This reverts commit e7ff59686e. It
defined pg_atomic_fetch_add_u32_impl() without defining
pg_atomic_compare_exchange_u32_impl(), which is incompatible with
src/include/port/atomics/fallback.h. Per buildfarm member prairiedog.
Discussion: https://postgr.es/m/7517.1568470247@sss.pgh.pa.us
Use the explicit_bzero() function in places where it is important that
security information such as passwords is cleared from memory. There
might be other places where it could be useful; this is just an
initial collection.
For platforms that don't have explicit_bzero(), provide various
fallback implementations. (explicit_bzero() itself isn't standard,
but as Linux/glibc, FreeBSD, and OpenBSD have it, it's the most common
spelling, so it makes sense to make that the invocation point.)
Discussion: https://www.postgresql.org/message-id/flat/42d26bde-5d5b-c90d-87ae-6cab875f73be%402ndquadrant.com
fe0a0b5 has removed the last use of this routine from pgcrypto, leading
to a useless symbol definition and an extra configure check.
Author: Michael Paquier
Reviewed-by: Daniel Gustafsson, Tom Lane
Discussion: https://postgr.es/m/20190626142544.GN1714@paquier.xyz
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
Deal with silent-underflow errors in float4 for cygwin and mingw by
using our strtof() wrapper; deal with misrounding errors by adding
them to the resultmap. Some slight reorganization of declarations was
done to avoid duplicating material between cygwin.h and win32_port.h.
While here, remove from the resultmap all references to
float8-small-is-zero; inspection of cygwin output suggests it's no
longer required there, and the freebsd/netbsd/openbsd entries should
no longer be necessary (these date back to c. 2000). This commit
doesn't remove the file itself nor the documentation references for
it; that will happen in a subsequent commit if all goes well.
This reverts commits fc6c72747a, 109de05cbb, d0b4663c23 and
711bab1e4d.
Somebody will have to try harder before submitting this patch again.
I've spent entirely too much time on it already, and the #ifdef maze yet
to be written in order for it to build at all got on my nerves. The
amount of work needed to get a platform-specific performance improvement
that's barely above the noise level is not worth it.
Split out these new functions in three parts: one in a new file that
uses the compiler builtin and gets compiled with the -mpopcnt compiler
option if it exists; another one that uses the compiler builtin but not
the compiler option; and finally the fallback with open-coded
algorithms.
Split out the configure logic: in the original commit, it was selecting
to use the -mpopcnt compiler switch together with deciding whether to
use the compiler builtin, but those two things are really separate.
Split them out. Also, expose whether the builtin exists to
Makefile.global, so that src/port's Makefile can decide whether to
compile the hw-optimized file.
Remove CPUID test for CTZ/CLZ. Make pg_{right,left}most_ones use either
the compiler intrinsic or open-coded algo; trying to use the
HW-optimized version is a waste of time. Make them static inline
functions.
Discussion: https://postgr.es/m/20190213221719.GA15976@alvherre.pgsql
We were using uint64 function arguments as "long int" arguments to
compiler builtins, which fails on machines where long ints are 32 bits:
the upper half of the uint64 was being ignored. Fix by using the "ll"
builtin variants instead, which on those machines take 64 bit arguments.
Also, remove configure tests for __builtin_popcountl() (as well as
"long" variants for ctz and clz): the theory here is that any compiler
version will provide all widths or none, so one test suffices. Were
this theory to be wrong, we'd have to add tests for
__builtin_popcountll() and friends, which would be tedious.
Per failures in buildfarm member lapwing and ensuing discussion.
These opcodes have been around in the AMD world since 2007, and 2008 in
the case of intel. They're supported in GCC and Clang via some __builtin
macros. The opcodes may be unavailable during runtime, in which case we
fall back on a C-based implementation of the code. In order to get the
POPCNT instruction we must pass the -mpopcnt option to the compiler. We
do this only for the pg_bitutils.c file.
David Rowley (with fragments taken from a patch by Thomas Munro)
Discussion: https://postgr.es/m/CAKJS1f9WTAGG1tPeJnD18hiQW5gAk59fQ6WK-vfdAKEHyRg2RA@mail.gmail.com
Previously, floating-point output was done by rounding to a specific
decimal precision; by default, to 6 or 15 decimal digits (losing
information) or as requested using extra_float_digits. Drivers that
wanted exact float values, and applications like pg_dump that must
preserve values exactly, set extra_float_digits=3 (or sometimes 2 for
historical reasons, though this isn't enough for float4).
