PR jit/64780: configure: --enable-host-shared and the jit

ChangeLog:
	PR jit/64780
	* configure.ac: Require the user to explicitly specify
	--enable-host-shared if the jit is enabled.
	* configure: Regenerate.

From-SVN: r220253

ChangeLog

+2015-01-29  David Malcolm  <dmalcolm@redhat.com>
+
+	PR jit/64780
+	* configure.ac: Require the user to explicitly specify
+	--enable-host-shared if the jit is enabled.
+	* configure: Regenerate.
+
 2015-01-27  Robert Suchanek  <robert.suchanek@imgtec.com>
 
 	* MAINTAINERS (Write After Approval): Add myself.

configure

@@ -14750,6 +14750,30 @@ fi
 
 
 
+# PR jit/64780: Require the user to explicitly specify
+# --enable-host-shared if the jit is enabled, hinting
+# that they might want to do a separate configure/build of
+# the jit, to avoid users from slowing down the rest of the
+# compiler by enabling the jit.
+if test ${host_shared} = "no" ; then
+  case "${enable_languages}" in
+    *jit*)
+      as_fn_error "
+Enabling language \"jit\" requires --enable-host-shared.
+
+--enable-host-shared typically slows the rest of the compiler down by
+a few %, so you must explicitly enable it.
+
+If you want to build both the jit and the regular compiler, it is often
+best to do this via two separate configure/builds, in separate
+directories, to avoid imposing the performance cost of
+--enable-host-shared on the regular compiler." "$LINENO" 5
+      ;;
+    *)
+      ;;
+  esac
+fi
+
 # Specify what files to not compare during bootstrap.
 
 compare_exclusions="gcc/cc*-checksum\$(objext) | gcc/ada/*tools/*"

configure.ac

@@ -3467,6 +3467,30 @@ AC_ARG_ENABLE(host-shared,
 [host_shared=$enableval], [host_shared=no])
 AC_SUBST(host_shared)
 
+# PR jit/64780: Require the user to explicitly specify
+# --enable-host-shared if the jit is enabled, hinting
+# that they might want to do a separate configure/build of
+# the jit, to avoid users from slowing down the rest of the
+# compiler by enabling the jit.
+if test ${host_shared} = "no" ; then
+  case "${enable_languages}" in
+    *jit*)
+      AC_MSG_ERROR([
+Enabling language "jit" requires --enable-host-shared.
+
+--enable-host-shared typically slows the rest of the compiler down by
+a few %, so you must explicitly enable it.
+
+If you want to build both the jit and the regular compiler, it is often
+best to do this via two separate configure/builds, in separate
+directories, to avoid imposing the performance cost of
+--enable-host-shared on the regular compiler.])
+      ;;
+    *)
+      ;;
+  esac
+fi
+
 # Specify what files to not compare during bootstrap.
 
 compare_exclusions="gcc/cc*-checksum\$(objext) | gcc/ada/*tools/*"