[PATCH] gdb: mips: Fix the handling of complex type of function return value

[Youling Tang <tangyouling@loongson.cn>]

$ objdump -d outputs/gdb.base/varargs/varargs
00000001200012e8 <find_max_float_real>:
...
   1200013b8:   c7c10000        lwc1    $f1,0(s8)
   1200013bc:   c7c00004        lwc1    $f0,4(s8)
   1200013c0:   46000886        mov.s   $f2,$f1
   1200013c4:   46000046        mov.s   $f1,$f0
   1200013c8:   46001006        mov.s   $f0,$f2
   1200013cc:   46000886        mov.s   $f2,$f1
   1200013d0:   03c0e825        move    sp,s8
   1200013d4:   dfbe0038        ld      s8,56(sp)
   1200013d8:   67bd0080        daddiu  sp,sp,128
   1200013dc:   03e00008        jr      ra
   1200013e0:   00000000        nop

From the above disassembly, we can see that when the return value of the
function is a complex type and len <= 2 * MIPS64_REGSIZE, the return value
will be passed through $f0 and $f2, so fix the corresponding processing
in mips_n32n64_return_value().

$ make check RUNTESTFLAGS='GDB=../gdb gdb.base/varargs.exp --outdir=test'

Before applying the patch:
 FAIL: gdb.base/varargs.exp: print find_max_float_real(4, fc1, fc2, fc3, fc4)
 FAIL: gdb.base/varargs.exp: print find_max_double_real(4, dc1, dc2, dc3, dc4)

 # of expected passes		9
 # of unexpected failures	2

After applying the patch:
 # of expected passes            11

Signed-off-by: Youling Tang <tangyouling@loongson.cn>
---
 gdb/mips-tdep.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
index 7e37578..cddb8f8 100644
--- a/gdb/mips-tdep.c
+++ b/gdb/mips-tdep.c
@@ -5224,9 +5224,10 @@ mips_n32n64_return_value (struct gdbarch *gdbarch, struct value *function,
 
   if (TYPE_LENGTH (type) > 2 * MIPS64_REGSIZE)
     return RETURN_VALUE_STRUCT_CONVENTION;
-  else if (type->code () == TYPE_CODE_FLT
+  else if ((type->code () == TYPE_CODE_FLT
 	   && TYPE_LENGTH (type) == 16
 	   && tdep->mips_fpu_type != MIPS_FPU_NONE)
+	   || (type->code () == TYPE_CODE_COMPLEX))
     {
       /* A 128-bit floating-point value fills both $f0 and $f2.  The
 	 two registers are used in the same as memory order, so the
-- 
2.1.0