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QString: add Q_NEVER_INLINE for ucstricmp() 

Case-insensitive comparisons are not common, but both GCC and Clang
inlined the ucstricmp() functions into QtPrivate::compareStrings(), with
the side-effect that a lot of unnecessary setup code saving CPU
registers was executed in the prologue of those functions.

After this, Clang 13 emits both compareString() functions without any
push/pop to save registers on x86-64; GCC 11 still emits a few, but
fewer than before (it's emitting some unnecessary overhead for the
loops).

Change-Id: I0e5f6bec596a4a78bd3bfffd16c8fc2c0be9165f
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
bb10
Thiago Macieira 2022-01-10 10:28:50 -08:00
parent ba0864ae52
commit 2c2e2a67c3
1 changed files with 3 additions and 3 deletions
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6
src/corelib/text/qstring.cpp
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@ -1006,7 +1006,7 @@ void qt_to_latin1_unchecked(uchar *dst, const char16_t *src, qsizetype length)
}
// Unicode case-insensitive comparison
static int ucstricmp(const QChar *a, const QChar *ae, const QChar *b, const QChar *be)
Q_NEVER_INLINE static int ucstricmp(const QChar *a, const QChar *ae, const QChar *b, const QChar *be)
{
if (a == b)
return (ae - be);
@ -1036,7 +1036,7 @@ static int ucstricmp(const QChar *a, const QChar *ae, const QChar *b, const QCha
}
// Case-insensitive comparison between a Unicode string and a QLatin1String
static int ucstricmp(const QChar *a, const QChar *ae, const char *b, const char *be)
Q_NEVER_INLINE static int ucstricmp(const QChar *a, const QChar *ae, const char *b, const char *be)
{
auto e = ae;
if (be - b < ae - a)
@ -1058,7 +1058,7 @@ static int ucstricmp(const QChar *a, const QChar *ae, const char *b, const char
}
// Case-insensitive comparison between a Unicode string and a UTF-8 string
static int ucstricmp8(const char *utf8, const char *utf8end, const QChar *utf16, const QChar *utf16end)
Q_NEVER_INLINE static int ucstricmp8(const char *utf8, const char *utf8end, const QChar *utf16, const QChar *utf16end)
{
auto src1 = reinterpret_cast<const uchar *>(utf8);
auto end1 = reinterpret_cast<const uchar *>(utf8end);