postgres

Tom Lane 02a6a54ecd Make use of compiler builtins and/or assembly for CLZ, CTZ, POPCNT. Test for the compiler builtins __builtin_clz, __builtin_ctz, and __builtin_popcount, and make use of these in preference to handwritten C code if they're available. Create src/port infrastructure for "leftmost one", "rightmost one", and "popcount" so as to centralize these decisions. On x86_64, __builtin_popcount generally won't make use of the POPCNT opcode because that's not universally supported yet. Provide code that checks CPUID and then calls POPCNT via asm() if available. This requires indirecting through a function pointer, which is an annoying amount of overhead for a one-instruction operation, but it's probably not worth working harder than this for our current use-cases. I'm not sure we've found all the existing places that could profit from this new infrastructure; but we at least touched all the ones that used copied-and-pasted versions of the bitmapset.c code, and got rid of multiple copies of the associated constant arrays. While at it, replace c-compiler.m4's one-per-builtin-function macros with a single one that can handle all the cases we need to worry about so far. Also, because I'm paranoid, make those checks into AC_LINK checks rather than just AC_COMPILE; the former coding failed to verify that libgcc has support for the builtin, in cases where it's not inline code. David Rowley, Thomas Munro, Alvaro Herrera, Tom Lane Discussion: https://postgr.es/m/CAKJS1f9WTAGG1tPeJnD18hiQW5gAk59fQ6WK-vfdAKEHyRg2RA@mail.gmail.com		6 years ago
config	Make use of compiler builtins and/or assembly for CLZ, CTZ, POPCNT.	6 years ago
contrib	Make use of compiler builtins and/or assembly for CLZ, CTZ, POPCNT.	6 years ago
doc	doc: Update README.links	6 years ago
src	Make use of compiler builtins and/or assembly for CLZ, CTZ, POPCNT.	6 years ago
.dir-locals.el	Make Emacs perl-mode indent more like perltidy.	7 years ago
.gitattributes	Remove contrib/tsearch2.	8 years ago
.gitignore	Support for optimizing and emitting code in LLVM JIT provider.	7 years ago
COPYRIGHT	Update copyright for 2019	7 years ago
GNUmakefile.in	Process EXTRA_INSTALL serially, during the first temp-install.	7 years ago
HISTORY	Change documentation references to PG website to use https: not http:	8 years ago
Makefile	Fix non-GNU makefiles for AIX make.	8 years ago
README	Change documentation references to PG website to use https: not http:	8 years ago
README.git	Change documentation references to PG website to use https: not http:	8 years ago
aclocal.m4	Fix configure's AC_CHECK_DECLS tests to work correctly with clang.	7 years ago
configure	Make use of compiler builtins and/or assembly for CLZ, CTZ, POPCNT.	6 years ago
configure.in	Make use of compiler builtins and/or assembly for CLZ, CTZ, POPCNT.	6 years ago

README

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/.