Bug 528131 - build config should check whether __force_align_arg_pointer__ is valid. r=ted

config/autoconf.mk.in

@@ -641,6 +641,7 @@ WRAP_SYSTEM_INCLUDES = @WRAP_SYSTEM_INCLUDES@
 
 HAVE_ARM_SIMD = @HAVE_ARM_SIMD@
 HAVE_ARM_NEON = @HAVE_ARM_NEON@
+HAVE_GCC_ALIGN_ARG_POINTER = @HAVE_GCC_ALIGN_ARG_POINTER@
 
 MOZ_SPLASHSCREEN = @MOZ_SPLASHSCREEN@
 

configure.in

@@ -3128,6 +3128,26 @@ fi         # Sun Studio on Solaris
 AC_SUBST(WRAP_SYSTEM_INCLUDES)
 AC_SUBST(VISIBILITY_FLAGS)
 
+dnl Check for __force_align_arg_pointer__ for SSE2 on gcc
+dnl ========================================================
+if test "$GNU_CC"; then
+  CFLAGS_save="${CFLAGS}"
+  CFLAGS="${CFLAGS} -Werror"
+  AC_CACHE_CHECK(for __force_align_arg_pointer__ attribute,
+                 ac_cv_force_align_arg_pointer,
+                 [AC_TRY_COMPILE([__attribute__ ((__force_align_arg_pointer__)) void test() {}],
+                                 [],
+                                 ac_cv_force_align_arg_pointer="yes",
+                                 ac_cv_force_align_arg_pointer="no")])
+  CFLAGS="${CFLAGS_save}"
+  if test "$ac_cv_force_align_arg_pointer" = "yes"; then
+    HAVE_GCC_ALIGN_ARG_POINTER=1
+  else
+    HAVE_GCC_ALIGN_ARG_POINTER=
+  fi
+fi
+AC_SUBST(HAVE_GCC_ALIGN_ARG_POINTER)
+
 dnl Checks for header files.
 dnl ========================================================
 AC_HEADER_DIRENT