Small speedup of construction of uninitialized QByteArrays

Directly construct uninitialized QByteArrays of required size
instead of default-constructing one and resizing it afterwards.

Reviewed-by: mariusSO

8 files changed, 18 insertions, 36 deletions

diff --git a/src/corelib/codecs/qfontlaocodec.cpp b/src/corelib/codecs/qfontlaocodec.cpp
index 85017e0..6dd87de 100644
--- a/src/corelib/codecs/qfontlaocodec.cpp
+++ b/src/corelib/codecs/qfontlaocodec.cpp
@@ -97,8 +97,7 @@ QString QFontLaoCodec::convertToUnicode(const char *, int, ConverterState *) con
 
 QByteArray QFontLaoCodec::convertFromUnicode(const QChar *uc, int len, ConverterState *) const
 {
-    QByteArray rstring;
-    rstring.resize(len);
+    QByteArray rstring(len, Qt::Uninitialized);
     uchar *rdata = (uchar *) rstring.data();
     const QChar *sdata = uc;
     int i = 0;
diff --git a/src/corelib/codecs/qiconvcodec.cpp b/src/corelib/codecs/qiconvcodec.cpp
index 6b9c77b..1bf76ea 100644
--- a/src/corelib/codecs/qiconvcodec.cpp
+++ b/src/corelib/codecs/qiconvcodec.cpp
@@ -225,11 +225,10 @@ QString QIconvCodec::convertToUnicode(const char* chars, int len, ConverterState
     char *inBytes = const_cast<char *>(chars);
 #endif
 
-    QByteArray in;
     if (remainingCount) {
         // we have to prepend the remaining bytes from the previous conversion
         inBytesLeft += remainingCount;
-        in.resize(inBytesLeft);
+        QByteArray in(inBytesLeft, Qt::Uninitialized);
         inBytes = in.data();
 
         memcpy(in.data(), remainingBuffer, remainingCount);
@@ -238,9 +237,8 @@ QString QIconvCodec::convertToUnicode(const char* chars, int len, ConverterState
         remainingCount = 0;
     }
 
-    QByteArray ba;
     size_t outBytesLeft = len * 2 + 2;
-    ba.resize(outBytesLeft);
+    QByteArray ba(outBytesLeft, Qt::Uninitialized);
     char *outBytes = ba.data();
     do {
         size_t ret = iconv(state->cd, &inBytes, &inBytesLeft, &outBytes, &outBytesLeft);
@@ -328,8 +326,7 @@ QByteArray QIconvCodec::convertFromUnicode(const QChar *uc, int len, ConverterSt
         state = new IconvState(QIconvCodec::createIconv_t(0, UTF16));
         if (state->cd != reinterpret_cast<iconv_t>(-1)) {
             size_t outBytesLeft = len + 3; // +3 for the BOM
-            QByteArray ba;
-            ba.resize(outBytesLeft);
+            QByteArray ba(outBytesLeft, Qt::Uninitialized);
             outBytes = ba.data();
 
 #if !defined(NO_BOM)
@@ -358,18 +355,16 @@ QByteArray QIconvCodec::convertFromUnicode(const QChar *uc, int len, ConverterSt
     }
  
     size_t outBytesLeft = len;
-    QByteArray ba;
-    ba.resize(outBytesLeft);
+    QByteArray ba(outBytesLeft, Qt::Uninitialized);
     outBytes = ba.data();
 
     // now feed iconv() the real data
     inBytes = const_cast<char *>(reinterpret_cast<const char *>(uc));
     inBytesLeft = len * sizeof(QChar);
 
-    QByteArray in;
     if (convState && convState->remainingChars) {
         // we have one surrogate char to be prepended
-        in.resize(sizeof(QChar) + len);
+        QByteArray in(sizeof(QChar) + len, Qt::Uninitialized);
         inBytes = in.data();
 
         QChar remaining = convState->state_data[0];
diff --git a/src/corelib/codecs/qisciicodec.cpp b/src/corelib/codecs/qisciicodec.cpp
index a33fd0d..c054313 100644
--- a/src/corelib/codecs/qisciicodec.cpp
+++ b/src/corelib/codecs/qisciicodec.cpp
@@ -187,8 +187,7 @@ QByteArray QIsciiCodec::convertFromUnicode(const QChar *uc, int len, ConverterSt
     }
     int invalid = 0;
 
-    QByteArray result;
-    result.resize(2*len); //worst case
+    QByteArray result(2 * len, Qt::Uninitialized); //worst case
 
     uchar *ch = reinterpret_cast<uchar *>(result.data());
 
@@ -250,8 +249,7 @@ QString QIsciiCodec::convertToUnicode(const char* chars, int len, ConverterState
         halant = state->state_data[0];
     }
 
