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postgres/config/llvm.m4
Peter Eisentraut 7a0aa99e51 Revert "Use -isystem for LLVM include directories"
This reverts commit 704ef84ef2.

The configure solution in that commit doesn't work if llvm-config
returns a system directory such as /usr/include.  The resulting
-isystem /usr/include puts the C headers before the C++ headers in the
include file order, which is not supposed to be done and causes
failures.  (Using -I /usr/include doesn't have that problem because it
is handled specially by the compiler.)  Per buildfarm members
hippopotamus and jay.

The meson solution does work because it specifically filters out
system includes.  This logic could theoretically be ported to
configure, but that would be a separate undertaking.
2026-09-12 15:50:08 +02:00

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# config/llvm.m4
# PGAC_LLVM_SUPPORT
# -----------------
#
# Look for the LLVM installation, check that it's new enough, set the
# corresponding LLVM_{CFLAGS,CXXFLAGS,BINPATH,LIBS}
# variables. Also verify that CLANG is available, to transform C
# into bitcode.
#
AC_DEFUN([PGAC_LLVM_SUPPORT],
[
AC_REQUIRE([AC_PROG_AWK])
AC_ARG_VAR(LLVM_CONFIG, [path to llvm-config command])
PGAC_PATH_PROGS(LLVM_CONFIG, llvm-config)
# no point continuing if llvm wasn't found
if test -z "$LLVM_CONFIG"; then
AC_MSG_ERROR([llvm-config not found, but required when compiling --with-llvm, specify with LLVM_CONFIG=])
fi
# check if detected $LLVM_CONFIG is executable
pgac_llvm_version="$($LLVM_CONFIG --version 2> /dev/null || echo no)"
if test "x$pgac_llvm_version" = "xno"; then
AC_MSG_ERROR([$LLVM_CONFIG does not work])
fi
# and whether the version is supported
if echo $pgac_llvm_version | $AWK -F '.' '{ if ([$]1 >= 14) exit 1; else exit 0;}';then
AC_MSG_ERROR([$LLVM_CONFIG version is $pgac_llvm_version but at least 14 is required])
fi
AC_MSG_NOTICE([using llvm $pgac_llvm_version])
# need clang to create some bitcode files
AC_ARG_VAR(CLANG, [path to clang compiler to generate bitcode])
PGAC_PATH_PROGS(CLANG, clang)
if test -z "$CLANG"; then
AC_MSG_ERROR([clang not found, but required when compiling --with-llvm, specify with CLANG=])
fi
# make sure clang is executable
if test "x$($CLANG --version 2> /dev/null || echo no)" = "xno"; then
AC_MSG_ERROR([$CLANG does not work])
fi
# Could check clang version, but it doesn't seem that
# important. Systems with a new enough LLVM version are usually
# going to have a decent clang version too. It's also not entirely
# clear what the minimum version is.
# Collect compiler flags necessary to build the LLVM dependent
# shared library.
for pgac_option in `$LLVM_CONFIG --cppflags`; do
case $pgac_option in
-I*|-D*) LLVM_CPPFLAGS="$pgac_option $LLVM_CPPFLAGS";;
esac
done
for pgac_option in `$LLVM_CONFIG --ldflags`; do
case $pgac_option in
-L*) LLVM_LIBS="$LLVM_LIBS $pgac_option";;
esac
done
# ABI influencing options, standard influencing options
for pgac_option in `$LLVM_CONFIG --cxxflags`; do
case $pgac_option in
-fno-rtti*) LLVM_CXXFLAGS="$LLVM_CXXFLAGS $pgac_option";;
-std=*) LLVM_CXXFLAGS="$LLVM_CXXFLAGS $pgac_option";;
esac
done
# Look for components we're interested in, collect necessary
# libs. As some components are optional, we can't just list all of
# them as it'd raise an error.
pgac_components='';
for pgac_component in `$LLVM_CONFIG --components`; do
case $pgac_component in
engine) pgac_components="$pgac_components $pgac_component";;
debuginfodwarf) pgac_components="$pgac_components $pgac_component";;
orcjit) pgac_components="$pgac_components $pgac_component";;
passes) pgac_components="$pgac_components $pgac_component";;
native) pgac_components="$pgac_components $pgac_component";;
perfjitevents) pgac_components="$pgac_components $pgac_component";;
esac
done;
# And then get the libraries that need to be linked in for the
# selected components. They're large libraries, we only want to
# link them into the LLVM using shared library.
for pgac_option in `$LLVM_CONFIG --libs --system-libs $pgac_components`; do
case $pgac_option in
-l*) LLVM_LIBS="$LLVM_LIBS $pgac_option";;
esac
done
LLVM_BINPATH=`$LLVM_CONFIG --bindir`
dnl LLVM_CONFIG, CLANG are already output via AC_ARG_VAR
AC_SUBST(LLVM_LIBS)
AC_SUBST(LLVM_CPPFLAGS)
AC_SUBST(LLVM_CFLAGS)
AC_SUBST(LLVM_CXXFLAGS)
AC_SUBST(LLVM_BINPATH)
])# PGAC_LLVM_SUPPORT