Unfortunately, decimal rounded output is slow enough to become a
noticable bottleneck when dealing with large result sets or COPY of
large tables when many floating-point values are involved.
Floating-point output can be done much faster when the output is not
rounded to a specific decimal length, but rather is chosen as the
shortest decimal representation that is closer to the original float
value than to any other value representable in the same precision. The
recently published Ryu algorithm by Ulf Adams is both relatively
simple and remarkably fast.
Accordingly, change float4out/float8out to output shortest decimal
representations if extra_float_digits is greater than 0, and make that
the new default. Applications that need rounded output can set
extra_float_digits back to 0 or below, and take the resulting
performance hit.
We make one concession to portability for systems with buggy
floating-point input: we do not output decimal values that fall
exactly halfway between adjacent representable binary values (which
would rely on the reader doing round-to-nearest-even correctly). This
is known to be a problem at least for VS2013 on Windows.
Our version of the Ryu code originates from
https://github.com/ulfjack/ryu/ at commit c9c3fb1979, but with the
following (significant) modifications:
- Output format is changed to use fixed-point notation for small
exponents, as printf would, and also to use lowercase 'e', a
minimum of 2 exponent digits, and a mandatory sign on the exponent,
to keep the formatting as close as possible to previous output.
- The output of exact midpoint values is disabled as noted above.
- The integer fast-path code is changed somewhat (since we have
fixed-point output and the upstream did not).
- Our project style has been largely applied to the code with the
exception of C99 declaration-after-statement, which has been
retained as an exception to our present policy.
- Most of upstream's debugging and conditionals are removed, and we
use our own configure tests to determine things like uint128
availability.
Changing the float output format obviously affects a number of
regression tests. This patch uses an explicit setting of
extra_float_digits=0 for test output that is not expected to be
exactly reproducible (e.g. due to numerical instability or differing
algorithms for transcendental functions).
Conversions from floats to numeric are unchanged by this patch. These
may appear in index expressions and it is not yet clear whether any
change should be made, so that can be left for another day.
This patch assumes that the only supported floating point format is
now IEEE format, and the documentation is updated to reflect that.
Code by me, adapting the work of Ulf Adams and other contributors.
References:
https://dl.acm.org/citation.cfm?id=3192369
Reviewed-by: Tom Lane, Andres Freund, Donald Dong
Discussion: https://postgr.es/m/87r2el1bx6.fsf@news-spur.riddles.org.uk
Using strtod() creates a double-rounding problem; the input decimal
value is first rounded to the nearest double; rounding that to the
nearest float may then give an incorrect result.
An example is that 7.038531e-26 when input via strtod and then rounded
to float4 gives 0xAE43FEp-107 instead of the correct 0xAE43FDp-107.
Values output by earlier PG versions with extra_float_digits=3 should
all be read in with the same values as previously. However, values
supplied by other software using shortest representations could be
mis-read.
On platforms that lack a strtof() entirely, we fall back to the old
incorrect rounding behavior. (As strtof() is required by C99, such
platforms are considered of primarily historical interest.) On VS2013,
some workarounds are used to get correct error handling.
The regression tests now test for the correct input values, so
platforms that lack strtof() will need resultmap entries. An entry for
HP-UX 10 is included (more may be needed).
Reviewed-By: Tom Lane
Discussion: https://postgr.es/m/871s5emitx.fsf@news-spur.riddles.org.uk
Discussion: https://postgr.es/m/87d0owlqpv.fsf@news-spur.riddles.org.uk
The comment marker "#" is copied to the output, so it's only
appropriate for comments that make sense in the shell output. For
comments about the Autoconf language, "dnl" should be used.
While Windows (allegedly) has _configthreadlocale() pretty far back,
it seems MinGW didn't acquire support for that till more recently.
Fortunately, we can use an autoconf probe on that toolchain,
instead of guessing whether it's there. (Hm, I wonder whether Cygwin
will need this also.)
Per buildfarm.
Discussion: https://postgr.es/m/20190121193512.tdmcnic2yjxlufaw@alap3.anarazel.de
ecpglib attempts to force the LC_NUMERIC locale to "C" while reading
server output, to avoid problems with strtod() and related functions.
