Re: [Qemu-devel] Re: Qemu 32-bit i386, gcc >= 3.4 spill error fix

[Aurelien Jarno]

On Sun, May 04, 2008 at 09:13:52PM -0400, Ben Taylor wrote:
> On Sun, May 4, 2008 at 5:41 PM, Ben Taylor <address@hidden> wrote:
> > This patch applies some additional flags to op.c and helper.c
> >  for compiling on i386 32-bit systems with gcc >= 3.4.
> >
> >  This has been tested on both ubuntu 7.10/32-bit and
> >  Solaris SXCE/32-bit with both gcc-3.3 and gcc-3.4
> >  and the behavior is consistent between both.
> >
> >  This is just a short term fix til the SSE ops are converted
> >  to TCG.
> >
> 
> I updated the patch to take care of -mtune options that might
> be set by --extra-cflags, as well as the -march flags. I added
> support for athlon-xp, as someone mentioned it in #qemu
> with the exact error that helper.c sees in this context, so I
> fixed it as I have an athlon-xp.
> 
> Ben

> diff -ruN qemu.ORIG/configure qemu/configure
> --- qemu.ORIG/configure       2008-05-04 17:21:08.000000000 -0400
> +++ qemu/configure    2008-05-04 17:36:55.000000000 -0400
> @@ -1199,6 +1199,13 @@
>      then
>        echo "#define USE_KQEMU 1" >> $config_h
>      fi
> +    gcc3minver=`$cc --version 2> /dev/null| fgrep "(GCC) 3." | awk '{ print 
> $3 }' | cut -f2 -d.`
> +    if test -n "$gcc3minver" -a $gcc3minver -gt 3
> +    then
> +      echo "HAVE_GT_GCC_3_3=true" >> $config_mak
> +    else
> +      echo "HAVE_GT_GCC_3_3=false" >> $config_mak
> +    fi
>    ;;
>    x86_64)
>      echo "TARGET_ARCH=x86_64" >> $config_mak
> diff -ruN qemu.ORIG/Makefile.target qemu/Makefile.target
> --- qemu.ORIG/Makefile.target 2008-05-04 17:21:08.000000000 -0400
> +++ qemu/Makefile.target      2008-05-04 20:58:47.000000000 -0400
> @@ -96,6 +96,12 @@
>  ifeq ($(ARCH),i386)
>  HELPER_CFLAGS+=-fomit-frame-pointer
>  OP_CFLAGS+=-mpreferred-stack-boundary=2 -fomit-frame-pointer
> +# OP_CFLAGS needs this on 32-bit x86 system to avoid
> +# a compiler spill error. This can probably go away
> +# once the SSE ops have been converted to TCG
> +ifeq ($(HAVE_GT_GCC_3_3), true)
> +MTUNE_CFLAGS=-march=i486 -mtune=i686

MTUNE is not really a good name, given it overrides both -mtune and
-march. What about I386_CFLAGS?

> +endif
>  endif
>  
>  ifeq ($(ARCH),ppc)
> @@ -309,7 +315,7 @@
>       $(DYNGEN) -g -o $@ $<
>  
>  op.o: op.c
> -     $(CC) $(OP_CFLAGS) $(CPPFLAGS) -c -o $@ $<
> +     $(CC) $(OP_CFLAGS) $(CPPFLAGS) $(MTUNE_CFLAGS) -c -o $@ $<
>  
>  machine.o: machine.c
>       $(CC) $(OP_CFLAGS) $(CPPFLAGS) -c -o $@ $<
> @@ -317,9 +323,24 @@
>  # HELPER_CFLAGS is used for all the code compiled with static register
>  # variables
>  ifeq ($(TARGET_BASE_ARCH), i386)
> +  # if current host is i386 and gcc >= -3.4, CFLAGS requires some
> +  # handling as helper.c generates a compiler spill error if 
> +  # "-march=i686 -mtune=i686" or -"march=athlon-xp -mtune=athlon-xp"
> +  # We set MTUNE_CFLAGS="-march=i486 -mtune=i686" here
> +  # Once SSE ops are converted to TCG, this can go away
> +  HCFLAGS=$(CFLAGS)
> +  ifeq ($(ARCH), i386)
> +    ifeq ($(HAVE_GT_GCC_3_3), true)
> +      # if CFLAGS has -march=i686, remove it so helper.o
> +      # can compile on 32-bit intel systems
> +      HCFLAGS=`echo $(CFLAGS) | sed 's,-march=i686,,' | sed 
> 's,-mtune=i686,,' \
> +        | sed 's,-march=athlon-xp,,' |  sed 's,-mtune=athlon-xp,,'`
> +    endif
> +  endif
> +

This part looks overcomplicated, and probably doesn't handle all cases.
What's the point of trying to remove options from CFLAGS? Multiple
-march or -mtune should be harmless, gcc should use the latest provided
one. So just make sure MTUNE_CFLAGS or I386_CFLAGS is after CFLAGS.

>  # XXX: rename helper.c to op_helper.c
>  helper.o: helper.c
> -     $(CC) $(HELPER_CFLAGS) $(CPPFLAGS) $(CFLAGS) -c -o $@ $<
> +     $(CC) $(HELPER_CFLAGS) $(CPPFLAGS) $(MTUNE_CFLAGS) $(HCFLAGS) -c -o $@ 
> $<
>  else
>  op_helper.o: op_helper.c
>       $(CC) $(HELPER_CFLAGS) $(CPPFLAGS) $(CFLAGS) -c -o $@ $<


-- 
  .''`.  Aurelien Jarno             | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   address@hidden         | address@hidden
   `-    people.debian.org/~aurel32 | www.aurel32.net