Break up aclocal.m4

66 files changed, 2638 insertions, 0 deletions

diff --git a/m4/bootstrapping_ghc_info_field.m4 b/m4/bootstrapping_ghc_info_field.m4
new file mode 100644
index 0000000000..54936263cd
--- /dev/null
+++ b/m4/bootstrapping_ghc_info_field.m4
@@ -0,0 +1,13 @@
+# BOOTSTRAPPING_GHC_INFO_FIELD
+# --------------------------------
+# Set the variable $1 to the value of the ghc --info field $2.
+AC_DEFUN([BOOTSTRAPPING_GHC_INFO_FIELD],[
+$1=`"$WithGhc" --info | grep "^ ,(\"$2\"," | sed -e 's/.*","//' -e 's/")$//'`
+tmp=${$1#\$topdir/}
+if test "${$1}" != "$tmp"
+then
+    topdir=`"$WithGhc" --print-libdir | sed 's#\\\\#/#g'`
+    $1="$topdir/$tmp"
+fi
+AC_SUBST($1)
+])
diff --git a/m4/check_for_gold_t22266.m4 b/m4/check_for_gold_t22266.m4
new file mode 100644
index 0000000000..73d8a73c6f
--- /dev/null
+++ b/m4/check_for_gold_t22266.m4
@@ -0,0 +1,89 @@
+# CHECK_FOR_GOLD_T22266
+# ----------------------
+#
+# Test for binutils #22266. This bug manifested as GHC bug #14328 (see also:
+# #14675, #14291).
+# Uses test from
+# https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=033bfb739b525703bfe23f151d09e9beee3a2afe
+#
+# $1 = linker to test
+# Sets $result to 0 if not affected, 1 otherwise
+AC_DEFUN([CHECK_FOR_GOLD_T22266],[
+    AC_MSG_CHECKING([for ld.gold object merging bug (binutils 22266)])
+    if ! $1 --version | grep -q "GNU gold"; then
+        # Not gold
+        result=0
+    elif test "$cross_compiling" = "yes"; then
+        AC_MSG_RESULT([cross-compiling, assuming LD can merge objects correctly.])
+        result=0
+    else
+        FPTOOLS_WRITE_FILE([conftest.a.c], [
+          __attribute__((section(".data.a")))
+          static int int_from_a_1 = 0x11223344;
+
+          __attribute__((section(".data.rel.ro.a")))
+          int *p_int_from_a_2 = &int_from_a_1;
+
+          const char *hello (void);
+
+          const char *
+          hello (void)
+          {
+            return "XXXHello, world!" + 3;
+          }
+        ])
+
+        FPTOOLS_WRITE_FILE([conftest.main.c], [
+          #include <stdlib.h>
+          #include <string.h>
+
+          extern int *p_int_from_a_2;
+          extern const char *hello (void);
+
+          int main (void) {
+            if (*p_int_from_a_2 != 0x11223344)
+              abort ();
+            if (strcmp(hello(), "Hello, world!") != 0)
+              abort ();
+            return 0;
+          }
+        ])
+
+        FPTOOLS_WRITE_FILE([conftest.t], [
+          SECTIONS
+          {
+              .text : {
+                  *(.text*)
+              }
+              .rodata :
+              {
+                  *(.rodata .rodata.* .gnu.linkonce.r.*)
+              }
+              .data.rel.ro : {
+                  *(.data.rel.ro*)
+              }
+              .data : {
+                  *(.data*)
+              }
+              .bss : {
+                  *(.bss*)
+              }
+          }
+        ])
+
+        $CC -c -o conftest.a.o conftest.a.c || AC_MSG_ERROR([Failed to compile test])
+        $MergeObjsCmd $MergeObjsArgs -T conftest.t conftest.a.o -o conftest.ar.o || AC_MSG_ERROR([Failed to merge test object])
+
+        $CC -c -o conftest.main.o conftest.main.c || AC_MSG_ERROR([Failed to compile test driver])
+        $CC conftest.ar.o conftest.main.o -o conftest || AC_MSG_ERROR([Failed to link test driver])
+
+        if ./conftest; then
+            AC_MSG_RESULT([not affected])
+            result=0
+        else
+            AC_MSG_RESULT([affected])
+            result=1
+        fi
+        rm -f conftest.a.o conftest.a.c  conttest.ar.o conftest.main.c conftest.main.o conftest
+    fi
+])
diff --git a/m4/check_ld_copy_bug.m4 b/m4/check_ld_copy_bug.m4
new file mode 100644
index 0000000000..a2d3c4ee93
--- /dev/null
+++ b/m4/check_ld_copy_bug.m4
@@ -0,0 +1,61 @@
+# CHECK_LD_COPY_BUG()
+# -------------------
+# Check for binutils bug #16177 present in some versions of the bfd ld
+# implementation affecting ARM relocations.
+# https://sourceware.org/bugzilla/show_bug.cgi?id=16177
+#
+# $1 = the platform
+#
+AC_DEFUN([CHECK_LD_COPY_BUG],[
+    case $1 in
+      arm*linux*)
+        AC_CHECK_TARGET_TOOL([READELF], [readelf])
+        AC_CHECK_TARGET_TOOL([AS], [as])
+        AC_MSG_CHECKING([for ld bug 16177])
+        cat >actest.s <<-EOF
+          .globl _start
+          .p2align 4
+        _start:
+          bkpt
+
+        .data
+          .globl data_object
+        object_reference:
+          .long data_object
+          .size object_reference, 4
+EOF
+
+        cat >aclib.s <<-EOF
+          .data
+          .globl data_object
+          .type data_object, %object
+          .size data_object, 4
+        data_object:
+            .long 123
+EOF
+
+        $AS -o aclib.o aclib.s
+        $LD -shared -o aclib.so aclib.o
+
+        $AS -o actest.o actest.s
+        $LD -o actest actest.o aclib.so
+
+        if $READELF -r actest | grep R_ARM_COPY > /dev/null; then
+            AC_MSG_RESULT([affected])
+            AC_MSG_ERROR(
+              [Your linker is affected by binutils #16177, which
+               critically breaks linkage of GHC objects. Please either upgrade
+               binutils or supply a different linker with the LD environment
+               variable.])
+        else
+            AC_MSG_RESULT([unaffected])
+        fi
+
+        rm -f aclib.s aclib.o aclib.so actest.s actest.o actest
+        ;;
+      *)
+        ;;
+    esac
+])
+
+
diff --git a/m4/find_ghc_bootstrap_prog.m4 b/m4/find_ghc_bootstrap_prog.m4
new file mode 100644
index 0000000000..4f9eb8bcbc
--- /dev/null
+++ b/m4/find_ghc_bootstrap_prog.m4
@@ -0,0 +1,17 @@
+# FIND_GHC_BOOTSTRAP_PROG()
+# --------------------------------
+# Parse the bootstrap GHC's compiler settings file for the location of things
+# like the `llc` and `opt` commands.
+#
+# $1 = the variable to set
+# $2 = The bootstrap compiler.
+# $3 = The string to grep for to find the correct line.
+#
+AC_DEFUN([FIND_GHC_BOOTSTRAP_PROG],[
+    BootstrapTmpCmd=`grep $3 $($2 --print-libdir)/settings 2>/dev/null | sed 's/.*", "//;s/".*//'`
+    if test -n "$BootstrapTmpCmd" && test `basename $BootstrapTmpCmd` = $BootstrapTmpCmd ; then
+        AC_PATH_PROG([$1], [$BootstrapTmpCmd], "")
+    else
+        $1=$BootstrapTmpCmd
+    fi
+])
diff --git a/m4/find_ld.m4 b/m4/find_ld.m4
new file mode 100644
index 0000000000..a6b5c9c598
--- /dev/null
+++ b/m4/find_ld.m4
@@ -0,0 +1,70 @@
+# FIND_LD
+# ---------
+# Find the version of `ld` to use and figure out how to get gcc to use it for
+# linking (if --enable-ld-override is enabled). This is used in both in the top
+# level configure.ac and in distrib/configure.ac.in.
+#
+# $1 = the platform
+# $2 = the variable to set with GHC options to configure gcc to use the chosen linker
+#
+AC_DEFUN([FIND_LD],[
+    AC_ARG_ENABLE(ld-override,
+      [AS_HELP_STRING([--disable-ld-override],
+        [Prevent GHC from overriding the default linker used by gcc. If ld-override is enabled GHC will try to tell gcc to use whichever linker is selected by the LD environment variable. [default=override enabled]])],
+      [],
+      [enable_ld_override=yes])
+
+    find_ld() {
+        # Make sure the user didn't specify LD manually.
+        if test "z$LD" != "z"; then
+            AC_CHECK_TARGET_TOOL([LD], [ld])
+            return
+        fi
+
+        # Manually iterate over possible names since we want to ensure that, e.g.,
+        # if ld.lld is installed but gcc doesn't support -fuse-ld=lld, that we
+        # then still try ld.gold and -fuse-ld=gold.
+        for possible_ld in ld.lld ld.gold ld; do
+            TmpLd="" # In case the user set LD
+            AC_CHECK_TARGET_TOOL([TmpLd], [$possible_ld])
+            if test "x$TmpLd" = "x"; then continue; fi
+
+            out=`$TmpLd --version`
+            case $out in
+              "GNU ld"*)
+                   FP_CC_LINKER_FLAG_TRY(bfd, $2) ;;
+              "GNU gold"*)
+                   FP_CC_LINKER_FLAG_TRY(gold, $2)
+                   if test "$cross_compiling" = "yes"; then
+                       AC_MSG_NOTICE([Using ld.gold and assuming that it is not affected by binutils issue 22266]);
+                   fi
+                   ;;
+              "LLD"*)
+                   FP_CC_LINKER_FLAG_TRY(lld, $2) ;;
+              *) AC_MSG_NOTICE([unknown linker version $out]) ;;
+            esac
+            if test "z$$2" = "z"; then
+                AC_MSG_NOTICE([unable to convince '$CC' to use linker '$TmpLd'])
+                # a terrible hack to prevent autoconf from caching the previous
+                # AC_CHECK_TARGET_TOOL result since next time we'll be looking
+                # for another ld variant.
+                $as_unset ac_cv_prog_ac_ct_TmpLd
+            else
+                LD="$TmpLd"
+                return
+            fi
+        done
+
+        # Fallback
+        AC_CHECK_TARGET_TOOL([LD], [ld])
+    }
+
+    if test "x$enable_ld_override" = "xyes"; then
+        find_ld
+    else
+        AC_CHECK_TARGET_TOOL([LD], [ld])
+    fi
+
+    CHECK_LD_COPY_BUG([$1])
+])
+
diff --git a/m4/find_llvm_prog.m4 b/m4/find_llvm_prog.m4
new file mode 100644
index 0000000000..79a6a502a5
--- /dev/null
+++ b/m4/find_llvm_prog.m4
@@ -0,0 +1,32 @@
+# FIND_LLVM_PROG()
+# --------------------------------
+# Find where the llvm tools are. We have a special function to handle when they
+# are installed with a version suffix (e.g., llc-7, llc-7.0) and without (e.g.
+# llc).
+#
+# $1 = the variable to set
+# $2 = the command to look for
+# $3 = the lower bound version of the command to look for
+# $4 = the upper bound version of the command to look for.
+#
+AC_DEFUN([FIND_LLVM_PROG],[
+    # Test for program with and without version name.
+    PROG_VERSION_CANDIDATES=$(for llvmVersion in `seq $4 -1 $3`; do echo "$2-$llvmVersion $2-$llvmVersion.0"; done)
+    AC_CHECK_TOOLS([$1], [$PROG_VERSION_CANDIDATES $2], [])
+    AS_IF([test x"$$1" != x],[
+        PROG_VERSION=`$$1 --version | awk '/.*version [[0-9\.]]+/{for(i=1;i<=NF;i++){ if(\$i ~ /^[[0-9\.]]+$/){print \$i}}}'`
+        AS_IF([test x"$PROG_VERSION" == x],
+          [AC_MSG_RESULT(no)
+           $1=""
+           AC_MSG_NOTICE([We only support llvm $3 to $4 (no version found).])],
+          [AC_MSG_CHECKING([$$1 version ($PROG_VERSION) is between $3 and $4])
+           AX_COMPARE_VERSION([$PROG_VERSION], [lt], [$3],
+            [AC_MSG_RESULT(no)
+             $1=""
+             AC_MSG_NOTICE([We only support llvm $3 to $4 (found $PROG_VERSION).])],
+            [AX_COMPARE_VERSION([$PROG_VERSION], [gt], [$4],
+             [AC_MSG_RESULT(no)
+              $1=""
+              AC_MSG_NOTICE([We only support llvm $3 to $4 (found $PROG_VERSION).])],
+             [AC_MSG_RESULT(yes)])])])])
+])
diff --git a/m4/find_merge_objects.m4 b/m4/find_merge_objects.m4
new file mode 100644
index 0000000000..fc16e57050
--- /dev/null
+++ b/m4/find_merge_objects.m4
@@ -0,0 +1,29 @@
+# FIND_MERGE_OBJECTS
+# ------------------
+# Find which linker to use to merge object files.
+#
+# See Note [Merging object files for GHCi] in GHC.Driver.Pipeline.
+AC_DEFUN([FIND_MERGE_OBJECTS],[
+    AC_REQUIRE([FIND_LD])
+
+    if test -z "$MergeObjsCmd"; then
+        MergeObjsCmd="$LD"
+    fi
+    if test -z "$MergeObjsArgs"; then
+        MergeObjsArgs="-r"
+    fi
+
+    CHECK_FOR_GOLD_T22266($MergeObjsCmd)
+    if test "$result" = "1"; then
+        AC_MSG_NOTICE([$MergeObjsCmd is broken due to binutils 22266, looking for another linker...])
+        MergeObjsCmd=""
+        AC_CHECK_TARGET_TOOL([MergeObjsCmd], [ld])
+        CHECK_FOR_GOLD_T22266($MergeObjsCmd)
+        if test "$result" = "1"; then
+            AC_MSG_ERROR([Linker is affected by binutils 22266 but couldn't find another unaffected linker. Please set the MergeObjsCmd variable to a functional linker.])
+        fi
+    fi
+
+    AC_SUBST([MergeObjsCmd])
+    AC_SUBST([MergeObjsArgs])
+])
diff --git a/m4/find_python.m4 b/m4/find_python.m4
new file mode 100644
index 0000000000..7e53b5877e
--- /dev/null
+++ b/m4/find_python.m4
@@ -0,0 +1,10 @@
+# FIND_PYTHON
+# -----------
+# Find the version of `python` to use (for the testsuite driver)
+#
+AC_DEFUN([FIND_PYTHON],[
+    dnl Prefer the mingw64 distribution on Windows due to #17483.
+    AC_PATH_PROG([PYTHON], [python3], [], [/mingw64/bin $PATH])
+    PythonCmd="$PYTHON"
+    AC_SUBST([PythonCmd])
+])
diff --git a/m4/fp_bfd_support.m4 b/m4/fp_bfd_support.m4
new file mode 100644
index 0000000000..89c051253f
--- /dev/null
+++ b/m4/fp_bfd_support.m4
@@ -0,0 +1,48 @@
+# FP_BFD_SUPPORT()
+# ----------------------
+# whether to use libbfd for debugging RTS
+AC_DEFUN([FP_BFD_SUPPORT], [
+    AC_SUBST([CabalHaveLibbfd], [False])
+    AC_ARG_ENABLE(bfd-debug,
+        [AS_HELP_STRING([--enable-bfd-debug],
+              [Enable symbol resolution for -debug rts ('+RTS -Di') via binutils' libbfd [default=no]])],
+        [
+            # don't pollute general LIBS environment
+            save_LIBS="$LIBS"
+            AC_CHECK_HEADERS([bfd.h])
+            dnl ** check whether this machine has BFD and libiberty installed (used for debugging)
+            dnl    the order of these tests matters: bfd needs libiberty
+            AC_CHECK_LIB(iberty, xmalloc)
+            dnl 'bfd_init' is a rare non-macro in libbfd
+            AC_CHECK_LIB(bfd,    bfd_init)
+
+            AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <bfd.h>]],
+                        [[
+                                /* mimic our rts/Printer.c */
+                                bfd* abfd;
+                                const char * name;
+                                char **matching;
+
+                                name = "some.executable";
+                                bfd_init();
+                                abfd = bfd_openr(name, "default");
+                                bfd_check_format_matches (abfd, bfd_object, &matching);
+                                {
+                                    long storage_needed;
+                                    storage_needed = bfd_get_symtab_upper_bound (abfd);
+                                }
+                                {
+                                    asymbol **symbol_table;
+                                    long number_of_symbols;
+                                    symbol_info info;
+
+                                    number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);
+                                    bfd_get_symbol_info(abfd,symbol_table[0],&info);
+                                }
+                        ]])],
+                        [AC_SUBST([CabalHaveLibbfd], [True])],dnl bfd seems to work
+                        [AC_MSG_ERROR([can't use 'bfd' library])])
+            LIBS="$save_LIBS"
+        ]
+    )
+])
diff --git a/m4/fp_cc_linker_flag_try.m4 b/m4/fp_cc_linker_flag_try.m4
new file mode 100644
index 0000000000..69af387d5d
--- /dev/null
+++ b/m4/fp_cc_linker_flag_try.m4
@@ -0,0 +1,20 @@
+# FP_CC_LINKER_FLAG_TRY()
+# --------------------
+# Try a particular linker to see whether we can use it. In particular, determine
+# whether we can convince gcc to use it via a -fuse-ld=... flag.