Historically it's just issued setlocale() calls to do that, but that
has major problems if we're in a threaded application. setlocale()
itself is not required by POSIX to be thread-safe (and indeed is not,
on recent OpenBSD). Moreover, its effects are process-wide, so that
we could cause unexpected results in other threads, or another thread
could change our setting.
On platforms having uselocale(), which is required by POSIX:2008,
we can avoid these problems by using uselocale() instead. Windows
goes its own way as usual, but we can make it safe by using
_configthreadlocale(). Platforms having neither continue to use the
old code, but that should be pretty much nobody among current systems.
This should get back-patched, but let's see what the buildfarm
thinks of it first.
Michael Meskes and Tom Lane; thanks also to Takayuki Tsunakawa.
Discussion: https://postgr.es/m/31420.1547783697@sss.pgh.pa.us
Commit c0d0e54084 replaced the ones in the documentation, but missed out
on the ones in the code. Replace those as well, but unlike c0d0e54084,
don't backpatch the code changes to avoid breaking translations.
Recent OpenBSD (at least 5.9 and up) has a version of getopt(3)
that will not cope with the "-:" spec we use to accept double-dash
options in postgres.c and postmaster.c. Admittedly, that's a hack
because POSIX only requires getopt() to allow alphanumeric option
characters. I have no desire to find another way, however, so
let's just do what we were already doing on Solaris: force use
of our own src/port/getopt.c implementation.
In passing, improve some of the comments around said implementation.
Per buildfarm and local testing. Back-patch to all supported branches.
Discussion: https://postgr.es/m/30197.1547835700@sss.pgh.pa.us
AC_ARG_VAR is necessary if an environment variable influences a
configure result that is then used by other tests that are cached.
With AC_ARG_VAR, a change in the variable is detected on subsequent
configure runs and the user is then advised to remove the cache.
This adds AC_ARG_VAR calls for: MSGFMT, PERL, PYTHON, TCLSH, XML2_CONFIG
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/30672.1546816567@sss.pgh.pa.us
This removes a portion of infrastructure introduced by fe0a0b5 to allow
compilation of Postgres in environments where no strong random source is
available, meaning that there is no linking to OpenSSL and no
/dev/urandom (Windows having its own CryptoAPI). No systems shipped
this century lack /dev/urandom, and the buildfarm is actually not
testing this switch at all, so just remove it. This simplifies
particularly some backend code which included a fallback implementation
using shared memory, and removes a set of alternate regression output
files from pgcrypto.
Author: Michael Paquier
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/20181230063219.GG608@paquier.xyz
It appears that all platforms that have sys_siglist[] also have
strsignal(), making that fallback case in pg_strsignal() dead code.
Getting rid of it allows dropping a configure test, which seems worth
more than providing textual signal descriptions on whatever platforms
might still hypothetically have use for the fallback case.
Discussion: https://postgr.es/m/25758.1544983503@sss.pgh.pa.us
At least as far back as the 2008 spec, POSIX has defined strsignal(3)
for looking up descriptive strings for signal numbers. We hadn't gotten
the word though, and were still using the crufty old sys_siglist array,
which is in no standard even though most Unixen provide it.
Aside from not being formally standards-compliant, this was just plain
ugly because it involved #ifdef's at every place using the code.
To eliminate the #ifdef's, create a portability function pg_strsignal,
which wraps strsignal(3) if available and otherwise falls back to
sys_siglist[] if available. The set of Unixen with neither API is
probably empty these days, but on any platform with neither, you'll
just get "unrecognized signal". All extant callers print the numeric
signal number too, so no need to work harder than that.
Along the way, upgrade pg_basebackup's child-error-exit reporting
to match the rest of the system.
Discussion: https://postgr.es/m/25758.1544983503@sss.pgh.pa.us
Calling AC_CHECK_DECLS before we've finished setting up the compiler's
CFLAGS seems like a pretty risky proposition, especially now that the
first use of that macro will result in a test to see whether the compiler
gives warning or error for undeclared built-in functions. That answer
could very easily get changed later than where PGAC_LLVM_SUPPORT is
called; furthermore, it's hardly unlikely that flags such as -D_GNU_SOURCE
could change visibility of declarations. Hence, be a little less cavalier
about where to do LLVM-related tests. This results in v11 and HEAD doing
the warning-or-error check at the same place in the script as older
branches are doing it, which seems like a good thing.
