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re PR libstdc++/40852 ([parallel-mode] parallel sort run time increases ~10 fold when vector size gets over ~4*10^9)

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2009-10-28  Johannes Singler  <singler@kit.edu>

        PR libstdc++/40852
        * include/parallel/multiseq_selection.h
        (multiseq_partition, multiseq_selection):  Avoid intermediate
        values exceeding the integer type range for very large inputs.

From-SVN: r153648
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Johannes Singler 2009-10-28 10:04:03 +00:00 committed by Johannes Singler
parent 533d4b998d
commit 15e2a6c05e
2 changed files with 14 additions and 21 deletions
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7
libstdc++-v3/ChangeLog
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@ -1,3 +1,10 @@
2009-10-28 Johannes Singler <singler@kit.edu>
PR libstdc++/40852
* include/parallel/multiseq_selection.h
(multiseq_partition, multiseq_selection): Avoid intermediate
values exceeding the integer type range for very large inputs.
2009-10-26 Paolo Carlini <paolo.carlini@oracle.com>
* include/std/chrono (duration<>::duration(const duration<>&)): Fix

26
libstdc++-v3/include/parallel/multiseq_selection.h
View File

@ -187,9 +187,6 @@ namespace __gnu_parallel
// equality iff __nmax = 2^__k - 1.
__l = (1ULL << __r) - 1;
// From now on, including padding.
__N = __l * __m;
for (int __i = 0; __i < __m; __i++)
{
__a[__i] = 0;
@ -215,7 +212,7 @@ namespace __gnu_parallel
__sample.push_back(
std::make_pair(__S(__i)[0] /*__dummy element*/, __i));
_DifferenceType __localrank = __rank * __m / __N ;
_DifferenceType __localrank = __rank / __l;
int __j;
for (__j = 0;
@ -265,15 +262,11 @@ namespace __gnu_parallel
__b[__i] -= __n + 1;
}
_DifferenceType __leftsize = 0, __total = 0;
_DifferenceType __leftsize = 0;
for (int __i = 0; __i < __m; __i++)
{
__leftsize += __a[__i] / (__n + 1);
__total += __l / (__n + 1);
}
_DifferenceType __skew = static_cast<_DifferenceType>
(static_cast<uint64_t>(__total) * __rank / __N - __leftsize);
_DifferenceType __skew = __rank / (__n + 1) - __leftsize;
if (__skew > 0)
{
@ -442,9 +435,6 @@ namespace __gnu_parallel
// equality iff __nmax = 2^__k - 1
__l = pow2(__r) - 1;
// From now on, including padding.
__N = __l * __m;
for (int __i = 0; __i < __m; ++__i)
{
__a[__i] = 0;
@ -472,7 +462,7 @@ namespace __gnu_parallel
__sample.push_back(
std::make_pair(__S(__i)[0] /*__dummy element*/, __i));
_DifferenceType __localrank = __rank * __m / __N ;
_DifferenceType __localrank = __rank / __l;
int __j;
for (__j = 0;
@ -513,15 +503,11 @@ namespace __gnu_parallel
__b[__i] -= __n + 1;
}
_DifferenceType __leftsize = 0, __total = 0;
_DifferenceType __leftsize = 0;
for (int __i = 0; __i < __m; ++__i)
{
__leftsize += __a[__i] / (__n + 1);
__total += __l / (__n + 1);
}
_DifferenceType __skew = ((unsigned long long)__total * __rank / __N
- __leftsize);
_DifferenceType __skew = __rank / (__n + 1) - __leftsize;
if (__skew > 0)
{