Re: [PATCH 2/3] Adjust Value.location for lval_register

[Yao Qi <qiyaoltc@gmail.com>]

On Fri, Nov 25, 2016 at 01:10:02PM +0100, Ulrich Weigand wrote:
> > On Fri, Nov 25, 2016 at 12:51:30PM +0100, Ulrich Weigand wrote:
> > > 
> > > 
> > > >    /* Describes offset of a value within lval of a structure in target
> > > >       addressable memory units.  If lval == lval_memory, this is an offset to
> > > > -     the address.  If lval == lval_register, this is a further offset from
> > > > -     location.address within the registers structure.  Note also the member
> > > > -     embedded_offset below.  */
> > > > +     the address.  Note also the member embedded_offset below.  */
> > > >    LONGEST offset;
> > > 
> > > Hmm, I think we recently had the discussion that *any* values should allow
> > > using an offset.  The comment should probably reflect this.
> > > 
> > 
> > How about "Describes offset of a value within lval of a structure.  Note 
> > also the member embedded_offset below."?
> 
> I think we should leave in the "in target addressable memory units" to clarify
> that this is a *byte* offset, not a bit offset.
> 
> Otherwise, looks good to me.
> 

OK, patch below is pushed in.

-- 
Yao (齐尧)

From 7dc54575d91a2b41f6c3e838eec44a7017a24436 Mon Sep 17 00:00:00 2001
From: Yao Qi <yao.qi@linaro.org>
Date: Mon, 28 Nov 2016 17:09:26 +0000
Subject: [PATCH] Adjust Value.location for lval_register

value.regnum and value.next_frame_id are only used for lval_register,
so this patch moves them to union value.location.  As a result, when
we copy value, only copy location, don't need to copy regnum and
next_frame_id.

This patch also changes regnum's type to int as there is no space
constraint, so update deprecated_value_regnum_hack return type too.

gdb:

2016-11-28  Yao Qi  <yao.qi@linaro.org>

	* valops.c (value_slice): Don't set frame id of slice.
	* value.c (struct value) <regnum, next_frame_id>: Move them to...
	(struct value) <location>: ... here.  Update comments.
	(allocate_value_lazy): Don't set frame id and regnum.
	(deprecated_value_next_frame_id_hack): Adjust.
	(deprecated_value_regnum_hack): Adjust.
	(value_copy): Don't copy frame id and regnu.
	(value_primitive_field): Likewise.
	(value_from_component): Likewise.
	(deprecated_value_regnum_hack): Return int *.
	* value.h (deprecated_value_regnum_hack): Update declaration.

diff --git a/gdb/valops.c b/gdb/valops.c
index 8a45641..3a7550d 100644
--- a/gdb/valops.c
+++ b/gdb/valops.c
@@ -3827,7 +3827,6 @@ value_slice (struct value *array, int lowbound, int length)
       }
 
     set_value_component_location (slice, array);
-    VALUE_NEXT_FRAME_ID (slice) = VALUE_NEXT_FRAME_ID (array);
     set_value_offset (slice, value_offset (array) + offset);
   }
 
diff --git a/gdb/value.c b/gdb/value.c
index 8d33501..13a0bb9 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -205,17 +205,23 @@ struct value
   /* If the value has been released.  */
   unsigned int released : 1;
 
-  /* Register number if the value is from a register.  */
-  short regnum;
-
   /* Location of value (if lval).  */
   union
   {
-    /* If lval == lval_memory, this is the address in the inferior.
-       If lval == lval_register, this is the byte offset into the
-       registers structure.  */
+    /* If lval == lval_memory, this is the address in the inferior  */
     CORE_ADDR address;
 
+    /*If lval == lval_register, the value is from a register.  */
+    struct
+    {
+      /* Register number.  */
+      int regnum;
+      /* Frame ID of "next" frame to which a register value is relative.
+	 If the register value is found relative to frame F, then the
+	 frame id of F->next will be stored in next_frame_id.  */
+      struct frame_id next_frame_id;
+    } reg;
+
     /* Pointer to internal variable.  */
     struct internalvar *internalvar;
 
