On Mon, Sep 15, 2014 at 08:10:18PM -0400, Chris Metcalf wrote:
strnlen() is based on the existing tile strlen() with length
checking added. It speeds up by up to 5x, but on average across
the benchtest corpus by around 35%. No regressions are seen.
strstr() does 8-byte aligned loads and compares using a 2-byte
filter on the first two bytes of the needle and then testing
the remaining bytes in needle using memcmp(). It speeds up
about 5x in the best case (for "found" needles), about 2x looking
at benchtest as a whole, with some slowdowns as much as 45%.
on a few cases (including the "fail" case for 128KB search).
strcasestr() is based on strstr() but uses a SIMD tolower
routine to convert 8-bytes to lower case in 5 instructions.
It also uses a 2-byte filter and then strncasecmp() for the
remaining bytes. strncasecmp() is not optimized for SIMD, so
there is futher room for improvement. However, it is still up
to 16x faster for "found" needles, averaging 2x faster on the
whole corpus of benchtests. It does slow down by up to 35%
on a few cases, similarly to strstr().
---
sysdeps/tile/tilegx/strcasestr.c | 55 ++++++++
sysdeps/tile/tilegx/string-endian.h | 22 ++-
sysdeps/tile/tilegx/strnlen.c | 58 ++++++++
sysdeps/tile/tilegx/strstr.c | 271 ++++++++++++++++++++++++++++++++++++
4 files changed, 401 insertions(+), 5 deletions(-)
create mode 100644 sysdeps/tile/tilegx/strcasestr.c
create mode 100644 sysdeps/tile/tilegx/strnlen.c
create mode 100644 sysdeps/tile/tilegx/strstr.c
I didn't notice this thread before so didn't comment.
First there is bug in strcasestr, as you couldn't always use vector ascii
conversion, you would need to check that with:
__locale_t loc = _NL_CURRENT_LOCALE;
struct __locale_data *ctype = loc->__locales[LC_CTYPE];
int nonascii = ctype->values[_NL_ITEM_INDEX(_NL_CTYPE_NONASCII_CASE)].word;
But you don't need vector conversion there. Just do comparisons with
tolower(x) and toupper(x). I just realized that my strcasestr was
overcomplicated as I assumed that many characters could have same
tolower(x).
Best course of action would be wait until I merge my strstr skeleton and
you map instrincs. Then we could delete these. You use same idea,
skeleton adds many technical speedups like that there was bottleneck in
checking last character alone instead of as digraph which is solved by
merging last two loads to get full word with characters.