c++ - Wrapper for __m256 producing segmentation fault with constructor -

-

i have union looks this

 union barevec8f {      __m256 m256; //avx 8x float vector     float floats[8];     int ints[8];     inline barevec8f(){     }     inline barevec8f(__m256 vec){         this->m256 = vec;     }     inline barevec8f &operator=(__m256 m256) {         this->m256 = m256;         return *this;     }      inline operator __m256 &() {         return m256;     } }

the __m256 needs aligned on 32 byte boundary used sse functions, , should automatically, within union.

and when this

barevec8f test = _mm256_set1_ps(1.0f);

i segmentation fault. code should work because of constructor made. however, when this

barevec8f test; test.m256 = _mm256_set1_ps(8.f);

i not segmentation fault.

so because works fine union aligned properly, there's segmentation fault being caused constructor seems

i'm using gcc 64bit windows compiler

---------------------------------edit matt managed produce simplest example of error seems happening here.

#include <immintrin.h>  void foo(__m256 x) {}  int main() {     __m256 r = _mm256_set1_ps(0.0f);     foo(r); }

i'm compiling -std=c++11 -mavx

this bug in g++ windows. not perform 32-byte stack alignment when should. bug 49001 bug 54412

on this thread made python script process assembly output g++ fix problem, 1 option.

otherwise, avoid in union make functions take __m256 value, take reference instead. shouldn't have performance penalty unless optimization low/off.

in case unaware - union aliasing causes undefined behaviour in c++, it's not permitted write m256 , read floats or ints example. perhaps there different solution problem.


Comments

Post a Comment

Popular posts from this blog

python - How to create jsonb index using GIN on SQLAlchemy? -

-
here's current code creating index jsonb. index("mytable_data_idx_id_key", mytable.data['id'].astext, postgresql_using='gin') but got error. sqlalchemy.exc.programmingerror: (psycopg2.programmingerror) data type text has no default operator class access method "gin" hint: must specify operator class index or define default operator class data type. [sql: "create index event_data_idx_id_key on event using gin ((data ->> 'id'))"] is there way create index on sqlalchemy? the postgresql specific sqlalchemy docs @ http://docs.sqlalchemy.org/en/latest/dialects/postgresql.html#operator-classes mention postgresql_ops dictionary provide "operator class" used postgresql, , provide example illustrating use: index('my_index', my_table.c.id, my_table.c.data, postgresql_ops={ 'data': 'text_pattern_ops', ...
Read more

PHP DOM loadHTML() method unusual warning -

-
i had following code works fine on localhost: $document = new domdocument(); $document->loadhtml($p_result); $form = $document->getelementsbytagname('form')->item(0); // code continues using $form variable after same code updated on outside server, loadhtml() failed , issued warning. warning: domdocument::loadhtml() expects parameter 1 valid path, string given in path/name/to/script.php returned null instead of object code pretty gets fatal error. note contents of $p_result absolutely same on outside server , on localhost. but why displays kind of warning , why not work? doesn't loadhtml() expects argument 1 string in first place? why method expects parameter 1 valid path ? just make clear i'm not calling loadhtmlfile() , i'm calling loadhtml() . thanks. you're affected one of php bugs . issue present in php 5.6.8 , 5.6.9. have affected php version on server, , bug-free version on localhost. the bug forbids null ...
Read more

c# - TransactionScope not rolling back although no complete() is called -

-
i'm using transactionscope rollback transaction fail bool errorreported = false; action<importerrorlog> newerrorcallback = e => { errorreported = true; errorcallback(e); }; using (var transaction = new transactionscope()) { foreach (importtaskdefinition task in taskdefinition) { loader.load(streamfile, newerrorcallback, task.destinationtable, processingtaskid); } if (!errorreported) transaction.complete(); } i'm sure there no transactionscope started ahead or after code. i'm using entity framework insert in db. regardless state of errorreported transaction never rolled in case of error. what missing ? transactionscope sets transaction.current . that's does. wants transacted must @ property. i believe ef each time connection opened reason. probably, connection open when scope installed. open connection inside of scope or enlist manually. ef has nasty "design decision": default opens ...
Read more