Support _Complex in hard-VFP abi

Hi,
When we pass "-mfloat-abi=hard" flag in the GDB testing, we see the
following fails,

FAIL: gdb.base/callfuncs.exp: p t_float_complex_values(fc1, fc2)
FAIL: gdb.base/callfuncs.exp: p t_float_complex_many_args(fc1, fc2, fc3, fc4, fc1, fc2, fc3, fc4, fc1, fc2, fc3, fc4, fc1, fc2, fc3, fc4)
FAIL: gdb.base/callfuncs.exp: p t_double_complex_values(dc1, dc2)
FAIL: gdb.base/callfuncs.exp: p t_double_complex_many_args(dc1, dc2, dc3, dc4, dc1, dc2, dc3, dc4, dc1, dc2, dc3, dc4, dc1, dc2, dc3, dc4)
FAIL: gdb.base/callfuncs.exp: p t_long_double_complex_values(ldc1, ldc2)
FAIL: gdb.base/callfuncs.exp: p t_long_double_complex_many_args(ldc1, ldc2, ldc3, ldc4, ldc1, ldc2, ldc3, ldc4, ldc1, ldc2, ldc3, ldc4, ldc1, ldc2, ldc3, ldc4)
FAIL: gdb.base/callfuncs.exp: call inferior func with struct - returns float _Complex
FAIL: gdb.base/callfuncs.exp: call inferior func with struct - returns double _Complex

The hard-VFP ABI was supported by GDB overal, done by this patch
https://sourceware.org/ml/gdb-patches/2009-07/msg00686.html but
"vectors and complex types are not currently supported", mentioned in
the patch.  As a result, these tests fail.

This patch is to support _Complex types in hard-VFP abi.  As specified
in "7.1.1, Procedure Call Standard for the ARM Arch", the layout of
_Complex types is a struct, which is identical to the layout on amd64,
so I copy Mark's comments to amd64 support.

Regression tested on arm-none-eabi target.  OK to apply?

gdb:

2014-08-19  Yao Qi  <yao@codesourcery.com>

	* arm-tdep.c (arm_vfp_cprc_sub_candidate): Handle _Complex
	types.

1 files changed, 32 insertions, 2 deletions

diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index b746eee..db97fed 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -3562,8 +3562,8 @@ arm_vfp_cprc_reg_char (enum arm_vfp_cprc_base_type b)
    classified from *BASE_TYPE, or two types differently classified
    from each other, return -1, otherwise return the total number of
    base-type elements found (possibly 0 in an empty structure or
-   array).  Vectors and complex types are not currently supported,
-   matching the generic AAPCS support.  */
+   array).  Vector types are not currently supported, matching the
+   generic AAPCS support.  */
 
 static int
 arm_vfp_cprc_sub_candidate (struct type *t,
@@ -3594,6 +3594,36 @@ arm_vfp_cprc_sub_candidate (struct type *t,
 	}
       break;
 
+    case TYPE_CODE_COMPLEX:
+      /* Arguments of complex T where T is one of the types float or
+	 double get treated as if they are implemented as:
+
+	 struct complexT
+	 {
+	   T real;
+	   T imag;
+	 };  */
+      switch (TYPE_LENGTH (t))
+	{
+	case 8:
+	  if (*base_type == VFP_CPRC_UNKNOWN)
+	    *base_type = VFP_CPRC_SINGLE;
+	  else if (*base_type != VFP_CPRC_SINGLE)
+	    return -1;
+	  return 2;
+
+	case 16:
+	  if (*base_type == VFP_CPRC_UNKNOWN)
+	    *base_type = VFP_CPRC_DOUBLE;
+	  else if (*base_type != VFP_CPRC_DOUBLE)
+	    return -1;
+	  return 2;
+
+	default:
+	  return -1;
+	}
+      break;
+
     case TYPE_CODE_ARRAY:
       {
 	int count;