-    QString result;
-    result.resize(len);
+    QString result(len, Qt::Uninitialized);
     QChar *uc = result.data();
 
     const int base = codecs[idx].base;
diff --git a/src/corelib/codecs/qlatincodec.cpp b/src/corelib/codecs/qlatincodec.cpp
index 176ae97..9113555 100644
--- a/src/corelib/codecs/qlatincodec.cpp
+++ b/src/corelib/codecs/qlatincodec.cpp
@@ -62,8 +62,7 @@ QString QLatin1Codec::convertToUnicode(const char *chars, int len, ConverterStat
 QByteArray QLatin1Codec::convertFromUnicode(const QChar *ch, int len, ConverterState *state) const
 {
     const char replacement = (state && state->flags & ConvertInvalidToNull) ? 0 : '?';
-    QByteArray r;
-    r.resize(len);
+    QByteArray r(len, Qt::Uninitialized);
     char *d = r.data();
     int invalid = 0;
     for (int i = 0; i < len; ++i) {
@@ -151,8 +150,7 @@ QString QLatin15Codec::convertToUnicode(const char* chars, int len, ConverterSta
 QByteArray QLatin15Codec::convertFromUnicode(const QChar *in, int length, ConverterState *state) const
 {
     const char replacement = (state && state->flags & ConvertInvalidToNull) ? 0 : '?';
-    QByteArray r;
-    r.resize(length);
+    QByteArray r(length, Qt::Uninitialized);
     char *d = r.data();
     int invalid = 0;
     for (int i = 0; i < length; ++i) {
diff --git a/src/corelib/codecs/qsimplecodec.cpp b/src/corelib/codecs/qsimplecodec.cpp
index aa7521d..0d14f67 100644
--- a/src/corelib/codecs/qsimplecodec.cpp
+++ b/src/corelib/codecs/qsimplecodec.cpp
@@ -676,8 +676,7 @@ QByteArray QSimpleTextCodec::convertFromUnicode(const QChar *in, int length, Con
             delete tmp;
     }
 
-    QByteArray r;
-    r.resize(length);
+    QByteArray r(length, Qt::Uninitialized);
     int i = length;
     int u;
     const QChar* ucp = in;
diff --git a/src/corelib/codecs/qtsciicodec.cpp b/src/corelib/codecs/qtsciicodec.cpp
index 7f660bf..c24d32d 100644
--- a/src/corelib/codecs/qtsciicodec.cpp
+++ b/src/corelib/codecs/qtsciicodec.cpp
@@ -82,8 +82,7 @@ QByteArray QTsciiCodec::convertFromUnicode(const QChar *uc, int len, ConverterSt
     }
     int invalid = 0;
 
-    QByteArray rstr;
-    rstr.resize(len);
+    QByteArray rstr(len, Qt::Uninitialized);
     uchar* cursor = (uchar*)rstr.data();
     for (int i = 0; i < len; i++) {
         QChar ch = uc[i];
diff --git a/src/corelib/codecs/qutfcodec.cpp b/src/corelib/codecs/qutfcodec.cpp
index fe826ad..abae6f7 100644
--- a/src/corelib/codecs/qutfcodec.cpp
+++ b/src/corelib/codecs/qutfcodec.cpp
@@ -471,8 +471,7 @@ QByteArray QUtf32Codec::convertFromUnicode(const QChar *uc, int len, ConverterSt
         endian = (QSysInfo::ByteOrder == QSysInfo::BigEndian) ? BE : LE;
     }
 
-    QByteArray d;
-    d.resize(length);
+    QByteArray d(length, Qt::Uninitialized);
     char *data = d.data();
     if (!state || !(state->flags & IgnoreHeader)) {
         if (endian == BE) {
diff --git a/src/corelib/tools/qbytearray.cpp b/src/corelib/tools/qbytearray.cpp
index 142dfeb..2d4010d 100644
--- a/src/corelib/tools/qbytearray.cpp
+++ b/src/corelib/tools/qbytearray.cpp
@@ -2992,8 +2992,7 @@ QByteArray QByteArray::simplified() const
 {
     if (d->size == 0)
         return *this;
-    QByteArray result;
-    result.resize(d->size);
+    QByteArray result(d->size, Qt::Uninitialized);
     const char *from = d->data;
     const char *fromend = from + d->size;
     int outc=0;
@@ -3444,8 +3443,7 @@ QByteArray QByteArray::toBase64() const
     const char padchar = '=';
     int padlen = 0;
 
-    QByteArray tmp;
-    tmp.resize(((d->size * 4) / 3) + 3);
+    QByteArray tmp((d->size * 4) / 3 + 3, Qt::Uninitialized);
 
     int i = 0;
     char *out = tmp.data();
@@ -3783,8 +3781,7 @@ QByteArray QByteArray::fromBase64(const QByteArray &base64)
 {
     unsigned int buf = 0;
     int nbits = 0;
-    QByteArray tmp;
-    tmp.resize((base64.size() * 3) / 4);
+    QByteArray tmp((base64.size() * 3) / 4, Qt::Uninitialized);
 
     int offset = 0;
     for (int i = 0; i < base64.size(); ++i) {
@@ -3832,8 +3829,7 @@ QByteArray QByteArray::fromBase64(const QByteArray &base64)
 */
 QByteArray QByteArray::fromHex(const QByteArray &hexEncoded)
 {
-    QByteArray res;
-    res.resize((hexEncoded.size() + 1)/ 2);
+    QByteArray res((hexEncoded.size() + 1)/ 2, Qt::Uninitialized);
     uchar *result = (uchar *)res.data() + res.size();
 
     bool odd_digit = true;
@@ -3870,8 +3866,7 @@ QByteArray QByteArray::fromHex(const QByteArray &hexEncoded)
 */
 QByteArray QByteArray::toHex() const
 {
-    QByteArray hex;
-    hex.resize(d->size*2);
+    QByteArray hex(d->size * 2, Qt::Uninitialized);
     char *hexData = hex.data();
     const uchar *data = (const uchar *)d->data;
     for (int i = 0; i < d->size; ++i) {