diff options
Diffstat (limited to 'src/corelib/tools/qstring.cpp')
| -rw-r--r-- | src/corelib/tools/qstring.cpp | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/src/corelib/tools/qstring.cpp b/src/corelib/tools/qstring.cpp index f8f4bdc97f..ee45cfdc49 100644 --- a/src/corelib/tools/qstring.cpp +++ b/src/corelib/tools/qstring.cpp @@ -3580,6 +3580,28 @@ static inline __m128i mergeQuestionMarks(__m128i chunk) { const __m128i questionMark = _mm_set1_epi16('?'); +# ifdef __SSE4_2__ + // compare the unsigned shorts for the range 0x0100-0xFFFF + // note on the use of _mm_cmpestrm: + // The MSDN documentation online (http://technet.microsoft.com/en-us/library/bb514080.aspx) + // says for range search the following: + // For each character c in a, determine whether b0 <= c <= b1 or b2 <= c <= b3 + // + // However, all examples on the Internet, including from Intel + // (see http://software.intel.com/en-us/articles/xml-parsing-accelerator-with-intel-streaming-simd-extensions-4-intel-sse4/) + // put the range to be searched first + // + // Disassembly and instruction-level debugging with GCC and ICC show + // that they are doing the right thing. Inverting the arguments in the + // instruction does cause a bunch of test failures. + + const int mode = _SIDD_UWORD_OPS | _SIDD_CMP_RANGES | _SIDD_UNIT_MASK; + const __m128i rangeMatch = _mm_cvtsi32_si128(0xffff0100); + const __m128i offLimitMask = _mm_cmpestrm(rangeMatch, 2, chunk, 8, mode); + + // replace the non-Latin 1 characters in the chunk with question marks + chunk = _mm_blendv_epi8(chunk, questionMark, offLimitMask); +# else // SSE has no compare instruction for unsigned comparison. // The variables must be shiffted + 0x8000 to be compared const __m128i signedBitOffset = _mm_set1_epi16(0x8000); @@ -3603,6 +3625,7 @@ static inline __m128i mergeQuestionMarks(__m128i chunk) // merge offLimitQuestionMark and correctBytes to have the result chunk = _mm_or_si128(correctBytes, offLimitQuestionMark); # endif +# endif return chunk; } #endif |