@@ -236,10 +242,8 @@ struct value
   } location;
 
   /* Describes offset of a value within lval of a structure in target
-     addressable memory units.  If lval == lval_memory, this is an offset to
-     the address.  If lval == lval_register, this is a further offset from
-     location.address within the registers structure.  Note also the member
-     embedded_offset below.  */
+     addressable memory units.  Note also the member embedded_offset
+     below.  */
   LONGEST offset;
 
   /* Only used for bitfields; number of bits contained in them.  */
@@ -262,12 +266,6 @@ struct value
      bitfields.  */
   struct value *parent;
 
-  /* Frame ID of "next" frame to which a register value is relative.  A
-     register value is indicated when the lval enum (above) is set to
-     lval_register.  So, if the register value is found relative to frame F,
-     then the frame id of F->next will be stored in next_frame_id.  */
-  struct frame_id next_frame_id;
-
   /* Type of the value.  */
   struct type *type;
 
@@ -945,11 +943,9 @@ allocate_value_lazy (struct type *type)
   val->enclosing_type = type;
   VALUE_LVAL (val) = not_lval;
   val->location.address = 0;
-  VALUE_NEXT_FRAME_ID (val) = null_frame_id;
   val->offset = 0;
   val->bitpos = 0;
   val->bitsize = 0;
-  VALUE_REGNUM (val) = -1;
   val->lazy = 1;
   val->embedded_offset = 0;
   val->pointed_to_offset = 0;
@@ -1586,13 +1582,13 @@ deprecated_value_internalvar_hack (struct value *value)
 struct frame_id *
 deprecated_value_next_frame_id_hack (struct value *value)
 {
-  return &value->next_frame_id;
+  return &value->location.reg.next_frame_id;
 }
 
-short *
+int *
 deprecated_value_regnum_hack (struct value *value)
 {
-  return &value->regnum;
+  return &value->location.reg.regnum;
 }
 
 int
@@ -1788,8 +1784,6 @@ value_copy (struct value *arg)
   val->offset = arg->offset;
   val->bitpos = arg->bitpos;
   val->bitsize = arg->bitsize;
-  VALUE_NEXT_FRAME_ID (val) = VALUE_NEXT_FRAME_ID (arg);
-  VALUE_REGNUM (val) = VALUE_REGNUM (arg);
   val->lazy = arg->lazy;
   val->embedded_offset = value_embedded_offset (arg);
   val->pointed_to_offset = arg->pointed_to_offset;
@@ -3229,8 +3223,6 @@ value_primitive_field (struct value *arg1, LONGEST offset,
 		   + value_embedded_offset (arg1));
     }
   set_value_component_location (v, arg1);
-  VALUE_REGNUM (v) = VALUE_REGNUM (arg1);
-  VALUE_NEXT_FRAME_ID (v) = VALUE_NEXT_FRAME_ID (arg1);
   return v;
 }
 
@@ -3814,8 +3806,6 @@ value_from_component (struct value *whole, struct type *type, LONGEST offset)
     }
   v->offset = value_offset (whole) + offset + value_embedded_offset (whole);
   set_value_component_location (v, whole);
-  VALUE_REGNUM (v) = VALUE_REGNUM (whole);
-  VALUE_NEXT_FRAME_ID (v) = VALUE_NEXT_FRAME_ID (whole);
 
   return v;
 }
diff --git a/gdb/value.h b/gdb/value.h
index 281b5a8..f776323 100644
--- a/gdb/value.h
+++ b/gdb/value.h
@@ -448,7 +448,7 @@ extern struct frame_id *deprecated_value_next_frame_id_hack (struct value *);
 #define VALUE_FRAME_ID(val) (get_prev_frame_id_by_id (VALUE_NEXT_FRAME_ID (val)))
 
 /* Register number if the value is from a register.  */
-extern short *deprecated_value_regnum_hack (struct value *);
+extern int *deprecated_value_regnum_hack (struct value *);
 #define VALUE_REGNUM(val) (*deprecated_value_regnum_hack (val))
 
 /* Return value after lval_funcs->coerce_ref (after check_typedef).  Return