#if defined(QT_CHECK_RANGE)
qWarning("QString::setNum: Invalid format char '%c'", f);
#endif
break;
}
return QLocaleData::c()->doubleToString(n, prec, form, -1, flags);
}
namespace {