Per further thought about commits 0b59b0e8b and 16fbac39f.
The test case that Autoconf uses to discover whether a function has
been declared doesn't work reliably with clang, because clang reports
a warning not an error if the name is a known built-in function.
On some platforms, this results in a lot of compile-time warnings about
strlcpy and related functions not having been declared.
There is a fix for this (by Noah Misch) in the upstream Autoconf sources,
but since they've not made a release in years and show no indication of
doing so anytime soon, let's just absorb their fix directly. We can
revert this when and if we update to a newer Autoconf release.
Back-patch to all supported branches.
Discussion: https://postgr.es/m/26819.1542515567@sss.pgh.pa.us
Any Autoconf macro that uses AC_REQUIRES -- directly or indirectly --
must not be inside a plain shell "if" test; if it is, whatever code
gets pulled in by the AC_REQUIRES will also be inside that "if".
Instead of "if" we can use AS_IF, which knows how to get this right
(cf commit 01051a987).
The only immediate problem from getting this wrong was that AC_PROG_AWK
had to be run twice, once inside the "if llvm" block and once in the
main line. However, it broke a different patch I'm about to submit
more thoroughly.
Add another transfer mode --clone to pg_upgrade (besides the existing
--link and the default copy), using special file cloning calls. This
makes the file transfer faster and more space efficient, achieving
speed similar to --link mode without the associated drawbacks.
On Linux, file cloning is supported on Btrfs and XFS (if formatted with
reflink support). On macOS, file cloning is supported on APFS.
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Forward to POSIX pread() and pwrite(), or emulate them if unavailable.
The emulation is not perfect as the file position is changed, so
we'll put pg_ prefixes on the names to minimize the risk of confusion
in future patches that might inadvertently try to mix pread() and read()
on the same file descriptor.
Author: Thomas Munro
Reviewed-by: Tom Lane, Jesper Pedersen
Discussion: https://postgr.es/m/CAEepm=02rapCpPR3ZGF2vW=SBHSdFYO_bz_f-wwWJonmA3APgw@mail.gmail.com
I added HAVE_IPV6 to Makefile.global way back in commit 7703e55c3
so that we could transmit its value to the shell-script version of
initdb. Since initdb was rewritten in C, it's been finding that
out from pg_config.h instead, so this is useless. Keeping it here
just wastes configure and make cycles, plus it's a potential
two-sources-of-truth problem.
The solution arrived at in commit e74dd00f5 presumes that the compiler
has a suitable default -isysroot setting ... but further experience
shows that in many combinations of macOS version, XCode version, Xcode
command line tools version, and phase of the moon, Apple's compiler
will *not* supply a default -isysroot value.
We could potentially go back to the approach used in commit 68fc227dd,
but I don't have a lot of faith in the reliability or life expectancy of
that either. Let's just revert to the approach already shipped in 11.0,
namely specifying an -isysroot switch globally. As a partial response to
the concerns raised by Jakob Egger, adjust the contents of Makefile.global
to look like
CPPFLAGS = -isysroot $(PG_SYSROOT) ...
PG_SYSROOT = /path/to/sysroot
This allows overriding the sysroot path at build time in a relatively
painless way.
Add documentation to installation.sgml about how to use the PG_SYSROOT
option. I also took the opportunity to document how to work around
macOS's "System Integrity Protection" feature.
As before, back-patch to all supported versions.
Discussion: https://postgr.es/m/20840.1537850987@sss.pgh.pa.us
To avoid the sorts of problems complained of by Jakob Egger, it'd be
best if configure didn't emit any references to the sysroot path at all.
In the case of PL/Tcl, we can do that just by keeping our hands off the
TCL_INCLUDE_SPEC string altogether. In the case of PL/Perl, we need to
substitute -iwithsysroot for -I in the compile commands, which is easily
handled if we change to using a configure output variable that includes
the switch not only the directory name. Since PL/Tcl and PL/Python
already do it like that, this seems like good consistency cleanup anyway.
Hence, this replaces the advice given to Perl-related extensions in commit
5e2217131; instead of writing "-I$(perl_archlibexp)/CORE", they should
just write "$(perl_includespec)". (The old way continues to work, but not
on recent macOS.)
It's still the case that configure needs to be aware of the sysroot
path internally, but that's cleaner than what we had before.
As before, back-patch to all supported versions.
