This patch merges the PostgreSQL 9.5 implementation of SSE4.2 into GPDB.
The SSE4.2 implementation was lifted right out of PostgreSQL without
change to make merging later PostgreSQL releases easier.

Update win32 configuration to support SSE4.2 runtime checks

This change was pulled from "src/include/pg_config.h.win32" from the
commits below.

configure.in changes, determining if cpu instruction for perfomring runtime
checks are availible, and moving some of the code to port SSE4.2 came from the
following PostgreSQL commits:

commit 3dc2d62d
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date:   Tue Apr 14 17:05:03 2015 +0300

    Use Intel SSE 4.2 CRC instructions where available.

    Modern x86 and x86-64 processors with SSE 4.2 support have special
    instructions, crc32b and crc32q, for calculating CRC-32C. They greatly
    speed up CRC calculation.

    Whether the instructions can be used or not depends on the compiler and the
    target architecture. If generation of SSE 4.2 instructions is allowed for
    the target (-msse4.2 flag on gcc and clang), use them. If they are not
    allowed by default, but the compiler supports the -msse4.2 flag to enable
    them, compile just the CRC-32C function with -msse4.2 flag, and check at
    runtime whether the processor we're running on supports it. If it doesn't,
    fall back to the slicing-by-8 algorithm. (With the common defaults on
    current operating systems, the runtime-check variant is what you get in
    practice.)

    Abhijit Menon-Sen, heavily modified by me, reviewed by Andres Freund.

commit b4eb2d16
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date:   Tue Apr 14 19:56:00 2015 +0300
	On gcc and clang, the _mm_crc32_u8 and _mm_crc32_u64 intrinsics are not
	defined at all, when not building with -msse4.2. But on icc, they are.
	So we cannot assume that if those intrinsics are defined, we can always use
	them safely, we might still need the runtime check.

	To fix, check if the __SSE_4_2__ preprocessor symbol is defined. That's
	supposed to be defined only when the compiler is targeting a processor that
	has SSE 4.2 support.

	Per buildfarm members fulmar and okapi.

It's important to pay attention to compiler warnings, but -Werror isn't
buying us much at the moment. Firstly, there are a lot of warnings on modern
versions of gcc. I have to pass: "-Wno-error=unused-but-set-variable
-Wno-error=enum-compare -Wno-error=address -Wno-error=maybe-uninitialized"
to make it compile. More important than erroring out on warnings is to make
sure there are no warnings to begin with. Once we get to that state, any
warnings will stick out like sore thumb anyway, and you won't need -Werror
to make them more annoying.

We have a long way until we are 100% warning free, but most of the warnings
come from upstream code. They have been fixed in later versions of
PostgreSQL, so they will go away as we merge with upstream.

specify it explicitly in backend/Makefile.  Arrange for this value to
be known by get_stack_depth_rlimit() too.  Per suggestion from Magnus.

repeatedly.  Now that we don't have to worry about memory leaks from
glibc's qsort, we can safely put CHECK_FOR_INTERRUPTS into the tuplesort
comparators, as was requested a couple months ago.  Also, get rid of
non-reentrancy and an extra level of function call in tuplesort.c by
providing a variant qsort_arg() API that passes an extra void * argument
through to the comparison routine.  (We might want to use that in other
places too, I didn't look yet.)

an earlier discussion.  Centralize assumptions about what libpq depends
on in one place in Makefile.global.  I am unconvinced that this list
is complete, but since ecpg seems to have gotten along with just these
entries, we'll try it this way and see what happens.

than before.  Albe Laurenz (but editorialized heavily by me, so if it
doesn't work it's my fault).

Use initializer string length as size for character strings.
Added ecpg_config.h file that is created via configure.

by Robert Lor

-built-in mechanism through the -MP flag.  Adjust the file extensions to
look more like Automake practice.  This frees up the .d suffix for use by
DTrace.

no evidence that any currently-supported platform needs this, and good
reason to think that any platform that did need it couldn't use the static
libraries anyway --- libpq, at least, has circular references.  Removing
the code shuts up tsort warnings about the circular references on some
platforms.

--enable-depend it often tries to create the .deps directory twice and
bails out when it already exists due to a race condition of if doesn't
exist, then create.  This patch prevents mkdir from returning an error.

Kris Jurka

relocated after installation.  We can't trust the installation paths
inserted into Makefile.global by configure, so instead we must get the
paths from pg_config.  This requires extending pg_config to support all
the separately-configurable path names, but that was on TODO anyway.

of special case for Windows port.  Put a PG_TRY around most of createdb()
to ensure that we remove copied subdirectories on failure, even if the
failure happens while creating the pg_database row.  (I think this explains
Oliver Siegmar's recent report.)  Having done that, there's no need for
the fragile assumption that copydir() mustn't ereport(ERROR), so simplify
its API.  Eliminate the old code that used system("cp ...") to copy
subdirectories, in favor of using copydir() on all platforms.  This not
only should allow much better error reporting, but allows us to fsync
the created files before trusting that the copy has succeeded.

problems:

---------------------------------------------------------------------------

Support cross compilation by compiling "zic" with a native compiler.
This relies on the output of zic being platform independent, but that is
currently the case.

is used in the toplevel configure.  Per Marko Kreen.

relies on the output of zic being platform independent, but that is
currently the case.

for testing PLs and contrib_regression for testing contrib, instead of
overwriting the core system's regression database as formerly done.
Andrew Dunstan

This reduces header file install from 8 seconds to 0.40 seconds.

immunte to changes in libpq's usage of pgport between major versions.

linking to libpq.  This insulates applications from changes in libpq's
usage of libpgport functions.

Backpatched to 8.0.X.

APPDATA directory on Windows.  Magnus Hagander

DLL pginstaller installs.

PTHREAD_LIBS to all libpq-usage builds.

binary compiles, and adjust configure tests for AIX.

in terms of macro 'rpathdir', as I proposed a few weeks ago.  In itself
this commit shouldn't change the behavior at all, but it opens the door
to using special rpaths for the PL shared libraries, as seems to be
needed for plperl in particular.

  -O2 -Wall -Wmissing-prototypes -Wpointer-arith

Check whether the version of GCC we are using supports any of:

  -Wdeclaration-after-statement
  -Wendif-labels
  -Wold-style-definition

And add the supported flags to CFLAGS.

"make", even if nothing had changed. With this patch, it's only relinked
if it's actually updated.

//Magnus

PS. Yes, the old buildrule for the .rc file is still needed, as it's
used by pgevent.rc (or any other binary in the future that would need
it's own .rc file)

Magnus Hagander

>
>    ./configure LDFLAGS=-static-libgcc LDFLAGS_SL=-static-libgcc
>
> to produce binaries that do not depend on libgcc_s.so at all.

Oliver Jowett

-L spec rather than assuming libpython is in the standard search path
(this returns to the way 7.4 did it).  But check the distutils output
to see if it looks like Python has built a shared library, and if so
link with that instead of the probably-not-shared library found in
configdir.

Magnus Hagander

Magnus Hagander

if the user has defined LDFLAGS themselves.