Restrict alpha_convert_register_p

This patch restricts alpha_convert_register_p from
"TYPE_LENGTH (type) != 8" to "TYPE_LENGTH (type) == 4", because,

 - we have check "TYPE_LENGTH (valtype) == 4" in alpha_register_to_value
   and alpha_value_to_register,
 - alpha lds and sts instruction access 4 bytes,
 - comments "It might need to convert the [float] register into the
   corresponding [integer] type (see Alpha)" and integer is 4-byte on
   alpha,

I think it is the right restrict condition to "TYPE_LENGTH (valtype) == 4".

gdb:

2017-05-24  Yao Qi  <yao.qi@linaro.org>

	* alpha-tdep.c (alpha_convert_register_p): Return true if type
	length is 4.
	(alpha_register_to_value): Remove type length check.
	(alpha_value_to_register): Likewise.

1 files changed, 9 insertions, 18 deletions

diff --git a/gdb/alpha-tdep.c b/gdb/alpha-tdep.c
index 672e578ff1..d7cc0f4974 100644
--- a/gdb/alpha-tdep.c
+++ b/gdb/alpha-tdep.c
@@ -227,7 +227,7 @@ alpha_sts (struct gdbarch *gdbarch, void *out, const void *in)
 /* The alpha needs a conversion between register and memory format if the
    register is a floating point register and memory format is float, as the
    register format must be double or memory format is an integer with 4
-   bytes or less, as the representation of integers in floating point
+   bytes, as the representation of integers in floating point
    registers is different.  */
 
 static int
@@ -235,7 +235,7 @@ alpha_convert_register_p (struct gdbarch *gdbarch, int regno,
 			  struct type *type)
 {
   return (regno >= ALPHA_FP0_REGNUM && regno < ALPHA_FP0_REGNUM + 31
-	  && TYPE_LENGTH (type) != 8);
+	  && TYPE_LENGTH (type) == 4);
 }
 
 static int
@@ -252,14 +252,10 @@ alpha_register_to_value (struct frame_info *frame, int regnum,
 				 in, optimizedp, unavailablep))
     return 0;
 
-  if (TYPE_LENGTH (valtype) == 4)
-    {
-      alpha_sts (gdbarch, out, in);
-      *optimizedp = *unavailablep = 0;
-      return 1;
-    }
-
-  error (_("Cannot retrieve value from floating point register"));
+  gdb_assert (TYPE_LENGTH (valtype) == 4);
+  alpha_sts (gdbarch, out, in);
+  *optimizedp = *unavailablep = 0;
+  return 1;
 }
 
 static void
@@ -268,14 +264,9 @@ alpha_value_to_register (struct frame_info *frame, int regnum,
 {
   gdb_byte out[MAX_REGISTER_SIZE];
 
-  switch (TYPE_LENGTH (valtype))
-    {
-    case 4:
-      alpha_lds (get_frame_arch (frame), out, in);
-      break;
-    default:
-      error (_("Cannot store value in floating point register"));
-    }
+  gdb_assert (TYPE_LENGTH (valtype) == 4);
+  alpha_lds (get_frame_arch (frame), out, in);
+
   put_frame_register (frame, regnum, out);
 }