Discussion: https://postgr.es/m/20840.1537850987@sss.pgh.pa.us
Rethink the solution applied in commit 5e2217131 to get PL/Tcl to
build on macOS Mojave. I feared that adding -isysroot globally might
have undesirable consequences, and sure enough Jakob Egger reported
one: it complicates building extensions with a different Xcode version
than was used for the core server. (I find that a risky proposition
in general, but apparently it works most of the time, so we shouldn't
break it if we don't have to.)
We'd already adopted the solution for PL/Perl of inserting the sysroot
path directly into the -I switches used to find Perl's headers, and we
can do the same thing for PL/Tcl by changing the -iwithsysroot switch
that Apple's tclConfig.sh reports. This restricts the risks to PL/Perl
and PL/Tcl themselves and directly-dependent extensions, which is a lot
more pleasing in general than a global -isysroot switch.
Along the way, tighten the test to see if we need to inject the sysroot
path into $perl_includedir, as I'd speculated about upthread but not
gotten round to doing.
As before, back-patch to all supported versions.
Discussion: https://postgr.es/m/20840.1537850987@sss.pgh.pa.us
The idea here is that patches that add items to these lists will often
be easier to rebase over other additions to the same lists, because
they won't be trying to touch the very same line of configure.in.
There will still be merge conflicts in the configure script, but that
can be fixed just by re-running autoconf (or by leaving configure out
of the submitted patch to begin with ...)
Implementation note: use of m4_normalize() is necessary to get rid of
the newlines, else incorrect shell syntax will be emitted. But with
that hack, the generated configure script is identical to what it
was before.
Discussion: https://postgr.es/m/19344.1539050134@sss.pgh.pa.us
In combination, these changes make our version of snprintf as fast
or faster than most platforms' native snprintf, except for cases
involving floating-point conversion (which we still delegate to
the native sprintf). The speed penalty for a float conversion
is down to around 10% though, much better than before.
Notable changes:
* Rather than always parsing the format twice to see if it contains
instances of %n$, do the extra scan only if we actually find a $.
This obviously wins for non-localized formats, and even when there
is use of %n$, we can avoid scanning text before the first % twice.
* Use strchrnul() if available to find the next %, and emit the
literal text between % escapes as strings rather than char-by-char.
* Create a bespoke function (dopr_outchmulti) for the common case
of emitting N copies of the same character, in place of writing
loops around dopr_outch.
* Simplify construction of the format string for invocations of sprintf
for floats.
* Const-ify some internal functions, and avoid unnecessary use of
pass-by-reference arguments.
Patch by me, reviewed by Andres Freund
Discussion: https://postgr.es/m/11787.1534530779@sss.pgh.pa.us
We've spent an awful lot of effort over the years in coping with
platform-specific vagaries of the *printf family of functions. Let's just
forget all that mess and standardize on always using src/port/snprintf.c.
This gets rid of a lot of configure logic, and it will allow a saner
approach to dealing with %m (though actually changing that is left for
a follow-on patch).
Preliminary performance testing suggests that as it stands, snprintf.c is
faster than the native printf functions for some tasks on some platforms,
and slower for other cases. A pending patch will improve that, though
cases with floating-point conversions will doubtless remain slower unless
we want to put a *lot* of effort into that. Still, we've not observed
that *printf is really a performance bottleneck for most workloads, so
I doubt this matters much.
Patch by me, reviewed by Michael Paquier
Discussion: https://postgr.es/m/2975.1526862605@sss.pgh.pa.us
elog.c has long had a private strerror wrapper that handles assorted
possible failures or deficiencies of the platform's strerror. On Windows,
it also knows how to translate Winsock error codes, which the native
strerror does not. Move all this code into src/port/strerror.c and
define strerror() as a macro that invokes it, so that both our frontend
and backend code will have all of this behavior.
I believe this constitutes an actual bug fix on Windows, since AFAICS
our frontend code did not report Winsock error codes properly before this.
However, the main point is to lay the groundwork for implementing %m
in src/port/snprintf.c: the behavior we want %m to have is this one,
not the native strerror's.
Note that this throws away the prior use of src/port/strerror.c,
which was to implement strerror() on platforms lacking it. That's
been dead code for nigh twenty years now, since strerror() was
already required by C89.
We should likewise cause strerror_r to use this behavior, but
I'll tackle that separately.
