Re: arm64 softfloat

[Leif Lindholm]

On Tue, Jun 02, 2015 at 02:25:15PM +0200, Vladimir 'phcoder' Serbinenko wrote:
> Please give more details as to where we have floats. We shouldn't have any

Ok, seems I was tripping over myself with the internal compiler error
workaround (-mgeneral-regs-only), and applying it on the host tools
as well, where +nofp was (correctly) not being enforced, causing a
clash.

So, rewinding a bit - in order to work around the gcc 5.1 build issue
(which is not Fedora specific), we can use -mgeneral-regs-only
instead of -march=armv8-a+nofp. If we do this, we can also get
rid of the arm64-specific twiddling that drops the +nosimd.

Like so:

>From 43d4231432838821cabe4f6aea4f0f50e87af9c4 Mon Sep 17 00:00:00 2001
From: Leif Lindholm <address@hidden>
Date: Tue, 2 Jun 2015 15:41:09 +0100
Subject: [PATCH] configure.ac: clean up arm64 soft-float handling

Fix compilation with gcc 5.1 (avoid internal compiler error), by
replacing explicit -march +nofp+nosimd options with -mgeneral-regs-only.

This also enables the removal of some further conditional build flag
setting.
---
 configure.ac | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/configure.ac b/configure.ac
index 891c14f..fd8a62e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -686,9 +686,9 @@ if test x"$platform" != xemu ; then
   AC_CACHE_CHECK([for options to get soft-float], 
grub_cv_target_cc_soft_float, [
     grub_cv_target_cc_soft_float=no
     if test "x$target_cpu" = xarm64; then
-       CFLAGS="$TARGET_CFLAGS -march=armv8-a+nofp+nosimd -Werror"
+       CFLAGS="$TARGET_CFLAGS -mgeneral-regs-only -Werror"
        AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])],
-                        
[grub_cv_target_cc_soft_float="-march=armv8-a+nofp+nosimd"], [])
+                        [grub_cv_target_cc_soft_float="-mgeneral-regs-only"], 
[])
     fi
     if test "x$target_cpu" = xia64; then
        CFLAGS="$TARGET_CFLAGS -mno-inline-float-divide -mno-inline-sqrt 
-Werror"
@@ -720,15 +720,7 @@ if test x"$platform" != xemu ; then
       TARGET_CFLAGS="$TARGET_CFLAGS $grub_cv_target_cc_soft_float"
       ;;
   esac
-  case x"$grub_cv_target_cc_soft_float" in
-    x"-march=armv8-a+nofp+nosimd")
-      # +nosimd disables also the cache opcodes that we need in asm.
-      TARGET_CCASFLAGS="$TARGET_CCASFLAGS -march=armv8-a+nofp"
-      ;;
-    *)
-      TARGET_CCASFLAGS="$TARGET_CCASFLAGS $grub_cv_target_cc_soft_float"
-      ;;
-  esac
+  TARGET_CCASFLAGS="$TARGET_CCASFLAGS $grub_cv_target_cc_soft_float"
 
 fi
 
-- 
2.1.4