Factor out GHC_ADJUSTORS_METHOD m4 macro

1 files changed, 48 insertions, 0 deletions

diff --git a/m4/ghc_adjustors_method.m4 b/m4/ghc_adjustors_method.m4
new file mode 100644
index 0000000000..3371c3d11d
--- /dev/null
+++ b/m4/ghc_adjustors_method.m4
@@ -0,0 +1,48 @@
+dnl GHC_ADJUSTORS_METHOD(Platform)
+dnl --------------------------------------------------------------
+dnl Use libffi for adjustors?
+AC_DEFUN([GHC_ADJUSTORS_METHOD],
+[
+  case [$]{$1[Arch]} in
+      i386|x86_64)
+          # We have native adjustor support on these platforms
+          HaveNativeAdjustor=yes
+          ;;
+      *)
+          HaveNativeAdjustor=no
+          ;;
+  esac
+
+  AC_ARG_ENABLE(libffi-adjustors,
+      [AS_HELP_STRING(
+          [--enable-libffi-adjustors],
+          [Force use of libffi for adjustors, even on platforms which have support for more efficient, native adjustors.])],
+      UseLibffiForAdjustors=$enableval,
+      dnl do nothing
+  )
+
+  AC_MSG_CHECKING([whether to use libffi for adjustors])
+  AC_MSG_RESULT([$UseLibffiForAdjustors])
+  if test "$UseLibffiForAdjustors" = "yes" ; then
+      # Use libffi is the user explicitly requested it
+      AdjustorType="libffi"
+  elif test "$HaveNativeAdjustor" = "yes"; then
+      # Otherwise if we have a native adjustor implementation use that
+      AdjustorType="native"
+  else
+      # If we don't have a native adjustor implementation then default to libffi
+      AdjustorType="libffi"
+  fi
+
+  case "$AdjustorType" in
+  libffi)
+      UseLibffiForAdjustors=YES
+      ;;
+  native)
+      UseLibffiForAdjustors=NO
+      ;;
+  *)
+      AC_MSG_ERROR([Internal error: Invalid AdjustorType])
+      exit 1
+  esac
+])