[PATCH v3 2/2] configure: Check -falign-jumps=1 beside -falign-loops=1

[Fangrui Song]

Clang does not support -falign-jumps and only recently gained support
for -falign-loops. -falign-jumps=1 should be tested beside
-fliang-loops=1 to avoid passing unrecognized options to Clang:

    clang-14: error: optimization flag '-falign-jumps=1' is not supported 
[-Werror,-Wignored-optimization-argument]

-falign-functions=1 is supported by GCC 5.1.0/Clang 3.8.0, so just add
the option unconditionally.

Acked-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Fangrui Song <maskray@google.com>
---
 configure.ac | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 9a12151bd..eeb5d2211 100644
--- a/configure.ac
+++ b/configure.ac
@@ -798,6 +798,8 @@ fi
 
 # Force no alignment to save space on i386.
 if test "x$target_cpu" = xi386; then
+  TARGET_CFLAGS="$TARGET_CFLAGS -falign-functions=1"
+
   AC_CACHE_CHECK([whether -falign-loops works], [grub_cv_cc_falign_loop], [
     CFLAGS="$TARGET_CFLAGS -falign-loops=1 -Werror"
     AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])],
@@ -806,7 +808,18 @@ if test "x$target_cpu" = xi386; then
   ])
 
   if test "x$grub_cv_cc_falign_loop" = xyes; then
-    TARGET_CFLAGS="$TARGET_CFLAGS -falign-jumps=1 -falign-loops=1 
-falign-functions=1"
+    TARGET_CFLAGS="$TARGET_CFLAGS -falign-loops=1"
+  fi
+
+  AC_CACHE_CHECK([whether -falign-jumps works], [grub_cv_cc_falign_jumps], [
+    CFLAGS="$TARGET_CFLAGS -falign-jumps=1 -Werror"
+    AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])],
+        [grub_cv_cc_falign_jumps=yes],
+        [grub_cv_cc_falign_jumps=no])
+  ])
+
+  if test "x$grub_cv_cc_falign_jumps" = xyes; then
+    TARGET_CFLAGS="$TARGET_CFLAGS -falign-jumps=1"
   fi
 fi
 
-- 
2.33.0.rc2.250.ged5fa647cd-goog