diff options
| author | Thiago Macieira <thiago.macieira@intel.com> | 2021-12-16 15:26:57 -0300 |
|---|---|---|
| committer | Thiago Macieira <thiago.macieira@intel.com> | 2021-12-18 18:09:19 -0300 |
| commit | 1a9e7a3aad58426d6162e3ab4aad21b48d004e25 (patch) | |
| tree | 1c778d540b8f26947ff57073248dfb4d7138c34a /src/corelib/text | |
| parent | 449f6d5f6116af98df67d372e1a038062fac4b9b (diff) | |
QString: don't let the compiler emit unnecessary looping
When AVX2 was enabled, we know we don't need to loop in qt_is_ascii()
(QtPrivate::isAscii(QLatin1String)).
Pick-to: 6.3 6.2
Change-Id: Ib42b3adc93bf4d43bd55fffd16c14f8f95ae8678
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Diffstat (limited to 'src/corelib/text')
| -rw-r--r-- | src/corelib/text/qstring.cpp | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp index 940810e8af..02b7895645 100644 --- a/src/corelib/text/qstring.cpp +++ b/src/corelib/text/qstring.cpp @@ -474,6 +474,7 @@ bool qt_is_ascii(const char *&ptr, const char *end) noexcept { #if defined(__SSE2__) // Testing for the high bit can be done efficiently with just PMOVMSKB + bool loops = true; # if defined(__AVX2__) while (ptr + 32 <= end) { __m256i data = _mm256_loadu_si256(reinterpret_cast<const __m256i *>(ptr)); @@ -485,7 +486,9 @@ bool qt_is_ascii(const char *&ptr, const char *end) noexcept } ptr += 32; } + loops = false; # endif + while (ptr + 16 <= end) { __m128i data = _mm_loadu_si128(reinterpret_cast<const __m128i *>(ptr)); quint32 mask = _mm_movemask_epi8(data); @@ -495,6 +498,9 @@ bool qt_is_ascii(const char *&ptr, const char *end) noexcept return false; } ptr += 16; + + if (!loops) + break; } if (ptr + 8 <= end) { __m128i data = _mm_loadl_epi64(reinterpret_cast<const __m128i *>(ptr)); |