+#
+# $1 = the name of the linker to try
+# $2 = the variable to set with the appropriate GHC flag if the linker is
+# found to be usable
+AC_DEFUN([FP_CC_LINKER_FLAG_TRY], [
+    AC_MSG_CHECKING([whether C compiler supports -fuse-ld=$1])
+    echo 'int main(void) {return 0;}' > conftest.c
+    if $CC -o conftest.o -fuse-ld=$1 conftest.c > /dev/null 2>&1
+    then
+        $2="-fuse-ld=$1"
+        AC_MSG_RESULT([yes])
+    else
+        AC_MSG_RESULT([no])
+    fi
+    rm -f conftest.c conftest.o
+])
diff --git a/m4/fp_cc_llvm_backend.m4 b/m4/fp_cc_llvm_backend.m4
new file mode 100644
index 0000000000..75cdf759bf
--- /dev/null
+++ b/m4/fp_cc_llvm_backend.m4
@@ -0,0 +1,18 @@
+dnl Check to see if the C compiler is clang or llvm-gcc
+dnl
+AC_DEFUN([FP_CC_LLVM_BACKEND],
+  [AC_REQUIRE([AC_PROG_CC])
+   AC_MSG_CHECKING([whether C compiler has an LLVM back end])
+   $CC -x c /dev/null -dM -E > conftest.txt 2>&1
+   if grep "__llvm__" conftest.txt >/dev/null 2>&1; then
+     AC_DEFINE([CC_LLVM_BACKEND], [1], [Define (to 1) if C compiler has an LLVM back end])
+     CcLlvmBackend=YES
+     AC_MSG_RESULT([yes])
+   else
+     CcLlvmBackend=NO
+     AC_MSG_RESULT([no])
+   fi
+   AC_SUBST(CcLlvmBackend)
+
+   rm -f conftest.txt
+])
diff --git a/m4/fp_check_alignment.m4 b/m4/fp_check_alignment.m4
new file mode 100644
index 0000000000..a000c42582
--- /dev/null
+++ b/m4/fp_check_alignment.m4
@@ -0,0 +1,22 @@
+# FP_CHECK_ALIGNMENT(TYPE, [IGNORED], [INCLUDES = DEFAULT-INCLUDES])
+# ------------------------------------------------------------------
+# A variation of AC_CHECK_SIZEOF for computing the alignment restrictions of a
+# given type. Defines ALIGNMENT_TYPE.
+AC_DEFUN([FP_CHECK_ALIGNMENT],
+[AS_LITERAL_IF(m4_translit([[$1]], [*], [p]), [],
+               [AC_FATAL([$0: requires literal arguments])])[]dnl
+AC_CHECK_TYPE([$1], [], [], [$3])[]dnl
+m4_pushdef([fp_Cache], [AS_TR_SH([fp_cv_alignment_$1])])[]dnl
+AC_CACHE_CHECK([alignment of $1], [fp_Cache],
+[if test "$AS_TR_SH([ac_cv_type_$1])" = yes; then
+  FP_COMPUTE_INT([offsetof(struct { char c; $1 ty; },ty)],
+                 [fp_Cache],
+                 [AC_INCLUDES_DEFAULT([$3])],
+                 [AC_MSG_ERROR([cannot compute alignment ($1)
+See `config.log' for more details.], [77])])
+else
+  fp_Cache=0
+fi])[]dnl
+AC_DEFINE_UNQUOTED(AS_TR_CPP(alignment_$1), $fp_Cache, [The alignment of a `$1'.])[]dnl
+m4_popdef([fp_Cache])[]dnl
+])# FP_CHECK_ALIGNMENT
diff --git a/m4/fp_check_func.m4 b/m4/fp_check_func.m4
new file mode 100644
index 0000000000..ff24c80e24
--- /dev/null
+++ b/m4/fp_check_func.m4
@@ -0,0 +1,16 @@
+# FP_CHECK_FUNC(FUNCTION, PROLOGUE, BODY, [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
+# ---------------------------------------------------------------------------------
+# A variant of AC_CHECK_FUNCS, limited to a single FUNCTION, but with the
+# additional flexibility of specifying the PROLOGUE and BODY.
+AC_DEFUN([FP_CHECK_FUNC],
+[AS_VAR_PUSHDEF([fp_func], [fp_cv_func_$1])dnl
+AC_CACHE_CHECK([for $1], fp_func,
+[AC_LINK_IFELSE([AC_LANG_PROGRAM([$2], [$3])],
+                [AS_VAR_SET(fp_func, yes)],
+                [AS_VAR_SET(fp_func, no)])])
+AS_IF([test AS_VAR_GET(fp_func) = yes],
+      [AC_DEFINE(AS_TR_CPP(HAVE_$1), [1],
+                [Define to 1 if you have the `]$1[' function.]) $4],
+      [$5])dnl
+AS_VAR_POPDEF([fp_func])dnl
+])# FP_CHECK_FUNC
diff --git a/m4/fp_check_prog.m4 b/m4/fp_check_prog.m4
new file mode 100644
index 0000000000..33ad72732b
--- /dev/null
+++ b/m4/fp_check_prog.m4
@@ -0,0 +1,8 @@
+# FP_CHECK_PROG(VARIABLE, PROG-TO-CHECK-FOR,
+#               [VALUE-IF-NOT-FOUND], [PATH], [REJECT])
+# -----------------------------------------------------
+# HACK: A small wrapper around AC_CHECK_PROG, setting VARIABLE to the full path
+# of PROG-TO-CHECK-FOR when found.
+AC_DEFUN([FP_CHECK_PROG],
+[AC_CHECK_PROG([$1], [$2], [$as_dir/$ac_word$ac_exec_ext], [$3], [$4], [$5])][]dnl
+)# FP_CHECK_PROC
diff --git a/m4/fp_check_sizeof_and_alignment.m4 b/m4/fp_check_sizeof_and_alignment.m4
new file mode 100644
index 0000000000..c0ded07891
--- /dev/null
+++ b/m4/fp_check_sizeof_and_alignment.m4
@@ -0,0 +1,8 @@
+# FP_CHECK_SIZEOF_AND_ALIGNMENT(TYPE)
+# ------------------------------------------------------------------
+# Combines AC_CHECK_SIZEOF and FP_CHECK_ALIGNMENT.
+AC_DEFUN([FP_CHECK_SIZEOF_AND_ALIGNMENT],
+[AC_CHECK_SIZEOF([$1])
+FP_CHECK_ALIGNMENT([$1])
+])# FP_CHECK_SIZEOF_AND_ALIGNMENT
+
diff --git a/m4/fp_check_timer_create.m4 b/m4/fp_check_timer_create.m4
new file mode 100644
index 0000000000..e698885065
--- /dev/null
+++ b/m4/fp_check_timer_create.m4
@@ -0,0 +1,112 @@
+# Check for a working timer_create().  We need a pretty detailed check
+# here, because there exist partially-working implementations of
+# timer_create() in certain versions of Linux (see bug #1933).
+#
+AC_DEFUN([FP_CHECK_TIMER_CREATE],[
+AC_CHECK_FUNC([timer_create],[HAVE_timer_create=yes],[HAVE_timer_create=no])
+
+if test "$HAVE_timer_create" = "yes"
+then
+  if test "$cross_compiling" = "yes"
+  then
+    # We can't test timer_create when we're cross-compiling, so we
+    # optimistiaclly assume that it actually works properly.
+    AC_DEFINE([USE_TIMER_CREATE], 1,  [Define to 1 if we can use timer_create(CLOCK_REALTIME,...)])
+  else
+  AC_CACHE_CHECK([for a working timer_create(CLOCK_REALTIME)],
+    [fptools_cv_timer_create_works],
+    [AC_TRY_RUN([
+#include <stdio.h>
+#if defined(HAVE_STDLIB_H)
+#include <stdlib.h>
+#endif
+#if defined(HAVE_TIME_H)
+#include <time.h>
+#endif
+#if defined(HAVE_SIGNAL_H)
+#include <signal.h>
+#endif
+#if defined(HAVE_UNISTD_H)
+#include <unistd.h>
+#endif
+
+static volatile int tock = 0;
+static void handler(int i)
+{
+   tock = 1;
+}
+
+static void timeout(int i)
+{
+  // timer_settime() has been known to hang, so just in case
+  // we install a 1-second timeout (see #2257)
+  exit(99);
+}
+
+int main(int argc, char *argv[])
+{
+
+    struct sigevent ev;
+    timer_t timer;
+    struct itimerspec it;
+    struct sigaction action;
+    int m,n,count = 0;
+
+    ev.sigev_notify = SIGEV_SIGNAL;
+    ev.sigev_signo  = SIGVTALRM;
+
+    action.sa_handler = handler;
+    action.sa_flags = 0;
+    sigemptyset(&action.sa_mask);
+    if (sigaction(SIGVTALRM, &action, NULL) == -1) {
+        fprintf(stderr,"SIGVTALRM problem\n");
+        exit(3);
+    }
+
+    action.sa_handler = timeout;
+    action.sa_flags = 0;
+    sigemptyset(&action.sa_mask);
+    if (sigaction(SIGALRM, &action, NULL) == -1) {
+      fprintf(stderr,"SIGALRM problem\n");
+      exit(3);
+    }
+    alarm(1);
+
+    if (timer_create(CLOCK_REALTIME, &ev, &timer) != 0) {
+        fprintf(stderr,"No CLOCK_REALTIME timer\n");
+        exit(2);
+    }
+
+    tock = 0;
+
+    it.it_value.tv_sec = 0;
+    it.it_value.tv_nsec = 1000000; // 1ms
+    it.it_interval = it.it_value;
+    if (timer_settime(timer, 0, &it, NULL) != 0) {
+        fprintf(stderr,"settime problem\n");
+        exit(4);
+    }
+
+    // some environments have coarse scheduler/timer granularity of ~10ms and worse
+    usleep(100000); // 100ms
+
+    if (!tock) {
+        fprintf(stderr,"no CLOCK_REALTIME signal\n");
+        exit(5);
+    }
+
+    timer_delete(timer);
+
+    exit(0);
+}
+     ],
+     [fptools_cv_timer_create_works=yes],
+     [fptools_cv_timer_create_works=no])
+  ])
+case $fptools_cv_timer_create_works in
+    yes) AC_DEFINE([USE_TIMER_CREATE], 1,
+                   [Define to 1 if we can use timer_create(CLOCK_REALTIME,...)]);;
+esac
+  fi
+fi
+])
diff --git a/m4/fp_compare_versions.m4 b/m4/fp_compare_versions.m4
new file mode 100644
index 0000000000..5acab9e4ff
--- /dev/null
+++ b/m4/fp_compare_versions.m4
@@ -0,0 +1,27 @@
+# FP_COMPARE_VERSIONS(VERSION1, TEST, VERSION2, [ACTION-IF-TRUE], [ACTION-IF-FALSE])
+# ----------------------------------------------------------------------------------
+# Compare dotted version numbers VERSION1 and VERSION2 lexicographically according
+# to TEST (one of -eq, -ne, -lt, -le, -gt, or -ge).
+AC_DEFUN([FP_COMPARE_VERSIONS],
+[fp_version1=$1; fp_version2=$3
+fp_save_IFS=$IFS; IFS='.'
+while test x"$fp_version1" != x || test x"$fp_version2" != x
+do
+
+  set dummy $fp_version1; shift
+  fp_num1=""
+  test $[@%:@] = 0 || { fp_num1="[$]1"; shift; }
+  test x"$fp_num1" = x && fp_num1="0"
+  fp_version1="[$]*"
+
+  set dummy $fp_version2; shift
+  fp_num2=""
+  test $[@%:@] = 0 || { fp_num2="[$]1"; shift; }
+  test x"$fp_num2" = x && fp_num2="0"
+  fp_version2="[$]*"
+
+  test "$fp_num1" = "$fp_num2" || break;
+done
+IFS=$fp_save_IFS
+AS_IF([test "$fp_num1" $2 "$fp_num2"], [$4], [$5])[]dnl
+])# FP_COMPARE_VERSIONS
diff --git a/m4/fp_compute_int.m4 b/m4/fp_compute_int.m4
new file mode 100644
index 0000000000..68afe22ef7
--- /dev/null
+++ b/m4/fp_compute_int.m4
@@ -0,0 +1,12 @@
+# FP_COMPUTE_INT(EXPRESSION, VARIABLE, INCLUDES, IF-FAILS)
+# --------------------------------------------------------
+# Assign VARIABLE the value of the compile-time EXPRESSION using INCLUDES for
+# compilation. Execute IF-FAILS when unable to determine the value. Works for
+# cross-compilation, too.
+#
+# Implementation note: We are lazy and use an internal autoconf macro, but it
+# is supported in autoconf versions 2.50 up to the actual 2.57, so there is
+# little risk.
+AC_DEFUN([FP_COMPUTE_INT],
+[AC_COMPUTE_INT([$2], [$1], [$3], [$4])[]dnl
+])# FP_COMPUTE_INT
diff --git a/m4/fp_copy_shellvar.m4 b/m4/fp_copy_shellvar.m4
new file mode 100644
index 0000000000..f58601a3f1
--- /dev/null
+++ b/m4/fp_copy_shellvar.m4
@@ -0,0 +1,3 @@
+# Helper for cloning a shell variable's state
+AC_DEFUN([FP_COPY_SHELLVAR],
+[if test -n "${$1+set}"; then $2="$$1"; else unset $2; fi ])
diff --git a/m4/fp_cpp_cmd_with_args.m4 b/m4/fp_cpp_cmd_with_args.m4
new file mode 100644
index 0000000000..3f2d39df40
--- /dev/null
+++ b/m4/fp_cpp_cmd_with_args.m4
@@ -0,0 +1,99 @@
+# FP_CPP_CMD_WITH_ARGS()
+# ----------------------
+# sets CPP command and its arguments
+#
+# $1 = the variable to set to CPP command
+# $2 = the variable to set to CPP command arguments
+
+AC_DEFUN([FP_CPP_CMD_WITH_ARGS],[
+dnl ** what cpp to use?
+dnl --------------------------------------------------------------
+AC_ARG_WITH(hs-cpp,
+[AS_HELP_STRING([--with-hs-cpp=ARG],
+      [Path to the (C) preprocessor for Haskell files [default=autodetect]])],
+[
+    if test "$HostOS" = "mingw32"
+    then
+        AC_MSG_WARN([Request to use $withval will be ignored])
+    else
+        HS_CPP_CMD=$withval
+    fi
+],
+[
+
+    # We can't use $CPP here, since HS_CPP_CMD is expected to be a single
+    # command (no flags), and AC_PROG_CPP defines CPP as "/usr/bin/gcc -E".
+    HS_CPP_CMD=$CC
+
+    SOLARIS_GCC_CPP_BROKEN=NO
+    SOLARIS_FOUND_GOOD_CPP=NO
+    case $host in
+        i386-*-solaris2)
+        GCC_MAJOR_MINOR=`$CC --version|grep "gcc (GCC)"|cut -d ' ' -f 3-3|cut -d '.' -f 1-2`
+        if test "$GCC_MAJOR_MINOR" != "3.4"; then
+          # this is not 3.4.x release so with broken CPP
+          SOLARIS_GCC_CPP_BROKEN=YES
+        fi
+        ;;
+    esac
+
+    if test "$SOLARIS_GCC_CPP_BROKEN" = "YES"; then
+      # let's try to find if GNU C 3.4.x is installed
+      if test -x /usr/sfw/bin/gcc; then
+        # something executable is in expected path so let's
+        # see if it's really GNU C
+        NEW_GCC_MAJOR_MINOR=`/usr/sfw/bin/gcc --version|grep "gcc (GCC)"|cut -d ' ' -f 3-3|cut -d '.' -f 1-2`
+        if test "$NEW_GCC_MAJOR_MINOR" = "3.4"; then
+          # this is GNU C 3.4.x which provides non-broken CPP on Solaris
+          # let's use it as CPP then.
