[Qemu-devel] [5465] hw/apic.c: use __builtin funtions instead of assembly code

[Qemu-devel] [5465] hw/apic.c: use __builtin funtions instead of assembly code

[Aurelien Jarno]

Revision: 5465
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5465
Author:   aurel32
Date:     2008-10-12 00:53:17 +0000 (Sun, 12 Oct 2008)

Log Message:
-----------
hw/apic.c: use __builtin funtions instead of assembly code

Suggested by malc.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

Modified Paths:
--------------
    trunk/hw/apic.c

Modified: trunk/hw/apic.c
===================================================================
--- trunk/hw/apic.c	2008-10-12 00:53:08 UTC (rev 5464)
+++ trunk/hw/apic.c	2008-10-12 00:53:17 UTC (rev 5465)
@@ -104,15 +104,14 @@
 static void apic_set_irq(APICState *s, int vector_num, int trigger_mode);
 static void apic_update_irq(APICState *s);
 
-/* Find first bit starting from msb. Return 0 if value = 0 */
+/* Find first bit starting from msb */
 static int fls_bit(uint32_t value)
 {
+#if defined(__GNUC__)
+    return 31 - __builtin_clz(value);
+#else
     unsigned int ret = 0;
 
-#if defined(HOST_I386) || defined(HOST_X86_64)
-    __asm__ __volatile__ ("bsr %1, %0\n" : "+r" (ret) : "rm" (value));
-    return ret;
-#else
     if (value > 0xffff)
         value >>= 16, ret = 16;
     if (value > 0xff)
@@ -125,15 +124,14 @@
 #endif
 }
 
-/* Find first bit starting from lsb. Return 0 if value = 0 */
+/* Find first bit starting from lsb */
 static int ffs_bit(uint32_t value)
 {
+#if defined(__GNUC__)
+    return __builtin_ffs(value) - 1;
+#else
     unsigned int ret = 0;
 
-#if defined(HOST_I386) || defined(HOST_X86_64)
-    __asm__ __volatile__ ("bsf %1, %0\n" : "+r" (ret) : "rm" (value));
-    return ret;
-#else
     if (!value)
         return 0;
     if (!(value & 0xffff))

[Qemu-devel] Re: [5465] hw/apic.c: use __builtin funtions instead of assembly code

[Jan Kiszka]

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Aurelien Jarno wrote:
> Revision: 5465
>           http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5465
> Author:   aurel32
> Date:     2008-10-12 00:53:17 +0000 (Sun, 12 Oct 2008)
> 
> Log Message:
> -----------
> hw/apic.c: use __builtin funtions instead of assembly code
> 
> Suggested by malc.
> 
> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
> 
> Modified Paths:
> --------------
>     trunk/hw/apic.c
> 
> Modified: trunk/hw/apic.c
> ===================================================================
> --- trunk/hw/apic.c	2008-10-12 00:53:08 UTC (rev 5464)
> +++ trunk/hw/apic.c	2008-10-12 00:53:17 UTC (rev 5465)
> @@ -104,15 +104,14 @@
>  static void apic_set_irq(APICState *s, int vector_num, int trigger_mode);
>  static void apic_update_irq(APICState *s);
>  
> -/* Find first bit starting from msb. Return 0 if value = 0 */
> +/* Find first bit starting from msb */
>  static int fls_bit(uint32_t value)
>  {
> +#if defined(__GNUC__)
> +    return 31 - __builtin_clz(value);

That as well as most (if not all) of the __builtin_* changes are gcc3.4+
stuff. Thus gcc3.3 builds are unfortunately broken now.

Jan


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Re: [Qemu-devel] Re: [5465] hw/apic.c: use __builtin funtions instead of assembly code

[Aurelien Jarno]

On Sun, Oct 12, 2008 at 12:21:47PM +0200, Jan Kiszka wrote:
> Aurelien Jarno wrote:
> > Revision: 5465
> >           http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5465
> > Author:   aurel32
> > Date:     2008-10-12 00:53:17 +0000 (Sun, 12 Oct 2008)
> > 
> > Log Message:
> > -----------
> > hw/apic.c: use __builtin funtions instead of assembly code
> > 
> > Suggested by malc.
> > 
> > Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
> > 
> > Modified Paths:
> > --------------
> >     trunk/hw/apic.c
> > 
> > Modified: trunk/hw/apic.c
> > ===================================================================
> > --- trunk/hw/apic.c	2008-10-12 00:53:08 UTC (rev 5464)
> > +++ trunk/hw/apic.c	2008-10-12 00:53:17 UTC (rev 5465)
> > @@ -104,15 +104,14 @@
> >  static void apic_set_irq(APICState *s, int vector_num, int trigger_mode);
> >  static void apic_update_irq(APICState *s);
> >  
> > -/* Find first bit starting from msb. Return 0 if value = 0 */
> > +/* Find first bit starting from msb */
> >  static int fls_bit(uint32_t value)
> >  {
> > +#if defined(__GNUC__)
> > +    return 31 - __builtin_clz(value);
> 
> That as well as most (if not all) of the __builtin_* changes are gcc3.4+
> stuff. Thus gcc3.3 builds are unfortunately broken now.
> 

That should be fixed now.

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

Re: [Qemu-devel] [5465] hw/apic.c: use __builtin funtions instead of assembly code

[Paul Brook]

On Sunday 12 October 2008, Aurelien Jarno wrote:
>  static int fls_bit(uint32_t value)
>  {
> +#if defined(__GNUC__)
> +    return 31 - __builtin_clz(value);

This should be using clz32, not duplicating this code.

Paul