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6b9bba2df8
Get rid of the multiplier and addend variables in favor of hard-wired constants. Do the multiply-and-add using uint64 arithmetic, rather than manually combining several narrower multiplications and additions. Make _dorand48 return the full-width new random value, and have its callers use that directly (after suitable masking) rather than reconstructing what they need from the unsigned short[] representation. On my machine, this is good for a nearly factor-of-2 speedup of pg_erand48(), probably mostly from needing just one call of ldexp() rather than three. The wins for the other functions are smaller but measurable. While none of the existing call sites are really performance-critical, a cycle saved is a cycle earned; and besides the machine code is smaller this way (at least on x86_64). Patch by me, but the original idea to optimize this by switching to int64 arithmetic is from Fabien Coelho. Discussion: https://postgr.es/m/1551.1546018192@sss.pgh.pa.us |
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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/.