+          HS_CPP_CMD=/usr/sfw/bin/gcc
+          SOLARIS_FOUND_GOOD_CPP=YES
+        fi
+      fi
+      if test "$SOLARIS_FOUND_GOOD_CPP" = "NO"; then
+        AC_MSG_WARN([Your GNU C provides broken CPP and you do not have GNU C 3.4.x installed.])
+        AC_MSG_WARN([Please install GNU C 3.4.x to solve this issue. It will be used as CPP only.])
+      fi
+    fi
+]
+)
+
+dnl ** what cpp flags to use?
+dnl -----------------------------------------------------------
+AC_ARG_WITH(hs-cpp-flags,
+  [AS_HELP_STRING([--with-hs-cpp-flags=ARG],
+      [Flags to the (C) preprocessor for Haskell files [default=autodetect]])],
+  [
+      if test "$HostOS" = "mingw32"
+      then
+          AC_MSG_WARN([Request to use $withval will be ignored])
+      else
+          HS_CPP_ARGS=$withval
+      fi
+  ],
+[
+  $HS_CPP_CMD -x c /dev/null -dM -E > conftest.txt 2>&1
+  if grep "__clang__" conftest.txt >/dev/null 2>&1; then
+    HS_CPP_ARGS="-E -undef -traditional -Wno-invalid-pp-token -Wno-unicode -Wno-trigraphs"
+  else
+      $HS_CPP_CMD  -v > conftest.txt 2>&1
+      if  grep "gcc" conftest.txt >/dev/null 2>&1; then
+          HS_CPP_ARGS="-E -undef -traditional"
+        else
+          $HS_CPP_CMD  --version > conftest.txt 2>&1
+          if grep "cpphs" conftest.txt >/dev/null 2>&1; then
+            HS_CPP_ARGS="--cpp -traditional"
+          else
+            AC_MSG_WARN([configure can't recognize your CPP program, you may need to set --with-hs-cpp-flags=FLAGS explicitly])
+            HS_CPP_ARGS=""
+          fi
+      fi
+  fi
+  ]
+)
+
+$1=$HS_CPP_CMD
+$2=$HS_CPP_ARGS
+
+])
+
diff --git a/m4/fp_curses.m4 b/m4/fp_curses.m4
new file mode 100644
index 0000000000..a0c30637cb
--- /dev/null
+++ b/m4/fp_curses.m4
@@ -0,0 +1,15 @@
+# FP_CURSES
+# -------------
+AC_DEFUN([FP_CURSES],
+[
+  dnl--------------------------------------------------------------------
+  dnl * Deal with arguments telling us curses is somewhere odd
+  dnl--------------------------------------------------------------------
+
+  AC_ARG_WITH([curses-libraries],
+    [AS_HELP_STRING([--with-curses-libraries],
+      [directory containing curses libraries])],
+      [CURSES_LIB_DIRS=$withval])
+
+  AC_SUBST(CURSES_LIB_DIRS)
+])# FP_CURSES
diff --git a/m4/fp_default_choice_override_check.m4 b/m4/fp_default_choice_override_check.m4
new file mode 100644
index 0000000000..7c265fcfd4
--- /dev/null
+++ b/m4/fp_default_choice_override_check.m4
@@ -0,0 +1,41 @@
+# FP_DEFAULT_CHOICE_OVERRIDE_CHECK(
+#   flag, name, anti name, var name, help string,
+#   [var true val], [var false val], [flag true val])
+# ---------------------------------------------------
+# Helper for when there is a automatic detection and an explicit flag for the
+# user to override disable a feature, but not override enable a feature.
+#
+# $1 = flag of feature
+# $2 = name of feature
+# $3 = name of anti feature
+# $4 = name of variable
+# $5 = help string
+# $6 = when true
+# $7 = when false
+# $8 = default explicit case (yes/no). Used for handle "backwards" legacy
+#      options where enabling makes fewer assumptions than disabling.
+AC_DEFUN([FP_DEFAULT_CHOICE_OVERRIDE_CHECK],
+    [AC_ARG_ENABLE(
+        [$1],
+        [AS_HELP_STRING(
+            [--enable-$1],
+            [$5])],
+        [AS_IF(
+           [test x"$enableval" = x"m4_default([$8],yes)"],
+           [AS_CASE(
+               [x"$$4Default"],
+               [x"m4_default([$6],YES)"],
+                 [AC_MSG_NOTICE([user chose $2 matching default for platform])],
+               [x"m4_default([$7],NO)"],
+                 [AC_MSG_ERROR([user chose $2 overriding only supported option for platform])],
+               [AC_MSG_ERROR([invalid default])])
+            $4=m4_default([$6],YES)],
+           [AS_CASE(
+               [x"$$4Default"],
+               [x"m4_default([$6],YES)"],
+                 [AC_MSG_NOTICE([user chose $3 overriding for platform])],
+               [x"m4_default([$7],NO)"],
+                 [AC_MSG_NOTICE([user chose $3 matching default for platform])],
+               [AC_MSG_ERROR([invalid default])])
+            $4=m4_default([$7],NO)])],
+        [$4="$$4Default"])])
diff --git a/m4/fp_find_root.m4 b/m4/fp_find_root.m4
new file mode 100644
index 0000000000..37099984ea
--- /dev/null
+++ b/m4/fp_find_root.m4
@@ -0,0 +1,37 @@
+# --------------------------------------------------------------
+# Calculate absolute path to build tree
+# --------------------------------------------------------------
+
+AC_DEFUN([FP_FIND_ROOT],[
+AC_MSG_CHECKING(for path to top of build tree)
+    if test "$windows" = YES
+    then
+      dnl Make sure this is a c:/foo/bar (mixed) style path. Some parts of
+      dnl the build system might depend on it (such as the sed expression
+      dnl `"s|$(TOP)/||i"` in addCFileDeps in rules/build-dependencies.mk).
+      hardtop=$(cygpath -m "$(pwd)")
+    else
+      hardtop=$(pwd)
+    fi
+
+    dnl Remove common automounter nonsense
+    hardtop=`echo $hardtop | sed 's|^/tmp_mnt.*\(/local/.*\)$|\1|' | sed 's|^/tmp_mnt/|/|'`
+
+    if ! test -d "$hardtop"; then
+        AC_MSG_ERROR([cannot determine current directory])
+    fi
+
+    dnl We don't support building in directories with spaces.
+    case "$hardtop" in
+    *' '*)
+        AC_MSG_ERROR([
+        The build system does not support building in a directory
+        containing space characters.
+        Suggestion: move the build tree somewhere else.])
+        ;;
+    esac
+
+    AC_SUBST(hardtop)
+
+    AC_MSG_RESULT($hardtop)
+])
diff --git a/m4/fp_gcc_extra_flags.m4 b/m4/fp_gcc_extra_flags.m4
new file mode 100644
index 0000000000..16121eeabf
--- /dev/null
+++ b/m4/fp_gcc_extra_flags.m4
@@ -0,0 +1,20 @@
+# FP_GCC_EXTRA_FLAGS
+# ------------------
+# Determine which extra flags we need to pass gcc when we invoke it
+# to compile .hc code.
+#
+# -fwrapv is needed for gcc to emit well-behaved code in the presence of
+# integer wrap around. (#952)
+#
+AC_DEFUN([FP_GCC_EXTRA_FLAGS],
+[AC_REQUIRE([FP_GCC_VERSION])
+AC_CACHE_CHECK([for extra options to pass gcc when compiling via C], [fp_cv_gcc_extra_opts],
+[
+ if test "$Unregisterised" = "YES"; then
+   # These used to be conditioned on gcc version but we no longer support
+   # GCC versions which lack support for these flags
+   fp_cv_gcc_extra_opts="-fwrapv -fno-builtin"
+ fi
+])
+AC_SUBST([GccExtraViaCOpts],$fp_cv_gcc_extra_opts)
+])
diff --git a/m4/fp_gcc_supports__atomics.m4 b/m4/fp_gcc_supports__atomics.m4
new file mode 100644
index 0000000000..81fc44c500
--- /dev/null
+++ b/m4/fp_gcc_supports__atomics.m4
@@ -0,0 +1,17 @@
+# FP_GCC_SUPPORTS__ATOMICS
+# ------------------------
+# Does gcc support the __atomic_* family of builtins?
+AC_DEFUN([FP_GCC_SUPPORTS__ATOMICS],
+[
+   AC_REQUIRE([AC_PROG_CC])
+   AC_MSG_CHECKING([whether GCC supports __atomic_ builtins])
+   echo 'int test(int *x) { int y; __atomic_load(x, &y, __ATOMIC_SEQ_CST); return y; }' > conftest.c
+   if $CC -c conftest.c > /dev/null 2>&1; then
+       CONF_GCC_SUPPORTS__ATOMICS=YES
+       AC_MSG_RESULT([yes])
+   else
+       CONF_GCC_SUPPORTS__ATOMICS=NO
+       AC_MSG_RESULT([no])
+   fi
+   rm -f conftest.c conftest.o
+])
diff --git a/m4/fp_gcc_supports_no_pie.m4 b/m4/fp_gcc_supports_no_pie.m4
new file mode 100644
index 0000000000..880a1e4cfa
--- /dev/null
+++ b/m4/fp_gcc_supports_no_pie.m4
@@ -0,0 +1,19 @@
+# FP_GCC_SUPPORTS_NO_PIE
+# ----------------------
+# Does gcc support the -no-pie option? If so we should pass it to gcc when
+# joining objects since -pie may be enabled by default.
+AC_DEFUN([FP_GCC_SUPPORTS_NO_PIE],
+[
+   AC_REQUIRE([AC_PROG_CC])
+   AC_MSG_CHECKING([whether GCC supports -no-pie])
+   echo 'int main() { return 0; }' > conftest.c
+   # Some GCC versions only warn when passed an unrecognized flag.
+   if $CC -no-pie -Werror -x c /dev/null -dM -E > conftest.txt 2>&1 && ! grep -i unrecognized conftest.txt > /dev/null 2>&1; then
+       CONF_GCC_SUPPORTS_NO_PIE=YES
+       AC_MSG_RESULT([yes])
+   else
+       CONF_GCC_SUPPORTS_NO_PIE=NO
+       AC_MSG_RESULT([no])
+   fi
+   rm -f conftest.c conftest.o conftest
+])
diff --git a/m4/fp_gcc_version.m4 b/m4/fp_gcc_version.m4
new file mode 100644
index 0000000000..df581a69f4
--- /dev/null
+++ b/m4/fp_gcc_version.m4
@@ -0,0 +1,27 @@
+# FP_GCC_VERSION
+# -----------
+# Extra testing of the result AC_PROG_CC, testing the gcc version no. Sets the
+# (unsubstituted) output variable GccVersion.
+AC_DEFUN([FP_GCC_VERSION], [
+  AC_REQUIRE([AC_PROG_CC])
+  if test -z "$CC"; then
+    AC_MSG_ERROR([C compiler is required])
+  fi
+
+  if $CC --version | grep -q gcc; then
+    AC_CACHE_CHECK([version of gcc], [fp_cv_gcc_version],
+    [
+        # Be sure only to look at the first occurrence of the "version " string;
+        # Some Apple compilers emit multiple messages containing this string.
+        AC_MSG_CHECKING([version of gcc])
+        fp_cv_gcc_version="`$CC -v 2>&1 | sed -n -e '1,/version /s/.*version [[^0-9]]*\([[0-9.]]*\).*/\1/p'`"
+        AC_MSG_RESULT([$fp_cv_gcc_version])
+        # 4.7 is needed for __atomic_ builtins.
+        FP_COMPARE_VERSIONS([$fp_cv_gcc_version], [-lt], [4.7],
+                            [AC_MSG_ERROR([Need at least gcc version 4.7 (newer recommended)])])
+    ])
+    AC_SUBST([GccVersion], [$fp_cv_gcc_version])
+  else
+    AC_MSG_NOTICE([\$CC is not gcc; assuming it's a reasonably new C compiler])
+  fi
+])# FP_GCC_VERSION
diff --git a/m4/fp_gmp.m4 b/m4/fp_gmp.m4
new file mode 100644
index 0000000000..bbf054910a
--- /dev/null
+++ b/m4/fp_gmp.m4
@@ -0,0 +1,35 @@
+# FP_GMP
+# -------------
+AC_DEFUN([FP_GMP],
+[
+  dnl--------------------------------------------------------------------
+  dnl * Deal with arguments telling us gmp is somewhere odd
+  dnl--------------------------------------------------------------------
+
+  AC_ARG_WITH([gmp-includes],
+    [AS_HELP_STRING([--with-gmp-includes],
+      [directory containing gmp.h])],
+      [GMP_INCLUDE_DIRS=$withval])
+
+  AC_ARG_WITH([gmp-libraries],
+    [AS_HELP_STRING([--with-gmp-libraries],
+      [directory containing gmp library])],
+      [GMP_LIB_DIRS=$withval])
+
+  AC_ARG_WITH([intree-gmp],
+    [AS_HELP_STRING([--with-intree-gmp],
+      [force using the in-tree GMP])],
+      [GMP_FORCE_INTREE=YES],
+      [GMP_FORCE_INTREE=NO])
+
+  AC_ARG_WITH([gmp-framework-preferred],
+    [AS_HELP_STRING([--with-gmp-framework-preferred],
+      [on OSX, prefer the GMP framework to the gmp lib])],
+      [GMP_PREFER_FRAMEWORK=YES],
+      [GMP_PREFER_FRAMEWORK=NO])
+
+  AC_SUBST(GMP_INCLUDE_DIRS)
+  AC_SUBST(GMP_LIB_DIRS)
+  AC_SUBST(GMP_FORCE_INTREE)
+  AC_SUBST(GMP_PREFER_FRAMEWORK)
+])# FP_GMP
diff --git a/m4/fp_iconv.m4 b/m4/fp_iconv.m4
new file mode 100644
index 0000000000..d6322a038b
--- /dev/null
+++ b/m4/fp_iconv.m4
@@ -0,0 +1,25 @@
+# FP_ICONV
+# -------------
+AC_DEFUN([FP_ICONV],
+[
+  dnl--------------------------------------------------------------------
+  dnl * Deal with arguments telling us iconv is somewhere odd
+  dnl--------------------------------------------------------------------
+
+  dnl Note: ICONV_LIB_DIRS and ICONV_INCLUDE_DIRS are not predefined
+  dnl to the empty string to allow them to be overridden from the
+  dnl environment.
+
+  AC_ARG_WITH([iconv-includes],
+    [AS_HELP_STRING([--with-iconv-includes],
+      [directory containing iconv.h])],
+      [ICONV_INCLUDE_DIRS=$withval])
+
+  AC_ARG_WITH([iconv-libraries],
+    [AS_HELP_STRING([--with-iconv-libraries],
+      [directory containing iconv library])],
+      [ICONV_LIB_DIRS=$withval])
+
+  AC_SUBST(ICONV_INCLUDE_DIRS)
+  AC_SUBST(ICONV_LIB_DIRS)
+])# FP_ICONV
diff --git a/m4/fp_leading_underscore.m4 b/m4/fp_leading_underscore.m4
new file mode 100644
index 0000000000..5fac9f9624
--- /dev/null
+++ b/m4/fp_leading_underscore.m4
@@ -0,0 +1,56 @@
+# FP_LEADING_UNDERSCORE
+# ---------------------
+# Test for determining whether symbol names have a leading underscore. We assume
+# that they _haven't_ if anything goes wrong. Sets the output variable
+# LeadingUnderscore to YES or NO and defines LEADING_UNDERSCORE correspondingly.
+#
+# Some nlist implementations seem to try to be compatible by ignoring a leading
+# underscore sometimes (eg. FreeBSD). We therefore have to work around this by
+# checking for *no* leading underscore first. Sigh.  --SDM
+#
+# Similarly on OpenBSD, but this test doesn't help. -- dons
+#
+AC_DEFUN([FP_LEADING_UNDERSCORE],
+[AC_CHECK_LIB([elf], [nlist], [LIBS="-lelf $LIBS"])
+AC_CACHE_CHECK([leading underscore in symbol names], [fptools_cv_leading_underscore], [
+# Hack!: nlist() under Digital UNIX insist on there being an _,
+# but symbol table listings shows none. What is going on here?!?
