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This loop is basically the same as the inner loop of mul_var(), which was auto-vectorized in commit 8870917623, but the compiler will only consider auto-vectorizing the div_var_fast() loop if the assignment target div[qi + i] is replaced by div_qi[i], where div_qi = &div[qi]. Additionally, since the compiler doesn't know that qdigit is guaranteed to fit in a 16-bit NumericDigit, cast it to NumericDigit before multiplying to make the resulting auto-vectorized code more efficient (avoiding unnecessary multiplication of the high 16 bits). While at it, per suggestion from Tom Lane, change var1digit in mul_var() to be a NumericDigit rather than an int for the same reason. This actually makes no difference with modern gcc, but it might help other compilers generate more efficient assembly. Dean Rasheed, reviewed by Tom Lane. Discussion: https://postgr.es/m/CAEZATCVwsBi-ND-t82Cuuh1=8ee6jdOpzsmGN+CUZB6yjLg9jw@mail.gmail.com
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.