Patch by me, reviewed by Michael Paquier
Discussion: https://postgr.es/m/2975.1526862605@sss.pgh.pa.us
Apple's latest rearrangements of the system-supplied headers have broken
building of PL/Perl and PL/Tcl. The only practical way to fix PL/Tcl is to
start using the "-isysroot" compiler flag to point to SDK-supplied headers,
as Apple expects. We must also start distinguishing where to find Perl's
headers from where to find its shared library; but that seems like good
cleanup anyway.
Extensions that formerly did something like -I$(perl_archlibexp)/CORE
should now do -I$(perl_includedir)/CORE instead. perl_archlibexp
is still the place to look for libperl.so, though.
If for some reason you don't like the default -isysroot setting, you can
override that by setting PG_SYSROOT in configure's arguments. I don't
currently think people would need to do so, unless maybe for cross-version
build purposes.
In addition, teach configure where to find tclConfig.sh. Our traditional
method of searching $auto_path hasn't worked for the last couple of macOS
releases, and it now seems clear that Apple's not going to change that.
The workaround of manually specifying --with-tclconfig was annoying
already, but Mojave's made it a lot more so because the sysroot path now
has to be included as well. Let's just wire the knowledge into configure
instead. To avoid breaking builds against non-default Tcl installations
(e.g. MacPorts) wherein the $auto_path method probably still works,
arrange to try the additional case only after all else has failed.
Back-patch to all supported versions, since at least the buildfarm
cares about that. The changes are set up to not do anything on macOS
releases that are old enough to not have functional sysroot trees.
Previously, pgbench always used select(2) for this purpose, but that's
problematic for very high client counts, because select() can't deal
with file descriptor numbers larger than FD_SETSIZE. It's pretty common
for that to be only 1024 or so, whereas modern OSes can allow many more
open files than that. Using poll(2) would surmount that problem, but it
creates another one: poll()'s timeout resolution is only 1ms, which is
poor enough to cause problems with --rate specifications approaching or
exceeding 1K TPS.
On platforms that have ppoll(2), which includes Linux and recent
FreeBSD, we can use that to avoid the FD_SETSIZE problem without any
loss of timeout resolution. Hence, add configure logic to test for
ppoll(), and use it if available.
This patch introduces an abstraction layer into pgbench that could
be extended to support other kernel event-wait APIs such as kevents.
But actually adding such support is a matter for some future patch.
Doug Rady, reviewed by Robert Haas and Fabien Coelho, and whacked around
a good bit more by me
Discussion: https://postgr.es/m/23D017C9-81B7-484D-8490-FD94DEC4DF59@amazon.com
As clang currently doesn't support -fexcess-precision=standard,
compiling x86-32 code with SSE2 disabled, can lead to problems with
floating point overflow checks and the like.
This issue was noticed because clang, on at least some BSDs, defaults
to i386 compatibility, whereas it defaults to pentium4 on Linux. Our
forced usage of __builtin_isinf() lead to some overflow checks not
triggering when compiling for i386, e.g. when the result of the
calculation didn't overflow in 80bit registers, but did so in 64bit.
While we could just fall back to a non-builtin isinf, it seems likely
that the use of 80bit registers leads to other problems (which is why
we force the flag for GCC already). Therefore error out when
detecting clang in that situation.
Reported-By: Victor Wagner
Analyzed-By: Andrew Gierth and Andres Freund
Author: Andres Freund
Discussion: https://postgr.es/m/20180905005130.ewk4xcs5dgyzcy45@alap3.anarazel.de
Backpatch: 9.3-, all supported versions are affected
In 86d78ef50e I enabled configure to check for C99 support, with the
goal of checking which platforms support C99. While there are a few
machines without C99 support among our buildfarm animals,
de-supporting them for v12 was deemed acceptable.
While not tested in aforementioned commit, the biggest increase in
minimum compiler version comes from MSVC, which gained C99 support
fairly late. The subset in MSVC 2013 is sufficient for our needs, at
this point. While that is a significant increase in minimum version,
the existing windows binaries are already built with a new enough
version.
Make configure error out if C99 support could not be detected. For
MSVC builds, increase the minimum version to 2013.
The increase to MSVC 2013 allows us to get rid of VCBuildProject.pm,
as that was only required for MSVC 2005/2008.
Author: Andres Freund
Discussion: https://postgr.es/m/97d4b165-192d-3605-749c-f614a0c4e783@2ndquadrant.com
Noah Misch