+case $TargetPlatform in
+    # Apples mach-o platforms use leading underscores
+    *-apple-*) fptools_cv_leading_underscore=yes;;
+    *linux-android*) fptools_cv_leading_underscore=no;;
+    *openbsd*) # x86 openbsd is ELF from 3.4 >, meaning no leading uscore
+      case $build in
+        i386-*2\.@<:@0-9@:>@ | i386-*3\.@<:@0-3@:>@ ) fptools_cv_leading_underscore=yes ;;
+        *) fptools_cv_leading_underscore=no ;;
+      esac ;;
+    i386-unknown-mingw32) fptools_cv_leading_underscore=yes;;
+    x86_64-unknown-mingw32) fptools_cv_leading_underscore=no;;
+    *) AC_RUN_IFELSE([AC_LANG_SOURCE([[#if defined(HAVE_NLIST_H)
+#include <nlist.h>
+struct nlist xYzzY1[] = {{"xYzzY1", 0},{0}};
+struct nlist xYzzY2[] = {{"_xYzzY2", 0},{0}};
+#endif
+
+int main(argc, argv)
+int argc;
+char **argv;
+{
+#if defined(HAVE_NLIST_H)
+    if(nlist(argv[0], xYzzY1) == 0 && xYzzY1[0].n_value != 0)
+        exit(1);
+    if(nlist(argv[0], xYzzY2) == 0 && xYzzY2[0].n_value != 0)
+        exit(0);
+#endif
+    exit(1);
+}]])],[fptools_cv_leading_underscore=yes],[fptools_cv_leading_underscore=no],[fptools_cv_leading_underscore=no])
+;;
+esac]);
+AC_SUBST([LeadingUnderscore], [`echo $fptools_cv_leading_underscore | sed 'y/yesno/YESNO/'`])
+if test x"$fptools_cv_leading_underscore" = xyes; then
+   AC_SUBST([CabalLeadingUnderscore],[True])
+   AC_DEFINE([LEADING_UNDERSCORE], [1], [Define to 1 if C symbols have a leading underscore added by the compiler.])
+else
+   AC_SUBST([CabalLeadingUnderscore],[False])
+fi
+])# FP_LEADING_UNDERSCORE
diff --git a/m4/fp_prog_ar.m4 b/m4/fp_prog_ar.m4
new file mode 100644
index 0000000000..0ad6c694ac
--- /dev/null
+++ b/m4/fp_prog_ar.m4
@@ -0,0 +1,23 @@
+# FP_PROG_AR
+# ----------
+# Sets fp_prog_ar to a path to ar. Exits if no ar can be found
+# The host normalization on Windows breaks autoconf, it no longer
+# thinks that target == host so it never checks the unqualified
+# tools for Windows. See #14274.
+AC_DEFUN([FP_PROG_AR],
+[AC_SUBST(fp_prog_ar,$AR)
+if test -z "$fp_prog_ar"; then
+  if test "$HostOS" = "mingw32"
+  then
+    AC_PATH_PROG([fp_prog_ar], [ar])
+    if test -n "$fp_prog_ar"; then
+      fp_prog_ar=$(cygpath -m $fp_prog_ar)
+    fi
+  else
+    AC_CHECK_TARGET_TOOL([fp_prog_ar], [ar])
+  fi
+fi
+if test -z "$fp_prog_ar"; then
+  AC_MSG_ERROR([cannot find ar in your PATH, no idea how to make a library])
+fi
+])# FP_PROG_AR
diff --git a/m4/fp_prog_ar_args.m4 b/m4/fp_prog_ar_args.m4
new file mode 100644
index 0000000000..c76a67248d
--- /dev/null
+++ b/m4/fp_prog_ar_args.m4
@@ -0,0 +1,36 @@
+# FP_PROG_AR_ARGS
+# ---------------
+# Sets fp_prog_ar_args to the arguments for ar and the output variable ArCmd
+# to an invocation of ar including these arguments.
+AC_DEFUN([FP_PROG_AR_ARGS],
+[AC_REQUIRE([FP_PROG_AR_IS_GNU])
+AC_CACHE_CHECK([for ar arguments], [fp_cv_prog_ar_args],
+[
+# GNU ar needs special treatment: it appears to have problems with
+# object files with the same name if you use the 's' modifier, but
+# simple 'ar q' works fine, and doesn't need a separate ranlib.
+if test $fp_prog_ar_is_gnu = yes; then
+  fp_cv_prog_ar_args="q"
+else
+  touch conftest.dummy
+  for fp_var in qclsZ qcls qcs qcl qc ; do
+     rm -f conftest.a
+     if "$fp_prog_ar" $fp_var conftest.a conftest.dummy > /dev/null 2> /dev/null ; then
+       # Also check that a result was created; it seems some llvm-ar versions
+       # exit with code zero even if they fail to parse the command line.
+       if test -f conftest.a ; then
+         fp_cv_prog_ar_args=$fp_var
+         break
+       fi
+     fi
+  done
+  rm -f conftest*
+  if test -z "$fp_cv_prog_ar_args"; then
+    AC_MSG_ERROR([cannot figure out how to use your $fp_prog_ar])
+  fi
+fi])
+fp_prog_ar_args=$fp_cv_prog_ar_args
+AC_SUBST([ArCmd], ["$fp_prog_ar"])
+AC_SUBST([ArArgs], ["$fp_prog_ar_args"])
+
+])# FP_PROG_AR_ARGS
diff --git a/m4/fp_prog_ar_is_gnu.m4 b/m4/fp_prog_ar_is_gnu.m4
new file mode 100644
index 0000000000..0962f1d7b2
--- /dev/null
+++ b/m4/fp_prog_ar_is_gnu.m4
@@ -0,0 +1,14 @@
+# FP_PROG_AR_IS_GNU
+# -----------------
+# Sets fp_prog_ar_is_gnu to yes or no, depending on whether it is GNU ar or not.
+AC_DEFUN([FP_PROG_AR_IS_GNU],
+[AC_REQUIRE([FP_PROG_AR])
+AC_CACHE_CHECK([whether $fp_prog_ar is GNU ar], [fp_cv_prog_ar_is_gnu],
+[if "$fp_prog_ar" --version 2> /dev/null | grep "GNU" > /dev/null 2>&1; then
+  fp_cv_prog_ar_is_gnu=yes
+else
+  fp_cv_prog_ar_is_gnu=no
+fi])
+fp_prog_ar_is_gnu=$fp_cv_prog_ar_is_gnu
+AC_SUBST([ArIsGNUAr], [`echo $fp_prog_ar_is_gnu | tr 'a-z' 'A-Z'`])
+])# FP_PROG_AR_IS_GNU
diff --git a/m4/fp_prog_ar_needs_ranlib.m4 b/m4/fp_prog_ar_needs_ranlib.m4
new file mode 100644
index 0000000000..e9882951fe
--- /dev/null
+++ b/m4/fp_prog_ar_needs_ranlib.m4
@@ -0,0 +1,49 @@
+# FP_PROG_AR_NEEDS_RANLIB
+# -----------------------
+# Sets the output variable RANLIB_CMD to "ranlib" if it is needed and
+# found, to "true" otherwise. Sets REAL_RANLIB_CMD to the ranlib program,
+# even if we don't need ranlib (libffi might still need it).
+AC_DEFUN([FP_PROG_AR_NEEDS_RANLIB],[
+    AC_REQUIRE([FP_PROG_AR_IS_GNU])
+    AC_REQUIRE([FP_PROG_AR_ARGS])
+    AC_REQUIRE([AC_PROG_CC])
+
+    AC_PROG_RANLIB
+
+    if test $fp_prog_ar_is_gnu = yes
+    then
+        fp_cv_prog_ar_needs_ranlib=no
+    elif test "$TargetVendor_CPP" = "apple"
+    then
+        # It's quite tedious to check for Apple's crazy timestamps in
+        # .a files, so we hardcode it.
+        fp_cv_prog_ar_needs_ranlib=yes
+    else
+        case $fp_prog_ar_args in
+        *s*)
+            fp_cv_prog_ar_needs_ranlib=no;;
+        *)
+            fp_cv_prog_ar_needs_ranlib=yes;;
+        esac
+    fi
+
+    # workaround for AC_PROG_RANLIB which sets RANLIB to `:' when
+    # ranlib is missing on the target OS. The problem is that
+    # ghc-cabal cannot execute `:' which is a shell built-in but can
+    # execute `true' which is usually simple program supported by the
+    # OS.
+    # Fixes #8795
+    if test "$RANLIB" = ":"
+    then
+        RANLIB="true"
+    fi
+    REAL_RANLIB_CMD="$RANLIB"
+    if test $fp_cv_prog_ar_needs_ranlib = yes
+    then
+        RANLIB_CMD="$RANLIB"
+    else
+        RANLIB_CMD="true"
+    fi
+    AC_SUBST([REAL_RANLIB_CMD])
+    AC_SUBST([RANLIB_CMD])
+])# FP_PROG_AR_NEEDS_RANLIB
diff --git a/m4/fp_prog_ar_supports_atfile.m4 b/m4/fp_prog_ar_supports_atfile.m4
new file mode 100644
index 0000000000..b6c4a12c50
--- /dev/null
+++ b/m4/fp_prog_ar_supports_atfile.m4
@@ -0,0 +1,26 @@
+# FP_PROG_AR_SUPPORTS_ATFILE
+# -----------------
+# Sets fp_prog_ar_supports_atfile to yes or no, depending on whether
+# or not it supports the @file syntax
+AC_DEFUN([FP_PROG_AR_SUPPORTS_ATFILE],
+[AC_REQUIRE([FP_PROG_AR])
+ AC_REQUIRE([FP_PROG_AR_ARGS])
+AC_CACHE_CHECK([whether $fp_prog_ar supports @file], [fp_cv_prog_ar_supports_atfile],
+[
+rm -f conftest*
+touch conftest.file
+echo conftest.file  > conftest.atfile
+echo conftest.file >> conftest.atfile
+"$fp_prog_ar" $fp_prog_ar_args conftest.a @conftest.atfile > /dev/null 2>&1
+fp_prog_ar_supports_atfile_tmp=`"$fp_prog_ar" t conftest.a 2> /dev/null | grep -c conftest.file`
+rm -f conftest*
+if test "$fp_prog_ar_supports_atfile_tmp" -eq 2
+then
+  fp_cv_prog_ar_supports_atfile=yes
+else
+  fp_cv_prog_ar_supports_atfile=no
+fi])
+fp_prog_ar_supports_atfile=$fp_cv_prog_ar_supports_atfile
+AC_SUBST([ArSupportsAtFile], [`echo $fp_prog_ar_supports_atfile | tr 'a-z' 'A-Z'`])
+])# FP_PROG_AR_SUPPORTS_ATFILE
+
diff --git a/m4/fp_prog_context_diff.m4 b/m4/fp_prog_context_diff.m4
new file mode 100644
index 0000000000..886f73ce4c
--- /dev/null
+++ b/m4/fp_prog_context_diff.m4
@@ -0,0 +1,23 @@
+# FP_PROG_CONTEXT_DIFF
+# --------------------
+# Figure out how to do context diffs. Sets the output variable ContextDiffCmd.
+#
+# Note: NeXTStep thinks diff'ing a file against itself is "trouble".
+AC_DEFUN([FP_PROG_CONTEXT_DIFF],
+[AC_CACHE_CHECK([for a working context diff], [fp_cv_context_diff],
+[echo foo > conftest1
+echo foo > conftest2
+fp_cv_context_diff=no
+for fp_var in '-U 1' '-u1' '-C 1' '-c1'
+do
+  if diff $fp_var conftest1 conftest2 > /dev/null 2>&1; then
+    fp_cv_context_diff="diff $fp_var"
+    break
+  fi
+done])
+if test x"$fp_cv_context_diff" = xno; then
+   AC_MSG_ERROR([cannot figure out how to do context diffs])
+fi
+AC_SUBST(ContextDiffCmd, [$fp_cv_context_diff])
+])# FP_PROG_CONTEXT_DIFF
+
diff --git a/m4/fp_prog_find.m4 b/m4/fp_prog_find.m4
new file mode 100644
index 0000000000..77f4fbf5cc
--- /dev/null
+++ b/m4/fp_prog_find.m4
@@ -0,0 +1,18 @@
+# FP_PROG_FIND
+# ------------
+# Find a non-WinDoze version of the "find" utility.
+AC_DEFUN([FP_PROG_FIND],
+[AC_PATH_PROGS([fp_prog_find], [gfind find], find)
+echo foo > conftest.txt
+$fp_prog_find conftest.txt -print > conftest.out 2>&1
+if grep '^conftest.txt$' conftest.out > /dev/null 2>&1 ; then
+  # OK, looks like a real "find".
+  FindCmd="$fp_prog_find"
+else
+  # Found a poor WinDoze version of "find", ignore it.
+  AC_MSG_WARN([$fp_prog_find looks like a non-*nix find, ignoring it])
+  FP_CHECK_PROG([FindCmd], [find], [], [], [$fp_prog_find])
+fi
+rm -f conftest.txt conftest.out
+AC_SUBST([FindCmd])[]dnl
+])# FP_PROG_FIND
diff --git a/m4/fp_prog_ghc_pkg.m4 b/m4/fp_prog_ghc_pkg.m4
new file mode 100644
index 0000000000..72e8c05997
--- /dev/null
+++ b/m4/fp_prog_ghc_pkg.m4
@@ -0,0 +1,21 @@
+# FP_PROG_GHC_PKG
+# ----------------
+# Try to find a ghc-pkg matching the ghc mentioned in the environment variable
+# WithGhc. Sets the output variable GhcPkgCmd.
+AC_DEFUN([FP_PROG_GHC_PKG],
+[AC_CACHE_CHECK([for ghc-pkg matching $WithGhc], fp_cv_matching_ghc_pkg,
+[
+# If we are told to use ghc-stage2, then we're using an in-tree
+# compiler. In this case, we just want ghc-pkg, not ghc-pkg-stage2,
+# so we sed off -stage[0-9]$. However, if we are told to use
+# ghc-6.12.1 then we want to use ghc-pkg-6.12.1, so we keep any
+# other suffix.
+fp_ghc_pkg_guess=`echo "$WithGhc" | sed -e 's/-stage@<:@0-9@:>@$//' -e 's,ghc\(@<:@^/\\@:>@*\)$,ghc-pkg\1,'`
+if "$fp_ghc_pkg_guess" list > /dev/null 2>&1; then
+  fp_cv_matching_ghc_pkg=$fp_ghc_pkg_guess
+else
+  AC_MSG_ERROR([Cannot find matching ghc-pkg])
+fi])
+GhcPkgCmd=$fp_cv_matching_ghc_pkg
+AC_SUBST([GhcPkgCmd])
+])# FP_PROG_GHC_PKG
diff --git a/m4/fp_prog_ld_build_id.m4 b/m4/fp_prog_ld_build_id.m4
new file mode 100644
index 0000000000..7260bd4529
--- /dev/null
+++ b/m4/fp_prog_ld_build_id.m4
@@ -0,0 +1,24 @@
+# FP_PROG_LD_BUILD_ID
+# ------------
+# Sets the output variable LdHasBuildId to YES if ld supports
+# --build-id, or NO otherwise.
+AC_DEFUN([FP_PROG_LD_BUILD_ID],
+[
+AC_CACHE_CHECK([whether ld understands --build-id], [fp_cv_ld_build_id],
+[echo 'int foo() { return 0; }' > conftest.c
+${CC-cc} -c conftest.c
+if ${LdCmd} -r --build-id=none -o conftest2.o conftest.o > /dev/null 2>&1; then
+   fp_cv_ld_build_id=yes
+else
+   fp_cv_ld_build_id=no
+fi
+rm -rf conftest*])
+if test "$fp_cv_ld_build_id" = yes; then
+  LdHasBuildId=YES
+else
+  LdHasBuildId=NO
+fi
+AC_SUBST([LdHasBuildId])
+])# FP_PROG_LD_BUILD_ID
+
+
diff --git a/m4/fp_prog_ld_filelist.m4 b/m4/fp_prog_ld_filelist.m4
new file mode 100644
index 0000000000..60e206baa4
--- /dev/null
+++ b/m4/fp_prog_ld_filelist.m4
@@ -0,0 +1,29 @@
+# FP_PROG_LD_FILELIST
+# -------------------
+# Sets the output variable LdHasFilelist to YES if ld supports
+# -filelist, or NO otherwise.
+AC_DEFUN([FP_PROG_LD_FILELIST],
+[
+AC_CACHE_CHECK([whether ld understands -filelist], [fp_cv_ld_has_filelist],
+[
+    echo 'int foo() { return 0; }' > conftest1.c
+    echo 'int bar() { return 0; }' > conftest2.c
+    ${CC-cc} -c conftest1.c
+    ${CC-cc} -c conftest2.c
+    echo conftest1.o  > conftest.o-files
+    echo conftest2.o >> conftest.o-files
+    if ${LdCmd} -r -filelist conftest.o-files -o conftest.o > /dev/null 2>&1
+    then
+        fp_cv_ld_has_filelist=yes
+    else
+        fp_cv_ld_has_filelist=no
+    fi
+    rm -rf conftest*
+])
+if test "$fp_cv_ld_has_filelist" = yes; then
+    LdHasFilelist=YES
+else
+    LdHasFilelist=NO
+fi
+AC_SUBST([LdHasFilelist])
+])# FP_PROG_LD_FILELIST
diff --git a/m4/fp_prog_ld_flag.m4 b/m4/fp_prog_ld_flag.m4
new file mode 100644
index 0000000000..8617d7ceb3
--- /dev/null
+++ b/m4/fp_prog_ld_flag.m4
@@ -0,0 +1,17 @@
+# FP_PROG_LD_FLAG
+# ---------------
+# Sets the output variable $2 to $1 if ld supports the $1 flag.
