Fix altivec vector return location

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Fix altivec vector return location

Andreas Schwab
powerpc-linux is not using -mabi=altivec by default, thus vector types are
returned in general registers instead of altivec registers.

Andreas.

2007-03-15  Andreas Schwab  <[hidden email]>

        * ppc-linux-tdep.c (ppc_linux_return_value): Vectors are returned
        in general registers.

Index: gdb/ppc-linux-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/ppc-linux-tdep.c,v
retrieving revision 1.81
diff -u -a -p -u -p -a -r1.81 gdb/ppc-linux-tdep.c
--- gdb/ppc-linux-tdep.c 9 Jan 2007 17:58:55 -0000 1.81
+++ gdb/ppc-linux-tdep.c 15 Mar 2007 17:15:50 -0000
@@ -484,17 +484,47 @@ ppc_linux_memory_remove_breakpoint (stru
 /* For historic reasons, PPC 32 GNU/Linux follows PowerOpen rather
    than the 32 bit SYSV R4 ABI structure return convention - all
    structures, no matter their size, are put in memory.  Vectors,
-   which were added later, do get returned in a register though.  */
+   which were added later, do get returned in a register, although
+   not in an AltiVec register.  */
 
 static enum return_value_convention
 ppc_linux_return_value (struct gdbarch *gdbarch, struct type *valtype,
  struct regcache *regcache, gdb_byte *readbuf,
  const gdb_byte *writebuf)
 {  
-  if ((TYPE_CODE (valtype) == TYPE_CODE_STRUCT
-       || TYPE_CODE (valtype) == TYPE_CODE_UNION)
-      && !((TYPE_LENGTH (valtype) == 16 || TYPE_LENGTH (valtype) == 8)
-   && TYPE_VECTOR (valtype)))
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  if (TYPE_LENGTH (valtype) == 16
+      && TYPE_CODE (valtype) == TYPE_CODE_ARRAY
+      && TYPE_VECTOR (valtype))
+    {
+      /* Return value is in r3-r6.  */
+      if (readbuf)
+ {
+  regcache_cooked_read (regcache, tdep->ppc_gp0_regnum + 3,
+ readbuf + 0);
+  regcache_cooked_read (regcache, tdep->ppc_gp0_regnum + 4,
+ readbuf + 4);
+  regcache_cooked_read (regcache, tdep->ppc_gp0_regnum + 5,
+ readbuf + 8);
+  regcache_cooked_read (regcache, tdep->ppc_gp0_regnum + 6,
+ readbuf + 12);
+ }
+      if (writebuf)
+ {
+  regcache_cooked_write (regcache, tdep->ppc_gp0_regnum + 3,
+ writebuf + 0);
+  regcache_cooked_write (regcache, tdep->ppc_gp0_regnum + 4,
+ writebuf + 4);
+  regcache_cooked_write (regcache, tdep->ppc_gp0_regnum + 5,
+ writebuf + 8);
+  regcache_cooked_write (regcache, tdep->ppc_gp0_regnum + 6,
+ writebuf + 12);
+ }
+      return RETURN_VALUE_REGISTER_CONVENTION;
+    }
+  else if (TYPE_CODE (valtype) == TYPE_CODE_STRUCT
+   || TYPE_CODE (valtype) == TYPE_CODE_UNION)
     return RETURN_VALUE_STRUCT_CONVENTION;
   else
     return ppc_sysv_abi_return_value (gdbarch, valtype, regcache, readbuf,

--
Andreas Schwab, SuSE Labs, [hidden email]
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."
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Re: Fix altivec vector return location

Daniel Jacobowitz-2
On Thu, Mar 15, 2007 at 06:17:51PM +0100, Andreas Schwab wrote:
> powerpc-linux is not using -mabi=altivec by default, thus vector types are
> returned in general registers instead of altivec registers.
>
> Andreas.
>
> 2007-03-15  Andreas Schwab  <[hidden email]>
>
> * ppc-linux-tdep.c (ppc_linux_return_value): Vectors are returned
> in general registers.

Hmmm... but what about people who do use -mabi=altivec?  IIRC you can
do that by configuring for powerpc-linux-gnualtivec.  I know some
distributors patch GCC to do this too for their distributions.

--
Daniel Jacobowitz
CodeSourcery
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Re: Fix altivec vector return location

Andreas Schwab
Daniel Jacobowitz <[hidden email]> writes:

> On Thu, Mar 15, 2007 at 06:17:51PM +0100, Andreas Schwab wrote:
>> powerpc-linux is not using -mabi=altivec by default, thus vector types are
>> returned in general registers instead of altivec registers.
>>
>> Andreas.
>>
>> 2007-03-15  Andreas Schwab  <[hidden email]>
>>
>> * ppc-linux-tdep.c (ppc_linux_return_value): Vectors are returned
>> in general registers.
>
> Hmmm... but what about people who do use -mabi=altivec?

I have no idea how to detect that.

Andreas.

--
Andreas Schwab, SuSE Labs, [hidden email]
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."
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Re: Fix altivec vector return location

Daniel Jacobowitz-2
On Wed, Apr 11, 2007 at 12:23:31AM +0200, Andreas Schwab wrote:

> Daniel Jacobowitz <[hidden email]> writes:
>
> > On Thu, Mar 15, 2007 at 06:17:51PM +0100, Andreas Schwab wrote:
> >> powerpc-linux is not using -mabi=altivec by default, thus vector types are
> >> returned in general registers instead of altivec registers.
> >>
> >> Andreas.
> >>
> >> 2007-03-15  Andreas Schwab  <[hidden email]>
> >>
> >> * ppc-linux-tdep.c (ppc_linux_return_value): Vectors are returned
> >> in general registers.
> >
> > Hmmm... but what about people who do use -mabi=altivec?
>
> I have no idea how to detect that.

I think it's a bad idea to trade off broken in one configuration for
broken in another, so let's not change it right now.

The only way I can think of to detect it would be to add something to
the linker, like other platforms do (including E500).  I wonder if the
new Power ABI discussions will provide something useful...

--
Daniel Jacobowitz
CodeSourcery