On 2021-08-25, Daniel Kiper wrote:
On Mon, Aug 23, 2021 at 11:18:38PM -0700, Fangrui Song wrote:
Clang does not support -falign-jumps and only recently gained support
for -falign-loops. Test all the alignment options to avoid passing
unrecognized options to Clang:
clang-14: error: optimization flag '-falign-jumps=1' is not supported
[-Werror,-Wignored-optimization-argument]
When compiled with older Clang, the alignment options are not added, so
just avoid the complexity for each option.
Signed-off-by: Fangrui Song <mask...@google.com>
---
configure.ac | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/configure.ac b/configure.ac
index 9a12151bd..8625e6776 100644
--- a/configure.ac
+++ b/configure.ac
@@ -798,8 +798,9 @@ fi
# Force no alignment to save space on i386.
if test "x$target_cpu" = xi386; then
- AC_CACHE_CHECK([whether -falign-loops works], [grub_cv_cc_falign_loop], [
- CFLAGS="$TARGET_CFLAGS -falign-loops=1 -Werror"
+ AC_CACHE_CHECK([whether -falign-jumps=1 -falign-loops=1 -falign-functions=1
works],
+ [grub_cv_cc_falign_loop], [
+ CFLAGS="$TARGET_CFLAGS -falign-jumps=1 -falign-loops=1 -falign-functions=1
-Werror"
I would prefer if you add a separate check for every -falign-* option.
Daniel
The attached patch checks both -falign-jumps=1 and -falign-loops=1
>From fbef8198d26babeb402b480d333a4a5212069afb Mon Sep 17 00:00:00 2001
From: Fangrui Song <mask...@google.com>
Date: Wed, 25 Aug 2021 09:28:46 -0700
Subject: [PATCH] configure: Check -falign-jumps=1 beside -falign-loops=1
Clang does not support -falign-jumps and only recently gained support
for -falign-loops. -falign-jumps=1 should be tested beside
-fliang-loops=1 to avoid passing unrecognized options to Clang:
clang-14: error: optimization flag '-falign-jumps=1' is not supported [-Werror,-Wignored-optimization-argument]
-falign-functions=1 is supported by GCC 5.1.0/Clang 3.8.0, so just add
the option unconditionally.
Signed-off-by: Fangrui Song <mask...@google.com>
---
configure.ac | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/configure.ac b/configure.ac
index 9a12151bd..91a6ef128 100644
--- a/configure.ac
+++ b/configure.ac
@@ -798,6 +798,8 @@ fi
# Force no alignment to save space on i386.
if test "x$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
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