+# Otherwise the variable's value is empty.
+AC_DEFUN([FP_PROG_LD_FLAG],
+[
+AC_CACHE_CHECK([whether ld understands $1], [fp_cv_$2],
+[echo 'int foo() { return 0; }' > conftest.c
+${CC-cc} -c conftest.c
+if ${LdCmd} -r $1 -o conftest2.o conftest.o > /dev/null 2>&1; then
+   fp_cv_$2=$1
+else
+   fp_cv_$2=
+fi
+rm -rf conftest*])
+$2=$fp_cv_$2
+])# FP_PROG_LD_FLAG
diff --git a/m4/fp_prog_ld_is_gnu.m4 b/m4/fp_prog_ld_is_gnu.m4
new file mode 100644
index 0000000000..90f6d5fcda
--- /dev/null
+++ b/m4/fp_prog_ld_is_gnu.m4
@@ -0,0 +1,13 @@
+# FP_PROG_LD_IS_GNU
+# -----------------
+# Sets the output variable LdIsGNULd to YES or NO, depending on whether it is
+# GNU ld or not.
+AC_DEFUN([FP_PROG_LD_IS_GNU],[
+AC_CACHE_CHECK([whether ld is GNU ld], [fp_cv_gnu_ld],
+[[if ${LdCmd} --version 2> /dev/null | grep "GNU" > /dev/null 2>&1; then
+  fp_cv_gnu_ld=YES
+else
+  fp_cv_gnu_ld=NO
+fi]])
+AC_SUBST([LdIsGNULd],["$fp_cv_gnu_ld"])
+])# FP_PROG_LD_IS_GNU
diff --git a/m4/fp_prog_ld_no_compact_unwind.m4 b/m4/fp_prog_ld_no_compact_unwind.m4
new file mode 100644
index 0000000000..152037658d
--- /dev/null
+++ b/m4/fp_prog_ld_no_compact_unwind.m4
@@ -0,0 +1,22 @@
+# FP_PROG_LD_NO_COMPACT_UNWIND
+# ----------------------------
+# Sets the output variable LdHasNoCompactUnwind to YES if ld supports
+# -no_compact_unwind, or NO otherwise.
+AC_DEFUN([FP_PROG_LD_NO_COMPACT_UNWIND],
+[
+AC_CACHE_CHECK([whether ld understands -no_compact_unwind], [fp_cv_ld_no_compact_unwind],
+[echo 'int foo() { return 0; }' > conftest.c
+${CC-cc} -c conftest.c
+if ${LdCmd} -r -no_compact_unwind -o conftest2.o conftest.o > /dev/null 2>&1; then
+   fp_cv_ld_no_compact_unwind=yes
+else
+   fp_cv_ld_no_compact_unwind=no
+fi
+rm -rf conftest*])
+if test "$fp_cv_ld_no_compact_unwind" = yes; then
+  LdHasNoCompactUnwind=YES
+else
+  LdHasNoCompactUnwind=NO
+fi
+AC_SUBST([LdHasNoCompactUnwind])
+])# FP_PROG_LD_NO_COMPACT_UNWIND
diff --git a/m4/fp_prog_sort.m4 b/m4/fp_prog_sort.m4
new file mode 100644
index 0000000000..699ed15247
--- /dev/null
+++ b/m4/fp_prog_sort.m4
@@ -0,0 +1,18 @@
+# FP_PROG_SORT
+# ------------
+# Find a Unix-like sort
+AC_DEFUN([FP_PROG_SORT],
+[AC_PATH_PROG([fp_prog_sort], [sort])
+echo conwip > conftest.txt
+$fp_prog_sort -f conftest.txt > conftest.out 2>&1
+if grep 'conwip' conftest.out > /dev/null 2>&1 ; then
+  # The goods
+  SortCmd="$fp_prog_sort"
+else
+  # Summink else..pick next one.
+  AC_MSG_WARN([$fp_prog_sort looks like a non-*nix sort, ignoring it])
+  FP_CHECK_PROG([SortCmd], [sort], [], [], [$fp_prog_sort])
+fi
+rm -f conftest.txt conftest.out
+AC_SUBST([SortCmd])[]dnl
+])# FP_PROG_SORT
diff --git a/m4/fp_set_cflags_c99.m4 b/m4/fp_set_cflags_c99.m4
new file mode 100644
index 0000000000..b9644efe66
--- /dev/null
+++ b/m4/fp_set_cflags_c99.m4
@@ -0,0 +1,38 @@
+# FP_SET_CFLAGS_C99
+# ----------------------------------
+# figure out which CFLAGS are needed to place the compiler into C99 mode
+# $1 is name of CC variable (unmodified)
+# $2 is name of CC flags variable (augmented if needed)
+# $3 is name of CPP flags variable (augmented if needed)
+AC_DEFUN([FP_SET_CFLAGS_C99],
+[
+    dnl save current state of AC_PROG_CC_C99
+    FP_COPY_SHELLVAR([CC],[fp_save_CC])
+    FP_COPY_SHELLVAR([CFLAGS],[fp_save_CFLAGS])
+    FP_COPY_SHELLVAR([CPPFLAGS],[fp_save_CPPFLAGS])
+    FP_COPY_SHELLVAR([ac_cv_prog_cc_c99],[fp_save_cc_c99])
+    dnl set local state
+    CC="$$1"
+    CFLAGS="$$2"
+    CPPFLAGS="$$3"
+    unset ac_cv_prog_cc_c99
+    dnl perform detection
+    AC_PROG_CC_C99
+    fp_cc_c99="$ac_cv_prog_cc_c99"
+    case "x$ac_cv_prog_cc_c99" in
+      x)   ;; # noop
+      xno) AC_MSG_ERROR([C99-compatible compiler needed]) ;;
+      *)   $2="$$2 $ac_cv_prog_cc_c99"
+           $3="$$3 $ac_cv_prog_cc_c99"
+           ;;
+    esac
+    dnl restore saved state
+    FP_COPY_SHELLVAR([fp_save_CC],[CC])
+    FP_COPY_SHELLVAR([fp_save_CFLAGS],[CFLAGS])
+    FP_COPY_SHELLVAR([fp_save_CPPFLAGS],[CPPFLAGS])
+    FP_COPY_SHELLVAR([fp_save_cc_c99],[ac_cv_prog_cc_c99])
+    dnl cleanup
+    unset fp_save_CC
+    unset fp_save_CFLAGS
+    unset fp_save_cc_c99
+])
diff --git a/m4/fp_settings.m4 b/m4/fp_settings.m4
new file mode 100644
index 0000000000..09a24f33e1
--- /dev/null
+++ b/m4/fp_settings.m4
@@ -0,0 +1,125 @@
+# FP_SETTINGS
+# ----------------------------------
+# Set the variables used in the settings file
+# See Note [tooldir: How GHC finds mingw on Windows]
+AC_DEFUN([FP_SETTINGS],
+[
+    if test "$windows" = YES -a "$EnableDistroToolchain" = "NO"
+    then
+        mingw_bin_prefix='$$tooldir/mingw/bin/'
+        SettingsCCompilerCommand="${mingw_bin_prefix}gcc.exe"
+        SettingsHaskellCPPCommand="${mingw_bin_prefix}gcc.exe"
+        SettingsHaskellCPPFlags="$HaskellCPPArgs"
+        SettingsLdCommand="${mingw_bin_prefix}ld.exe"
+        # Overrides FIND_MERGE_OBJECTS in order to avoid hard-coding linker
+        # path on Windows (#18550).
+        SettingsMergeObjectsCommand="${SettingsLdCommand}"
+        SettingsMergeObjectsFlags="-r --oformat=pe-bigobj-x86-64"
+        SettingsArCommand="${mingw_bin_prefix}ar.exe"
+        SettingsRanlibCommand="${mingw_bin_prefix}ranlib.exe"
+        SettingsDllWrapCommand="${mingw_bin_prefix}dllwrap.exe"
+        SettingsWindresCommand="${mingw_bin_prefix}windres.exe"
+        SettingsTouchCommand='$$topdir/bin/touchy.exe'
+    elif test "$EnableDistroToolchain" = "YES"
+    then
+        SettingsCCompilerCommand="$(basename $CC)"
+        SettingsCCompilerFlags="$CONF_CC_OPTS_STAGE2"
+        SettingsCxxCompilerFlags="$CONF_CXX_OPTS_STAGE2"
+        SettingsHaskellCPPCommand="$(basename $HaskellCPPCmd)"
+        SettingsHaskellCPPFlags="$HaskellCPPArgs"
+        SettingsLdCommand="$(basename $LdCmd)"
+        SettingsMergeObjectsCommand="$(basename $MergeObjsCmd)"
+        SettingsMergeObjectsFlags="$MergeObjsArgs"
+        SettingsArCommand="$(basename $ArCmd)"
+        SettingsDllWrapCommand="$(basename $DllWrapCmd)"
+        SettingsWindresCommand="$(basename $WindresCmd)"
+        SettingsTouchCommand='$$topdir/bin/touchy.exe'
+    else
+        SettingsCCompilerCommand="$CC"
+        SettingsHaskellCPPCommand="$HaskellCPPCmd"
+        SettingsHaskellCPPFlags="$HaskellCPPArgs"
+        SettingsLdCommand="$LdCmd"
+        SettingsMergeObjectsCommand="$MergeObjsCmd"
+        SettingsMergeObjectsFlags="$MergeObjsArgs"
+        SettingsArCommand="$ArCmd"
+        SettingsRanlibCommand="$RanlibCmd"
+        if test -z "$DllWrapCmd"
+        then
+            SettingsDllWrapCommand="/bin/false"
+        else
+            SettingsDllWrapCommand="$DllWrapCmd"
+        fi
+        if test -z "$WindresCmd"
+        then
+            SettingsWindresCommand="/bin/false"
+        else
+            SettingsWindresCommand="$WindresCmd"
+        fi
+       SettingsTouchCommand='touch'
+    fi
+    if test -z "$LibtoolCmd"
+    then
+      SettingsLibtoolCommand="libtool"
+    else
+      SettingsLibtoolCommand="$LibtoolCmd"
+    fi
+    if test -z "$ClangCmd"
+    then
+        SettingsClangCommand="clang"
+    else
+        SettingsClangCommand="$ClangCmd"
+    fi
+    if test -z "$LlcCmd"
+    then
+      SettingsLlcCommand="llc"
+    else
+      SettingsLlcCommand="$LlcCmd"
+    fi
+    if test -z "$OptCmd"
+    then
+      SettingsOptCommand="opt"
+    else
+      SettingsOptCommand="$OptCmd"
+    fi
+    if test -z "$OtoolCmd"
+    then
+      SettingsOtoolCommand="otool"
+    else
+      SettingsOtoolCommand="$OtoolCmd"
+    fi
+    if test -z "$InstallNameToolCmd"
+    then
+      SettingsInstallNameToolCommand="install_name_tool"
+    else
+      SettingsInstallNameToolCommand="$InstallNameToolCmd"
+    fi
+    SettingsCCompilerFlags="$CONF_CC_OPTS_STAGE2"
+    SettingsCxxCompilerFlags="$CONF_CXX_OPTS_STAGE2"
+    SettingsCCompilerLinkFlags="$CONF_GCC_LINKER_OPTS_STAGE2"
+    SettingsCCompilerSupportsNoPie="$CONF_GCC_SUPPORTS_NO_PIE"
+    SettingsLdFlags="$CONF_LD_LINKER_OPTS_STAGE2"
+    SettingsUseDistroMINGW="$EnableDistroToolchain"
+    AC_SUBST(SettingsCCompilerCommand)
+    AC_SUBST(SettingsHaskellCPPCommand)
+    AC_SUBST(SettingsHaskellCPPFlags)
+    AC_SUBST(SettingsCCompilerFlags)
+    AC_SUBST(SettingsCxxCompilerFlags)
+    AC_SUBST(SettingsCCompilerLinkFlags)
+    AC_SUBST(SettingsCCompilerSupportsNoPie)
+    AC_SUBST(SettingsLdCommand)
+    AC_SUBST(SettingsLdFlags)
+    AC_SUBST(SettingsMergeObjectsCommand)
+    AC_SUBST(SettingsMergeObjectsFlags)
+    AC_SUBST(SettingsArCommand)
+    AC_SUBST(SettingsRanlibCommand)
+    AC_SUBST(SettingsOtoolCommand)
+    AC_SUBST(SettingsInstallNameToolCommand)
+    AC_SUBST(SettingsDllWrapCommand)
+    AC_SUBST(SettingsWindresCommand)
+    AC_SUBST(SettingsLibtoolCommand)
+    AC_SUBST(SettingsTouchCommand)
+    AC_SUBST(SettingsClangCommand)
+    AC_SUBST(SettingsLlcCommand)
+    AC_SUBST(SettingsOptCommand)
+    AC_SUBST(SettingsUseDistroMINGW)
+])
diff --git a/m4/fp_setup_project_version.m4 b/m4/fp_setup_project_version.m4
new file mode 100644
index 0000000000..26df01865b
--- /dev/null
+++ b/m4/fp_setup_project_version.m4
@@ -0,0 +1,102 @@
+# FP_SETUP_PROJECT_VERSION
+# ---------------------
+AC_DEFUN([FP_SETUP_PROJECT_VERSION],
+[
+    if test "$RELEASE" = "NO"; then
+        AC_MSG_CHECKING([for GHC version date])
+        if test -f VERSION_DATE; then
+            PACKAGE_VERSION=${PACKAGE_VERSION}.`cat VERSION_DATE`
+            AC_MSG_RESULT(given $PACKAGE_VERSION)
+        elif test -e .git; then
+            changequote(, )dnl
+            ver_posixtime=`git log -1 --pretty=format:%ct`
+            ver_date=`perl -MPOSIX -e "print strftime('%Y%m%d', gmtime($ver_posixtime));"`
+            if echo $ver_date | grep '^[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]$' 2>&1 >/dev/null; then true; else
+            changequote([, ])dnl
+                    AC_MSG_ERROR([failed to detect version date: check that git and perl are in your path])
+            fi
+            PACKAGE_VERSION=${PACKAGE_VERSION}.$ver_date
+            AC_MSG_RESULT(inferred $PACKAGE_VERSION)
+        elif test -f VERSION; then
+            PACKAGE_VERSION=`cat VERSION`
+            AC_MSG_RESULT(given $PACKAGE_VERSION)
+        else
+            AC_MSG_WARN([cannot determine snapshot version: no .git directory and no VERSION file])
+            dnl We'd really rather this case didn't happen, but it might
+            dnl do (in particular, people using lndir trees may find that
+            dnl the build system can't find any other date). If it does
+            dnl happen, then we use the current date.
+            dnl This way we get some idea about how recent a build is.
+            dnl It also means that packages built for 2 different builds
+            dnl will probably use different version numbers, so things are
+            dnl less likely to go wrong.
+            PACKAGE_VERSION=${PACKAGE_VERSION}.`date +%Y%m%d`
+        fi
+    fi
+
+    AC_MSG_CHECKING([for GHC Git commit id])
+    if test -e .git; then
+        git_commit_id=`git rev-parse HEAD`
+        if test -n "$git_commit_id" 2>&1 >/dev/null; then true; else
+            AC_MSG_ERROR([failed to detect revision: check that git is in your path])
+        fi
+        PACKAGE_GIT_COMMIT_ID=$git_commit_id
+        AC_MSG_RESULT(inferred $PACKAGE_GIT_COMMIT_ID)
+    elif test -f GIT_COMMIT_ID; then
+        PACKAGE_GIT_COMMIT_ID=`cat GIT_COMMIT_ID`
+        AC_MSG_RESULT(given $PACKAGE_GIT_COMMIT_ID)
+    else
+        AC_MSG_WARN([cannot determine snapshot revision: no .git directory and no 'GIT_COMMIT_ID' file])
+        PACKAGE_GIT_COMMIT_ID="0000000000000000000000000000000000000000"
+    fi
+
+
+    # Some renamings
+    AC_SUBST([ProjectName], [$PACKAGE_NAME])
+    AC_SUBST([ProjectVersion], [$PACKAGE_VERSION])
+    AC_SUBST([ProjectGitCommitId], [$PACKAGE_GIT_COMMIT_ID])
+
+    # Split PACKAGE_VERSION into (possibly empty) parts
+    VERSION_MAJOR=`echo $PACKAGE_VERSION | sed 's/^\(@<:@^.@:>@*\)\(\.\{0,1\}\(.*\)\)$/\1'/`
+    VERSION_TMP=`echo $PACKAGE_VERSION | sed 's/^\(@<:@^.@:>@*\)\(\.\{0,1\}\(.*\)\)$/\3'/`
+    VERSION_MINOR=`echo $VERSION_TMP | sed 's/^\(@<:@^.@:>@*\)\(\.\{0,1\}\(.*\)\)$/\1'/`
+    ProjectPatchLevel=`echo $VERSION_TMP | sed 's/^\(@<:@^.@:>@*\)\(\.\{0,1\}\(.*\)\)$/\3'/`
+
+    # Calculate project version as an integer, using 2 digits for minor version
+    case $VERSION_MINOR in
+      ?) ProjectVersionInt=${VERSION_MAJOR}0${VERSION_MINOR} ;;
+      ??) ProjectVersionInt=${VERSION_MAJOR}${VERSION_MINOR} ;;
+      *) AC_MSG_ERROR([bad minor version in $PACKAGE_VERSION]) ;;
+    esac
+    AC_SUBST([ProjectVersionInt])
+
+    # The project patchlevel is zero unless stated otherwise
+    test -z "$ProjectPatchLevel" && ProjectPatchLevel=0
+
+    # Save split version of ProjectPatchLevel
+    ProjectPatchLevel1=`echo $ProjectPatchLevel | sed 's/^\(@<:@^.@:>@*\)\(\.\{0,1\}\(.*\)\)$/\1/'`
+    ProjectPatchLevel2=`echo $ProjectPatchLevel | sed 's/^\(@<:@^.@:>@*\)\(\.\{0,1\}\(.*\)\)$/\3/'`
+
+    AC_SUBST([ProjectPatchLevel1])
+    AC_SUBST([ProjectPatchLevel2])
+
+    # Remove dots from the patch level; this allows us to have versions like 6.4.1.20050508
+    ProjectPatchLevel=`echo $ProjectPatchLevel | sed 's/\.//'`
+
+    AC_SUBST([ProjectPatchLevel])
+
+    # The version of the GHC package changes every day, since the
+    # patchlevel is the current date.  We don't want to force
+    # recompilation of the entire compiler when this happens, so for
+    # GHC HEAD we omit the patchlevel from the package version number.
+    #
+    # The ProjectPatchLevel1 > 20000000 iff GHC HEAD. If it's for a stable
+    # release like 7.10.1 or for a release candidate such as 7.10.1.20141224
+    # then we don't omit the patchlevel components.
+
+    ProjectVersionMunged="$ProjectVersion"
+    if test "$ProjectPatchLevel1" -gt 20000000; then
+      ProjectVersionMunged="${VERSION_MAJOR}.${VERSION_MINOR}"
+    fi
+    AC_SUBST([ProjectVersionMunged])
+])# FP_SETUP_PROJECT_VERSION
diff --git a/m4/fp_visibility_hidden.m4 b/m4/fp_visibility_hidden.m4
new file mode 100644
index 0000000000..5f5cebeeec
--- /dev/null
+++ b/m4/fp_visibility_hidden.m4
@@ -0,0 +1,16 @@
+# FP_VISIBILITY_HIDDEN
+# ----------------------------------
+# Is the visibility hidden attribute supported?
+AC_DEFUN([FP_VISIBILITY_HIDDEN],
+[
+    AC_MSG_CHECKING([whether __attribute__((visibility("hidden"))) is supported])
+    echo '__attribute__((visibility("hidden"))) void foo(void) {}' > conftest.c
+    if $CC -Wall -Werror -c conftest.c > /dev/null 2>&1
+    then
+        AC_MSG_RESULT([yes])
+        AC_DEFINE(HAS_VISIBILITY_HIDDEN, 1, [Has visibility hidden])
+    else
+        AC_MSG_RESULT([no])
+    fi
+    rm -f conftest.c conftest.o
+])
diff --git a/m4/fptools_alex.m4 b/m4/fptools_alex.m4
new file mode 100644
index 0000000000..527ee1e187
--- /dev/null
+++ b/m4/fptools_alex.m4
@@ -0,0 +1,33 @@
+dnl
+dnl Check for Alex and version.
+dnl
+dnl 1. Use alex specified in env var ALEX
+dnl 2. Find alex in path
+dnl 3. Check alex version
+dnl
+dnl If you increase the minimum version requirement, please also update:
+dnl https://gitlab.haskell.org/ghc/ghc/wikis/building/preparation/tools
+dnl
+AC_DEFUN([FPTOOLS_ALEX],
+[AC_PATH_PROG(ALEX,[alex],)
+AC_SUBST(AlexCmd,$ALEX)
+AC_CACHE_CHECK([for version of alex], fptools_cv_alex_version,
+changequote(, )dnl
+[if test x"$AlexCmd" != x; then
+   fptools_cv_alex_version=`"$AlexCmd" -v |
+              grep 'Alex [Vv]ersion' | sed -e 's/Alex [Vv]ersion \([0-9\.]*\).*/\1/g'` ;
+else
+   fptools_cv_alex_version="";
+fi;
+changequote([, ])dnl
+])
+if test ! -f compiler/GHC/Parser/Lexer.hs || test ! -f compiler/GHC/Cmm/Lexer.hs
+then
+    FP_COMPARE_VERSIONS([$fptools_cv_alex_version],[-lt],[3.2.6],
+      [AC_MSG_ERROR([Alex >= 3.2.6 && < 4 is required to compile GHC.])])[]
+    FP_COMPARE_VERSIONS([$fptools_cv_alex_version],[-ge],[4.0.0],
+      [AC_MSG_ERROR([Alex >= 3.2.6 && < 4 is required to compile GHC.])])[]
+fi
+AlexVersion=$fptools_cv_alex_version;
+AC_SUBST(AlexVersion)
+])
diff --git a/m4/fptools_float_word_order_bigendian.m4 b/m4/fptools_float_word_order_bigendian.m4
new file mode 100644
index 0000000000..c7dea385de
--- /dev/null
+++ b/m4/fptools_float_word_order_bigendian.m4
@@ -0,0 +1,25 @@
+# FPTOOLS_FLOAT_WORD_ORDER_BIGENDIAN
+# ----------------------------------
+# Little endian ARM on Linux with some ABIs has big endian word order
+# in doubles. Define FLOAT_WORDS_BIGENDIAN if this is the case.
+AC_DEFUN([FPTOOLS_FLOAT_WORD_ORDER_BIGENDIAN],
+  [AC_CACHE_CHECK([whether float word order is big endian], [fptools_cv_float_word_order_bigendian],
+    [AC_COMPILE_IFELSE(
+      [AC_LANG_PROGRAM(
+        [#include <endian.h>],
+        [#if defined(__FLOAT_WORD_ORDER) && __FLOAT_WORD_ORDER == BIG_ENDIAN
+             return 0;
+         #else
+             not float word order big endian
+         #endif]
+      )],
+      [fptools_cv_float_word_order_bigendian=yes],
+      [fptools_cv_float_word_order_bigendian=no])
+    ])
+  case $fptools_cv_float_word_order_bigendian in
+      yes)
+          AC_DEFINE([FLOAT_WORDS_BIGENDIAN], 1,
+          [Define to 1 if your processor stores words of floats with
+           the most significant byte first]) ;;
+  esac
+])
diff --git a/m4/fptools_ghc_version.m4 b/m4/fptools_ghc_version.m4
new file mode 100644
index 0000000000..3654d382d6
--- /dev/null
+++ b/m4/fptools_ghc_version.m4
@@ -0,0 +1,49 @@
+dnl
+dnl FPTOOLS_GHC_VERSION(version)
+dnl FPTOOLS_GHC_VERSION(major, minor [, patchlevel])
+dnl FPTOOLS_GHC_VERSION(version, major, minor, patchlevel)
+dnl
+dnl Test for version of installed ghc.  Uses $GHC.
+dnl [original version pinched from c2hs]
+dnl
+AC_DEFUN([FPTOOLS_GHC_VERSION],
+[FPTOOLS_NOCACHE_CHECK([version of ghc], [fptools_version_of_ghc],
+["${WithGhc-ghc}" --version > conftestghc 2>&1
+  cat conftestghc >&AS_MESSAGE_LOG_FD
+#Useless Use Of cat award...
+  fptools_version_of_ghc=`cat conftestghc | sed -n -e 's/, patchlevel *\([[0-9]]\)/.\1/;s/.* version \([[0-9]][[0-9.]]*\).*/\1/p'`
+  rm -fr conftest*
+  if test "[$]fptools_version_of_ghc" = ""
+  then
+    fptools_version_of_ghc='unknown'
+  fi
+fptools_version_of_ghc[_major]=`echo [$]fptools_version_of_ghc | sed -e 's/^\([[0-9]]\).*/\1/'`
+fptools_version_of_ghc[_minor]=`echo [$]fptools_version_of_ghc | sed -e 's/^[[0-9]]\.\([[0-9]]*\).*/\1/'`
+fptools_version_of_ghc[_pl]=`echo [$]fptools_version_of_ghc | sed -n -e 's/^[[0-9]]\.[[0-9]]*\.\([[0-9]]*\)/\1/p'`
+#
+if test "[$]fptools_version_of_ghc[_pl]" = ""
+then
+  fptools_version_of_ghc[_all]="[$]fptools_version_of_ghc[_major].[$]fptools_version_of_ghc[_minor]"
+  fptools_version_of_ghc[_pl]="0"
+else
+  fptools_version_of_ghc[_all]="[$]fptools_version_of_ghc[_major].[$]fptools_version_of_ghc[_minor].[$]fptools_version_of_ghc[_pl]"
+fi
+#
+ifelse($#, [1], [dnl
+[$1]="[$]fptools_version_of_ghc[_all]"
+], $#, [2], [dnl
+[$1]="[$]fptools_version_of_ghc[_major]"
+[$2]="[$]fptools_version_of_ghc[_minor]"
+], $#, [3], [dnl
+[$1]="[$]fptools_version_of_ghc[_major]"
+[$2]="[$]fptools_version_of_ghc[_minor]"
+[$3]="[$]fptools_version_of_ghc[_pl]"
+], $#, [4], [dnl
+[$1]="[$]fptools_version_of_ghc[_all]"
+[$2]="[$]fptools_version_of_ghc[_major]"
+[$3]="[$]fptools_version_of_ghc[_minor]"
+[$4]="[$]fptools_version_of_ghc[_pl]"
+])
+])
+])dnl
+
diff --git a/m4/fptools_happy.m4 b/m4/fptools_happy.m4
new file mode 100644
index 0000000000..d77621eaf7
--- /dev/null
+++ b/m4/fptools_happy.m4
@@ -0,0 +1,34 @@
+dnl
+dnl Check for Happy and version:
+dnl
+dnl 1. Use happy specified in env var HAPPY
+dnl 2. Find happy in path
+dnl 3. Check happy version
+dnl
+dnl If you increase the minimum version requirement, please also update:
+dnl https://gitlab.haskell.org/ghc/ghc/wikis/building/preparation/tools
+dnl
+AC_DEFUN([FPTOOLS_HAPPY],
+[AC_PATH_PROG(HAPPY,[happy],)
+AC_SUBST(HappyCmd,$HAPPY)
+AC_CACHE_CHECK([for version of happy], fptools_cv_happy_version,
+changequote(, )dnl
+[
+if test x"$HappyCmd" != x; then
+   fptools_cv_happy_version=`"$HappyCmd" -v |
+              grep 'Happy Version' | sed -e 's/Happy Version \([^ ]*\).*/\1/g'` ;
+else
+   fptools_cv_happy_version="";
+fi;
+changequote([, ])dnl
+])
+if test ! -f compiler/GHC/Parser.hs || test ! -f compiler/GHC/Cmm/Parser.hs
+then
+    FP_COMPARE_VERSIONS([$fptools_cv_happy_version],[-lt],[1.20.0],
+      [AC_MSG_ERROR([Happy version 1.20 or later is required to compile GHC.])])[]
+    FP_COMPARE_VERSIONS([$fptools_cv_happy_version],[-ge],[1.21.0],
+      [AC_MSG_ERROR([Happy version 1.20 or earlier is required to compile GHC.])])[]
+fi
+HappyVersion=$fptools_cv_happy_version;
+AC_SUBST(HappyVersion)
+])
diff --git a/m4/fptools_nocache_check.m4 b/m4/fptools_nocache_check.m4
new file mode 100644
index 0000000000..a309fd9792
--- /dev/null
+++ b/m4/fptools_nocache_check.m4
@@ -0,0 +1,11 @@
+dnl FPTOOLS_NOCACHE_CHECK prints a message, then sets the
+dnl values of the second argument to the result of running
+dnl the commands given by the third. It does not cache its
+dnl result, so it is suitable for checks which should be
+dnl run every time.
+dnl
+AC_DEFUN([FPTOOLS_NOCACHE_CHECK],
+[AC_MSG_CHECKING([$1])
+ $3
+ AC_MSG_RESULT([$][$2])
+])
diff --git a/m4/fptools_set_c_ld_flags.m4 b/m4/fptools_set_c_ld_flags.m4
new file mode 100644
index 0000000000..9cea4a832e
--- /dev/null
+++ b/m4/fptools_set_c_ld_flags.m4
@@ -0,0 +1,101 @@
+# FPTOOLS_SET_C_LD_FLAGS
+# ----------------------------------
+# Set the C, LD and CPP flags for a given platform.
+# $1 is the platform
+# $2 is the name of the CC flags variable
+# $3 is the name of the linker flags variable when linking with gcc
+# $4 is the name of the linker flags variable when linking with ld
+# $5 is the name of the CPP flags variable
+AC_DEFUN([FPTOOLS_SET_C_LD_FLAGS],
+[
+    AC_REQUIRE([FP_PROG_LD_IS_GNU])
+    AC_MSG_CHECKING([Setting up $2, $3, $4 and $5])
+    case $$1 in
+    i386-*)
+        # Workaround for #7799
+        $2="$$2 -U__i686"
+        ;;
+    esac
+
+    case $$1 in
+    i386-unknown-mingw32)
+        $2="$$2 -march=i686"
+        ;;
+    i386-portbld-freebsd*)
+        $2="$$2 -march=i686"
+        ;;
+    x86_64-unknown-solaris2)
+        # Solaris is a multi-lib platform, providing both 32- and 64-bit
+        # user-land. It appears to default to 32-bit builds but we of course want to
+        # compile for 64-bits on x86-64.
+        #
+        # On OpenSolaris uses gnu ld whereas SmartOS appears to use the Solaris
+        # implementation, which rather uses the -64 flag.
+        $2="$$2 -m64"
+        $3="$$3 -m64"
+        $5="$$5 -m64"
+        if test "$fp_cv_gnu_ld" = "yes"; then
+            $4="$$4 -m64"
+        else
+            $4="$$4 -64"
+        fi
+        ;;
+    alpha-*)
+        # For now, to suppress the gcc warning "call-clobbered
+        # register used for global register variable", we simply
+        # disable all warnings altogether using the -w flag. Oh well.
+        $2="$$2 -w -mieee -D_REENTRANT"
+        $3="$$3 -w -mieee -D_REENTRANT"
+        $5="$$5 -w -mieee -D_REENTRANT"
+        ;;
+    hppa*)
+        # ___HPUX_SOURCE, not _HPUX_SOURCE, is #defined if -ansi!
+        # (very nice, but too bad the HP /usr/include files don't agree.)
+        $2="$$2 -D_HPUX_SOURCE"
+        $3="$$3 -D_HPUX_SOURCE"
+        $5="$$5 -D_HPUX_SOURCE"
+        ;;
+
+    arm*freebsd*)
+        # On arm/freebsd, tell gcc to generate Arm
+        # instructions (ie not Thumb).
+        $2="$$2 -marm"
+        $3="$$3 -Wl,-z,noexecstack"
+        $4="$$4 -z noexecstack"
+        ;;
+    arm*linux*)
+        # On arm/linux and arm/android, tell gcc to generate Arm
+        # instructions (ie not Thumb).
+        $2="$$2 -marm"
+        $3="$$3 -Wl,-z,noexecstack"
+        $4="$$4 -z noexecstack"
+        ;;
+
+    aarch64*freebsd*)
+        $3="$$3 -Wl,-z,noexecstack"
+        $4="$$4 -z noexecstack"
+        ;;
+    aarch64*linux*)
+        $3="$$3 -Wl,-z,noexecstack"
+        $4="$$4 -z noexecstack"
+        ;;
+
+    powerpc-ibm-aix*)
+        # We need `-D_THREAD_SAFE` to unlock the thread-local `errno`.
+        $2="$$2 -D_THREAD_SAFE"
+        $3="$$3 -D_THREAD_SAFE -Wl,-bnotextro"
+        $4="$$4 -bnotextro"
+        $5="$$5 -D_THREAD_SAFE"
+        ;;
+
+    x86_64-*-openbsd*)
+        # We need -z wxneeded at least to link ghc-stage2 to workaround
+        # W^X issue in GHCi on OpenBSD current (as of Aug 2016)
+        $3="$$3 -Wl,-z,wxneeded"
+        $4="$$4 -z wxneeded"
+        ;;
+
+    esac
+
+    AC_MSG_RESULT([done])
+])
diff --git a/m4/fptools_set_haskell_platform_vars.m4 b/m4/fptools_set_haskell_platform_vars.m4
new file mode 100644
index 0000000000..7aec2e1d57
--- /dev/null
+++ b/m4/fptools_set_haskell_platform_vars.m4
@@ -0,0 +1,224 @@
+# FPTOOLS_SET_HASKELL_PLATFORM_VARS
+# ----------------------------------
+# Set the Haskell platform variables
+AC_DEFUN([FPTOOLS_SET_HASKELL_PLATFORM_VARS],
+[
+    checkArch() {
+        case [$]1 in
+        i386)
+            test -z "[$]2" || eval "[$]2=ArchX86"
+            ;;
+        x86_64|amd64)
+            test -z "[$]2" || eval "[$]2=ArchX86_64"
+            ;;
+        powerpc)
+            test -z "[$]2" || eval "[$]2=ArchPPC"
+            ;;
+        powerpc64)
+            test -z "[$]2" || eval "[$]2=\"ArchPPC_64 ELF_V1\""
+            ;;
+        powerpc64le)
+            test -z "[$]2" || eval "[$]2=\"ArchPPC_64 ELF_V2\""
+            ;;
+        s390x)
+            test -z "[$]2" || eval "[$]2=ArchS390X"
+            ;;
+        sparc)
+            test -z "[$]2" || eval "[$]2=ArchSPARC"
+            ;;
+        sparc64)
+            test -z "[$]2" || eval "[$]2=ArchSPARC64"
+            ;;
+        arm)
+            GET_ARM_ISA()
+            test -z "[$]2" || eval "[$]2=\"ArchARM \$ARM_ISA \$ARM_ISA_EXT \$ARM_ABI\""
+            ;;
+        aarch64)
+            test -z "[$]2" || eval "[$]2=ArchAArch64"
+            ;;
+        alpha)
+            test -z "[$]2" || eval "[$]2=ArchAlpha"
+            ;;
+        mips|mipseb)
+            test -z "[$]2" || eval "[$]2=ArchMipseb"
+            ;;
+        mipsel)
+            test -z "[$]2" || eval "[$]2=ArchMipsel"
+            ;;
+        riscv64)
+            test -z "[$]2" || eval "[$]2=ArchRISCV64"
+            ;;
+        hppa|hppa1_1|ia64|m68k|nios2|riscv32|rs6000|s390|sh4|vax)
+            test -z "[$]2" || eval "[$]2=ArchUnknown"
+            ;;
+        *)
+            echo "Unknown arch [$]1"
+            exit 1
+            ;;
+        esac
+    }
+
+    checkVendor() {
+        case [$]1 in
+        dec|none|unknown|hp|apple|next|sun|sgi|ibm|montavista|portbld|alpine)
+            ;;
+        *)
+            AC_MSG_WARN([Unknown vendor [$]1])
+            ;;
+        esac
+    }
+
+    checkOS() {
+        case [$]1 in
+        linux|linux-android)
+            test -z "[$]2" || eval "[$]2=OSLinux"
+            ;;
+        darwin|ios|watchos|tvos)
+            test -z "[$]2" || eval "[$]2=OSDarwin"
+            ;;
+        solaris2)
+            test -z "[$]2" || eval "[$]2=OSSolaris2"
+            ;;
+        mingw32)
+            test -z "[$]2" || eval "[$]2=OSMinGW32"
+            ;;
+        freebsd)
+            test -z "[$]2" || eval "[$]2=OSFreeBSD"
+            ;;
+        dragonfly)
+            test -z "[$]2" || eval "[$]2=OSDragonFly"
+            ;;
+        kfreebsdgnu)
+            test -z "[$]2" || eval "[$]2=OSKFreeBSD"
+            ;;
+        openbsd)
+            test -z "[$]2" || eval "[$]2=OSOpenBSD"
+            ;;
+        netbsd)
+            test -z "[$]2" || eval "[$]2=OSNetBSD"
+            ;;
+        haiku)
+            test -z "[$]2" || eval "[$]2=OSHaiku"
+            ;;
+        nto-qnx)
+            test -z "[$]2" || eval "[$]2=OSQNXNTO"
+            ;;
+        dragonfly|hpux|linuxaout|freebsd2|nextstep2|nextstep3|sunos4|ultrix)
+            test -z "[$]2" || eval "[$]2=OSUnknown"
+            ;;
+        aix)
+            test -z "[$]2" || eval "[$]2=OSAIX"
+            ;;
+        gnu)
+            test -z "[$]2" || eval "[$]2=OSHurd"
+            ;;
+        *)
+            echo "Unknown OS '[$]1'"
+            exit 1
+            ;;
+        esac
+    }
+
+    dnl Note [autoconf assembler checks and -flto]
+    dnl ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+    dnl
+    dnl Autoconf's AC_COMPILE_IFELSE macro is fragile in the case of checks
+    dnl which require that the assembler is run. Specifically, GCC does not run
+    dnl the assembler if invoked with `-c -flto`; it merely dumps its internal
+    dnl AST to the object file, to be compiled and assembled during the final
+    dnl link.
+    dnl
+    dnl This can cause configure checks like that for the
+    dnl .subsections_via_symbols directive to pass unexpected (see #16440),
+    dnl leading the build system to incorrectly conclude that the directive is
+    dnl supported.
+    dnl
+    dnl For this reason, it is important that configure checks that rely on the
+    dnl assembler failing use AC_LINK_IFELSE rather than AC_COMPILE_IFELSE,
+    dnl ensuring that the assembler sees the check.
+    dnl
+
+    dnl ** check for Apple-style dead-stripping support
+    dnl    (.subsections-via-symbols assembler directive)
+
+    AC_MSG_CHECKING(for .subsections_via_symbols)
+    dnl See Note [autoconf assembler checks and -flto]
+    AC_LINK_IFELSE(
+        [AC_LANG_PROGRAM([], [__asm__ (".subsections_via_symbols");])],
+        [AC_MSG_RESULT(yes)
+         if test x"$TargetArch" = xaarch64; then
+            dnl subsections via symbols is busted on arm64
+            TargetHasSubsectionsViaSymbols=NO
+         else
+            TargetHasSubsectionsViaSymbols=YES
+            AC_DEFINE([HAVE_SUBSECTIONS_VIA_SYMBOLS],[1],
+                   [Define to 1 if Apple-style dead-stripping is supported.])
+         fi
+        ],
+        [TargetHasSubsectionsViaSymbols=NO
+         AC_MSG_RESULT(no)])
+
+    dnl ** check for .ident assembler directive
+
+    AC_MSG_CHECKING(whether your assembler supports .ident directive)
+    dnl See Note [autoconf assembler checks and -flto]
+    AC_LINK_IFELSE(
+        [AC_LANG_PROGRAM([__asm__ (".ident \"GHC x.y.z\"");], [])],
+        [AC_MSG_RESULT(yes)
+         TargetHasIdentDirective=YES],
+        [AC_MSG_RESULT(no)
+         TargetHasIdentDirective=NO])
+
+    dnl *** check for GNU non-executable stack note support (ELF only)
+    dnl     (.section .note.GNU-stack,"",@progbits)
+
+    dnl This test doesn't work with "gcc -g" in gcc 4.4 (GHC trac #3889:
+    dnl     Error: can't resolve `.note.GNU-stack' {.note.GNU-stack section} - `.Ltext0' {.text section}
+    dnl so we empty CFLAGS while running this test
+    CFLAGS2="$CFLAGS"
+    CFLAGS=
+    case $TargetArch in
+      arm)
+        dnl See #13937.
+        progbits="%progbits"
+        ;;
+      *)
+        progbits="@progbits"
+        ;;
+    esac
+    AC_MSG_CHECKING(for GNU non-executable stack support)
+    dnl See Note [autoconf assembler checks and -flto]
+    AC_LINK_IFELSE(
+       dnl the `main` function is placed after the .note.GNU-stack directive
+       dnl so we need to ensure that the active segment is correctly set,
+       dnl otherwise `main` will be placed in the wrong segment.
+        [AC_LANG_PROGRAM([
+           __asm__ (".section .note.GNU-stack,\"\",$progbits");
+           __asm__ (".section .text");
+         ], [0])],
+        [AC_MSG_RESULT(yes)
+         TargetHasGnuNonexecStack=YES],
+        [AC_MSG_RESULT(no)
+         TargetHasGnuNonexecStack=NO])
+    CFLAGS="$CFLAGS2"
+
+    checkArch "$BuildArch" "HaskellBuildArch"
+    checkVendor "$BuildVendor"
+    checkOS "$BuildOS" ""
+
+    checkArch "$HostArch" "HaskellHostArch"
+    checkVendor "$HostVendor"
+    checkOS "$HostOS" "HaskellHostOs"
+
+    checkArch "$TargetArch" "HaskellTargetArch"
+    checkVendor "$TargetVendor"
+    checkOS "$TargetOS" "HaskellTargetOs"
+
+    AC_SUBST(HaskellHostArch)
+    AC_SUBST(HaskellHostOs)
+    AC_SUBST(HaskellTargetArch)
+    AC_SUBST(HaskellTargetOs)
+    AC_SUBST(TargetHasSubsectionsViaSymbols)
+    AC_SUBST(TargetHasIdentDirective)
+    AC_SUBST(TargetHasGnuNonexecStack)
+])
diff --git a/m4/fptools_set_platform_vars.m4 b/m4/fptools_set_platform_vars.m4
new file mode 100644
index 0000000000..185661a3df
--- /dev/null
+++ b/m4/fptools_set_platform_vars.m4
@@ -0,0 +1,145 @@
+# FPTOOLS_SET_PLATFORM_VARS
+# ----------------------------------
+# Set the platform variables
+AC_DEFUN([FPTOOLS_SET_PLATFORM_VARS],
+[
+    # If no argument was given for a configuration variable, then discard
+    # the guessed canonical system and use the configuration of the
+    # bootstrapping ghc. If an argument was given, map it from gnu format
+    # to ghc format.
+    #
+    # For why we do it this way, see: #3637, #1717, #2951
+    #
+    # In bindists, we haven't called AC_CANONICAL_{BUILD,HOST,TARGET}
+    # so this justs uses $bootstrap_target.
+
+    if test "$build_alias" = ""
+    then
+        if test "$bootstrap_target" != ""
+        then
+            build=$bootstrap_target
+            echo "Build platform inferred as: $build"
+        else
+            echo "Can't work out build platform"
+            exit 1
+        fi
+
+        BuildArch=`echo "$build" | sed 's/-.*//'`
+        BuildVendor=`echo "$build" | sed -e 's/.*-\(.*\)-.*/\1/'`
+        BuildOS=`echo "$build" | sed 's/.*-//'`
+    else
+        GHC_CONVERT_CPU([$build_cpu], [BuildArch])
+        GHC_CONVERT_VENDOR([$build_vendor], [BuildVendor])
+        GHC_CONVERT_OS([$build_os], [$BuildArch], [BuildOS])
+    fi
+
+    if test "$host_alias" = ""
+    then
+        if test "$bootstrap_target" != ""
+        then
+            host=$bootstrap_target
+            echo "Host platform inferred as: $host"
+        else
+            echo "Can't work out host platform"
+            exit 1
+        fi
+
+        HostArch=`echo "$host" | sed 's/-.*//'`
+        HostVendor=`echo "$host" | sed -e 's/.*-\(.*\)-.*/\1/'`
+        HostOS=`echo "$host" | sed 's/.*-//'`
+    else
+        GHC_CONVERT_CPU([$host_cpu], [HostArch])
+        GHC_CONVERT_VENDOR([$host_vendor], [HostVendor])
+        GHC_CONVERT_OS([$host_os], [$HostArch], [HostOS])
+    fi
+
+    if test "$target_alias" = ""
+    then
+        if test "$host_alias" != ""
+        then
+            GHC_CONVERT_CPU([$host_cpu], [TargetArch])
+            GHC_CONVERT_VENDOR([$host_vendor], [TargetVendor])
+            GHC_CONVERT_OS([$host_os], [$TargetArch],[TargetOS])
+        else
+            if test "$bootstrap_target" != ""
+            then
+                target=$bootstrap_target
+                echo "Target platform inferred as: $target"
+            else
+                echo "Can't work out target platform"
+                exit 1
+            fi
+
+            TargetArch=`echo "$target" | sed 's/-.*//'`
+            TargetVendor=`echo "$target" | sed -e 's/.*-\(.*\)-.*/\1/'`
+            TargetOS=`echo "$target" | sed 's/.*-//'`
+        fi
+    else
+        GHC_CONVERT_CPU([$target_cpu], [TargetArch])
+        GHC_CONVERT_VENDOR([$target_vendor], [TargetVendor])
+        GHC_CONVERT_OS([$target_os], [$TargetArch], [TargetOS])
+    fi
+
+    GHC_LLVM_TARGET([$target],[$target_cpu],[$target_vendor],[$target_os],[LlvmTarget])
+
+    GHC_SELECT_FILE_EXTENSIONS([$host], [exeext_host], [soext_host])
+    GHC_SELECT_FILE_EXTENSIONS([$target], [exeext_target], [soext_target])
+    windows=NO
+    case $host in
+    *-unknown-mingw32)
+        windows=YES
+        ;;
+    esac
+
+    BuildPlatform="$BuildArch-$BuildVendor-$BuildOS"
+    BuildPlatform_CPP=`echo "$BuildPlatform" | sed -e 's/\./_/g' -e 's/-/_/g'`
+    BuildArch_CPP=`    echo "$BuildArch"     | sed -e 's/\./_/g' -e 's/-/_/g'`
+    BuildVendor_CPP=`  echo "$BuildVendor"   | sed -e 's/\./_/g' -e 's/-/_/g'`
+    BuildOS_CPP=`      echo "$BuildOS"       | sed -e 's/\./_/g' -e 's/-/_/g'`
+
+    HostPlatform="$HostArch-$HostVendor-$HostOS"
+    HostPlatform_CPP=`echo "$HostPlatform" | sed -e 's/\./_/g' -e 's/-/_/g'`
+    HostArch_CPP=`    echo "$HostArch"     | sed -e 's/\./_/g' -e 's/-/_/g'`
+    HostVendor_CPP=`  echo "$HostVendor"   | sed -e 's/\./_/g' -e 's/-/_/g'`
+    HostOS_CPP=`      echo "$HostOS"       | sed -e 's/\./_/g' -e 's/-/_/g'`
+
+    TargetPlatform="$TargetArch-$TargetVendor-$TargetOS"
+    TargetPlatform_CPP=`echo "$TargetPlatform" | sed -e 's/\./_/g' -e 's/-/_/g'`
+    TargetArch_CPP=`    echo "$TargetArch"     | sed -e 's/\./_/g' -e 's/-/_/g'`
+    TargetVendor_CPP=`  echo "$TargetVendor"   | sed -e 's/\./_/g' -e 's/-/_/g'`
+    TargetOS_CPP=`      echo "$TargetOS"       | sed -e 's/\./_/g' -e 's/-/_/g'`
+
+    # we intend to pass trough --targets to llvm as is.
+    LLVMTarget_CPP=`    echo "$LlvmTarget"`
+
+    echo "GHC build  : $BuildPlatform"
+    echo "GHC host   : $HostPlatform"
+    echo "GHC target : $TargetPlatform"
+    echo "LLVM target: $LlvmTarget"
+
+    AC_SUBST(BuildPlatform)
+    AC_SUBST(HostPlatform)
+    AC_SUBST(TargetPlatform)
+    AC_SUBST(HostPlatform_CPP)
+    AC_SUBST(BuildPlatform_CPP)
+    AC_SUBST(TargetPlatform_CPP)
+
+    AC_SUBST(HostArch_CPP)
+    AC_SUBST(BuildArch_CPP)
+    AC_SUBST(TargetArch_CPP)
+
+    AC_SUBST(HostOS_CPP)
+    AC_SUBST(BuildOS_CPP)
+    AC_SUBST(TargetOS_CPP)
+    AC_SUBST(LLVMTarget_CPP)
+
+    AC_SUBST(HostVendor_CPP)
+    AC_SUBST(BuildVendor_CPP)
+    AC_SUBST(TargetVendor_CPP)
+
+    AC_SUBST(exeext_host)
+    AC_SUBST(exeext_target)
+    AC_SUBST(soext_host)
+    AC_SUBST(soext_target)
+])
+
diff --git a/m4/fptools_write_file.m4 b/m4/fptools_write_file.m4
new file mode 100644
index 0000000000..e66690808f
--- /dev/null
+++ b/m4/fptools_write_file.m4
@@ -0,0 +1,9 @@
+# FPTOOLS_WRITE_FILE
+# ------------------
+# Write $2 to the file named $1.
+AC_DEFUN([FPTOOLS_WRITE_FILE],
+[
+cat >$1 <<ACEOF
+$2
+ACEOF
+])
diff --git a/m4/get_arm_isa.m4 b/m4/get_arm_isa.m4
new file mode 100644
index 0000000000..9b458bb09f
--- /dev/null
+++ b/m4/get_arm_isa.m4
@@ -0,0 +1,117 @@
+# GET_ARM_ISA
+# ----------------------------------
+# Get info about the ISA on the ARM arch
+AC_DEFUN([GET_ARM_ISA],
+[
+    AC_COMPILE_IFELSE([
+        AC_LANG_PROGRAM(
+            [],
+            [#if defined(__ARM_ARCH_2__)  || \
+                 defined(__ARM_ARCH_3__)  || \
+                 defined(__ARM_ARCH_3M__) || \
+                 defined(__ARM_ARCH_4__)  || \
+                 defined(__ARM_ARCH_4T__) || \
+                 defined(__ARM_ARCH_5__)  || \
+                 defined(__ARM_ARCH_5T__) || \
+                 defined(__ARM_ARCH_5E__) || \
+                 defined(__ARM_ARCH_5TE__)
+                 return 0;
+             #else
+                 not pre arm v6
+             #endif]
+        )],
+        [AC_DEFINE(arm_HOST_ARCH_PRE_ARMv6, 1, [ARM pre v6])
+         AC_DEFINE(arm_HOST_ARCH_PRE_ARMv7, 1, [ARM pre v7])
+         changequote(, )dnl
+         ARM_ISA=ARMv5
+         ARM_ISA_EXT="[]"
+         changequote([, ])dnl
+        ],
+        [
+            AC_COMPILE_IFELSE([
+                AC_LANG_PROGRAM(
+                    [],
+                    [#if defined(__ARM_ARCH_6__)   || \
+                         defined(__ARM_ARCH_6J__)  || \
+                         defined(__ARM_ARCH_6T2__) || \
+                         defined(__ARM_ARCH_6Z__)  || \
+                         defined(__ARM_ARCH_6ZK__) || \
+                         defined(__ARM_ARCH_6K__)  || \
+                         defined(__ARM_ARCH_6KZ__) || \
+                         defined(__ARM_ARCH_6M__)
+                         return 0;
+                     #else
+                         not pre arm v7
+                     #endif]
+                )],
+                [AC_DEFINE(arm_HOST_ARCH_PRE_ARMv7, 1, [ARM pre v7])
+                 if grep -q Raspbian /etc/issue && uname -m | grep -q armv7; then
+                   # Raspbian unfortunately makes some extremely questionable
+                   # packaging decisions, configuring gcc to compile for ARMv6
+                   # despite the fact that the RPi4 is ARMv8. As ARMv8 doesn't
+                   # support all instructions supported by ARMv6 this can
+                   # break. Work around this by checking uname to verify
+                   # that we aren't running on armv7.
+                   # See #17856.
+                   AC_MSG_NOTICE([Found compiler which claims to target ARMv6 running on ARMv7, assuming this is ARMv7 on Raspbian (see T17856)])
+                   ARM_ISA=ARMv7
+                   changequote(, )dnl
+                   ARM_ISA_EXT="[VFPv2]"
+                   changequote([, ])dnl
+                 else
+                   ARM_ISA=ARMv6
+                   AC_COMPILE_IFELSE([
+                          AC_LANG_PROGRAM(
+                                  [],
+                                  [#if defined(__VFP_FP__)
+                                       return 0;
+                                  #else
+                                       no vfp
+                                  #endif]
+                          )],
+                          [changequote(, )dnl
+                           ARM_ISA_EXT="[VFPv2]"
+                           changequote([, ])dnl
+                          ],
+                          [changequote(, )dnl
+                           ARM_ISA_EXT="[]"
+                           changequote([, ])dnl
+                          ]
+                  )
+                fi],
+                [changequote(, )dnl
+                 ARM_ISA=ARMv7
+                 ARM_ISA_EXT="[VFPv3,NEON]"
+                 changequote([, ])dnl
+                ])
+        ])
+
+        AC_COMPILE_IFELSE(
+               [AC_LANG_PROGRAM(
+                       [],
+                       [#if defined(__SOFTFP__)
+                            return 0;
+                       #else
+                            not softfp
+                       #endif]
+               )],
+               [changequote(, )dnl
+                ARM_ABI="SOFT"
+                changequote([, ])dnl
+               ],
+               [AC_COMPILE_IFELSE(
+                    [AC_LANG_PROGRAM(
+                       [],
+                       [#if defined(__ARM_PCS_VFP)
+                            return 0;
+                       #else
+                            no hard float ABI
+                       #endif]
+                    )],
+                    [ARM_ABI="HARD"],
+                    [ARM_ABI="SOFTFP"]
+               )]
+        )
+
+        AC_SUBST(ARM_ISA)
+])
diff --git a/m4/ghc_convert_cpu.m4 b/m4/ghc_convert_cpu.m4
new file mode 100644
index 0000000000..15dda712df
--- /dev/null
+++ b/m4/ghc_convert_cpu.m4
@@ -0,0 +1,88 @@
+# GHC_CONVERT_CPU(cpu, target_var)
+# --------------------------------
+# Converts cpu from gnu to ghc naming, and assigns the result to $target_var.
+# Should you modify this list, you are invited to reflect the changes in
+# `libraries/base/System/Info.hs`'s documentation.
+AC_DEFUN([GHC_CONVERT_CPU],[
+case "$1" in
+  aarch64*|arm64*)
+    $2="aarch64"
+    ;;
+  alpha*)
+    $2="alpha"
+    ;;
+  arm*)
+    $2="arm"
+    ;;
+  hppa1.1*)
+    $2="hppa1_1"
+    ;;
+  hppa*)
+    $2="hppa"
+    ;;
+  i386|i486|i586|i686)
+    $2="i386"
+    ;;
+  ia64)
+    $2="ia64"
+    ;;
+  m68k*)
+    $2="m68k"
+    ;;
+  mipseb*)
+    $2="mipseb"
+    ;;
+  mipsel*)
+    $2="mipsel"
+    ;;
+  mips*)
+    $2="mips"
+    ;;
+  nios2)
+    $2="nios2"
+    ;;
+  powerpc64le*)
+    $2="powerpc64le"
+    ;;
+  powerpc64*)
+    $2="powerpc64"
+    ;;
+  powerpc*)
+    $2="powerpc"
+    ;;
+  riscv64*)
+    $2="riscv64"
+    ;;
+  riscv|riscv32*)
+    $2="riscv32"
+    ;;
+  rs6000)
+    $2="rs6000"
+    ;;
+  s390x*)
+    $2="s390x"
+    ;;
+  s390*)
+    $2="s390"
+    ;;
+  sh4)
+    $2="sh4"
+    ;;
+  sparc64*)
+    $2="sparc64"
+    ;;
+  sparc*)
+    $2="sparc"
+    ;;
+  vax)
+    $2="vax"
+    ;;
+  x86_64|amd64)
+    $2="x86_64"
+    ;;
+  *)
+    echo "Unknown CPU $1"
+    exit 1
+    ;;
+  esac
+])
diff --git a/m4/ghc_convert_os.m4 b/m4/ghc_convert_os.m4
new file mode 100644
index 0000000000..dbced12850
--- /dev/null
+++ b/m4/ghc_convert_os.m4
@@ -0,0 +1,54 @@
+# GHC_CONVERT_OS(os, converted_cpu, target_var)
+# --------------------------------
+# converts os from gnu to ghc naming, and assigns the result to $target_var
+AC_DEFUN([GHC_CONVERT_OS],[
+    case "$1" in
+      gnu*) # e.g. i686-unknown-gnu0.9
+        $3="gnu"
+        ;;
+      # watchos and tvos are ios variants as of May 2017.
+      ios|watchos|tvos)
+        $3="ios"
+        ;;
+      linux-android*)
+        $3="linux-android"
+        ;;
+      linux-*|linux)
+        $3="linux"
+        ;;
+      netbsd*)
+        $3="netbsd"
+        ;;
+      openbsd*)
+        $3="openbsd"
+        ;;
+      # As far as I'm aware, none of these have relevant variants
+      freebsd|dragonfly|hpux|linuxaout|kfreebsdgnu|freebsd2|mingw32|darwin|nextstep2|nextstep3|sunos4|ultrix|haiku)
+        $3="$1"
+        ;;
+      msys)
+        AC_MSG_ERROR([Building GHC using the msys toolchain is not supported; please use mingw instead. Perhaps you need to set 'MSYSTEM=MINGW64 or MINGW32?'])
+        ;;
+      aix*) # e.g. powerpc-ibm-aix7.1.3.0
+        $3="aix"
+        ;;
+      darwin*) # e.g. aarch64-apple-darwin14
+        $3="darwin"
+        ;;
+      solaris2*)
+        $3="solaris2"
+        ;;
+      freebsd*) # like i686-gentoo-freebsd7
+                #      i686-gentoo-freebsd8
+                #      i686-gentoo-freebsd8.2
+        $3="freebsd"
+        ;;
+      nto-qnx*)
+        $3="nto-qnx"
+        ;;
+      *)
+        echo "Unknown OS $1"
+        exit 1
+        ;;
+      esac
+])
diff --git a/m4/ghc_convert_vendor.m4 b/m4/ghc_convert_vendor.m4
new file mode 100644
index 0000000000..df4c22d393
--- /dev/null
+++ b/m4/ghc_convert_vendor.m4
@@ -0,0 +1,20 @@
+# GHC_CONVERT_VENDOR(vendor, target_var)
+# --------------------------------
+# converts vendor from gnu to ghc naming, and assigns the result to $target_var
+AC_DEFUN([GHC_CONVERT_VENDOR],[
+  case "$1" in
+  pc|gentoo|w64) # like i686-pc-linux-gnu, i686-gentoo-freebsd8, x86_64-w64-mingw32
+    $2="unknown"
+    ;;
+  softfloat) # like armv5tel-softfloat-linux-gnueabi
+    $2="unknown"
+    ;;
+  hardfloat) # like armv7a-hardfloat-linux-gnueabi
+    $2="unknown"
+    ;;
+  *)
+    #pass thru by default
+    $2="$1"
+    ;;
+  esac
+])
diff --git a/m4/ghc_llvm_target.m4 b/m4/ghc_llvm_target.m4
new file mode 100644
index 0000000000..33150e9a8c
--- /dev/null
+++ b/m4/ghc_llvm_target.m4
@@ -0,0 +1,45 @@
+# GHC_LLVM_TARGET(target, target_cpu, target_vendor, target_os, llvm_target_var)
+# --------------------------------
+# converts the canonicalized target into something llvm can understand
+AC_DEFUN([GHC_LLVM_TARGET], [
+  llvm_target_cpu=$2
+  case "$1" in
+    *-freebsd*-gnueabihf)
+      llvm_target_vendor="unknown"
+      llvm_target_os="freebsd-gnueabihf"
+      ;;
+    *-hardfloat-*eabi)
+      llvm_target_vendor="unknown"
+      llvm_target_os="$4""hf"
+      ;;
+    *-mingw32|*-mingw64|*-msys)
+      llvm_target_vendor="unknown"
+      llvm_target_os="windows"
+      ;;
+    # apple is a bit about their naming scheme for
+    # aarch64; and clang on macOS doesn't know that
+    # aarch64 would be arm64. So for LLVM we'll need
+    # to call it arm64; while we'll refer to it internally
+    # as aarch64 for consistency and sanity.
+    aarch64-apple-*|arm64-apple-*)
+      llvm_target_cpu="arm64"
+      GHC_CONVERT_VENDOR([$3],[llvm_target_vendor])
+      GHC_CONVERT_OS([$4],[$2],[llvm_target_os])
+      ;;
+    *)
+      GHC_CONVERT_VENDOR([$3],[llvm_target_vendor])
+      GHC_CONVERT_OS([$4],[$2],[llvm_target_os])
+      ;;
+  esac
+  case "$4" in
+      # retain any android and gnueabi linux flavours
+      # for the LLVM Target. Otherwise these would be
+      # turned into just `-linux` and fail to be found
+      # in the `llvm-targets` file.
+      *-android*|*-gnueabi*|*-musleabi*)
+        GHC_CONVERT_VENDOR([$3],[llvm_target_vendor])
+        llvm_target_os="$4"
+        ;;
+  esac
+  $5="$llvm_target_cpu-$llvm_target_vendor-$llvm_target_os"
+])
diff --git a/m4/ghc_select_file_extensions.m4 b/m4/ghc_select_file_extensions.m4
new file mode 100644
index 0000000000..751298a7f3
--- /dev/null
+++ b/m4/ghc_select_file_extensions.m4
@@ -0,0 +1,22 @@
+AC_DEFUN([GHC_SELECT_FILE_EXTENSIONS],
+[
+    $2=''
+    $3='.so'
+    case $1 in
+    *-unknown-cygwin32)
+        AC_MSG_WARN([GHC does not support the Cygwin target at the moment])
+        AC_MSG_WARN([I'm assuming you wanted to build for i386-unknown-mingw32])
+        exit 1
+        ;;
+    # examples: i386-unknown-mingw32, i686-w64-mingw32, x86_64-w64-mingw32
+    *-mingw32)
+        windows=YES
+        $2='.exe'
+        $3='.dll'
+        ;;
+    # apple platform uses .dylib (macOS, iOS, ...)
+    *-apple-*)
+        $3='.dylib'
+        ;;
+    esac
+])
diff --git a/m4/library_version.m4 b/m4/library_version.m4
new file mode 100644
index 0000000000..f0a9e8219c
--- /dev/null
+++ b/m4/library_version.m4
@@ -0,0 +1,10 @@
+# LIBRARY_VERSION(lib, [cabal_file])
+# --------------------------------
+# Gets the version number of a library.
+# If $1 is ghc-prim, then we define LIBRARY_ghc_prim_VERSION as 1.2.3
+# $2 points to the directory under libraries/
+AC_DEFUN([LIBRARY_VERSION],[
+cabal_file=m4_default([$2],[$1/$1.cabal])
+LIBRARY_[]translit([$1], [-], [_])[]_VERSION=`grep -i "^version:" libraries/${cabal_file} | sed "s/.* //"`
+AC_SUBST(LIBRARY_[]translit([$1], [-], [_])[]_VERSION)
+])
diff --git a/m4/maybe_override_stage0.m4 b/m4/maybe_override_stage0.m4
new file mode 100644
index 0000000000..d83473af03
--- /dev/null
+++ b/m4/maybe_override_stage0.m4
@@ -0,0 +1,6 @@
+AC_DEFUN([MAYBE_OVERRIDE_STAGE0],[
+  if test ! -z "$With_$1" -a "$CrossCompiling" != "YES"; then
+      AC_MSG_NOTICE([Not cross-compiling, so --with-$1 also sets $2])
+      $2=$With_$1
+  fi
+])
diff --git a/m4/xcode_version.m4 b/m4/xcode_version.m4
new file mode 100644
index 0000000000..e59604d6b8
--- /dev/null
+++ b/m4/xcode_version.m4
@@ -0,0 +1,25 @@
+# XCODE_VERSION()
+# --------------------------------
+# Gets the version number of Xcode, if on a Mac
+AC_DEFUN([XCODE_VERSION],[
+    if test "$TargetVendor_CPP" = "apple"
+    then
+        AC_MSG_CHECKING(Xcode version)
+        XcodeVersion=`(xcode-select -p >& /dev/null && xcodebuild -version) | grep Xcode | sed "s/Xcode //"`
+        # Old Xcode versions don't actually give the Xcode version
+        if test "$XcodeVersion" = ""
+        then
+            AC_MSG_RESULT(not found (too old?))
+            XcodeVersion1=0
+            XcodeVersion2=0
+        else
+            AC_MSG_RESULT($XcodeVersion)
+            XcodeVersion1=`echo "$XcodeVersion" | sed 's/\..*//'`
+            changequote(, )dnl
+            XcodeVersion2=`echo "$XcodeVersion" | sed 's/[^.]*\.\([^.]*\).*/\1/'`
+            changequote([, ])dnl
+            AC_MSG_NOTICE(Xcode version component 1: $XcodeVersion1)
+            AC_MSG_NOTICE(Xcode version component 2: $XcodeVersion2)
+        fi
+    fi
+])